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Castor bean, Ricinus communis L., as a host of Liriomyza leafminers (Diptera:Agromyzidae) in the Everglades agricultural area of South Florida

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Title:
Castor bean, Ricinus communis L., as a host of Liriomyza leafminers (Diptera:Agromyzidae) in the Everglades agricultural area of South Florida
Creator:
Parkman, James Patrick, 1954-
Publication Date:
Language:
English
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x, 121 leaves : ill. ; 28 cm.

Subjects

Subjects / Keywords:
Celery ( jstor )
Female animals ( jstor )
Glades ( jstor )
Larvae ( jstor )
Leafminers ( jstor )
Leaves ( jstor )
Parasitism ( jstor )
Parasitoids ( jstor )
Pests ( jstor )
Species ( jstor )
Agromyzidae -- Biological control -- Florida ( lcsh )
Castor beans ( lcsh )
Celery -- Diseases and pests -- Florida ( lcsh )
Dissertations, Academic -- Entomology and Nematology -- UF
Entomology and Nematology thesis Ph.D
Leafminers ( lcsh )
City of Gainesville ( local )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1987.
Bibliography:
Includes bibliographical references (leaves 108-120).
Additional Physical Form:
Also available online.
General Note:
Typescript.
General Note:
Vita.
Statement of Responsibility:
by James Patrick Parkman.

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CASTOR BEAN, Ricinus communis L., AS A HOST
OF Liriomyza LEAFMINERS (Diptera:Agromyzidae)
IN THE EVERGLADES AGRICULTURAL AREA OF SOUTH FLORIDA









By


JAMES PATRICK PARKMAN



















A DISSERTATION PRESENTED TO THE GRADUATE
SCHOOL OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY


UNIVERSITY OF FLORIDA

1987
















ACKNOWLEDGEMENTS





I would first like to thank my committee chairman and

cochairman, Drs. V.H. Waddill and J.A. Dusky, for their

guidance, friendship, and support (especially financial)

during my graduate studies. I also wish to acknowledge and

thank my other committee members, Drs. D.H. Habeck and D.J.

Schuster, for their valuable suggestions in the preparation

of this manuscript. Others providing information and

suggestions during the course of my research and writi-:c

were Drs. H.L. CroTnroy, R.E. Foster, G.L. Leibee and J.I.

Stimac, and Mr. M.D. Remick, Hr. F.L. Petitt and Mr. F.A.

Wolf.

I would also like to thank the staff members at

Everglades Research and Education Center, Belle Glade, vlo

assisted me in my research and J. and N. Phillips who node

my stay at EPEC bearable.

I also wish to express my sircerest apprecicticn arcd

gratitude for the support, encourLajement anrd patience of

family.








ii
















TABLE OF CONTENTS

Paae

ACKNOWLEDGEMENTS . . . . . . . . . . i i

LIST OF TABLES . . . . . . . . . . v

LIST OF FIGURES . . . . . . . . . .. vii

ABSTRACT . . . . . . . . . . . .

CHAPTERS

I INTRODUCTION . . . . . . . . . 1

II LITERATURE REVIEW . . . . . . . . 5

Systematics of Liriomyza trifolii (Burgess) and
L. sativae Blanchard . . . . . . . 5
Descriptions of L. trifolii and L. sativae . . 8
Distributions and Host Ranges . . . . . 10
Life History and Biology . . . . . . . ].
Control of Liriomyza on Celery . . . . . 16
Chemical Control . . . . . . . . 16
Natural Control by Parasitoids . . . . 19
Effects of Cultural Methods . . . . . 22
Pest Management in Celery . . . . . 2A
Celery Production . . . . . . . . 24
Beneficial Aspects of Weeds . . . . . ..
Description, History and Status of Castor been . 31

III LEAFMINER AND LEAFMINER PARASITOID INCIDENCE
ON SELECTED WEEDS IN SOUTF FLORIDA . . . 34

Introduction . . . . . . . . . 3.
Methods and Materiae . . . . . . . 3
Host PrefeLence Study . . . . . . ..
Seasonal Abundance . . . . . . . 37
Results and Discussion . . . . . . . .3
Host Preference Study . . . . . . 3
Seasonal Abundance . . . . . . . 54

IV EFF:CTS OF CD STOR R.A'. OlC, LEAF MINER AND L.EAPF ,INEK
PARASITOID POPULATIONS I ACACEEI CiLERY . f

Introduction . . . . . . . . . 61
Materials and Methods . . . . . . . .3


iii










Migration Study . . . . . . . . 63
Host Preference . . . . . . . . 66
Results and Discussion . . . . . . . 67
Migration Study . . . . . . . . 67
Host Preference . . . . . . . . 86

V BIOLOGY OF Liriomyza sativae BLANCHARD ON
CASTOR BEAN . . . . . . . . . 90
Introduction...................90
Introduction . . . . . . . . . 90
Materials and Methods . . . . . . . 91
Development at Constant Temperatures . . . .
Lifetime Oviposition . . . . . . . 92
Results and Discussion . . . . . 93
Development at Constant Temperatures . . . 93
Lifetime Oviposition . . . . . . .. (

VI CONCLUSIONS . . . . . . . . . 103

LITERATURE CITED . . . . . . . . . . 08

BIOGRAPHICAL SKETCH . . . . . . . . . 121


































iv
















LIST OF TABLES



Table Pace

3.1 Hymenopteran parasitoid species reared from
Liriomyza trifolii and L. sativae on cast-
or bean in Belle Glade, FL (May-July 1984) . 45

3.2 Mean percent parasitism of L. trifolii and L.
sativae on castor bean by the four most pre-
valent species of parasitoids, Belle Glade,
FL (May-July 1984) . . . . . . . 48

3.3 Mean number of old and active mines collected
and L. trifolii and L. sativae adults reared
per 5000 sq. cm of castor bean foliage, Belle
Glade, FL (May-July 1984) . . . . . 50

3.4 Mean number of total, larval and larval-puEal
parasitoids reared per 5000 sq. cm foliage
from L. trifolii and L. sativae on castor
bean, Belle Glade, FL (May-July 1984) . . 52

3.5 Mean percent total, larval and larval-pupal
parasitism of L. trifolii and L. sativae ce
castor bean, Belle Glade, FL (Hay-July 1984). 53

3.6 Hymenopteran parasitoid species reared from
Liriomyza trifolii and L. sativae on caster
bean, Belle Glade, FL (Aug 1984-July 1985) . 57

4.1 Hymenopteran parasitoid species reared from L.
trifolii on celery adjacent to castor bean,
from two sites at Belle Glide, FL, 1985 . . 71

4.2 Mean number of L. trifolii and total, larval
and larval-pupal para.sitoids reared per two
trifoliates of celer.y .adjacent to castor bear,
frcu two sites at Belle Glade, FL, 1985 .. "'2

4.3 Mean percent total, larval a;nd ]arval-pupal
parasitism of L. trifolii per two trifoli-
ates of celery adjacent to castor bean, f;om
two sites at Belle Glade, FL, 1985 . . 74



v











4.4 Mean number of L. trifolii and total, larval
and larval-pupal parasitoids reared per two
trifoliates of celery adjacent to castor
bean, Belle Glade, FL, 1985 . . . . . 75

4.5 Mean percent total, larval and larval-pupal
parasitism of L. trifolii per two trifoli-
ates of celery adjacent to castor bean,
Belle Glade, FL, 1985 . . . . . . 76

4.6 Hymenopteran parasitoids of L. trifolii col-
lected on sticky traps in celery adjacent to
castor bean, from two sites at Belle Glade,
FL, 1985 . . . . . . . . . 79

4.7 Mean number of L. trifolii and total, larval and
larval-pupal parasitoids collected per sticky
trap in celery adjacent to castor bean, from
two sites at Belle Glade, FL, 1985 . . . 81

4.8 Mean number of L. trifolii and total, larval
and larval-pupal parasitoids collected per
sticky trap in celery adjacent to castor
bean, Belle Glade, FL, 1985 . . . . . .. 7

4.9 Mean number of L. trifolii and total, larval
and larval-pupal parasitoids collected per
sticky trap in celery adjacent to caster
bean, Belle Glade, FL, 1985 . . . . . 84

4.10 Mean number of larvae, pupae and adults of
Liriomyza spp. produced on celery arid castor
bean offered simultaneously to fenm&es for
oviposition . . . . . . . . . .

5.1 Development time, development rate, thermal
units in degree days and development thresh-
old for life stages, and pupal survival for
L. sativae on castor bean at 20; 25, 3C arid
35 C . . . . . . . . . . 95

5.2 Linear regression equations and r values for
developent rate and temperature (CC) for ecc-
larval and pupal stages of L. sativae on
castor bean . . . . . . . . 98

5.3 Percent survival of izrval and pu[al pc'Ceny
and sex ratio of IesuLltrcl adults for L.. sat-
ivae on castor bean at 25 C . . . . . ] 0





vi















LIST OF FIGURES



Figure Pace

3.1 Mean number of old and active mines of L. sativae
and L. trifolii collected per 5000 sq. cm of
castor bean foliage, Belle Glade, FL (1984) . 40

3.2 Mean number of L. sativae and L. trifolii reared
per 5000 sq. cm of castor bean foliage collect-
ed, Belle Glade, FL (1984) . . . . . 42

3.3 Mean number of adult parasitoids reared per 5000
sq. cm foliage collected from L. sativae and L.
trifolii on castor bean, Belle Glade, FL
(1984) . . . . . . . . . . 44

3.4 Mean percent parasitism of L. sativae and L. tri-
folii on castor bean by larval and larval-pupal
parasitoids, Belle Glade, FL (1984) . . . 47

3.5 Mean growth of castor bean at EREC, Belle Clade,
FL (1984) . . . . . . . . . 51

3.6 Mean number of mines collected and LiriomEiza
adults reared per 3 w x 3 m plot of castor
bean, Belle Glade, FL (1984-85) . . . . 55

3.7 Mean number of larval and larval-pupal adult
parasitoids reared per 3 r. x 3 m plot from
L. sativae and L. trifolii on castor bean,
Belle Glade, FL (1984-85) . . . . . 50

3.8 Mean percent larval and larval-pupal psraitism
of L. sativae and L. trifolii on casco: bean,
Belle Glade, FL (1984-05) . . . . . 59

4.1 Mean number of L. trifolii and total and larval
parasitoids reared per two trifoliate&s of
celery adjacent to castor bean, from twvc
sites at Belle Glade, FL (1985) . . . .

4.2 Mean number of L. trifolij and total and larval
parasitoics collected per yellcw sticky trapc
in celery adjacent to castor bean, fromi two
sites at Belle Glade, FL (1985) . . . . 78


vii










5.1 Relationship of development time to temperature
( C) for the combined egg and larval (egg-lar-
val) stage and the pupal stage of L. sativae
on castor bean . . . . . . . . 94

5.2 Relationship of development rate (1/days x 1CO)
to temperature ( C) for the combined egg and
larval (egg-larval) stage and the pupal stage
of L. sativae on castor bean . . . . . 97

5.3 Mean number of larval progeny produced per fe-
male per day through8ut the life of L. sativae
on castor bean at 25 C . . . . . . 100










































viii















Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy


CASTOR BEAN, Ricinus communis L., AS A HOST
OF Liriomyza LEAFMINERS (Diptera:Agromyzidae)
IN THE EVERGLADES AGRICULTURAL AREA OF SOUTE FLORIDA

By

James Patrick Parkman

May 1987


Chairman: Van H. Waddill
Cochairman: Joan A. Dusky
Major Department: Entomology and Nematology


A field study determined castor bean, Ricinus commuris

L., the most prominent host of leafminers and leafriiner

parasitoids of three weeds tested. Active mine populations

peaked at 22 per 5000 sq. cn. of castor bean foliage during

the first sampling period (May 24, 1984). Liriomrza sativae

Blanchard and L. trifolii (Burgess) accounted for all

leafminer adults reared from foliage with the former

comprising 63.3% of specimens collected.

Eleven species of paiasitoids were reared from

Liriomyza. Cpius spp. and Halticoptera circulus (Walker)

were the most abundant. More tlhan 9.6 adult parasitoid per

5000 sq. cm of fc:iage were reared May 24 and parasitism

rates as high as 10C' occurred during three othe;- sarmpj ing



ix










periods. Abundance and performance of parasitoids varied

with castor bean canopy layer.

Leafminer abundance on castor bean peaked again ir

March and April 1985 with 37 active mines per 9 mr plot

occurring on April 22. Liriomyza sativae comprised 74.5% of

Liriomyza collected from August 1984 to July 1985. Cpius

spp. accounted for >85% of parasitoids reared and percent

parasitism peaked during the weeks of April 8 and July 16 at

94.8 and 100%, respectively.

Celery trifoliate collections suggested castor bear

perhaps influenced leafminer parasitism in celery rocws

nearest the weed. Liriomyza trifolii was the only leafminer

reared from celery and Diglyphus intermedius (Girault) was

the most abundant parasitoid reared from celery and

collected on sticky traps.

Liriomyza trifolii females exhibited a significant

preference for celery as an oviposition substrate c'ver

castorbean. Castor bean was preferred by L. sativae fer;-caes

for oviposition as they virtually rejected celery as a host.

Development times for combired egg and larval stages

were 13.22, 8.75, 6.31 and 6.17 6 at 20, 25, 30 and :35 C

for L. sativae on castor bean. PuLal development times ,.eo.'e

15.33, 9.61 and 6.81 d at 20, 25 and 30 C. No pupae

survived at 35 C. Females produced a mearn of 164.49 larvae

at 250 C on castor bean over ar, average lifespan of 13.36 d.

Fecundity peaked at five days of age.



x















CHAPTER I
INTRODUCTION



Celery, Apium graveoluns L. var. dulce, is one of the

major vegetable crops grown in Florida with 9300 acres

planted in 1984-85, 7295 of those in the Everglades

Agricultural Area around Belle Glade (Anon. 1986). A record

total monetary value of $64,546,C00 was recorded in 1983-84

(Anon. 1986) when the net return for growers in the

Everglades region averaged $657.31 per acre (Taylor and

Locascio 1985). A considerable amount of money ($680 per

acre in 1983-84), however, is spent attempting to contrcl

pestiferous insect, weed and fungus species (Taylor ard

Locascio 1985) which would otherwise devastate the crop.

The leafmining fly Liriomyza trifolii (Burgess) is

considered the most important insect pest of celerl it. the

Belle Glade area (Guzman et al. 1973). Approximately h12f

of insecticide costs for celery can be appropriated for

control of L. trifolii with as many as three treatments

applied per week (M.D. Pemick, personal communicaticn,

1987). Adult females damage leaves by ovipositing and

creating feeding punctures. Larvae mine the leaves reducing

photosynthetically active tissue, providing entry points fo:-

pathogens and causing cosmetic damage (Musgrave et al.

1978). The tremendous reproductive potential of L.


1







2

trifolii, ca. three times that of other economically

important Liriomyza spp. (Parrella and Keil 1984), enables

the pest to reach exceedingly high densities in relatively

short periods of time.

Although L. trifolii is currently the dominant, if not

only, leafminer species attacking celery in Florida, earlier

reports implicated a very similar species, L. sativE.e

Blanchard, as the major pest. A shift in dominance froro the

latter to the former species may have occurred as a result

of L. trifolii's greater tolerance to insecticides (Parrella

and Keil 1984). However, a shift in dominance may never

have occurred. Rather, L. trifolii may have been

misidentified as L. sativae and/or its synonyms in these

early studies as the two are sympatric, highly polyphagous

(sharing many of the same host plants) and very similer

morphologically (Spencer and Stegmaier 1,93, Stegmaier

1981). The doubts surrounding this possible

misidentificaticn have impeded irterpretation of results cf

earlier studies and hampered their utilization in recert

control efforts.

The aforementioned tolerance to insecticides is

probably the major cause for L. trifoii_'s prominence ar.ong

celery pests. The widespread, sometimes nonjudicious use of

a variety of compounds on celery and other vegetables

(Leibee 1981) coupled with the species' large reproduct:ive

potential have inevitably allowed for the evolution arnd

continuation of insecticide resistance. Also, considerable









mortality potentially inflicted by the large parasitoid

complex attacking L. trifolii has been negated in most cases

by the detrimental effects of insecticides upon the

parasitoids, further aggravating the problem (Poe et al.

1978, Waddill 1981).

The failure of various chemical insecticides to

provide adequate and economically sound leafminer control

plus increasing concern of the effects of such compounds

within the environment have prompted research of control

tactics and insecticides emphasizing the conservation arid

utilization of parasitoids (Genung et al. 1978, Schuster and

Price 1985, Trumble and Toscano 1983, Trumble 1985). The

contribution host plants other than the crop may make

towards parasitoid incidence has also been reported.

Schuster et al. (1982) found high rates of LiricreY7a

parasitism occurring on weeds near tomato fields on

Florida's gulf coast while Genung and Janes (1975) and

Genung et al. (1978) working near Belle Glade noted higher

rates of leafminer parasitism in celery nearest fielc

borders adjacent to weeds. Genung (1981) stated certain

weeds which harbor natural enemies of LirJiciyza may even be

considered beneficial when occurring near celery fields.

Despite this knowledge, no studies have been

undertaken to examine this component cf the celery

agroecosystem in south FloriCa. Certain weed species in

this region are reported to serve as hosts of L. satil;e but

not L. trifolii (Stegmaier 1981). Also, the two leafminer







4

species are attacked by many of the same parasitoids

(Chandler 1982, Stegmaier 1981). Considering these reports

plus the fact that L. sativae in Florida presumably no

longer attacks celery, the potential exists for the

manipulation of a weed host of L. sativae in hopes of

increasing parasitism of L. trifolii within celery.

The objectives of the following studies were to

investigate this comparatively unknown area of leafminer

biological control by first determining leafminer anc

leafminer parasitoid incidence and abundance on weeds

reported as hosts of Liriomyza species in south Florida: to

determine the effect of castor bean, Ricinus communis L., on

Liriomyza and parasitoid occurrence within adjacent celery

plots; and to determine the preference for celery and castor

bean by L. trifolii and sativae as well as the bioloJy of

the latter on castor bean.















CHAPTER II
LITERATURE REVIEW



Systematics of Liriomyza trifolii (Buroess)
and L. sativae Blanchard


There are over 300 species of Liriomyza worldwide, 78

within the United States, and many are polyphagous (Spencer

1981b). The taxonomic history of the genus is marked by

confusion and misidentifications and only recently has the

systematics of this group been relatively clarified (Spencer

1973, Spencer and Stegmaier 1973, Spencer 1981a). Indicc-

tive of this confusion are the taxonomic histories of L.

trifolii and L. sativae.

Burgess in 1880 first described L. trifolii as OscJnis.

trifolii collected on white clover in the District of

Columbia. 0. trifolii and C. brassicae Riley were

synonymized with Agromyza diminuta Walker by Coquillet

(1898) and Malloch (1913) synonymized 0. trifolii and 0.

brassicae with A. pusilla Meigen. Pelander (1913)

synonymized A. diminuta Walker with A. scutellata Fallen anrl

used the name Liriomyza without placing A. scutellata in it.

A. pusilla was reported to occur on 24 different host

species by Webster and Parks (1913) although Spencer ('19 b)

later reported they were working with L. trifo3ii, I.

sativae, L. huidobrensis (Blanchard) and other species.


5







6


In 1925 de Hejiere placed 0. trifolii in the genus

Liriomyza and noted the synonymy of A. trifolii (Burgess)

Coquillet 1898 and A. trifolii Kaltenbach 1E74 (Zoebisch

1984), now considered a homonymy of A. nana (Meigen) 1830

(Spencer 1981b). Zoebisch (1984) stated this homonymy

violates article 35 of the International Commission on

Zoological Nomenclature (Schenk and McMasters 1936), thus,

L. trifolii should be renamed. L. allivora (Frick 1955) and

L. archiboldi (Frost 1962) have recently been synonymized

with L. trifolii by Spencer (1981a).

L. sativae, occurring on alfalfa in Argentina, was

first described by Blanchard in 1938 (Spencer 1S81a). In

1952 Frick described three species from Hawaii, L. pullata,

canomarcinis, and minuseta, all synonymized with L. sativae

by Spencer (1973). Spencer also synonymized L. munda reared

frcrm tomatoes in California by Frick (1957) with L. sati.vae

(Spencer 1973). L. quytona Freeman (1956) ccllected in

Alabama was synonymized with L. munda by Steyskal (1964) and

later with L. sativae by Spencer (1973). In 1973 Steyskal

synonymized L. p ro eusilla- Frost with L. munCa. 1.

propepusilla bad originally been described as A. subpusilla

by Frost in 1943 but was renamed by him in 1S54.

Frick (1957) applied the name A. pigctelia, orirainally

described by Thomsor in 186c (Spencer 19%lIb), to specimens

he reared from 16 different hosts. Spencer (198]b) notes he

was dealing with at least six different species one being

a color variant ofL. sativae. The name pictella, however,







7


became widely used and Oatman and Michelbacher (1958) and

Oatman (1959a,1959b) published studies on the biology,

ecology, and host range of L. pictella, the "melon

leafminer." Crossbreeding studies utilizing L. pictella and

L. sativae (as L. munda), the "tomato leafminer," were also

conducted (Oatman 1961). Spencer (1981b) believes the

"melon leafminer" and L. munda of these experiments to

possibly represent different host strains differentiating on

tomato and melon. No specimens were preserved, disallo~ing

later determinations of the species. Jensen and Koehler

(197C) reported on the seasonal and distributional abundance

of two species on alfalfa, L. sativae (as L. munda) and L.

trifoliearum, which was undescribed at the time but

misidentified by the authors as L. pictella (Spencer IS83b).

Spencer (1973) noted L. sativae and L. trifolii coulc

be easily confused. They are quite similar morphologically,

sympatric and they have several host plants in commor

(Stegmaier 1983). To add to the confusion, Poe and Montz

(1981) suggested that the predominance withinr a hcst crop

may shift from one species to another due to differential

resistance to particular insecticides. Therefore, ever,

recent reports and studies concerning L. sativae and _.

trifolii may contain a misidentification of one specieF; as

the other.












Descriptions of L. trifolii and L. sativae



L. trifolii and sativae adults are very small flies

with wing lengths of 1.25-1.90 mm and 1.25-1.70 mm,

respectively (Spencer 1981a). Spencer (1965) described a

neotype of L. trifolii stored in the U.S. National Museumrr

and Spencer and Stegmaier (1973) gave a similar descripticn:


Orbits entirely yellow, both vertical bri-
stles on yellow ground; all antennal seg-
ments bright yellow, third with inconspic-
uous pubescence; mesonotum blackish gray,
distinctly mat, acrostichals in 3 or 4
rows in front, reduced to 2 rows behind,
yellow patch at each hind corner adjoin-
ing scutellum, mesopleura with black patch
extending along lower margin; abdomen with
tergites variably yellow laterally and on
hind margins; legs: coxae yellow, femora
largely so but with slight, variable brown-
ish striation; tibia and tarsi darker,
brown (p. 109).


Although very similar in appearance, L. sativae eaults

differ morphologically from those of L. trifolii in several

characteristics. The hind margin of the eye of L. sativae

is entirely dark, or nearly so, extending to the base of the

outer vertical bristle and frequently along the upper orbIts

beside the eye margin. Even more conspicuous is the

mesonotum which is deep black and shirirg on L. satilvae

(Spencer 1961b). To make a definite distinction betweer the

two species, the aedeagjus must be e:amiined. Spencer and

Stegmaier (1973) and Spencer (1981a) gave illustr.aticon., of

the male genitalia of the two species.







9


Differences in female genitalia were described by

Knodel-Montz and Poe (1982) using scanning electron

microscopy. The denticles of L. trifolii are angular and

the egg-guide is V-shaped while the denticles and egg-guide

of L. sativae are elongate and acutely angled, respectively.

Zehnder et al. (1983), using scanning electron microscopy,

found a dense covering of microsetae on the mesonotum of L_.

trifolii which gives it a mat-grey appearance. The shiny

black mesonotum of L. sativae resulted from having few

microsetae.

The larvae and leafmines of the two species are very

similar and can not be distinguished visually although

Spencer and Stegmaier (1973) noted the mines of L. trifolii

are generally longer. Menken and Ulenberg (1986), however,

distinguished between the larvae as well as the pupae and

adults of four Liriomvza species, including trifolji. anrc

sativae, by allczyme analysis using starch gel

electrcphoresis. Different enzyme mobilities were alio

reported by Zehnder et al. (1983) for L. trifolii, sativbe

and brassicae. Host food and geographic site of location

did not influence enzyme mobiJlity for conspecific strains of

L. trifolii and sativae.







10


Distributions and Host Ranqes



Although distributed throughout the world, the genus

Liriomyza is best represented in the neotropical region

(Spencer and Stegmaier 1973, Spencer 1981a). L. trifolii

has been recorded from North America, South America, the

Caribbean, Africa and Europe (Eartlett and Powell 1981,

d'Aguillar and Martinez 1979, deLima 1979, Fagoonee and

Toory 1984, Frick 1959, Poe and Montz 1981, Spencer 185,

Spencer and Stegmaier 1973). Ontario is the northern limit

of its range (Spencer and Stegmaier 1973) and it has been

reported as far south as Colombia (Poe and Montz 1981).

Much of the movement of L. trifolii into areas outsice

of North America is believed to have occurred or infested

plant parts (Poe and Montz 1981). Reports and outbreaks of

L. trifolii in Kenya (deLima 1979), the Netherlands (Spencer

1981a), Great Britain (Anon. 1977) and Colombia (Price 1i82)

are believed to have resulted fron, importation of infested

chrysanthemum cuttings from the U.S., particularly Flor.ica

(Price 1981, Spencer 1981a).

L. sativae is recorded frcm Alabama, California,

Florida, Ohio, South Carolira, Tennessee and Texas, and frcm

Mexico, Central America, South America, Cuba, Jamaica anu

Barbados (Musgrave et al. 1975b, Spencer !S98a). Aithougjh

reported from Hawaii, Guan. arind Tahiti, occurrences, i these

areas are proLably due to recent irtroductions. ('Musrac e et

al. 1975b).









Both species are highly polyphagous and many hosts are

attacked by both species. Patel (1986) compiled a list of

hosts for L. trifolii from sources published since 1981 when

Spencer's report (1981b) alleviated much of the confusion

concerning identification of the species. Patel (198E)

recorded 144 hosts worldwide in 32 families, the most widely

attacked being Asteraceae (=Compositae) (46 spp.),

Cruciferae (10 spp.), Cucurbitaceae (E spp.), Fabaceae

(=Leguminosae) (17 spp.) and Solanaceae (12 spp.).

L. sativae (as L. munda) was found on 37 host species

in IC families in Florida (Stegmaier 1966a). Musgrave et

al. (1975b) reported 60 hosts of L. sativae in 14 families,

with Asteraceae (=Compositae) (16 spp.), Fabaceae

(=Leguminosae) (14 spp.) and Solanaceae (9 spp.) most

heavily attacked. The most economically important ho t

species reported for L. sativae occur in the farilies

Curcubitaceae (watermelon, cucumber and squash), Fabeceae

(=Leguminoseae) (alfalfa, clover, peas and lima beans),

Solanaceae (tomato, eggplant ard potato) and Unbe liferae

(celery and carrot) (Musgrave et al. 1,75b, Tryon 197c).







Life Fistorpyv and E icoQy



A Liriomnya (LiricnmL:a = L. trifolii and L. sativae)

female lays eggs singly within the leaf mesophyl'l, inserting







12


her ovipositor through the epidermis, creating a puncture or

"stipple". A female often creates stipples without

depositing eggs, feeding from the exudates of ruptured cells

(Trumble 1981). Oviposition stipples are smaller than

feeding stipples (Zoebisch 1984). Eggs are oblong, creamy

white, and 0.25 to 0.30 mm long and 0.10 to 0.20 mm wide

(Patel 1986). Eggs increase in size after deposition and

darken as they mature (Dimetry 1971, Patel 1986).

Upon hatching the first instar begins feeding upon the

palisade parynchema cells creating a serpentine mine which

widens as the larva develops. Newly emerged larvae are 0.12

mm long (Patel 1986) and mature through three instars to a

length of two to three mm (Zoebisch 1984). Completincj

development, a third instar larva chews a semicircular hole

in the epidermis, exits the leaf and drops to the 9round to

pupate.

Liriomyza pupates, as do all cyclorrhaphan Diptera,

within the cuticle of tie last larval instar, the puparia.

Adults can mate within one day of emergence (Patel 1986) and

females feed from stippling punctures, while males

apparently do not (Zoebisch and Schuster, unpubl i shed data).

Both have been demonstrated to feed from other nutrient

sources such as honeydew (Zoebisch and Schuster, urpublished

data).

Developmental tines for Lirioryza life staices are

affected by temperature and rmay also vary with host plant.

Egg development of L. trifolii on celery was 1.99 d at 350







13

C, but 9.97 d at 15 C (Leibee 1984). Charlton and Allen

(1981) reported similar results for L. trifolii on pink

beans (Phaseolus sp.); however, at lower temperatures (20

and 250 C) egg development took longer when chrysanthemum

was the host.

Larval development of L. trifolii on pink beans ranged

from 3.4 d (32.50 C) to 30.9 d (13.80 C) (Charlton and Allen

1981). Similar development times were recorded for L.

trifolii on chrysanthemums (Charlton and Allen 1981) and

tomato (Schuster and Patel 1985). Celery, however,

apparently increases L. trifolii larval development time.

Larvae feeding on celery required 3.1, 3.5, 5.3 and 13.2 d

longer to develop at 30, 25, 20 and 150 C, respectively,

than when utilizing pink beans as a host (Charlton and Allen

1981, Leibee 1984).

Pupal development tinmes for L. trifolii on cel]ry

decreased from 28.2 d at 15 C to 6.7 d at 350 C (Leibee

1984). Pupae of L. trifolii individuals reared on pink

beans and chrysanthemums exhibited similar development timeE.

(Charlton and Allen 1981).

Longevity of adults is dependent on availability and

quality of food source as well as temperature. Unfed ad &t

L. trifolii survived only 3 d at 23.80 C (Charlton and Allen

1981). In the same study females and males lived 7.2 and

2.3 d, respectively, wren offered blackeyed pea foliage, but

22.7 and 13.9 d, respectively, when offered tl-e same fc] ae

plus honey. Female L. trifolii ovipositing and feedinc on







14


celery survived 13.0 d at 35 C and 27.7 d at 15c C with a

10% honey supplement (Leibee 1984). Parrella (1984)

reported L. trifolii adults lived for 3.1 and 16.7 d at 37.8

and 15.6 C, respectively, on chrysanthemum and honey.

Fecundity is also apparently affected by temperature,

nutrient availability, and in addition, age of female.

L. trifolii produced an average of 177 eggs per female cn

blackeyed pea foliage and 439 eggs when presented foliage

plus honey (Chariton and Allen 1981). L. trifolii femrr.es

were most fecund at 26.70 C averaging 278.9 eggs per

individual and least fecund at 37.8c C (0.9 egg per

individual) on chrysanthemum on honey (Parrella 1984). On

celery, females with a honey supplement produced

considerably more eggs with a maximum of 405.7 per

individual deposited at 30 C (Leibee 1984). Only 24.3 eggs

were produced at 350 C.

Greatest egg deposition per female per day (35 to 39

eggs) occurred at 1, 2 and 4 d of age at 35, 30 and 25. C,

respectively (Leibee 1984). Parrella (1984; founc greatest

oviposition occurred at 2, 4, 8, 10 and 16 d of age at 3-/.8,

32.2, 26.7, 2].1 and 15.60 C, respectively, for L. tr ifolii.

Extremes in temperature are known to influence

mortality of L. trifolii pupae. Nirety-twc percent of pupae

perished at 350 C; however, only 1C% died at 150 C (Leibee

1984). All pupae reared from chrys5arthremum died at 37.0 C

(Parrella et al. 1983t).







15


Results of Charlton and Allen (1981) suggest host

species may affect leafminer survival. Total percent

mortality for L. trifolii was 26.9, 26.8, 52.6 and 99.0

when reared on pink bean, blackeyed pea,' Show-off'

chrysanthemum and 'Yellow Knight' chrysanthemum,

respectively.

I. trifolii apparently exhibits a diurnal pattern ii

its behavior. Charlton and Allen (1981) found larval

emergence occurs most frequently from 0830 to 1230 and adult

emergence from the soil peaks from 0930 to 1230. No adult

emergence occurred before 0830 and after 1430. Mcst eggs

are deposited from 1130 to 1530. Feeding occurred

throughout the daylight hours.

Due to the emergence of L. trifolii as the dominant

economic pest in the last 10 years, most recent biological

studies have been concerned with this species. Earlier

results from studies of L. sativae, as L. pictella (Catr!a-r

and Michelbacher 1958, Oatman 1959a, 196C) and a's part of

the serpentine leafminer complex (Cenung and Har-ris 1_61),

are questionable since it is possible I. sativae was not the

only species invclved.










Control of Liriomyza on Celery



Chemical Control

Leafminers were not considered pests of celery and

other vegetables in Florida until the mid-1940s when the use

of chlorinated hydrocarbon insecticides became widespread

(Baranowski 1958, Leibee 1981). Chlordane was recommended

for leafminer control on potatoes by Wolfenbarger (1947);

however, it and other chlorinated hydrocarbons such as BHC

and aldrin had lost their effectiveness after the first or

second season of use (Wolfenbarger 1958). Since then,

several insecticides reported in the past as giving

satisfactory leafminer control have become ineffective.

Leibee (1981) gave an account of the history cf leafnminer-

control with insecticides which is summarized below.

Toxaphene gave satisfactory control from 1i47 to i952r

then decreased in effectiveness as did parathion; after 10

years of use, by the 1956-57 season. Diazirnon, recommrencde

for only two to three years, provided poor control or;

vegetables in south Florida by tle early 1960s. Peportec as

giving adequate control on celery in 1962, diazinon ard

naled had become ineffective by 1974, as had azirphos-

methyl. Dimethcate, approved for use on celery in that

year, also failed to give a desired level cf control.

Oxamyl and perr.ethrip, approved for celery use in 1975 and

1978, respectively, became relatively ineffective ir twc







17

years or less and methamidiphos, registered in 1S77, has

exhibited decreased effectiveness.

The history of leafminer control in California,

another major celery-producing region, is not as involved as

that of Florida. The major leafminer pest of celery there,

up until ca. 1980, was L. sativae which only reached

economic levels every five to 10 years and is satisfactorily

controlled with insecticides (Trumble 1981). However, L.

trifolii, supposedly introduced from Florida, emerged as the

major pest since ca. 1980 and its history of resistance to

insecticides in California is consistent with those fLocr

other states where this species is a serious problem

(Parrella et al. 1981a).

Insecticide resistance due to extensive use of tiese

compounds and the detrimental effects they have upor.

leafminer parasitoids have resulted in an almost comp;lete

breakdown of past Liriomyza control programs. Use of DET

for celery pests other than leafminers probably caused cross.

resistance to permethrin, a pyrethroid (Leibee 1981).

Eymenopteran parasitoids are very susceptible to brcad-

spectrum insecticides sucl as chlorinated hyCrocarbonz

(Baranowski 1958, 1959) and carbametes (Catrman ard Kennedy

1976, Waddill 1978). If leafminer populations ha.ve

developed resistance to these compounds, the effects of

parasitoid mortality are greatly e.acerbated.

Insect growtlj regulators (IGR's), chemical compoubnd-,

which disrupt or inhibit normal growth processes, have









recently exhibited promise for Liriomyza control as they are

potentially compatible with biological control agents due to

their low toxicity, host specificity and nonpersistence in

the environment (Parrella et al. 1982). Significant

leafminer larval mortality (Parrella et al. 1983a) and

sublethal effects on adults exposed as larvae (Robb and

Parrella 1984) have been reported for IGR treatments.

Trumble (1985) and Parrella et al. (1983a) reported that

IGR's did not significantly reduce survival of parasitoids

although Trumble found cyromazine significantly reduced

abundance of some key parasitoid species in celery.

An extract of seeds from the neem tree, AzaOirachta

indica A. Juss, has also recently received attention as a

broad-spectrum insect antifeedant and pesticide (Webb et al.

1983). Foliar applications reduced L. trifolii ovipositJio

and caused greater than 98% L. trifolii and sativae lar-al

mortality (Webb et al. 1983). Soil applications also

reduced survival of L. trifolii larvae and pupae, although

oviposition and adult feeding were not inhibited (Knodel-

Montz et al. 1985, Larew et al. 1985).

Currently, Florida celery growers, as well as those in

California, rely on cyromazine (Trigaa C ), a l]avicie,

methamidiphos (monitor )), a larvicide and adulticide, and

permethrir. (AmbushA ), an aculticice, for Liricm za cont-cl

(R.F. Foster, personal conimur'ication, 1906). In the Belle

Glade area cyroma;zine is usually alpplied at 0.125 lb A! per

acre once a week during normal infestations while









methamidiphos and permethrin are applied at 1.0 lb and 0.2

lb AI per acre, respectively, as often as two to three tin:es

a week (R.E. Foster, personal communication, 1986).





Natural Control by Parasitoids

Parasitoids of various species in several fawrilies

play an important role in the natural regulation of

Liriomyza and other agromyzids (Griffiths 1962, Oatman

1959b). Webster and Parks (1913) presented one of the

earliest records of Liriomyza (as Aoromyza) parasitoids

reporting 28 spp. reared from A. pusilla on alfalfa and

other forages with Diglyphus (as Diaulinus) begini (Ashmead)

as the most important. Hills and Taylor (1951) reported 10

spp. of parasitoids representing five families of

Hymenoptera from Liriomyza spp. on lettuce ancd cantalLouIe

with parasitism rates ranging from 0-100%. Oatman (1959b-,

found 19 spp. representing six families attacking I.

pictella in California and noted D. (as Solenotus) becini

and Halticoptera aenea (Walker) were the most prevalent

species. Harding (1965) reported 21 spp. of parasitoieds in

four families attacking L. nunda on 13 vegetable crop-. anricd

two weed spp. in the winter garder. area of Texas, wvile

Stegmaier (1966a, 1966b) reared five and nire spp.from t.

sativae (as munda) and L. trifoiji, respectively, in south

Florida.







20


Liriomyza sativae parasitoid complex composition and

abundance were reported by Oatman and Kennedy (1976) and

Johnson et al. (1980b) for California tomatoes and by

McClanahan (1977) for greenhouse beans in Canada. Diglyphus

begini, Chrysonotomyia punctiventris (Crawford) and Opius

dimidiatus (Ashmead) were the most abundant species reared

from host larvae and pupae. Chandler (1982) found eight

spp. of parasitoids attacking L. sativae and trifolii on

cantaloupe in Texas but noted under optimal environmental

conditions leafminer populations increase too rapidly for

effective control by parasitoids. Poe and Montz (1981)

listed 53 parasitoid spp. from five families reported from

four economically important Liriomyza species: L. trifol__i,

sativae, huidobrensis, and brassicae (Riley). Most

parasitoid species (31 in 11 genera) occurred in the family

Eulophidae.

In Florida, Genung and Janes (1975) reared several

species of parasitoids from both leafminer-infested celery

and weeds in the Belle Glade area with parasitism rates as

high as 100 and 94% from the weeds dog fennel, Eupatoij u:r

capillifolium (Lam.), and water pennywort, ydrocot jle

umbellata L., respectively. Thirty-two percent parasitism

occurred on celery. Genung (1981) surveyed important weed

hosts in the celery-growing region near Belle CGade and

observed parasitism was more prevalent in celery nearest

weedy borders. Parasitism rates of ca. 90% were deterrrined

for Liriomyza in California celery (Trumble and Nakakihara







21


1983). Diglyphus intermedius (Girault) and D. begini were

the most prevalent parasitoids reared.

Detrimental effects of DDT, methoxychlor, dieldrin,

endrin, and lindane on Liriomyza parasitoids were noted by

Wene (1955) and by Getzin (196C) for diazinon, parathion,

and ethion. Baranowski (1958) stated DDT use was a major

factor of ineffective control of Liriomyza in pole beans in

south Florida, while Oatman (1959b) noted the same effect of

such chlorinated hydrocarbons on parasitoids of Liriomyza in

California melons. Methomyl was found to be most injurious

to parasitoids in tomatoes while causing increases in L.

sativae populations (Johnson et al. 1980a, Oatnian and

Kennedy 1976). Parasitization by Chrysocharis parksi

Crawford was reduced ca. 40% at the lower treatment rate of

metbomyl (Johnson et al. 1980a). Schuster and Price (1985)

found methomy. and pernmethrin significantly reduced the

number of parasitoids reared from treated tomato foliage ard

leafminer pupae collected from treated foliage. Zehnder anc

Trumble (1985) also determined permethrin to be most

injurious to leafminer parasitoids of six insecticides

tested.

Insecticides which increase mortality cf leafminers

without a similar increase in parasitoid mortality have been
studied for incorporation into pest management prograns.

Trumble and Toscano (1983) found methlamiciiphos allowved for

50% more parasitism of leafminers in celery than mnetbor .

Trumble (1985) suppressed leafminer populations in celery







22


with abamectin (=avermectin), a neural transmission

inhibitor without adversely affecting percent parasitism,

adult parasitoid mortality or immature parasitoid survival

and emergence. He determined abamectin the most suitable

compound of those tested for integration into a pest

management program for L. trifolii in celery. Although

applied only for lepidopterous larvae control, the

biological insecticide Dipel Bacillus thurin gensis var.

kerstaki, and chlordimeform, a lepidopteran ovicide, proved

least injurious to the major leafminer parasitoids D. becini

and C. punctiventris when applied in combination to tomatoes

(Johnson et al. 1980b).



Effects of Cultural Methods

Polyethylene mulches and staking of tomatoes increased

Liriomvza and, consequently, Liriomyza parasitoid incidence.

Plants which were both mulched and staked contained gre:atest

leafminer infestaticns (Price and Poe 1976). Percent

parasitismi was highest on nonstaked plants. Vebb and Smith

(1973) found mulched snap beans contained more L. sativae

(as L. munda) than nonmulched bEans, but aluminumr foil

mulches apparently repelled Liricomryza spp. in tomatoes nrd

squash (Wolfenbarger anrd loore 1968).

Increased feitilizaticn resulted Jr ircreased

Liriomyza survival (as percentage cf miner completed: on

chrysanthemums (Foe et al. 1976) Average nuirber of onir.ef

per leaf and percent leaves infested did not vary







23

significantly with fertilization rates. Woltz and

Kelsheimer (1958), however, found chrysanthemum with higher

levels of nitrogen most heavily damaged by leafminers.

Harbaugh et al. (1983) reported L. trifolii damage of

chrysanthemum increased linearly as leaf nitrogen increased

from 2.2 to 4.0%.

Sanitation in celery (i.e. plowing under of crop

debris and weed control) is considered the most effective

method of cultural control of leafminers (Guzman et al.

1973), although weeds on field borders harbor many

beneficial arthropod species capable of inflicting

significant mortality upon Liriomyza (Genung and Janes 1975,

Genung 1981). Seedbed clippings, which contained ca. 50% of

the seedbed leafminer population, were implicated as sources

of reinfestation and a recommendation was made to collect

and destroy them (Genung and Janes 1975). Sanitation i.

also considered important for leafminer control iU

chrysanthemums (Short and Price 198]).

Postharvest flooding of fields is an important

technique in controlling nematodes, soil-borne diseases,

weeds and insects in celery (Cuzmai: et- al. 1973, Genune

1976). This measure, however, probably does. little to

decrease leafminer populations in celery e:cept fo-,

controlling certain weeds that may serve as hosts of

Liriomvgza (Joan Dusky, persona; <:osrmurication, 1986).







24


Pest Management in Celery

In the mid-1970s a pest management progran for celery

in the Belle Glade area was devised and evaluated utilizing

insect, disease, and weed surveys (Genung et al. 1978). A

second study emphasized factors pertaining to celery growvth

and composition and concluded the program "in all cases

reduced the use of pesticides, was less expensive, and

savings were more than adequate to compensate for scouting"

(Guzman et al. 1979).

The current strategy for L. trifolii used by some

Belle Glade area growers consists of monitoring fields

daily, collecting celery trifoliate samples and estimating

fluctuations in leafminer density utilizing the pupa] drop

count method of Foster (1986). Decisions to treat are not

based on economic thresholds but on changes in population

levels and effectiveness of prior treatments (F:.F. Foste-,

personal communication, 1986).





Celery Production



In the Everglades region of south Florida celery

plants are grown from seed in raised seedbeds cortairiintj a

irrigation and drainage net.cLk. Seedbeds are coveted b,

shading structures from May to October during the first five

weeks after seeding when unshaded soil surface temperature-

are too hot for seed germination. The tops of seedlings are







25


trimmed to toughen the lower tissues thus better enabling

the plants to withstand the shock of transplanting.

Depending on the season, two to eight toppings are made.

Seedlings are grown from May until early April and take an

average of 70 d to reach transplanting stage (Guznan et a].

1973).

Transplanting of seedlings from seedbed to field

occurs from early August to April. Seedlings are pulled and

boxed by hand, watered, then transplanted by workers using

transplanting equipment. Immediately after transplanting,

the celery is overhead-irrigated until water is standing in

the field. The water table, manipulated by sub-irrigation,

is kept as high as possible before and after transplanting,

but after plants have recovered from transplant shock it is

maintained at 18 to 20 inches. Harvesting occurs from

November to late June with mean time fromi transplant in to

harvest being 90 days (Guzman et al. 1973).

Five varieties constitute practically all the celery

grown in the Belle Glade area. Florida 683K strain, the

most widely grown, is used for the major crop in mid-wintrer

as it is susceptible to early blight and leafminers and

bolts early. June Belle variety, slightly resistant to

early blight and not as prone to bolting as 683k during

prolonged cold periods at early cjLowtl: stages, is the seccnd

most popular variety and is grown in the late spring.

Pecently released for early fall plantings, Floribelle (1REC

M9 line) has good resistance to early blight, some tolerance







26


to bacterial leaf spot and some leafminer resistance and is

the next most popular variety. Florida Slobolt (EREC T168-

29-5), just released for harvest in April and early May, has

long ribs and good resistance to early blight, premature

seeding and bolting. Once the most widely grown variety,

Florida 2-14 is very attractive to leafminers and,

therefore, its popularity has declined considerably in the

last decade (E.A. Wolf, personal communication, 1986).

Seedbeds and fields are plowed, disked, levelled and

flooded. After drying they are plowed, disked, levelled,

mole-drained, and fertilized prior to transplanting. The

flooding procedure entails four weeks of flooding, two of

drying, then four more of flooding which is necessary to

insure mortality of the hardiest pests such as wireorms.

Soil fumigation of seedbeds and applications of

insecticides, herbicides, and fungicides to the crop, in

addition to flooding, are required to assure adequate yield.

Soil pH is often adjusted with applications of sulfur

usually incorporated at the time of fertilization (Guzman et

al. 1973).

The first commercial celery planting in Florica made

in 1897 at Sanford was 0.75 of an acre and netted $1,3CC

(Guzman et al. 1973). In 1984-85, 9,300 acres of celery

were planted in Florida (7,295 in the Everglades area);

8,600 of tlese were harvested yielding an average of 665

crates per acre (one crate:60, !bs). Season average mor:eta ry

value was $6.38 per crate resulting in a total value of







27


&36,515,000, down from the record value recorded in 1983-84

of $64,546,000 (Anon. 1986).





Beneficial Aspects of Weeds



Weeds are primarily considered competitors of crops

for sunlight, water and soil nutrients and often as

reservoirs for pestiferous arthropod species and plant

pathogens. However, certain ecological and physiological

aspects documented in recent decades have proven the

beneficial role of certain species and their potential for

use through manipulation in pest management systems (Altieri

and Whitcomb 1979a).

Ecosystems consisting of many and varied plant species

are known to contain a greater variety of insect species

(Fimentel 1961, Risch et al. 1983). Consequently, pest

mortality due to natural enemies in such systems is often

greater than in less diversified ones. Altieri et al.

(197F) found 26, 45 and 14% fewer leafhoppers, Empeasca

kraemeri Ross and Moore, banded cucumber beetles, DJabrotica

balteata Le Conte, and fall arrryworms, Spooptera fruc.ipe:da

J.E. Smith, respectively, in a bean-corn polycuiture than in

bean or corn alone. Presence of weeds enhanced predaticn

and/or parasitism of cabbage white butterfly larvae, Pier is

rapae (L.), in brussels sprouts (Dempster 1969), fall

armyworm in corn (Altieri and Whitcomb 1980) and Mexican









bean beetle, Epilachna varivestis Mulsant, in soybeans

(Shelton and Edwards 1983). Predation by fire ants,

Solenopsis invicta Buren, in sugar cane was also enhanced

(Ali et al. 1984). Risch et al. (1983) noted, however, that

herbivore movement patterns may be more important than

natural enemy activity in explaining reduction of certain

pest populations in diverse annual systems.

Nonpestiferous herbivores on weeds may serve as

prey/host sources for beneficials, thus increasing the

survival and ,possibly, population levels of these

entomophagous species (Altieri and Whitcomb 1979a, Perrin

1975). Surveys by Needham (1948) of Spanish needle, Bidens

pilosa L., Stegmaier (1971, 1973) of common ragweed,

Ambrosia artemisifolia L., and joe-pye weed, Eupatorium

coelestinum L., and Altieri and Whitcomb (1979b) cf Mexican

tea, Chenopodium ambrosioides L., determined certain weeds

can harbor an assortment of arthropod species. A famous

example of a natural enemy utilizing alternate hosts on: a

non-crop plant is that of the leafhopper parasitoid, Anacus

epo Cirault, which attacks eggs of a nonpestiferous species

year round on wild Rubus spp. (Doutt and NaKata 1973). In

summer, individuals migrate to grape to parasitize eggs of

the grape leafhopper, Erythroneura elegantula Osborr,

inflicting severe mortality in early season on this

important pest.

Weeds may also serve as sources of an ino acids and

carbohydrates for beneficials. Syme (1975) determined







29

longevity of individuals of two parasitoids of the European

pine shoot moth, Rhyacionia buoliana (Schiffermueller),

increased when feeding on various flowers over that of

starved controls. Fecundity of individuals of one species

fed flowers increased over those being fed honey. Leius

(1967) reported 18 times as many tent caterpillars,

Malacosoma americanum (F.), pupae were parasitized in

orchards with a rich undergrowth of wildflowers as in those

with poor wildflower undergrowth.

Certain non-crop plants are believed to act as pest

repellants or inhibitors, thus protecting crops when the tt.o

plant species occur together. Flea beetles, Phyllotreta

cruciferae Goeze, were significantly less attracted to a

combination of collards and common ragweed than collards

alone in laboratory experiments (Tahvanainen and Root 1972).

Altieri et al. (1977) and Schoonhoven et al. (1981)

determined populations of the leafhopper E. kraemeri on

beans were decreased by the presence of the grass weeds

Leptochloa filiformis (Lam.) and Eleusine indica (L.)

Gaertn. The grasses either repelled the pest, inhibitec

feeding or masked attractive odors of the crop.

Reduction in crop apparency (Feeny 1_76) resulting

from weed occurrence mray also influence pest and natura6]

enemy populations (Perrin and Phillips 1978, Altieri and

Whitcomb 1979a). Smith (1969) found larger population: of
cabbage aphid, Brevicorkne brassjcae (L.), and whiteflvy

Aleyrodes brassicae (Wlk.), on brussels sprouts in







30

cultivated plots with bare soil than in plots with a weed

cover. These results were confirmed by Horn (1981) working

with green peach aphid, Myzus persicae (Sulzer), on

collards.

Smith (1976) also discovered certain predators were

plant oriented. The syrphids Melanostoma spp.and

Platycheirus spp. and an anthocorid, Anthocoris sp., were

apparently attracted to weedy plots for oviposition. A

prey-oriented syrphid, Syrphus balteatus DeGeer, was

attracted to brussels sprouts which harbored more aphids.

Surveys of weed hosts of Liriomyza spp. have beer

conducted (Harding 1965, Stegmaier 1966a, 1066b, Spencer

1981a), but few studies have attempted to assess the imp-act

these alternate hosts have on vegetable agroecosystems.

Schuster et al. (1982) found downy groundcherry, Physaliw

pubescens L. (reported as groundcherry, P. angulata L.),

American black nightshade, Solanum americanum rill.

(reported as black nightshade, S. niururn L.) and cor.mmon

beggartick, Bidens alba (L.) (repcrted as Spanish needle,

Bidens spp.), the most important weed hosts of Liriomyza

adjacent to tomato fields. Over 80% parasitism was fornd

for mines collected from these and other weeds of the toi.ato

field borders surveyed.

Zoebisch (1984) studied the suitability of the three

weed species mentioned above and tomato as hosts for tomatc-

and weed-reared L. trifojii in the labo ratory American

black nightshade proved the most suitable of the weed hosts







31


as tomato-reared females preferred it and tomato as

oviposition substrates and fecundity was greatest on these

two hosts.

Genung and Janes (1975) found 22 plant species, most

of them composites, as important weed hosts of L. trifolii

in the celery agroecosystem near Belle Glade. Parasitism

rates greater than 90% occurred on four species of weeds

surveyed. Although potential sources of pestiferous

arthropods, virus infection, and infield weed infestaticn,

Genung (1981) stated "weedy marginal and interior ditch

banks in celery fields are more beneficial, through actual

conservation of parasites and predators of leafminers and

other insects, than detrimental" (p.68).





Description, History and Status of Castorbean



Castor bean, Ricinus communis L., is a rmembeL of the

family Euphorbiaceae, commonly called the spurge family,

predominant.ly indigenous to the tropics. Castor bean is the

only species of Ricinus, but it includes many pclymorpl-i<

types ranging from large perennials resembling small trees

to short-lived dwarf annuals. The erect, partially bciicV,

stem is marked by well-defined nodes from each cf which a

leaf arises. Leaves are glossy green, large-bladed, an(d

palmate with five to 11 lobes. Fiowers are normai1v

monoecious appearing terminally on main and lateral







32


branches. The fruit is roundish, three-sided, covered with

spines, and divided into three loculi. Seeds, one to a

locule, are broad, oval, compressed, of variegated color,

oleaginous, and very poisonous (Weiss 1971).

Domesticated in prehistoric times, castor bean is

considered Ethiopean in origin. Oil extracted from the

seeds was used as lamp oil, for annointments, as a medicine

acting as a purgative and as a lubricant. Seeds were an

important item of commerce in ancient Egypt and their uses

have appeared in ancient Greek, Roman, Indian, Hebrew and

Chinese writings. First introduced into England in 1548,

castor bean probably entered the New World with the slave

trade (Weiss 1971).

Today, oil from the seed is used primarily in resins,

plastics, paint, and varnishes (Weiss 1971). World seed

production for the 1984-5 season was one million metric tons

with India the largest producer (385,000 metric tons). T!e

Soviet Union, West Germany, the Netherlands, France, Great

Britain and the United States are the major importers (Emery

1985).

Production in the U.S. is negligible and virtually all

castor bean appears growing wild. Occurring predominantly

on canal and ditchbanks, castor bean is not considered a

major weed of crops in south Florida. Genung and Janes

(1975), however, considered it a major weed host of L.

trifolii and, consequently, its parasitoids in the Delle

Glade area. Greater than 85% parasitism of the pest on






33

castor bean occurred at each of two locations. Stegmaier

(1981), however, reported castor bean as a host of L.

sativae and not trifolii. He also mentioned finding a

castor bean leaf containing 80 L. sativae mines on two

separate occasions, illustrating the breeding potential of

this species on an alternate, wild host.















CHAPTER III
LEAFMINER AND LEAFMINER PARASITOID INCIDENCE ON
SELECTED WEEDS IN SOUTH FLORIDA


Introduction



Although the leafminer Liriomyza sativae (Elanchard)

was considered a pest of celery in Florida (Musgrave et al.

1975b, Poe and Montz 1981), L. trifolii (Burgess) is

currently the major, if not only Liriomyza spp. affecting

this crop (Stegmaier 1981, Leibee 1984). Both species are

attacked by the same parasitoid complex (Chandler 1982);

therefore, a weed species serving as a host of L. sati._ae

could act as a reservoir for these natural enemies and thus,

possibly enhance biological control of L. trifolli withir

nearby celery fields.

The ability of weeds to harbor beneficial arthropod

species has been studied and discussed by several authors:

Doutt and Nakata (1973), Perrin (1975), Altieri et al.

(1977), Altieri and Whitcomb (1979a,l79b) and Sheltron and

Edwards (1983), to name a few. Influence of weeds on

leafminer mortality in south Florida was noted by Genri.n- arnd

Janes (1975) and Genung et al. (1978), who reported

parasitism rates of Liriopmyza were higher on border:- of

celery fields adjacent to weeds. Such obse:vaticns justify


34n







35


investigations into the potential of certain native weed

species as reservoirs for parasitoids.

Of the 80 hosts reported by Stegmaier (1981) for L.

trifolii and sativae, 29 were attacked by the latter only.

Although found in south Florida, not all occur in the

celery-growing region near Belle Glade and fewer still in

sufficient numbers to warrant their study. Two weed

species, sicklepod, Cassia tora L. a legume, and castor

bean, Ricinus communis L., a euphorb, were reported by

Stegmaier (1981) as hosts of L. sativae only and are

commonly found in south Florida. These characteristics,

plus the fact seeds of the two species are readily

obtainable, make them amenable to study. Dayflower,

Commelina diffusa Burm., of the family Commelinaceae, was

also chosen for study. Although not attacked by either L.

sativae or trifolii, it is attacked by a similar species, L.

commelinae (Spencer and Stegmaier 1973), which may have

parasitoids in common with L. trifolii. Also, dayflowet is

very common in the Everglades region and cuttings for

transplanting are easily obtainable. L. commelinae is

reported to attack only plants of the genus Commelina

(Stegmaier 1966c).

The objectives of tl-is study were to 1) determine the

abundance of L. sativae and po sibly other leafriner species

on these three weeds, 2) monitor the abundance and species

composition of the parasitoids of these pests and 3)







36


ascertain leafminer and parasitoid occurrence and abundance

for a year on the weed species most preferred by LiriomyLza.





Methods and Materials


Host Preference Study

Test plots of castor bean, sicklepod and dayflower

were planted February 24, 1984 at two sites at the

Everglades Research and Education Center (EREC) two miles

east of Belle Glade. Plots consisted of five Lows 2 m long

and 3 m wide planted on 0.75 m centers. There were three

replications arranged in randomized complete block designs

at each site. Alleyways between plots were 1.5 m wide.

Castor bean and sicklepod were established from seed while

dayflower was transplanted using cuttings taken from EREC.

Plantings of castor bean and sicklepod were thinned to ca.

10 plants per row while dayflower was allowed to cover tle

entire plot.

Sampling began ir late May when leafmirier ir.festaticns

were first noticeable. One leaf of castor bean and. one

trifoliate of sicklepod were randomly selected from each of

three canopy layers (top, middle and bottorm) of 10 randorly

selected plants per plot. EayfloweL, a prostrate plant, was

sampled by collecting all foliage f:om 10 randomly selected

18 cm x IF cm aleas within a plot. Foliage was placed ir

plastic bags to minimize dessication during transport to the

laboratory.







37


Active mines (containing living leafminer larvae) and

old mines (those from which leafminers cr their parasitoids

had already exited) were counted from all samples. Mines

containing larvae which appeared dead were considered old.

Foliage containing active mines was placed on wire screen in

closed cardboard containers to allow for emergence of

parasitoid adults and mature leafminer larvae. Containers

were held at 24.0 + 5.50 C and 65 + 15% RH. Larval

parasitoid adults and leafminer puparia were collected after

foliage had dried (ca. 5 d). Puparia were held in class

vials until all leafminer and larval-pupal parasitoid adults

had emerged and died. Adults were identified and counted.

Prior to placing foliage in cardboard containers,

foliage was subsampled to determine leaf surface area. Or'e

half of the castor bean leaves and sicklepod trifoliates

from each canopy layer and one half of the dayflowe:

samples were randomly selected and leaf area measured using

a LICOR areameter. Also, plant height and nunber of

leaves per plant were determined for 10 randomly select-c?

plants from each castor bean and sicklepod plot for every

sampling period. Sampling was conducted ca. once veekly for

eight weeks ending the third week of July, 1984.


Seasonal Abundance

Sampling of castor beir to determine seasonal

variations in leafminer and parasitoid populations, arnc

percent parasitism was conducted for one year beginning

August 8, 1984. Plots utilized in the prior study were







38

examined biweekly, except in a few cases when they were

sampled once in three weeks. All foliage containirg active

mines was collected and held in the same manner and under

the same conditions as in the previous study. All leafminer

and parasitoid adults reared from foliage were identified

and counted.

Representative specimens of parasitoid species

collected in this and the prior study were identified by

E.E. Grissell, A.S. Menke and M.E. Schauff, Systematic

Entomology Laboratory, USDA, Washington, D.C., P.A. Wharton,

Department of Entomology, Texas A&M Universty, College

Station, Texas and C.M. Yoshimoto, Department of

Environment, Canadian Forestry Service, Ottawa, Ontario,

Canada.



Results and Discussion


Host Preference Study

Leafminer occurrence on sicklepod and dayflcwer during

the sampling period was slight. Of 87 mines found on

sicklepod foliage only two contained living larvae. Neither

larva developed to pupation. Although no adult leafmirerL-

were reared from sicklepod, most, if not all, mines may have

been those of Liriomvza since they were serpentine ii

appearance and the majority of them (62%) cccurred during

the first two weeks of samplJ inc when Liri.umy za ias mc'

abundant on castorbean. Thus, damage inflicted upon these

two plant species, particularly during this time, may have







39


been caused by the same leafminer infestation (i.e.

species).

Only 15 mines were collected from dayflower; four were

active and one L. commelinae adult and one pupal parasitoid

were reared from them. The parasitoid was a Cynipid,

possibly of the genus Ganaspidium, as it was very similer,

if not the same, as that reared from Liriomyza on castor

bean. The specimen, however, was not sent for

identification. Stegmaier (1966c) reared only one

parasitoid from L. commelinae in south Florida, Chrysocharis

majoriana (Girault), a neotropical eulophid. If the cynipid

reared is the same as that attacking L. trifolii, dayflcwer

may be considered beneficiial in that it harbors a natural

enemy of the pest.

Genung (1981) found dayflower to contain sign:ificant]y

more chalcidoid parasitoids than other weeds (e.g. SpariJ'.

needle, Bidens pilosa L., Virginia pepperweed, Le pi'.j.M

virginicum L., spiny amaranth, Pmaranthus sp nosusu L. and

others) sampled near celery fields with sticky trcps.

Flower nectar, however, rather than the presence of

leafminer larvae is believed the ma-jcr attractart of tlese

parasitoids to dayf lower (G.L. Leibee, persona.]

communication, 1586).

Liriomyyza populations on castor bean were rucL greater

than those on sicklepod or dayflowe_. Populatjcns peakec

the first week of sampling with more than 22 active mines

collected per 5000 sq. cm leaf surface area (Ficure 3.1).







4C
















180


160/ OLD


140


120- J \


z

S80

z\

60


40


20



MAY24 MAY30 JUN8 JUN19 JUN26 JUL4 JUL10 JUL 8











Ficure 3.3 Mean nuitbet of ol and active r.ine-; of L. sal:i-
vae and L. trifoli collected per 5000 sqo. cn of castor bean
foliage, Belle Glade, FL (1984).







41


Active mine density decreased significantly (P<0.05) after

the second sampling period and, except for a slight increase

during the fourth sampling period, were less than one active

mine per 5000 sq. cm.

As leafminers continued to attack castor bean, old

mines continued to accumulate and did not peak until the

third sampling period at greater than 162 mines per 5000 sq.

cm (Figure 3.1). The almost complete cessation of leafminer

activity and subsequent senescence of locwer leaves decreased

foliage area containing old mines. Although not an

indicator of present infestation levels, old mines can be

used to determine the extent of recent leafminer attacks and

the potential of plant species as hosts in the future.

All leafminer adults reared from castor bean foliage

were either L. sativae or L. trifolii with the formier

comprising 63.3% of the specimens. More than 4.2 adult

Liriomyza per 5000 sq. cm of foliage were reared during tie

first week of sampling (Figure 3.2) but numbers declined

steadily with the decrease in active mines. No L. trifolliJ

were reared after May 30 and L. sativae was collected only

twice (weeks of June 19 and July 18) during the sare per!od.

The disparity between number of active mines. collectel

and adults reared from these mines resulted in part from the-

dessication of foliage within cardboard rearing conta-ines.

Larvae collected as first and early to mid-second instars

probably lacked sufficient time to complete development

although foliage, when held in adequate amounts, remained







42

















2.5 -9- L sativae
K -* L trifolii


2-



S1.5
\ \

z 1









MAY24 MAY30 JUN8 JUN19 JUN26 JUL4 JUL 0 JUL18










Ficure 3.2. Mean nui be: of L. sat ivae and L. trifolij re&ec-
per 5000 sq. cm of castoL- bean foJiaoe collectec, Felle
Glade, FL (1984).







43


relatively moist several days after sampling. Tryon (1979)

found that fewer celery trifoliates per rearing container

resulted in accelerated dessication and fewer adults reared

per trifoliate. Filling containers three quarters full with

castor bean leaves was normally sufficient for rearing

adequate numbers of adults. Completely filling a container

usually promoted leaf tissue decay resulting in death cf

developing leafminers and parasitoids.

High levels of parasitism also accounted for reduced

leafminer emergence. More than 9.6 adult parasitoids per

5000 sq. cm were reared from Liriomyza collected during t.e

first sampling period (Figure 3.3). The majority of

parasitoids (9.5) were larval-pupal species in which females

parasitize the larvae and adults emerge from the puparia.

Although larval parasitoid (i.e. those that utilize only the

larval stage for development) incidence increased during the

week of May 30, the total number of parasitoids decreased

corresponding with the decrease in leafminers. Levels never

exceeded 0.65 per 5000 sq. cm for the remainder of the

study.

Eleven species of parasitoids representing four

families of Hymenoptera were reared from Liriomvza on caster

bean (Table 3.1). All braccnids plus Halticoptera cilculus

(Walker), Chrysocharis park si Crawford and Ganaspidium sp.

are larval-pupal parasitoids while the remairing are larval

parasitoids. Larval-pupal species accounted for over 82.0%

of all parasitoids reared for the entire sampling period







44














10


9-- LARVAL
\ -- LARVAL-PUPAL


8 i

0


. \

0 4- \
z



2

0 /



MAY24 MAY30 JUN8 JUN19 JUN26 JUL4 JUL10 JUL18










Figure 3.3. Mean number of Ecultt paaEsitoics rearer per 5000
sq. cm foliage collected from L. satiaae and L. t rifoli. on
castor bean, Belle CGlade. FL (1984).







45




Table 3.1. Hymenopteran parasitoid species reared
from L. trifolii and L. sativae on castor bean in
Belle Glade, FL (May-July 1984).


Family Species Abundance (%)


Braconidae Opius
dimidiatus
(Ashmead) 31.8

0. dissitus
Muesebeck 21.2

0. bruneipes
Gahan 2.]

Oenonogastra
microrhophalae
(Ashmead) 4.2

Eulophidae Diglyphus
intermedius
(Girault) .7

Chrysonotomyia
punctiventr is
(Crawford) 5.3

Chrysocharis
parksi
Crawford 2.]

Closterocerus sp. 1.8

Pnioalio
f lavipes
(Ashmead) 1.8

Pteromalidae Halticcptera
ci rculus
(Walker; 20.6

Cynipidae Canaspidlj m sp. 0.3






46


with species in the genus Opius the most prevalent (Table

3.1). Opius spp. also accounted for the majority of adult

parasitoids emerging from weed foliage adjacent to tomato

fields in central western Florida (Schuster et al. 1982).

Percent parasitism, calculated by dividing the number

of adult parasitoids reared from foliage by the nuimber of

adult leafminers plus parasitoids reared, was 10C% for

larval and larval-pupal parasitism combined for the third,

fifth and sixth sampling dates (Figure 3.4) when only

eleven, three, and two parasitoids, respectively, were

collected. (No leafminer or parasitoid adults were reared

the week of July 1C and this is represented by 0%

parasitism.) Genung et al. (197E) found over 90% paraskit ism

of mines occurring on castor bean ir the Belle Glade area.

O. dimidiatus accounted for all parasitism the fifth anC

sixth sampling dates while only two L. sativae were

collected during the final sampling period when no

parasitism occurred.

All parasitoids in general and Cplus spp. in

particular apparently exhibited exceptional searching

ability, attacking tie majcrity, and sometimes aE1,

leafminer larvae collected and Leared even when L[opulations

were extremely lobw. Parasitism ratres for tie four 'cst

prevalent species are presenteC ir Table 3.2. rMortalit; dtie

to the majority of larval-pupal parasitoids appears to be

density independent, (i.e. its effect does not var- w:tic the

occurrence or population density of the species regulated







47












100

S-- LARVAL
---X- LARVAL-PUPAL /





60-
A /


Dn
/
S401-




20 /




0 Ep
MAY24 MAY30 JUN8 JUN19 JUN26 JUL4 JUL10 JUL18









Figure 3.4. Mean peLcent parasitism of L. sativae end L.
trifolii on castor bean by !arvel and larval-pufal r as.i-
toids, Belle Glade, FL (1984).







48











Table 3.2. Mean percent parasitism of L. trifolii and L.
sativae on castor bean by the four most prevalent species
of parasitoids, Belle Glade, FL (1984).


O. 0. H. D.
Date n dimidiatus dissitus circulus intermedius


May24 567 33.8a 18.6ab 12.6a 1.Oa

May30 220 27.3a 9.4ab 1.9b 23.la

Jun 8 11 30.1a 34.Oa O.Ob 14.0a

Junl9 33 19.3a 1E.4ab 6.7ab 14.3a

Jun26 4 100.Ob 0.Ob 0.0b 0.0a

Jul 4 2 100.0b 0.0b 0.0b G.0a

JullO 0 -- -- --

Jul18 2 O.0a O.Ob O.Ob C.Oa


Means in columns followed by same letter not significant-
ly different by Duncan's new multiple range test
(P<0.05). Data transformed by arcsine (v'x) transformr,-
tion before analysis; untransformed data presented.







49


(van den Bosch et al. 1982)) since percent parasitism due to

these species remains relatively high despite changes in

leafminer density. Larval parasitoids, however, perhaps

exhibited a delayed density dependence, first inflicting

significant mortality a week after Liriomyza populations had

peaked and becoming relatively ineffective as leafminer

densities decreased.

Liriomyza adults apparently preferred to oviposit on

castor bean foliage occupying the mid-canopy region (Table

3.3) which, for the first two sampling periods when the

majority of active larvae were collected, was ca. 55-130 cm

above the ground. Mean plant heights were 166.2 and 191.4

cm for pericds one and two (Figure 3.5), respectively. The

mid-canopy regions, calculated as the middle third of these

heights, were ca. 55-110 and 64-128 cm for the tv'c pericds.

Most adult parasitoids were also reared fron mid-

canopy foliage (Table 3.4) which was to be expectec as most

leafminers occurred there. Larval parasitoids, however,

apparently exhibited a preference, although not significant,

for hosts in the lower canopy. These species, all small

eulophids, may be more effective nearer the ground where

lower wind speeds may alvlow for a more stable environment in

which to search for hosts. Percent parasitism was

significantly greater in the beotter, canopy layer for iartal

parasitoids (Table 3.5) again deronsrtrating the lower

canopy's possible enharncement of efficient hcst-fincin( fcL

these smaller species. In contrast, larval-pupal







50



















Table 3.3. Mean number of old and active mines
collected and L. trifolii and L. sativae adults
reared per 5000 sq. cm of castor bean foliage,
Belle Glade, FL (May-July 1984).


Canopy L. L.
layer Old Active trifolii sativae


Top 2.5a 0.5a <0.la <0.1a

Middle 122.5b 12.8b 0.6b ] .b

Bottom 158.6c 3.5a 0.la 0.2a


Means in columns followed by same letter not sig-
nificantly different by Duncan's new multiple
range test (P<0.05).






















350





300-


E /


-- 250

I



200





150 4 -
MAY24 MAY30 JUN8 JUN19 JUN26 JUL4 JUL10 JUL18









Figure 3.5. Mean growth of castor be-.r at EREC, BeeJ e Glade,
FL (1984).







52

















Table 3.4. Mean number of total, larval and larval-
pupal parasitoids reared per 5000 sq. cm foliage from
L. trifolii and L. sativae on castor bean, Belle
Glade, FL (May-July 1984).


Canopy
layer Total Larval Larval-Pupal


Top 0.07a 0.01a 0.06a

Middle 4.19b 0.38ab 3.82b

Eottom 1.24a 0.54b 0.70a


Means in columns followed by same letter nct signifi-
cantly different by Duncan's new multiple range test
(P<0.05).







53


















Table 3.5. Mean percent total, larval and larval-
pupal parasitism of L. trifolii and L. sativae on
castor bean, Belle Glade, FL (Way-July 1984).


Canopy
layer Total Larval Larval-pupal


Top 65.2a 18.7a 46.4a

Middle 78.8ab 11.2a 67.5a

Bottom 93.4b 54.5b 38.9a


Means in columns followed by same letter not signifi-
cantly different by Duncan's new multiple range test
(P<0.05). Data transformed before analysis by arcsine
(Vx) transformation; untransformed data presented.







54

parasitoids, most several times the size of the

aforementioned species, performed equally well within all

canopy layers.


Seasonal Abundance

Leafminer occurrence on castor bean was negligible for

the remainder of the summer of 1984 as populations never

exceeded one mine per plot (Figure 3.6). From September 9

to November 4, no mines were found in castor bean foliage;

however, populations increased slightly from late November

until mid-January when several frosts destroyed all foliage.

Regrowth appeared by early March and populaticns increasec

rapidly to peaks of greater than 36 and 37 mines on March 25

and April 22, respectively. Leafminer density decreaseC

steadily from early May until the end of sampling.

Parasitoids possibly regulate Liriomyza numbers ir

late spring and early summer. Increased temperatures, and

rainfall of mid- to late summer may inflict mocrtality by

increasing incidence of fungal diseases of larvae and pupae.

Muck soils like those of the Belle Glade regicn can stay

moist for days during this season and drowning cf newly

exited larvae and pupae may possibly occur. Charlton and

Allen (1981) found submergence in water for 50 h caused C%

mortality of L. t-rifolii pupae.

L. sativae comprised 74.5% of Lirjcmyzn adults reared

from foliage (Figure 3.6) and only once (Yrarch 12) did L.

trifolii adults reared exceed those of L. sativae. Although























40
55


















35- MINES

-- L sativae


U /I 2 /



320-
0
trifolii /





0

0 15-i
z /









D LJ >z
Z 20 "












Figure 3.6. Mean number of nirjes collected and Liricmyza acn-
ults reared per 3 I x 3 r plot of castor bean, Belle Ciade,
FL (1984-C5) .







56


Liriomyza was most abundant at approximately the same times

for both the host preference study and this study,

population densities encountered during the latter were

extremely low compared with those of the former study.

Foliage during the host preference study was younger with a

thinner epidermis and may have been more suitable as an

oviposition substrate. Also, ricin, the proteinaceous toxin

found in all plant parts, may accumulate as the plant ages,

thus possibly decreasing the plants' attractiveness to

ovipositing females and/or increasing mortality of eggs

and/or young larvae.

Again, larval-pupal parasitoid species comprised the

majority (96.3%) of parasitoids attacking Liriomyza (Table

3.6). C. parksi was reared in the previous study but was

not reared from foliage in this experiment.

Abundance of parasitoids (Figure 3.7) closely follcvec

that of leafminer hosts. Larval-pupal parasitoid density

followed that of Liriomyza, while larval parasitoids

occurred at relatively low, but steady levels. This

contradicts the observatior fiom the previous study

that these species were more density dependent than larval-

pupal species. Percent parasitism peaked at 94.6% on April

8 and 100% on July 16 (Figure 3.8), although the percentage

for the latter date represents the occurrence of only one

individual. Larval-pupal paLasitoids accounted for all

species reared on these two dates.







57









Table 3.6. Hymenopteran parasitoid species reared fiom
Liriomyza trifolii and L. sativae on castor bean, Belle
Glade, FL (Aug 1984-July 1985).


Family Species Abundance(%)


Braconidae Opius dimidiatus 47.7

0. dissitus 29.4

O. bruneipes 2.]

Oenonoqastra microrhophalae 6.1

Eulophidae Diglyphus intermedius 1.5

Chrysonotomyia punctiventris 1.]

Closterocerus sp. 0.8

Pnicalio flavipes 0 .

Pteromalidae Halticoptera circulus 9.7

Cynipidae Ganaspicium sp. 1.3







58
















25



20 ---- LARVAL
-9- LARVAL-PUPAL
i

15
.J / \





S10o






I __ I











Igure 3 7. Mean nunm be. of i rval and rval-upal aidult
parasitoids reared per 3 m x 3 i0 plot fLom L. sativac anc L.
trifolii on castor bear, Belle Clade, FL (1984-85).







59
















100

--8 LARVAL

-S-- LARVAL-PUPAL




(n 60-



I 40- /




SCL





D G o in rq 0 to

z z -









Figure 3.8. Mean percent larval and larval-pu'pa paa.it I&r.,
of L. sativae and L. t-:ifolii on castor bean, Belle Glade,
FL (1984-85) .







60

Results indicate castor bean, particularly young

plants, can harbor considerable numbers of Liriomyza and

their parasitoids. The high incidence of parasitism imparts

a beneficial aspect to castor bean as part of the celery

agroecosystem as it probably serves as a reservoir for these

natural enemies; however the occurrence of the pest L.

trifolii may negate any positive effects of the weed.

Considering the report of Stegmaier (1981), the abundance of

L. trifolii on this host plant is surprising although Genurg

and Janes (1975) believed it to be the species attacking

castor bean during their study and Spencer (1985) found it

on the same host in Kenya.

The extent to which castor bean can affect leafminer

and parasitoid occurrence is uncertain. Eased on this study

and reports of others on the "edge" effects of weeds on

Liriomyza and parasitoid incidence in celery (Genunc et a].

1978, Genung 1S81), the plant probably does play a role in

pest abundance and regulation under certain circumrstances.

Only further studies examining this specific phenomenon c-n

begin to elucidate this weed's impact within celery.















CHAPTER IV
EFFECTS OF CASTOR BEAN ON LEAFMINER AND LEAFMINER
PARASITOID POPULATIONS IN ADJACENT CELERY


Introduction



The leafminer Liriomyza trifolii (Burgess) is

considered the major insect pest of celery in south Florida

(Guzman et al. 1973). It is highly polyphagous attackinrg

over 140 host plants in 32 families worldwide (Patel 1986).

The capacity of these hosts, many of which are considered

weeds, to affect the population dynamics of L. trifolij and

its parasitoids is potentially considerable (Genung and

Janes 1975, Genung et al. 1978).

Weeds adjacent to celery and tomato fields are known

to act as reservoirs for leafminers and their naturea]

enemies in Florida (Genung 1983, Schuster et al. 1982).

Increased rates of parasitism have been reported for celery

at field borders nearest weeds (Genung and Janes 1975,

Genung et al. 1978). No experiments have been conducted to

attempt to quantify the effect weeds have on leafmine: ard

parasitoid population numbers in adjacent celery. Suc!:

knowledge may enable growers to utilize insecticides and

herbicides more effectively and efficiently and perl.aps

increase leafminer mortality in celery by manipulatir.g weec7

species harboring natural enemies.


61







62


Detection and quantification of movement of leafminers

and parasitoids from weeds to adjacent celery could be

inferred from data obtained by sampling celery nearest the

weeds and at set intervals into the field. However, another

method is required to detect and analyze these phenomena

conclusively. If leafminers and parasitoids could be marked

via the weed host and if such marked insects and/or their

progeny could be collected in adjacent celery, the origin of

these individuals could not be questioned. Radioactive

isotopes are ideal labels for such a study.

Radioactive isotopes have been used as markers or

labels in studies to estimate population numbers, dispersal

and mortality factors and study behavior and other aspects

of the biology of various organisms. They are relatively

easy to apply and detect and, when utilized correctly, dc

not affect normal behavior of labelled individuals

(Southwood 1978). The incorporation of isotopes into host

plants has been used to label lepidopterous larvae on

deadnettle, Lamium spp., (Cook and Kettlewell 1960) anid

balsam fir, Abies balsamea L., (Krall and Simmons 1977) and

the mirid Orthotylus vYiescens (Douglas and Scott) cn broom;

Sarothamous scoparius (L.) (Lewis and Waloff 1964). The

radionuclide of phosphorous, 32P, has been the most vwiCely

used isotope; however, -5S, due to its longer half 13fe (E7

dc vs 14.2 d for 32P), is better suited for a study condiuctec

over several weeks.










The purpose of this study was to determine if castor

bean (Ricinus communis L.), a major weed host of L. trifolii

and sativae, contributes to the occurrence of L. trifolii in

celery and if parasitoids attacking both leafminer species

in castor bean disperse and attack L. trifolii in celery.

Celery transplanted adjacent to 35S labelled castor bear in

the field was sampled with the goal of collecting labelled

individuals. Ovipositional preference of L. trifolii and L.

sativae females for castor bean and celery was quantified in

a laboratory study.





Methods and Materials



Migration Study

Ten day-old castor bean seedlings were labelled by

placing them in aluminum trays containing the isotope 35S ir

Hoagland's solution at 0.1 microcurie/ml. The bare root

systems were placed within the solution and plants were held

upright by 2.54 cm diameter chicken wire covering the tops

of the trays. Girdling of seedlings by wire was prevented

by ringing stems with cctton. Thirty plants were placed inr

each tray and trays contained 300 microcuries of 'S each.

Seedlings were held in this nanner for 72 b. A preliminary

autoradiography study determined 72 h was adequate time for

uptake and translocation of the isotope to all seedling

parts.







64


Seedling roots were washed twice in a magnesium

sulfate and water mixture (.0083 M MgSO = 1 g/1) to remove

the isotope-containing solution from the plants' outer

surfaces. The plants were then transplanted to two field

sites at EREC in two 50 plant rows spread 0.5 m apart and 25

m in length. Four days later, celery was transplanted at

each site in two plots, one on either side and adjacert to

the labelled plants. Plots, which were approximately three

meters from the castor bean, were 18.5 m in length and 20 m

wide at site one and 26 m in length and 15 m wide at site

two. Sampling in celery began 12 d after transplanting.

This was approximately one week after mines began appearing

in the labelled castor bean plants.

Two trifoliates were randomly selected from each of

two sites along the two rows closest to the castor bear and

from rows every five meters away from the castor bean

thereafter. Therefore, trifoliates were sampled at four

distances from castor bean at site one (3, 8, 13 and 18 m)

and six distances (3, 8, 13, 18, 23 and 28 m) at site two.

Collected trifoliates were placed in 0.47 1 cardboard

rearing containers and held at 2E + 3 C and 65 + 10% PH

until all leafminer and parasitoid adults had emerged and

died (ca. two weeks). Adults were identified, counted and

examined by autoradiography and liquid scintillatior

analysis for possible incorporaticn of 35S. Sampling was

conducted weekly for 1C weeks f:cm April 18 tc June 20.







65

Adults were examined for isotope uptake by attaching

dead individuals to blotter paper with clear finger nail

polish. Blotter paper was taped to 17.5 cm x 12.5 cm Kodak

X-omat AR x-ray film so that specimens were in direct

contact with the film. Blotter paper with specimens and

film were placed in light-tight wooden boxes which were

placed in an ultra-cold freezer at ca. -75 C for 16-20 d.

Then the film was developed and examined for darkened areas

where individuals were in contact with film signifying

occurrence of the isotope. All handling of film pricr to

development was conducted in a darkroom under red light.

Adult leafminers and parasitoids were also sampled in

celery using 7.6 x 12.7 cm Tangle Foot -coated yellow

cards stapled to the tops of 30.5 cm stakes. These sticky

traps were placed in the field on the same rows from which

trifoliates were sampled. Two traps were placeC ir eacl,

row. Adults collected were identified and counted, then

cleaned of Tangle Foot & with alcohol and exarnined for

isotope incorporation in the same manner as those re.aed

from trifoliates. Sticky trap sampling was conducted

concurrently with trifoliate sampling.

Selected adult leafminers and parasitoids reared frcm

trifoliates and collected on sticky traps were also examined

for containment of tie isotope by liquid' scintillaticn

analysis. Specimens were placed in a standard fluor

cocktail solution for counting with a Tracor <' Anal tic ,







66

Delta 300 Series liquid scintillation counter. Counts were

made at the University of Florida campus, Gainesville.



Host Preference

To determine L. trifolii and L. sativae female

preference for castor bean and celery as oviposition

substrates, four females and two males (3-4 d old) of one

species were placed in 66 cm high x 36 cm wide x 36 cm deep

wooden, screened cages containing two castor bean and two

celery seedlings each. After 48 h, the flies were removed

and plants were monitored for leafmine development. When

resulting larvae had matured to mid-third instars

(approximately 9-12 d after exposure), infested foliage was

excised and placed in petri dishes containing moist filter

paper to allow for emergence and pupation of mature larvae.

Puparia were collected into small plastic cups where adults

emerged and died. Numbers of larvae, puparia and adults

produced per cage were noted and recorded. This procedure

was replicated 15 times for L. sativae and 16 times for L.

trifolii and was conducted at 25 + 3 C, 65 -_ 10% RH and a

photoperiod of L:D 14:10.






67


Results and Discussion



Migration Study

No adult leafminers and parasitoids reared from

foliage or trapped on sticky traps within celery during the

entire sampling period were found to contain the radioactive

isotope by either autoradiography or liquid scintillation

counting. Yellow sticky traps are considered a reliable

method for immediate detection of leafminer adults (Tryon et

al. 1980, Musgrave et al. 1975a). If adults are moving into

the celery after developing in isotope-containing castor

bean some of these labelled individuals should have been

collected in the traps. Also, any progeny of these adults

which developed in and were reared from celery shoulc

contain detectable traces of 35S within body tissues (E.L.

Cromroy, personal communication, 1985).

Although the initial results possibly indicate no

migration of leafminers and parasitoids from castor bean to

celery, another conclusion is possible. The isotope rmay

have dispersed within the castor bean and became too diluted

for developing leafminers and parasitoids to incorporate in

detectable amounts. Preliminary autoradiography analysi:-

found 35S was absorbed and distributed to all plant parts

and L. sativae adults reared frccm labelled plants shortly

after isotope exposure contained detectable amounts of the

element. Mines were first noticeable in the transplante(

castor bean more than two and one half weeks after







68


labelling. Therefore, these larvae were exposed to the

isotope at least ca. two weeks after labelling. Given the

extraordinary growth rate of castor bean (Chapter Three),

the 35S may have dispersed throughout plant tissues to

concentrations too low to be incorporated into developing

individuals and/or to be detected. Liquid scintillation

counts of leafminer and parasitoid adults reared from

labelled castor bean foliage collected May 7 and May 29 from

site two indicated no occurrence of 35S within insect

tissues. Despite these findings, some of the collection

data suggest castor bean perhaps does affect leafminer and

parasitoid population numbers in adjacent celery.

Liriomyza trifolii was the only Liricmyza species

reared from celery foliage during the entire ten weeks of

sampling. Although L. sativae was reported as a pest of

celery in Florida until the late 1970s, L. trifolii is now

considered the predominant, if not only, Liricm za species

attacking celery in this region (Leibee 1964). However,

both species have recently been reported on the crop in

California (Trumble and Nakakihara 1983, Zehnder and Trunble

1984).

Greatest number of adults reared per t\vo trifoliates

(11.8) occurred on May 15 (Figure 4.1). Poe et al. (197E)

reported rearing 17.2 to 114.5 adult L. sativae per 1C

trifoliates from control (untreated) celery plots near Belle

Glade. In California Zehnder and Trunble (1984) reared 4.1







69

















S--- LARVAL
101 / --- TOTAL
e \ e L. ttrifolii l
H / I



5. / ,

























parasitoids reare per t(o trifo2iate- of celery a6dacent to
castor bean, fror, two sites at Belle Glade, FL (1985).









L. trifolii per two trifoliates of celery while Trumble and

Nakakihara (1983) reared 3.6 L. trifolii and sativae adults

per two trifoliates.

The number of parasitoids reared from foliage followed

closely those of L. trifolii, peaking one or two weeks after

those of their host (Figure 4.1). Larval parasitoids of the

family Eulophidae constituted the majority of species

collected (Table 4.1) in contrast to results of rearings

from Liriomyza on castor bean (Chapter Three) where the

braconid larval-pupal parasitoids predominated. (Percent

abundance of Oenonogastra microrhophalae (Ashmead) appears

as a portion of that for Opius dimidiatus (Ashmead).

Morphological characters used to distinguish between these

two species were obscured by autoradiograrhy and liquid

scintillation analyses techniques. Species determinations

were not made until after these analyses were conducted.)

Diglyphus intermedius (Girault) and Chrvsonotomyia

punctiventris (Crawford) were the most abundant species

reared from L. trifolii in celery. Members of tlese genera

have previously been reported as the most numerous

parasitoids from celery foliage in Florida and Californi.

(Tryon and Poe 1981, Trumble and Nakakihara 1983).

Mean number of L. trifolii and parasitoid adults

reared per two trifoliates sampled at set distances frc- the

castor bean do not indicate that the weed influenced

population numbers in celery (Table 4.2). Although L.

trifolii collection results indicate-perhaps infestations







71










Table 4.1. Hymenopteran parasitoid species reared from
L. trifolii on celery adjacent to castor bean, from
two sites at Belle Glade, FL, 1985.


Family Species Abundance (%)


*
Braconidae Qpius
dimidiatus
(Ashmead) 17.0

0. dissitus
Muesebeck 14.6

0. bruneipes
Gahan 7.1

Eulophidae Dglypghus
intermedius
(Girault) 42.7

Chrysonotomyia
punctiventr is
(Crawford) 17.6

Chrysocharis
pa r k s i
Crawford 0.3

Pteromalidae Halticoptera
circulus
(Walker) 0.6



Abundance of Oencnopastra microrhophJa]Je (Ashmead) in-
cluded as portion of that for 0. dimidiatus.







72
















Table 4.2. Mean number of L. trifolii and total, larval
and larval-pupal parasitoids reared per two trifoliates of
celery adjacent to castor bean, from two sites at Belle
Glade, FL, 1985a


Parasitoids
b L. c c Larval-
Distance(m) trifolii Total Larval pupal


3 4.57 1.58 1.08 0.50

8 5.15 1.55 0.93 0.62

13 4.05 1.60 0.80 0.80

18 3.57 1.45 0.82 0.63

23 3.10 1.60 1.00 C.60

28 3.10 2.20 1.50 0.70

aAll means in columns not significantly different by Dun-

bcan's new multiple range test (P<0.05).
Distance from castor bean at which samples taken.
CLogl0(x+l) transformation before analysis; untransformed
data presented.







73

were greater, though not significantly, near castor bean,

parasitoid abundance exhibited no such trend and, in fact,

appeared greatest at distances farthest from the weed.

Analysis of percent parasitism of mines also failed to

indicate any significant influence of castor bean on natural

enemy occurrence (Table 4.3.).

Approximately midway through the study (ca. May 15)

almost all labelled castor bean plants at one site had been

severely defoliated by an unknown disease. Therefore,

results derived from data produced at both sites may not

adequately estimate the effect of castor bean as the plants

at the affected site (site one) contained considerably less

foliage than those at the unaffected site (site twc). Thus,

data from site two were analyzed separately to perhaps

better ascertain castor bean's role.

Number of adult L. trifolii and parasitoids reared per

two trifoliates from site two did not vary significantly

with distance from castor bean (Table 4.4). However,

movement of parasitoids from the weed to celery is

implicated as percent parasitism by larval-pupal species

nearest castor bean was significantly greater thar that

occurring 23 m away (Table 4.5). As these parasitoid

species are the most abundant reared from Liriomvza on

castor bean, the higher rates at which L. trifolij is

attacked by them in adjacent celery may indicate the

potential of castor bean as a harbora(ce for these natural

enemies.







74













Table 4.3. Mean percent total, larval and larval-pupal
parasitism of L. trifolii per two trifoliates of celery
adjacent to castor bean from two sites at Belle Glade,
FL, 1985 .


Distance(m)c Total Larval Larval-pupal


3 36.4 22.7 13.7

8 33.0 16.7 16.3

13 31.9 16.8 15.1

18 31.7 19.7 12.0

23 38.3 29.8 8.5

28 34.8 23.7 1] .1

aAll means in columns not significantly different by Dun-

bcan's new multiple range test (P Arcsine (\Vx) transformation before analysis; untrans-
formed data presented.
Distance from castor bean at which samples taken.







75













Table 4.4. Mean number of L. trifolii and total, larval and
larval-pupal parasitoids reared per two trifoliates of cel-
ery adjacent to castor bean, Belle Glade, FL, 1985ab.


Parasitoids
L. d Larval-
Distance(m)c trifolii Total Larval pupal


3 3.25 2.00 1.45 0.55

8 3.50 1.85 1.30 0.55

13 3.85 1.75 1.05 0.70

18 3.10 2.00 1.25 0.75

23 3.10 1.60 1.00 0.60

28 3.10 2.20 1.50 0.70


aSite two only.
All means in columns not significantly different by Dun-
can's new multiple range test (P<0.05).
dDistance from castor bean at which samples taken.
Logl0(x+l) transformation before analysis; untransformed
data presented.







76














Table 4.5. Mean percent total, larval and larval-pupal
parasitism of L. trifolii per two trifoliates oQ celery
adjacent to castor bean, Belle Glade, FL, 1985


Distance(m)c Totald Larval0 Larval-pupale


3 48.6 24.1 24.5 a

8 45.7 24.9 2C.8 ab

13 27.9 16.1 11.8 ab

18 34.3 20.6 13.7 ab

23 38.3 29.8 8.5 b

28 34.8 23.7 11.1 ib


bSite two only.
Arcsine \/x) transformation before analysis; u-ntrans-
formed data presented.
Distances from castor bean at which samples taken.
Means in columns not significant] y different by Duncan's
new multiple range test (P<0.05).
Means followed by same letter not significantly differ-
ent by Duncan's new multiple range test (P<0.05).







77



Populations of adult leafminers and parasitoids in

celery based on sticky trap collections did not peak until

the eighth week of sampling, ca. June 6 (Figure 4.2). The

greatest mean number of L. trifolii collected per trap was

7.75 while a mean of 8.95 parasitoids were trapped the same

sampling period. (Traps at site two were covered with dust

blown from an adjacent disked field on the last sampling

date, June 20, making collection and identification of

adults impossible. Results of catches for this date,

therefore, were obtained only for site one.)

Musgrave et al. (1975a) trapped a maximum mean per

sticky trap of 10.05 L. sativae adults in cucurbits and 9.69

parasitoids in legumes. They believed yellow sticky trap

cards were the preferred method of estimating leafminer

populations due to speed and ease of handling. Other

maximum catches per trap of Liriomyza species repcrtec are

22.4 (Chandler 1981) in alfalfa and 44.0 (Tryon et al. 1980)

in tomatoes. Genung (1981) trapped 13.8 parasitoids per

daylight hour (over six h) per trap in the weed creeping

cucumber, Melothria pendula L.

All Liriomyza trapped during the entire study 'Yere L.

trifolii except for one L. sativae trapped on May 30. At

least six species of parasitoids, the vast majcrity of tl-em

larval, were collected representing foui families of

Hymenoptera (Table 4.6). Although most species were

identifiable, sticky material used to trap adults often







78















10

-- L. trifolii
-- TOTAL
8- 9- LARVAL




6-



4 / \
Z 4-




2-




0 o 7
APR18 APR25 MAY2 MAY9 MAY15 MAY22 MAY30 JUN6 JUN13 JUN20








Figure 4.2. Mean number of L. trifolii and total and larval
parasitoids collected per yellow sticky trap in celery adja-
cent to castor bean, from two sites at Belle Clade, FL
(1985) .







79










Table 4.6. Hymenopteran parasitoids of L. trifolii
collected on sticky traps in celery adjacent to cas-
tor bean, from two sites at Belle Glade, FL, 1985.


Family Species Abundance (%)


*
Braconidae Opius spp.
and
Oenonogastra
microrhophalae 7.4

Cynipidae Ganaspidium sp. 0.3

Eulopbidae Diglyphus
intermedius 43.6

Chrysonotomyia
punctiventris 47.2

Chrysocharis
parksi 0.2

Pteromalidae Halticoptera
circulus 1.3


*
Includes Cpius dimidiatus. 0. dissitus and 0. brune-
ipes.







80


covered the individuals and made discrimination between

species of Braconidae virtually impossible. However,

specimens of Braconidae trapped may include all species

reared from trifoliates.

Although the majority of parasitoids caught in traps

were eulophids, this result may not reflect the true

composition of adult parasitoids in celery adjacent to

castor bean. Over 38% of parasitoids reared from

trifoliates were braconids compared to less than eight

percent found on sticky traps. This disparity may result

from a greater attraction to yellow cards of eulophids than

braconids. Genung (1981) reported the majority of

parasitoids caught on yellow sticky traps in weeds adjacent

to celery were chalcids including eulophids, however no

studies have been conducted to determine the relative

attractiveness of leafminer parasitoids to various colcred

traps.

Significantly more adult parasitoids, particularly

larval species, were caught in traps closest to castor ban

than those occurring 23 and 28 m away (Table 4.7).

Occurrence of larval-pupal species, the densities of which

were too low to affect patterns of total parasitoid

abundance, did not differ with distance from castor bean.

Catches of L. trifolii exhibited a pattern of decreasing

abundance with increasing distance, although not a

significant one.







81














Table 4.7. Mean number of L. trifolii and total, larval anc
larval-pupal parasitoids collected per sticky trap in cel-
ery adjagent to castor bean, from two sites at Belle Glade,
FL, 1985 .


Parasitoids
b L. Larval-
Distance(m) trifolii Totala Larval pupal


3 3.34 a 2.44 a 2.28 a 0.1G a

8 3.35 a 1.67 ab 1.56 ab 0.11 a

13 3.23 a 1.64 ab 1.41 ab 0.23 a

18 2.94 a 1.35 ab 1.19 ab 0.16 a

23 2.22 a 0.58 b 0.50 b 0.0C a

28 1.78 a 0.53 b 0.44 b 0.09 a


Means in columns followed by same letter not significantly
bdifferent by Duncan's new multiple range test (P<0.05).
bDistance from castor bean at which collections were made.
Logl0(x+l) transformation before analysis; untransformed
ddata presented.
VxT.5 transformation before analysis; untransformed data
presented.







82


Results from samples taken at site two failed to

reveal any possible effect of the weed on adult numbers in

celery (Table 4.8). Significantly fewer larval parasitoids

were caught at site two than at site one (Table 4.9) for

those dates when populations were greatest (June 6 and 13).

Castor bean may have attracted parasitoids from the celery,

thus affecting trap catches. Also, rows within celery were

generally more weed-free at site one, therefore, the yellow

traps may have been more visible and, thus, more attractive

to parasitoids there than at site two. Or perhaps other

factor(s) such as site location affected number and

composition of parasitoids occurring or their susceptibility

to being trapped.

Mean number of larval-pupal species trapped die not

differ significantly for plots at site one and site two

during the entire study (Table 4.9). Their generally low

abundance in celery was apparently unaffected by abundance

or scarcity of adjacent castor bean or other factors

mentioned above which may have influenced larval parasito-id

population numbers.

Results of this study remain largely inconclusive.

Clearly, radiation dosages greater than that used (0.1

microcurie per ml) should be incorporated in castor bcar to

sufficiently label, for several weeks, leafminers and

parasitoids developing within foliage. However,

transplanting plants exposed to higher dosages to the field

is potentially environmentally unsound (H.L. Cromroy,







83














Table 4.8. Mean number of L. trifolii and total, larval and
and larval-pupal parasitoids collected per sticky tra~, in
celery adjacent to castor bean, Belle Glade, FL, 1985


Parasitoids
L. Larval-
Distance(m)c trifolii Totale Larvale pupal e


3 2.25 0.91 0.72 0.19

8 3.05 0.69 0.58 0.11

13 2.39 1.11 0.86 0.25

18 1.69 1.08 0.89 0.19

23 2.22 0.58 0.50 0.08

28 1.78 0.53 0.44 0.09


bSite two only.
All means in columns not significantly different by Dun-
can's new multiple range test (P<0.05).
cDistance from castor bean at which collections were made.
Logl0(x+l) transformation before analysis; untransformed
data presented.
eVx+2.5 transformation before analysis; untransformed data
presented.







84




Table 4.9. Mean number of L. trifolii (LT) and
total (TP), larval (LP) and larval-pupal (LPP)
parasitoids collected per sticky trap in celery
adjacent to castorbean, Belle Glade, FL, 1985.


Site

Date Species One Two


Apr 18 LT 0.44 0.46

TP 0.00 0.00

LP 0.00 0.00

LPP 0.00 0.00

Apr 25 LT 0.31 0.12

TP 0.00 0.04

LP 0.00 0.C4

LPP 0.00 0.00

May 2 LT 1.31 2.41

TP 0.00 0.08

LP 0.00 0.08

LPP 0.00 0.00

May 9 LT 2.44 4.00

TP 0.12 0.00

LP 0.06 0.00

LPP 0.06 0.00

May 15 LT 0.75 0.83

TP 0.50 0.83

LP 0.50 0.83

LPP 0.00 0.00







85







Table 4.9 continued.


Site
Date Species One Two


May 22 LT 7.44 6.50

TP 1.06 0.62

LP 1.00 0.62

LPP 0.06 0.00

May 30 LT 8.75 3.12

TP 1.19 1.08

LP 1.00 0.83

LPP 0.19 0.25

Jun 6 LT 15.81 2.37

TP 15.44 4.71

LP 14.94 3.66

LPP 0.50 1.05

Jun 13 LT 2.50 0.25

TP 5.56 0.25

LP 5.25 0.16

IPP 0.31 0.09



Means in these rows significantly different by t-
test (P<0.05).







C 6

personal communication, 1985). Therefore, other methods of

detection such as activation analysis or X-ray micropoble

elemental analysis may need to be implemented to determine

castor bean's effect.

Analysis of collection data also failed to detect any

such effect. Although some data suggest leafminer and

parasitoid abundance is greater in celery nearest castor

bean, further studies entailing several years of sampling,

not only from celery but from castor bean, are required

before the role of this weed within the celery agroecosystem

of southern Florida can be adequately assessed.



Host Preference

Liriomyza sativae preferred castor bean over celery

for oviposition, as a total of only two larvae weie observed

on all celery seedlings offeree (Table 4.10). Liricp:e'a

trifolii females preferred celery as a host, although they

produced more progeny on their less preferred host (castor

bean) than L. sativae females did on celery.

Progeny production of these individuals is less than

that of females in previous studies. Leibee (1984; found I.

trifolii females produced an average of greater than 16 eggs

per day at 4.5 d of age while Parrella et al. (1983b)

recorded a mean daily viable egg production of 17.3 for L.

trifolii on celery. Low mean progeny production resulted in

part from extreme variaLility in oviposition by individual

females. Egg deposition (based on larval counts) by L.







87















Table 4.10. Mean number of larvae, pupae and adults
of Liriomyza spp. produced on celery and castor bear
offered simultaneously to females for oviposition".


L. sativae L. trifolii
life
stage celery castorbean celery castorbear


larvae 0.13 a 22.33 b 23.19 a 5.38 b

pupae 0.00 a 19.33 b 16.00 a 4.13 b

adults 0.00 a 15.73 b 12.56 a 3.06 b


bMean number per four females in 48 h.
Means in rows for each Liriomyza sp. followed by same
letter not significantly different by t-test (P<0.05).







88

sativae in castor bean occurred in only eight of the 15

cages as a mean of 41.9 larvae per four females were

produced in these cages. Four L. trifolii females produced

a mean of 33.7 larvae in the 11 cages where oviposition

occurred.

Leibee (1S84) and Parrella et al. (1983b), however,

followed female oviposition over entire lifetimes. The

exposure period of only 48 h used in this study may not have

allowed females enough time to produce or begin producing

progeny at their maximum rates. Leibee (1984) and Parrella

et al.(1983b) also used smaller cages to expose plants to

flies. Female Liriomyza contained in closer proximity to

host plants may oviposit sooner and more often than those in

a larger cage. Also, females may not have adequately

acclimated to cage conditions within 48 h to begin

ovipositing at rates representing their normal potential on

these host plants.

Liriomyza species' preference in the laboratory for

celery and castor bean as host plants for oviposition may

provide insights into factors affecting field populations

where celery and castor bean are in close proximity to one

another. Rejection of celery for ovipositon by L. sativze

is not surprising as it was not collected from celery in the

preceding field study and has not been found on this crop in

recent years in Florida (Leibee 19&4). Considering L.

sativae is the most abundant Liriomyza species found on

castor bean and the same complex of parasitoids attacks L.







89

sativae and L. trifolii, castor bean, in certain situaticns,

could be considered beneficial as a source of natural

control agents for L. trifolii in celery.















CHAPTER V
BIOLOGY OF Liriomyza sativae BLANCHARD ON CASTOR BEAN

Introduction



Liriomyza trifolii (Burgess) has recently emerged as

the dominant leafminer species affecting celery in Florida

and California (Leibee 1984, Trumble and Toscano 1983).

Weeds adjacent to celery fields of south Florida are

reported to affect leafminer and leafminer parasitoid

abundance in celery nearest weeds (Genung and Janes 1975,

Genung et al. 1978, Genung 1981). Stegmaier (1981) cited

castor bean, Ricinus communis L., as an important host of

Liriomyza in south Florida. This weed was found to harbor

large numbers of L. trifolii, L. sativae (a very similar

species) and several species of parasitoids known to attack

both leafmining pests (Chapter Three).

Castor bean is fairly common to the celery-growing

region of south Florida. Since L. sativae is the

predominant Liriomyza species occurring on this weed

(Chapter Three), an understanding of the biology of the

species on this weed may help in understanding the factors

affecting Liriomyza population dynamics within the celery

agroecosystem. This is especially true since certain

parasitoids are known to attack both L. sativae and I.

trifolii (Chandler 1982). Objectives of this study were to


90




Full Text

PAGE 1

CASTOR BEAN Ricinus communis L AS A HOST OF Liriomvza LEAFMINERS (Diptera : Agromyzidae) THE EVERGLADES AGRICULTURAL AREA OF SOUTH FLORIDA By JAMES PATRICK PARK MAN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1S87

PAGE 2

ACKNOWLEDGEMENTS I would first like to thank my committee chairman and cochairman, Drs. V.H. Waddill and J. A. Dusky, for their guidance, friendship, and support (especially financial) during my graduate studies. I also wish to acknowledge and thank my other committee members, Drs. D.H. Habeck and D.J. Schuster, for their valuable suggestions in the preparation of this manuscript. Others providing information and suggestions during the course of my research and writing were Drs. H.L. Cromroy, R.E. Foster, G.L. Leibee and 3.L. Stimac, and Mr. M.D. Remick, Mr. F.L. Fetitt and Mr. E.A. Wolf. I would also like to thank the staff members at Everglades Research and Education Center, Belle Glade, who assisted me in my research and J. and M. Phillips who mode my stay at EPEC bearable. I also wish to express my sincerest appreciation and gratitude for the support, encouragement and patience of my family

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TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ii LIST OF TABLES v LIST OF FIGURES vii ABSTRACT i* CHAPTERS I INTRODUCTION 1 II LITERATURE REVIEW 5 Systematics of L iriomy za t rifolii (Burgess) and L. sa tivae Blanchard 5 Descriptions of L. t r if ol i i and L. s ativae .... 8 Distributions and Host Ranges 10 Life History and Biology 11 Control of Liriomy za on Celery 16 Chemical Control 16 Natural Control by Parasitoids 19 Effects of Cultural Methods 22 Pest Management in Celery 24 Celery Production 24 Beneficial Aspects of VTeeds 27 Description, History and Status of Castor been 31 III LEAFMINER AND LEAFMINER PARASITOID INCIDENCE ON SELECTED WEEDS IN SOUTH FLORIDA 34 Introduction 34 Methods and Materials 36 Host Preference Study 36 Seasonal Abundance 3 7 Results and Discussion 3tf Host Preference Study 38 Seasonal Abundance 54 IV EFFECTS OF CASTOR BE A!-. ON LEAFMINER AMD LEAF MINER PARASITOID POPULATIONS IN ADJACENT CELERY .61 Introduction 61 Materials and Methods 63

PAGE 4

Migration Study 63 Host Preference 66 Results and Discussion 67 Migration Study 67 Host Preference 86 V EIOLOGY OF Liriomyza sativa e BLANCHARB ON CASTOR BEAN 90 Introduction 90 Materials and Methods 91 Development at Constant Temperatures 5.1 Lifetime Cviposition 92 Results and Discussion 93 Development at Constant Temperatures 93 Lifetime Oviposition ['6 VI CONCLUSIONS 103 LITERATURE CITED 108 BIOGRAPHICAL SKETCH 121 i v

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LIST OF TABLES Table Face 3.1 Hymenopteran parasitoid species reared from Lir iomyza trif olii and L. sati va e on castor bean in Belle Glade, FL (May-July 1984) 45 3.2 Mean percent parasitism of L. tr if ol ii and L. sati va e on castor bean by the four most prevalent species of parasitoids, Belle Glade, FL (May-July 1984) 4 8 3.3 Mean number of old and active mines collected and L. trif olii and L. sativae adults reared per 500 0 sq. cm of castor bean foliage, Belle Glade, FL (May-July 1984) 50 3.4 Mean number of total, larval and larval-pupal parasitoids reared per 5000 sq. cm foliage from L. tri f oli i and L. sat iva e on castor bean, Belle Glade, FL (May-July 198 4) . ,52 3.5 Mean percent total larval and larval-pupal parasitism of L. trif ol ii and L. sativae on castor bean, Belle Glade, FL (May-July 1984). 53 3.6 Hymenopteran parasitoid species reared from Lir iomy za trif olii and L. sa_tivae on caster bean, Belle Glade, FL (Aug 1984-July 1985) 57 4.1 Hymenopteran parasitoid species reared from L. tri f oli i on celery adjacent to castor bean, from two sites at Belle Glade, FL, 1985 .... 71 4.2 Mean number of L. t r i f ol i i and total, larval and larval-pupal parasitoids reared per two trifoliates of celery ad jacent to castor bean, from two sites at Belle Glade, FL, 1985 .... 72 4.3 Mean percent total, larval and larval-pupal parasitism of L. trif olii per two trifoliates of celery adjacent to castor bean, from two sites at Belle Glade, FL, 1985 74 v

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4.4 Mean nurr.be r of L. t r i f o 1 i i and total, larval and larval-pupal parasitoids reared per two trifoliates of celery adjacent to castor bean, Eelle Glade, FL, 1985 75 4.5 Mean percent total, larval and larval-pupal parasitism of L. trifolii per two trifoliates of celery adjacent to castor bean, Belle Glade, FL, 1985 76 4.6 Hymenopteran parasitoids of L. trif olii collected on sticky traps in celery adjacent to castor bean, from two sites at Belle Glade, FL, 1985 79 4.7 Mean number of L. t rif oli i and total, larval end larval-pupal parasitoids collected per sticky trap in celery adjacent to castor bean, from two sites at Belle Glade, FL 1985 81 4.8 Mean number of L. trif olii and total, larval and larval-pupal parasitoids collected per sticky trap in celery adjacent to castor bean, Belle Glade, FL, 1985 62 4.9 Mean number of L. tri folii and total, larval and larval-pupal parasitoids collected per sticky trap in celery adjacent to caster bean, Belle Glade, FL 1985 84 4.10 Mean number of larvae, pupae and adults of Lir i omyza spp. produced on celery and caste: bean offered simultaneously tc females for oviposit ion 87 5.1 Development time, development rate, thermal units in degree days and development threshold for life stages, and pupal survival for L. sati vae on castor bean at 20, 25, 30 and 35 C 95 5.2 Linear regression equations and r values for developent rate and temperature ( C C) for ecglarval and pupal stages of L. sativae on castor bean 9 8 5.3 Percent survival of larval and pupal progeny and sex ratio of resulting adults for L. sativae. on castor bean at 25 C 101 vi

PAGE 7

LIST OF FIGURES Figure Page 3.1 Mean number of old and active mines of L. sa tivae and L. trif olii collected per 5000 sq cm of castor bean foliage, Belle Glade, FL (1984) 40 3.2 Mean number of L. sat i vae and L. tri f olii reared per 5000 sq. cm of castor bean foliage collected, Belle Glade, FL (1984) 42 3.3 Mean number of adult parasitoids reared per 5000 sq cm foliage collected from L. sativae and L. trif olii on castor bean, Belle Glade, FL (1984) 44 3.4 Mean percent parasitism of L. sati vae and L. t r if olii on castor bean by larval and larval-pupal parasitoids, Belle Glade, FL (1984) 47 3.5 Mean growth of castor bean at EREC, Belle Glade, FL (1984) 51 3.6 Mean number of mines collected and L i r i omy z a adults reared per 3 rc x 3 m plot of castor bean, Belle Glade, FL (1984-85) 55 3.7 Mean number of larval and larval-pupal adult parasitoids reared per 3 m x 3 m plot from L. sati v ae and L. trif olii on castor bean. Belle Glade, FL (1984-85) 58 3.8 Mean percent larval and larval-pupal parasitism of L. sativae and L. trif olii on castor bean. Belle Glade, FL (1984-05) 59 4.1 Mean number of L. trifolii and total and larval parasitoids reared per two trifoliates of celery adjacent to castor bean, from twc sites at Belle Glade, FL (1985) 69 4.2 Mean number of L. trifolii and total and larval parasitoids collected per yellow sticky trap in celery adjacent to castor bean, from two sites at Belle Glade, FL (1985) 78 vi i

PAGE 8

5.1 Relationship of development time to temperature ( C) for the combined egg and larval (egg-larval) stage and the pupal stage of L. sativ ae on castor bean 94 5.2 Relationship of development rate (1/days x ICO) to temperature ( C) for the combined egg and larval (egg-larval) stage and the pupal stage of L. sativae on castor bean 97 5.3 Mean number of larval progeny produced per female per day throughout the life of L. sati vae on castor bean at 25 C 100 vii i

PAGE 9

Abstract of Dissertation Presentee to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CASTOR BEAK, Ricinus commu nis L AS A HOST OF Li r iomyaa LEAFKINERS (Diptera : Agromy zicae) IN THE EVERGLADES AGRICULTURAL AREA OF SCUTE FLORIDA By James Patrick Parkman Hay 19 87 Che ir man: Van H. Wad dill Cochairman: Joan A. Dusky Major Department: Entomology and Hematology A field study determined castor bean, Ricinus communis L., the most prominent host of leafminers and leafminer parasitoids of three weeds tested. Active mine populations peaked at 22 per 5000 sq cm of castor bean foliage during the first sampling period (May 24, 1984) Lir iomyza satiyae Blanchard and L. trifolii. (Burgess) accounted for ell leaf miner adults reared from foliage with the forme: comprising 63.3% of specimens collected. Eleven species of parasitoids were reared from Liriomyza Cpius spp. and Hal ticopt era ci rcu lus (Walker) were the most abundant. More than 9.6 adult parasitoids per 5000 sq. cm of foliage were reared May 24 and parasitism rates as high as IOCS occurred during three other samp] inc. ix

PAGE 10

periods. Abundance and performance of parasitoids varied with castor bean canopy layer. Leafniiner abundance on castor bean peaked again ir March and April 19 85 with 3 7 active mines per 9 m z plot occurring on April 22. Lir iom y za sati vae comprised 74.5% of Lir iomyz a collected from August 1984 to July 1985. Cpius spp. accounted for >85% of parasitoids reared and percent parasitism peaked during the weeks of April 8 and July 16 at 94.8 and 100%, respectively. Celery trifoliate collections suggested castor bean perhaps influenced leafminer parasitism in celery rows nearest the weed. Lir io myz a trifolii was the only leafminer reared from celery and Digly p hus intermedius (Girault) vvas the most abundant parasitoid reared from celery and collected on sticky traps. Lir iomyza trif oli i females exhibited a significant preference for celery as an oviposition substrate ever castorbean. Castor bean was preferred by L. sat i va e females for oviposition as they virtually rejected celery as a host. Development times for combined egg and larval stages were 13.22, 8.75, 6.31 and 6.17 d at 20, 25, 30 and 35 C for L. sati vae on castor bean. Pupal development; times were 15.33, 9.61 and 6.81 d at 2C, 2 5 and 3 0 C No pupae survived at 35 C. Females produced a mear. of 164 .49 larvae at 25 C on castor bean over an average lifespan of 13.36 a. Fecundity peaked at five days of age. x

PAGE 11

CHAPTFR I INTRODUCTION Celery, Apium q r aveoluns L. vat. dulce, is one of the major vegetable crops grown in Florida with 9300 acres planted in 1984-85, 7295 of those in the Everglades Agricultural Area around Belle Glade (Anon. 1986). A record total monetary value of $64,546,000 was recorded in 1983-84 (Anon. 1986) when the net return for growers in the Everglades region averaged $657.31 per acre (Taylor and Locascio 1985). A considerable amount of money ($680 per acre in 1983-84), however, is spent attempting to control pestiferous insect, weed and fungus species (Taylor and Locascio 1985) which would otherwise devastate the crop. The leaf mining fly Lir iom yza trifo lii (Burgess) is considered the most important insect pest of celery in the Belle Glade area (Guzman et al. 1973). Approximately half of insecticide costs for celery can be appropriated for control of L. trifoli i with as many as three treatments applied per week (K.D. P.emick, personal communication, 1987). Adult females damage leaves by ovipositing and creating feeding punctures. Larvae mine the leaves reducing photosynthetically active tissue, providing entry points for pathogens and causing cosmetic damage (Musgrave et al 1978) The tremendous reproductive potential of L. 1

PAGE 12

trifolii # ca. three times that of other economically important Lir iomyza spp. (Parrella and Keil 1984) enables the pest to reach exceedingly high densities in relatively short periods of time. Although L. trif o li i is currently the dominant, if net only, leafminer species attacking celery in Florida, earlier reports implicated a very similar species, L. sativa e Blanchard, as the major pest. A shift in dominance from the latter to the former species may have occurred as a result of L. trifolii s greater tolerance to insecticides (Parrella and Keil 1984). However, a shift in dominance may never have occurred. Rather, L. trifolii may have been misidentif ied as L. sati va e and/or its synonyms in these early studies as the two are sympatric, highly polypbagous (sharing many of the same host plants) and very similar morphologically (Spencer and Stegmaier 1S73, Stegmaier 1981). The doubts surrounding this possible misidentif icaticn have impeded interpretation of results cf earlier studies and hampered their utilization in recent control efforts. The aforementioned tolerance to insecticides is probably the major cause for L. tr ifoj ii 's prominence among celery pests. The widespread, sometimes non judicious use of a variety of compounds on celery and other vegetables (Leibee 1981) coupled with the species' large reproductive potential have inevitably allowed for the evolution arid continuation of insecticide resistance. Also, considerable

PAGE 13

1. mortality potentially inflicted by the large parasitoid complex attacking L. trifolii has been negated in most cases by the detrimental effects of insecticides upon the parasitoids, further aggravating the problem (Poe et al 1978, Waddill 1981) The failure of various chemical insecticides to provide adequate and economically sound leafminer control plus increasing concern of the effects of such compounds within the environment have prompted research of control tactics and insecticides emphasizing the conservation and utilization of parasitoids (Genung et al 1978, Schuster and Frice 1985, Trumble and Toscano 1983, T rumble 1985). The contribution host plants other than the crop may make towards parasitoid incidence has also been reported. Schuster et al (1982) found high rates of Lir io iry za parasitism occurring on weeds near tomato fields on Florida's gulf coast while Genung and Janes (1975) and Genung et al (1978) working near Belle Glace noted higher rates of leafminer parasitism in celery nearest field borders adjacent to weeds. Genung (1981) stated certain weeds which harbor natural enemies of Liriomyza may even be considered beneficial when occurring near celery fields. Despite this knowledge, no studies have been undertaken tc examine this component of the celery agroecosystem in south Florida. Certain weed species in this region are reported to serve as hosts of L sativae but not L. trifolii (Stegmaier 1981). Also, the two leafminer

PAGE 14

4 species are attacked by many of the same parasitoids (Chandler 1982, Stegmaier 1981). Considering these reports plus the fact that L. sati vae in Florida presumably no longer attacks celery, the potential exists for the manipulation of a weed host of L. sati vae in hopes of increasing parasitism of L. tr if olii within celery. The objectives of the following studies were to investigate this comparatively unknown area of leafminer biological control by first determining leafminer and leafminer parasitoid incidence and abundance on weeds reported as hosts of Lir iomyza species in south Florida; to determine the effect of castor bean, F.icinus communis L on Lir iomyza and parasitoid occurrence within adjacent celery plots; and to determine the preference for celery and castor bean by L. tr if olii and sa ti vae as well as the biology of the latter on castor bean.

PAGE 15

CHAPTER II LITERATURE REVIEW Systematics of Liriomyza t r ifolii (E urgess) and L sativae Bianch a rd There are over 300 species of Li r iomyza worldwide, 78 within the United States, and many are polyphagous (Spencer 1981b). The taxonomic history of the genus is marked by confusion and misidentif ications and only recently has the systematics of this group been relatively clarified (Spencer 1973, Spencer and Stegmaier 1973, Spencer 1981a). Indicative of this confusion are the taxonomic histories of L trifoli i and L sativae Burgess in 1880 first described L. tri fo lii as Osci nis trifolii collected on white clover in the District of Columbia. 0. trif oli i and 0. bras s icae Riley were synonym i zed with Agromy z a diminut a Walker by Coquillet (1898) and Malloch (1913) synonymized 0. trifolii and 0. brassicae with A. pusilla Meigen. Melander (1913) synonymized A. di min uta Walker with A. scu tel lata Fallen and used the name Liriomyza without placing A. scutel lata in it. A. pusilla was reported to occur on 24 different host species by Webster and Parks (1913) although Spencer (1981b) later reported they were working with L. trifolii L sativae L. huidob ren sis (Bianchard) and other species. 5

PAGE 16

In 19 25 de Meniere placed 0. t rif oli i in the genus Lir iomyza and noted the synonymy of A. trifolii (Burgess) Coquillet 1898 and A. trifolii Kaltenbach 1874 (Zoebisch 19 84) now considered a homonymy of A. nan a (Meigen) 183 0 (Spencer 1981b). Zoebisch (1984) stated this homonymy violates article 35 of the International Commission on Zoological Nomenclature (Schenk and McMasters 1936), thus, L. trifolii should be renamed. L. alli vora (Frick 1955) and L. arc hiboldi (Frost 1962) have recently been synonymized with L. t rif oli i by Spencer (1981a) h.' sa ti vae occurring on alfalfa in Argentina, was first described by Blanchard in 1938 (Spencer 1981a). In 1952 Frick described three species from Hawaii, L. pul lata canomarcin is and minu s eta all synonymized with L. sati vae by Spencer (1973) Spencer also synonym; i zed L. munda reared from tomatoes in California by Frick (1957) with L. sativae (Spencer 1973). L. guytona Freeman (1958) collected in Alabama was synonymized with L. round a by Steyskai (1964) and later with L. sativae by Spencer (1973). In 1973 Steyskal synonymized L. propepusilla Frost with L. rounoa L. prop epusilla had originally been described as A. subp usil ia by Frost in 1943 but was renamed by him in 1954. Frick (1957) applied the name A. pictella originally described by Thomson in 1869 (Spencer 1981b) to specimens he reared from 16 different hosts. Spencer (198]b) notes he was dealing with at least six different species one being a color variant of L. sativa e The name pictella however,

PAGE 17

7 became widely used and Oatman and Michelbacher (1958) and Oatman ( 1959a 1959b ) published studies on the biology, ecology, and host range of L. pictel la the "melon leaf miner Crossbreeding studies utilizing L. pictell a and L. sati vae (as L. munda) the "tomato leafminer," were also conducted (Oatman 1961) Spencer (1981b) believes the "melon leafminer" and L. munda of these experiments to possibly represent different host strains differentiating on tomato and melon. Mo specimens were preserved, disallowing later determinations of the species. Jensen and Koehler (197C) reported on the seasonal and distributional abundance of two species on alfalfa, L. sati vae (as L. munda) and L. trif oliearum which was undescribed at the time but misidentif ied by the authors as L. pictella (Spencer 1581b). Spencer (1973) noted L. sativae and L. tri folii coulc be easily confused. They are quite similar morphologically, sympatric and they have several host plants in common (Stegmaier 1981). To add to the confusion, Poe and Montz (1981) suggested that the predominance within a host crop may shift from one species to another due to differential resistance to particular insecticides. Therefore, ever, recent reports and studies concerning L sativae and L. trifo lii may contain a mis iden tif icat ion of one species as the other.

PAGE 18

e Descr i ptions of L. trif o lii an d L. sat ivae L. tr if oli i and sativae adults are very small flies with wing lengths of 1.25-1.90 mm and 1.25-1.70 mm, respectively (Spencer 1981a). Spencer (1965) described a neotype of L. trifolii stored in the U.S. National Museum and Spencer and Stegmaier (1973) gave a similar description: Orbits entirely yellow, both vertical bristles on yellow ground; all antennal segments bright yellow, third with inconspicuous pubescence; mesonotum blackish gray, distinctly mat, acrostichals in 3 or 4 rows in front, reduced to 2 rows behind, yellow patch at each hind corner adjoining scutellum, mesopleura with black patch extending along lower margin; abdomen with tergites variably yellow laterally and on hind margins; legs: coxae yellow, femora largely so but with slight, variable brownish striation; tibia and tarsi darker, brown (p. 109) Although very similar in appearance, L. sativae adults differ morphologically from those of L. tr if oli i in several characteristics. The hind margin of the eye of L. sativae is entirely dark, or nearly so, extending to the base of the outer vertical bristle and frequently along the upper orbits beside the eye margin. Even more conspicuous is the mesonotum which is deep black and shinirg on L. s ativ ae (Spencer 1981b). To make a definite distinction betweer the two species, the aedeagus must be examined. Spencer and Stegmaier (1973) and Spencer (1981a) gave illustration:-, of the male genitalia of the two species.

PAGE 19

9 Differences in female genitalia were described by Knodel-Montz and Poe (1982) using scanning electrcn microscopy. The denticles of L. trif o lii are angular and the egg-guide is V-shaped while the denticles and egg-guide of L. sativae are elongate and acutely angled, respectively. Zehnder et al (1983), using scanning electrcn microscopy, found a dense covering of microsetae on the mesonotum of L. trifolii which gives it a mat-grey appearance. The shiny black mesonotum of L. sati vae resulted from having few microsetae The larvae and leafmines of the two species are very similar and can not be distinguished visually although Spencer and Stegmaier (1973) noted the mines of L. trifolii are generally longer. Menken and Ulenberg (1986), however, distinguished between the larvae as well as the pupae and adults of four Lir io myza species, including trifolii end sativae by allczyme analysis using starch gel electrophoresis. Different enzyme mobilities were also reported by Zehnder et al (1983) for L. trifolii sativae and brassicae. Host food and geographic site of location did not influence enzyme mobility for conspecific strains of L. trifoli i and sativae

PAGE 20

Distributions and Host Ranges 10 Although distributed throughout the world, the genus Liriomyza is best represented in the neotropical region (Spencer and Stegmaier 1973, Spencer lS81a). L. trifolii has been recorded from North America, South America, the Caribbean, Africa and Europe (Bartlett and Powell 1981, d'Aguillar and Martinez 1979, deLima 1979, Fagoonee and Toory 1984, Frick 1959, Poe and Montz 1981, Spencer 1985, Spencer and Stegmaier 1973). Ontario is the northern limit of its range (Spencer and Stegmaier 1973) and it has been reported as far south as Colombia (Poe and Montz 1981) Much of the movement of L. trifo li i into areas outside of North America is believed to have occurred or infested plant parts (Poe and Montz 1981). Reports and outbreaks of L. t rif olii in Kenya (deLima 1979), the Netherlands (Spencer 1981a), Great Britain (Anon. 1977) and Colombia (Price 1982) are believed to have resulted from importation of infested chrysanthemum cuttings from the U.S., particularly Florida (Price 1981, Spencer 1981a). L sati vae is recorded from Alabama, California, Florida, Ohio, South Carolina, Tennessee and Texas, and frcm Mexico, Central America, South America, Cuba, Jamaica and Barbados (Kusgrave et al 1975b, Spencer 1981a). Although reported from Hawaii Guam and Tahiti, occurrence?, in these areas are probably due to recent introductions (Musgrave et al. 1975b).

PAGE 21

11 Both species are highly polyphagous and many hosts are attacked by both species. Patel (1986) compiled a list of hosts for L. trif oli i from sources published, since 1981 when Spencer's report (1981b) alleviated much of the confusion concerning identification of the species. Patel (1986) recorded 144 hosts worldwide in 32 families, the most widely attacked being Asteraceae (=Compositae ) (46 spp.), Cruciferae (10 spp.), Cucurbitaceae (£ spp.), Fabaceae (=Leguminosae) (17 spp.) and Solanaceae (12 spp.). L sati vae (as L munda ) was found on 3 7 host species in 1C families in Florida (Stegmaier 1966a) Musgrave et al (1975b) reported 60 hosts of L. sat i vae in 14 families, with Asteraceae (=Compositae ) (16 spp.), Fabaceae (=Leguminosae) (14 spp.) and Solanaceae (9 spp.) most heavily attacked. The most economically important host species reported for L. sati vae occur in the families Curcubitaceae (watermelon, cucumber and squash), Fabeceee (=Leguminoseae) (alfalfa, clover, peas and lima beans), Solanaceae (tomato, eggplant and potato) and Umbel li ferae (celery and carrot) (Musgrave et al 1975b, Tryon 1979). Li f e Hi st ory and B i olo gy A Liripjnyzc. (Liriomyza =_.L. tri folii and L. sati vae) female lays eggs singly within the leaf mesophyil, inserting

PAGE 22

her ovipositor through the epidermis, creating a puncture or "stipple". A female often creates stipples without depositing eggs, feeding from the exudates of ruptured cells (Trumble 1S81) Oviposition stipples are smaller than feeding stipples (Zoebisch 1984). Eggs are oblong, creamy white, and 0.25 to 0.30 mm long and 0.10 to 0.20 mm wide (Patel 1986). Eggs increase in size after deposition and darken as they mature (Dimetry 1971, Patel 1986). Upon hatching the first instar begins feeding upon the palisade parynchema cells creating a serpentine mine which widens as the larva develops. Newly emerged larvae are 0.12 mm long (Patel 1986) and mature through three instars to a length of two to three mm (Zoebisch 1984). Completing development, a third instar larva chews a semicircular hole in the epidermis, exits the leaf and drops to the ground to pupate Liriomyza pupates, as do all cyclor rhaphan Dipt era, within the cuticle of the last larval instar, the puparia. Adults can mate within one day of emergence (Patel 1986; and females feed from stippling punctures, while males apparently do not (Zoebisch and Schuster,unpublished data). Both have been demonstrated to feed from other nutrient sources such as honey dew (Zoebisch, and Schuster, unpublished data ) Developmental tines for Liri omyza life stages are affected by temperature and may also vary with host plant. Egg development of L trif olii on celery was 1.99 d at 35

PAGE 23

13 C, but 9.97 d at 15 C (Leibee 1984). Charlton and Allen (1981) reported similar results for L. trif olii on pink beans ( Phaseolus sp.); however, at lower temperatures (20 and 25 C) egg development took longer when chrysanthemum was the host Larval development of L. trifolii on pink beans ranged from 3.4 d (32.5 C) to 30.9 d (13.8 C) (Charlton and Allen 1981) Similar development times were recorded for L. trifolii on chrysanthemums (Charlton and Allen 1981) and tomato (Schuster and Patel 1985). Celery, however, apparently increases L. trifolii larval development time. Larvae feeding on celery required 3.1, 3.5, 5.3 and 13.2 d longer to develop at 30, 25, 20 and 15 C, respectively, than when utilizing pink beans as a host (CharltGn and Allen 1981, Leibee 1984) Pupal development times for L. t r i f oli j on celerydecreased from 28.2 d at 15 C to 6.7 d at 35 C (Leibee 1984). Pupae of L. tri folii individuals reared on pink beans and chrysanthemums exhibited similar development times (Charlton and Allen 1981). Longevity of adults is dependent on availability arid quality of food source as well as temperature. Unfed adult ktrifolii survived only 3 d at 23.8 C (Charlton and Allen 1981). In the same study females and males lived 7.2 and 2.3 d, respectively, when offered blackeyed pea foliage, but 22.7 and 13.9 d, respectively, when offeree the same foliage plus honey. Female L. t rifolii ovipositing and feeding en

PAGE 24

celery survived 13.0 d at 35 C and 27.7 d at 15 C C with a 10% honey supplement (Leibee IS 84) Parrella (1984) reported L. trifoli i adults lived for 3.1 and 16.7 d at 37. and 15.6 C, respectively, on chrysanthemum and honey. Fecundity is also apparently affected by temperature, nutrient availability, and in addition, age of female. L. trif oli i produced an average of 177 eggs per female on blackeyed pea foliage and 43S eggs when presented foliage plus honey (Charlton and Allen 1981). L. tr if olii females were most fecund at 26.7 C averaging 278.9 eggs per individual and least fecund at 37.8 C (0.9 egg per individual) on chrysanthemum on honey (Parrella 1984). On celery, females with a honey supplement produced considerably more eggs with a maximum of 405.7 per individual deposited at 30 C (Leibee 1984). Only 24.3 egg were produced at 35 C. Greatest egg deposition per female per day (35 to 39 eggs) occurred at 1, 2 and 4 d of age at 35, 30 and 25 C, respectively (Leibee 1984). Parrella (1984! found greatest oviposition occurred at 2, 4, 8, 10 and 16 d of ace at 37.8 32 .2, 26.7, 21.1 and 15.6 C, respectively.for L. trifoli i Extremes in temperature are known to influence mortality of L. trifo lii pupae. Finety-twc percent of pupa perished at 35 C; however, only 1C% died at 15 C (Leibee 1984). All pupae reared from chrysanthemum died at 37.8 C (Parrella et al 1983c).

PAGE 25

Results of Charlton and Allen (1981) suggest host species may affect leafminer survival. Total percent mortality for L. trifo] ii was 26.9, 26.8, 52.6 and 99.0 when reared on pink bean, blackeyed pea, x Show-off chrysanthemum and ^Yellow Knight' chrysanthemum, respectively L. t rifolii apparently exhibits a diurnal pattern in its behavior. Charlton and Allen (1981) found larval emergence occurs most frequently from 0830 to 1230 and adult emergence from the soil peaks from 093 C to 1230. No adult emergence occurred before 0830 and after ]430. Most eggs are deposited from 1130 to 1530. Feeding occurred throughout the daylight hours. Due to the emergence of L. t rifolii as the dominant economic pest in the last 1C years, most recent biological studies have been concerned with this species. Earlier results from studies of L. sativae, as L. pictel la (Catn.an and Michelbacher 1958, Oatman 1959a, I960) and as part of the serpentine leafminer complex (Cenung and Harris 1961), are questionable since it is possible L sati vae was not the only species involved.

PAGE 26

16 Control of Liriomyza on Celery Chemical Control Leafminers were not considered pests of celery and other vegetables in Florida until the mid-1940s when the use of chlorinated hydrocarbon insecticides became widespread (Earanowski 1958, Leibee 1981) Chlordane was recommended for leafminer control on potatoes by Wclfenbarger (1947); however, it and other chlorinated hydrocarbons such as BBC and aldrin had lost their effectiveness after the first or second season of use (Wol fenbarger 1958). Since then, several insecticides reported in the past as giving satisfactory leafminer control have become ineffective. Leibee (1981) gave an account of the history cf leafminer control with insecticides which is summarized below. Toxaphene gave satisfactory control from 15 47 to 1952, then decreased in effectiveness as did parathion, after 10 years of use, by the 1956-57 season. Diazinon, recommended for only two to three years, provided poor control on vegetables in south Florida by the early 1960s. reported as giving adequate control on celery in 1962, diazinon and naled had become ineffective by 1974, as had azinphosmethyl. Dimethcate, approved for use on celerv in that year, also failed to give a desired level cf control. Oxamyi and permethrin, approved for celery use in 1975 and 1978, respectively, became relatively ineffective ir two

PAGE 27

17 years or less and me thamidiphos registered in IS 77, has exhibited decreased effectiveness. The history of leafminer control in California, another major celery-producing region, is not as involved as that of Florida. The major leafminer pest of celery there, up until ca 19 80, was L. sa ti vae which only reached economic levels every five to 10 years and is satisfactorily controlled with insecticides (Trurnble 1981). However, b. trif oli i supposedly introduced from Florida, emerged as the major pest since ca 1980 and its history of resistance to insecticides in California is consistent with those fr another states where this species is a serious problem (Parrella et al 1981a) Insecticide resistance due to extensive use of these compounds and. the detrimental effects they have upon leafminer parasitoids have resulted in an almost comp] ete breakdown of past Lir io my za control programs. Use of DDT for celery pests other than leaf miners probably caused cross resistance to permethrin, a pyrethroic (Deibee 1981). Hymenopteran parasitoids are very susceptible to breadspectrum insecticides such as chlorinated hydrocarbons (Earanowski 1958, 1959) and carbamates (Catrnan and Kennedy 1976, Waddill 1978). If leafminer populations have developed resistance to these compounds, the effects of parasitoiu mortality are greatly e :;ace r tat ed Insect growth regulators (IGR's), chemical compounds which disrupt or inhibit normal growth processes, have

PAGE 28

recently exhibited promise for Li r iomy za control as they are potentially compatible with biological control agents due to their low toxicity, host specificity and nonpersistence in the environment (Parrella et al 1982). Significant leafminer larval mortality (Parrella et al 1983a) and. sublethal effects on adults exposed as larvae (Robb and Parrella 1984) have been reported for IGR treatments. Trumble (1985) and Parrella et al (1983a) reported that IGR's did not significantly reduce survival of parasitoids although Trumble found cyromazine significantly reduced abundance of some key parasitoid species in celery. An extract of seeds from the neem tree, Azadi rachta indica A. Juss, has also recently received attention as a broad-spectrum insect antifeedant and pesticide (Webb et al 1983). Foliar applications reduced L. trif olii ovipositiop and caused greater than 9 8% L. trif olii and sativae larval mortality (Webb et al 1963). Soil applications also reduced survival of L trifoli i larvae and pupae, although oviposition and adult feeding were not inhibited (KnodelMontz et al 1985, Larew et al 1985). Current] y, Florida celery growers, as well as those in California, rely on cyromazine (Trigard ) a larvicide, methamidiphos (Monitor), a larvicide and adulticide, and permethrin (Ambush), an adulticide, for L iriomvza control (P..F. Foster, personal communication, 1986). In the Belle Glade area cyromazine is usually applied at 0.3 25 lb Al per acre once a week during normal infestations while

PAGE 29

methamidiphos and permethrin are applied at 1.0 lb and 0.2 lb AI per acre, respectively, as often as two to three tiir.es a week (R.E. Foster, personal communication, 1986). Natura l Cont rol by Parasitoid s Parasitoids of various species in several families play an important role in the natural regulation of Lir iomyza and other agromyzids (Griffiths 1962, Oatman 1959b) Webster and Parks (1913) presented one of the earliest records of Lir iomyza (as Agr omy za ) parasitoids reporting 28 spp. reared from pusilla on alfalfa and other forages with Digl y phus (as Diaulinus ) begin i (Asbmead) as the most important. Hills and Taylor (1951) reported 10 spp. of parasitoids representing five families of Hymenoptera from Lir iomyza spp. on lettuce and cantaloupe with parasitism rates ranging from 0-100%. Oatman (1959b) found 19 spp. representing si>: families attacking L. pictella in California and noted D. (as Sol enotug ) beg ini and Haltico ptera aen ea (Walker) were the most prevalent species. Harding (1965) reported 21 spp. of parasitoids in four families attacking L. nun da on 13 vegetablecrop?, arid two weed spp. in the winter garden area of Texas, wrile Stegmaier (1966a, 1966b) reared five and nine spp. from L. sativ ae (as munda) and L. trif olii respectively, in south Flor ida

PAGE 30

20 Lir iomyz a sa ti vae parasitoid complex composition and abundance were reported by Oatman and Kennedy (1976) and Johnson et al (1980b) for California tomatoes and by McClanahan (1977) for greenhouse beans in Canada. Digiy phus begini Chrysonotomvia punctiventr is (Crawford) and O pius dimidiatus (Ashmead) were the most abundant species reared from host larvae and pupae. Chandler (1982) found eight spp. of parasitoids attacking L. sati vae and trif olii on cantaloupe in Texas but noted, under optimal environmental conditions leafminer populations increase too rapidly for effective control by parasitoids. Pee and Montz (1981) listed 53 parasitoid spp. from five families reported from, four economically important Lir iomyza species: L. trif oli i sativa e huidobrensis and br as sicae (Riley) Most parasitoid species (31 in 11 genera) occurred in the family Eulophidae In Florida, Genung and Janes (1975) reared several species of parasitoids from both leafminer-inf ested celery and weeds in the Belle Glade area with parasitism rates as high as 100 and 94% from the weeds dog fennel, Eu pa tori urn capil l if oli u rn (Lam.), and water pennywort, Hydrocotyle umbellata L. respectively. Thirty-two percent parasitism occurred on celery. Genung (1981) surveyed important weed hosts in the celery-growing region near Belie Glade and observed parasitism was more prevalent in celery nearest weedy borders. Parasitism rates of ca. 90% were determined for Liriomyza in California celery (Trumble and Nakakihara

PAGE 31

21 1983). Diglyphus in terme dius (Girault) and D. begin! were the most prevalent parasitoids reared. Detrimental effects of DDT, methoxychlor dieldrin, endrin, and lindane on Liriomyza parasitoids were noted by Wene (1955) and by Getzin (196C) for diazinon, parathion, and ethion. Baranowski (1958) stated DDT use was a major factor of ineffective control of Lir iomyza in pole beans in south Florida, while Oatman (1959b) noted the same effect of such chlorinated hydrocarbons on parasitoids of Liriomyza in California melons. Methomyl was found to be most injurious to parasitoids in tomatoes while causing increases ir. L. sativae populations (Johnson et al 1980a, Oatman and Kennedy 1976) Parasitization by Chrysochar is p a rksi Crawford was reduced ca. 40% at the lower treatment rate of methomyl (Johnson et al 1980a). Schuster and Price (1985) found methomyl and permethrin significantly reduced the number of parasitoids reared from treated tomato foliage and leafminer pupae collected from treated foliage. Zehnder and Trumble (1985) also determined permethrin to be most injurious to leafminer parasitoids of six insecticides tested Insecticides which increase mortality cf ie af miners without a similar increase in parasitoid mortality have been studied for incorporation into pest management programs. Trumble and Toscano (198?) found methamidiphos allowed for 50% more parasitism of leaf miners in celery than, methomyl. Trumble Q985) suppressed leafminer populations in celery

PAGE 32

22 with abamectin (=avermect in ) a neural transmission inhibitor without adversely affecting percent parasitism, adult parasitoid mortality or immature parasitoid survival and emergence. He determined abamectin the most suitable compound of those tested for integration into a pest management program for L. t rifoli i in celery. Although applied only for lepidopterous larvae control, the biological insecticide Dipel B acillus thu r ingi ensis var. kerstak i and chlordimef orm a lepidopteran ovicide, proved least injurious to the major leafminer parasitoids D. begin! and C. punctiven t r is when applied in combination to tomatoes (Johnson et al 1980b). Ef fects of Cultur al Methods Polyethylene mulches and staking of tomatoes increased Lir iomyz a and, consequently, Li r iom y 2 a parasitoid incidence. Plants which were both mulched and staked contained greatest leafminer infestations (Price and Foe 1976) Percent parasitism was highest on nonstaked plants. Webb and Smith (1973) found mulched snap beans contained mote L. sativ ae (as L. munda ) than nonmulched beans, but aluminum foil mulches apparently repelled Li r iomyza spp. in tomatoes and squash (Wclfenbarger and Moore 1968). Increased fertilization resulted ir increased Li r iomy z a survival (as percentage of mines completed: on chrysanthemums (Foe et al 1976). Average number of mines per leaf and percent leaves infested did not vary

PAGE 33

23 signif icantly with fertilization rates. Woitz and Kelsheimer (1958), however, found chrysanthemum with higher levels of nitrogen most heavily damaged by leaf miners. Harbaugh et al (1983) reported L. trifolii damage of chrysanthemum increased, linearly as leaf nitrogen increased from 2.2 to 4.0%. Sanitation in celery (i.e. plowing under of crop debris and weed control) is considered the mcst effective method of cultural control of leafminers (Guzman et al 1973) although weeds on field borders harbor many beneficial arthropod species capable of inflicting significant mortality upon Lir iomyz a (Genung and Janes 1975, Genung 1981). Seedbed clippings, which contained ca 50% of the seedbed leaf miner population, were implicated as source:, of reinf estation and a recommendation was made to cci Iceland destroy them (Genung and Janes 1975). Sanitation is also considered important for leafminer contro] ir chrysanthemums (Short and Price 1981). Postharvest flooding of fields is an important technique in controlling nematodes, soil-borne diseases, weeds and insects in celery (Guzman et al 1973, Genung 1976). This measure, however, probably does little to decrease leafminer populations in celery except for controlling certain weeds that may serve as hosts of Lir io myza (Jean Dusky, persona] commun icat i on 1986).

PAGE 34

24 Pes t Management in Celery In the mid-1970s a pest management program for celery in the Belle Glade area was devised and evaluated utilizing insect, disease, and weed surveys (Genung et al 1978). A second study emphasized factors pertaining to celery growth and composition and concluded the program "in all cases reduced the use of pesticides, was less expensive, and savings were more than adequate to compensate for scouting" (Guzman et al 1979). The current strategy for L. trifo lii used by seme Belle Glade area growers consists of monitoring fields daily, collecting celery trifoliate samples and estimating fluctuations in leafminer density utilizing the pupa] drop count method of Fester (1986). Decisions to treat are not based on economic thresholds but on changes in population levels and effectiveness of prior treatments (E.E. Foster, personal communication, 1986). C elery Prod uctien In the Everglades region of south Florida celery plants are grown from seed in raised seedbeds containing an irrigation and drainage network. Seedbeds are covered by shading structures from May to October during the first five weeks after seeding when unshaded soil surface temperatures are too hot for seed germination. The tops of seedlings are

PAGE 35

25 trimmed to toughen the lower tissues thus better enabling the plants to withstand the shock of transplanting. Depending on the season, two to eight toppings are made. Seedlings are grown from May until early April and take an average of 70 d to reach transplanting stage (Guzman et a] 1973) Transplanting of seedlings from seedbed to field occurs from early August to April. Seedlings are pulled and boxed by hand, watered, then transplanted by workers using transplanting equipment. Immediately after transplanting, the celery is overhead-irrigated until water is standing in the field. The water table, manipulated by sub-irrigation, is kept as high as possible before and after transplanting, but after plants have recovered from transplant shock it is maintained at 18 to 20 inches. Harvesting occurs from November to late June with mean time from transplanting to harvest being SO days (Guzman et al 1973). Five varieties constitute practically all the celery grown in the Belle Glade area. Florida 683K strain, the most widely grown, is used for the major crop in mid-winter as it is susceptible to early blight and leafminers and bolts early. June Belle variety, slightly resistant to early blight and not as prone to bolting as 683k during prolonged cold periods at early growth stages, is the second most popular variety and is grown in the late spring. Recently released for early fail plantings, Floribelle (EREC M9 line) has good resistance to early blight, some tolerance

PAGE 36

to bacterial leaf spot and some leafminer resistance and is the next most popular variety. Florida Slobolt (EREC M6829-5), just released for harvest in April and early May, ha long ribs and good resistance to early blight, premature seeding and bolting. Once the most widely grown variety, Florida 2-14 is very attractive to leafminers and, therefore, its popularity has declined considerably in the last decade (E.A. Wolf, personal communication, 1986). Seedbeds and fields are plowed, disked, levelled and flooded. After drying they are plowed, disked, levelled, mole-drained, and fertilized prior to transplanting. The flooding procedure entails four weeks of flooding, two of drying, then four more of flooding which is necessary to insure mortality of the hardiest pests such as wireworms. Soil fumigation of seedbeds and applications of insecticides, herbicides, and fungicides to the crop, in addition tc flooding, are required to assure adequate yield Soil pH is often adjusted with applications of sulfur usually incorporated at the time of fertilization (Guzman el al. 1973). The first commercial celery planting in Florida made in 1897 at Sanford was 0.75 of an acre and netted S1,30C (Guzman et al 1973). In 1984-85, 9,300 acres of celery were planted in Florida (7,295 in the Everglades area); 8,600 of these were harvested yielding an average of 665 crates per acre (one crate-60 lbs). Season average monetary value was $6.38 per crate resulting in a total value of

PAGE 37

27 £36,515,000, down from the record value recorded in 1983-84 cf $64,546,000 (Anon. 1986). Beneficial Aspects of Weeds Weeds are primarily considered competitors cf crops for sunlight, water and soil nutrients and often as reservoirs for pestiferous arthropod species and plant pathogens. However, certain ecological and physiological aspects documented in recent decades have proven the beneficial role of certain species and their potential for use through manipulation in pest management systems (Altieri and Whitcomb 1979a) Ecosystems consisting of many and varied plant species are known to contain a greater variety of insect species (Fimentel 1961, Risch et al 1983). Consequently, pest mortality due to natural enemies in such systems is often greater than in less diversified ones. Altieri et al (1978) found 26, 45 and 14% fewer leaf hoppers, Emp c asc a kraemer i Ross and Moore, banded cucumber beetles, Pi a bro t i ca baltea ta Le Conte, and fall armyworras, Spodoptera f rug i per da J.E. Smith, respectively, in a bean-corn polycuiture than in bean or corn alone. Presence of weeds enhanced precaticn and/or parasitism of cabbage white butterfly larvae, Pier is rapae (L ) in brussels sprouts (Dempster 1969), fall armyworm in corn (Altieri and Whitcomb 1980) and Mexican

PAGE 38

28 bean beetle, Epila c hna var ivestis Mulsant, in soybeans (Shelton and Edwards 1983). Predation by fire ants, Solenopsis invict a Buren, in sugar cane was also enhanced (Ali et al 1984). Pisch et al (1983) noted, however, that herbivore movement patterns may be more important than natural enemy activity in explaining reduction of certain pest populations in diverse annual systems. Nonpestiferous herbivores on weeds may serve as prey/host sources for beneficials, thus increasing the survival and possibly, population levels of these entomophagous species (Altieri and Whit comb 1979a, Perrin 1975). Surveys by Need ham (1948) of Spanish needle, Bicens pilos a L., Stegmaier (1971, 1973) of common ragweed, Amb r o s i a artemisifolia L ., and joe-pye weed, Eupator ium c oelestinum L and Altieri and Whitcomb (1979b) cf Mexican tea, Chenopodium amb ros icides L determined certain weeds can harbor an assortment of arthropod, species. A famous example of a natural enemy utilizing alternate hosts on a non-crop plant is that of the leaf hopper parasitoid, fenagus epo Girault, which attacks eggs of a nonpestiferous species year round on wild R ub us spp. (Doutt and Nakata 1973) In summer, individuals migrate to grape to parasitize eggs of the grape leaf hopper, Er ythr on eura eleg antu la Osborn, inflicting severe mortality in early season on this important pest. Weeds may also serve as sources cf airino acids and carbohydrates for beneficials. Syme (1975) determined

PAGE 39

29 longevity of individuals of two parasitoids of the European pine shoot moth, Rhyacionia buol iana (Schif f e rmuelle r ) increased when feeding on various flowers ever that of starved controls. Fecundity of individuals of one species fed flowers increased over those being fed honey. Leius (1967) reported 18 times as many tent caterpillars, Malacosoma amer i can u rn (F.), pupae were parasitized in orchards with a rich undergrowth of wildflowers as in those with poor wildf lower undergrowth. Certain non-crop plants are believed to act as pest repellants or inhibitors, thus protecting crops when the two plant species occur together. Flea beetles, Phyl lotre ta crucif erae Goeze, were significantly less attracted to a combination of collards and common ragweed than collards alone in laboratory experiments (Tahvanainen and Root 1972) Altieri et al (1977) and Schoonhoven et al (1981) determined populations of the leafhopper E. kra emer i on beans were decreased by the presence of the crass weeds L epto ch loa f ili forrnis (Lam.) and Eleusine indica (L.) Gaertn. The grasses either repelled the pest, inhibited feeding or masked attractive odors of the crop. Reduction in crop apparency (Feeny 1576) resulting from weed occurrence may also influence pest and nature:] enemy populations (Ferrin and Phillips 1978, Altieri and Whitcomb 1979a). Smith (1969) found larger population:-, of cabbage aphid, Bre^icoryjTe b^as sicae. (L ) and whitefly, Aleyrodes brassicae (Wlk.), on brussels sprouts in

PAGE 40

30 cultivated plots with bare soil than in plots with a weed cover. These results were confirmed by Horn (1981) working with green peach aphid, Myzus persicae (Sulzer), on collards Smith (1976) also discovered certain predators were plant oriented. The syrphids He lane stom a spp. and Platychei rus spp. and an anthocorid, A nthocor is sp., were apparently attracted to v/eedy plots for oviposition. A prey-oriented syrphid, Syrphus balteatus DeGeer, was attracted to brussels sprouts which harbored more aphids. Surveys of weed hosts of Lir iomyza spp. have been conducted (Harding 1965, Stegmaier 1966a, 1966b, Spencer 1981a), but few studies have attempted to assess the impact these alternate hosts have on vegetable agroecosystems Schuster et al (1982) found downy groundcherry Physalis pubes cen s L. (reported as groundcherry, P. angulata L ) American black nightshade, Solan urn amer i can urn Mill, (reported as black nightshade, S. nigrum L.) and common beggartick, Eid ens alba (L.) (reported as Spanish needle, Bidens spp.), the most important weed hosts of Lir iomyza adjacent to tomato fields. Over 80% parasitism was found for mines collected from these and other weeds of the tomato field borders surveyed. Zoebisch (1984) studied the suitability of the three weed species mentioned above and tomato as hosts for torcatcand weed-reared L. tri folii in the laboratory. American black nightshade proved the most suitable of the weed hosts

PAGE 41

as tomato-reared females preferred it and tomato as oviposition substrates and fecundity was greatest on these two hosts. Genung and Janes (1975) found 22 plant species, most of them composites, as important weed hosts of L. trif olii in the celery agroecosystem near Belle Glade. Parasitism rates greater than 90% occurred on four species of weeds surveyed. Although potential sources of pestiferous arthropods, virus infection, and infield weed infest at i c n Genung (1981) stated "weedy marginal and interior ditchbanks in celery fields are more beneficial, through actual conservation of parasites and predators of leafminers and other insects, than detrimental" (p. 68). Descri p tion, Histor y and S tatus of C as torbea n Castor bean, Ri c inus communis L. is a member of the family Euphorbiaceae commonly called the spurge family, predominantly indigenous to the tropics. Castor bean is th only species of Ric i nus but it includes many polymorphic types ranging from large perennials resembling small trees to short-lived dwarf annuals. The erect, partially hollow stem is marked by well-defined nodes from each of which a leaf arises. Leaves are glossy green, large-bladed and palmate with five to 11 lobes. Flowers are normally monoecious appearing terminally on main and lateral

PAGE 42

32 branches. The fruit is roundish, three-sided, covered with spines, and divided into three loculi. Seeds, one to a locule, are broad, oval, compressed, of variegated color, oleaginous, and very poisonous (Weiss 1971). Domesticated in prehistoric times, castor bean is considered Ethiopean in origin. Oil extracted from the seeds was used as lamp oil, for annointments as a medicine acting as a purgative and as a lubricant. Seeds were an important item of commerce in ancient Egypt and their uses have appeared in ancient Greek, Roman, Indian, Hebrew and Chinese writings. First introduced into England in 1548, castor bean probably entered the New World with the slave trade (Weiss 1971) Today, oil from, the seed is used primarily in resins, plastics, paint, and varnishes (Weiss 1971). World seed production for the 1984-5 season was one million metric tons with India the largest producer (385 COO metric tons). The Soviet Union, West Germany, the Netherlands, France, Great Britain and the United States are the major importers (Emery 1985) Production in the U.S. is negligible and virtually all castor bean appears growing wild. Occurring predominantly on canal and ditchbanks, castor bean is not considered a major weed of crops in south Florida. Genung and Janes (1975), however, considered it a major weed host of L. trif olii and, consequently, its parasitoids in the Belie Glade area. Greater than 85% parasitism of the pest on

PAGE 43

castor bean occurred at each of two locations. Stegrcaier (1981), however, reported castor bean as a host of L. sati vae and not tr if oli i He also mentioned finding a castor bean leaf containing 80 L. sati vae mines on two separate occasions, illustrating the breeding potentia] of this species on an alternate, wild host.

PAGE 44

CHAPTER III LEAFMINER AND LEAFMINER PARASITOID INCIDENCE ON SELECTED WEEDS IN SOUTH FLORIDA Introduction Although the leaf miner Liriomyze sa ti vae (Elanchard) was considered a pest of celery in Florida (Musgrave et al 1975b, Poe and Montz 1981), L. trif olii (Burgess) is currently the major, if not only Lir iomyza spp. affecting this crop (Stegmaier 1981, Leibee 1984). Both species are attacked by the same parasitoid complex (Chandler 1S82); therefore, a v/eed species serving as a host of L. sati vae could act as a reservoir for these natural enemies and thus, possibly enhance biological control of L. trif olii within nearby celery fields. The ability of weeds to harbor beneficial arthropod species has been studied and discussed by several authors: Doutt and Nakata (1973), Perrin (1975 ), Altieri et al (1977), Altieri and Whit comb (1979a 1979b) and Shelter; and Edwards (1983), to name a few. Influence of weeds on leafminer mortality in south Florida was noted by Genung and Janes (1975) and Genung et al (1978), who reported parasitism rates of Lir iomyza were higher on horde rt of celery fields adjacent to weeds. Such observations justify

PAGE 45

investigations into the potential of certain native weed species as reservoirs for parasitoids Of the 80 hosts reported by Stegmaier (1981) for L. t rifoli i and sativae 29 were attacked by the latter only. Although found in south Florida, not all occur in the celery-growing region near Belle Glace and fewer still insufficient numbers to warrant their study. Two weed species, sicklepod, Cassia tora L. a legume, and castor bean, Ricinus communis L a euphorb, were reported by Stegmaier (1981) as hosts of L. sat ivae only and are commonly found in south Florida. These characteristics, plus the fact seeds of the two species are readily obtainable, make them amenable to study. Dayf lower, Commeiina d iffusa Burm., of the family Conmel inaceae was also chosen for study. Although not attacked by either L. sativae or tr i f oli i it is attacked by a similar species, L commei inae (Spencer and Stegmaier 1973), which may have parasitoids in common with L. trifolii Also, dayflcwer. is very common in the Everglades region and cuttings for transplanting are easily obtainable. L. com mei inae is reported, to attack only plant? of the genus Commei ina (Stegmaier 1966c). The objectives of tr is study were to 1) determine the abundance of L. sativae and possibly other leafminer specie on these three weeds, 2) monitor the abundance and species composition of the parasitoids of these pests and 3)

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ascertain leafminer and parasitoid occurrence and abundance for a year on the weed species most preferred by Liriomyza Methods and Materials Host Preference Study Test plots of castor bean, sicklepod and dayf lower were planted February 24, 1984 at two sites at the Everglades Research and Education Center (EREC) tv/o miles east of Belle Glade. Plots consisted of five rows 3 m long and 3 m wide planted on 0.75 m centers. There were three replications arranged in randomized complete block designs at each site. Alleyways between plots were 1.5 m wide. Castor bean and sicklepod were established from seed v/hile dayf lower was transplanted using cuttings taken from EREC. Plantings of castor bean and sicklepod were thinned to ca 10 plants per row while dayflower was allowed to cove: the entire plot. Sampling began in late May when leaf miner infestation were first noticeable. One leaf of castor bean and. one trifoliate of sicklepod were randomly selectee from each of three canopy layers (top, middle and bottom) of 10 randomly selected plants per plot. Dayf loweL a prostrate plant,wa sampled by collecting all foliage from 10 randomly selected 18 cm x IF cm areas within a plot. Foliage was placed in plastic bags to minimize dessication during transport to th laboratory

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37 Active mines (containing living leafminer larvae) and old mines (those from which leafminers cr their parasitoids had already exited) were counted from all samples. Mines containing larvae which appeared dead were considered old. Foliage containing active mines was placed on wire screen in closed cardboard containers to allow for emergence of parasitoid adults and mature leafminer larvae. Containers were held at 24.0 5.5 C and 65 + 15% RH. Larval parasitoid adults and leafminer puparia were collected after foliage had dried (ca. 5 d). Puparia were held in class vials until all leafminer and larval-pupal parasitoid adults had emerged and died. Adults were identified and counted. Prior to placing foliage in cardboard containers, foliage was subsampled to determine leaf surface area. One half of the castor bean leaves and sicklepod trifoliates from each canopy layer and one half of the dayflowei samples were randomly selected and leaf area measured using a L1COR ^ areameter Also, plant height and number of leaves per plant were determined for 10 randomly selected plants from each castor bean and sicklepod plot for every sampling period. Sampling was conducted ca once weekly for eight weeks ending the third week of July, 1984. Seas on a 1 A bu n da n c e Sampling of castor bean to determine seasonal variations in leafminer and parasitoid populations and percent parasitism was conducted for one year beginning August 8, 1984. Plots utilized in the prior study were

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38 examined biweekly, except in a few cases when they we resampled once in three weeks. Ml foliage containing active mines was collected and held in the same manner and under the same conditions as in the previous study. All leaf miner and parasitoid adults reared from foliage were identified and counted. Representative specimens of parasitoid species collected in this and the prior study were identified by E.E. Grissell, A.S. Menke and M.E. Schauff, Systematic Entomology Laboratory, USDA, Washington, D.C., P. A. Wharton, Department of Entomology, Texas A&M Universty, College Station, Texas and CM. Yoshimoto, Department of Environment, Canadian Forestry Service, Ottawa, Ontario, Canada Re sults an d D iscussion Host P r eferenc e Stud y Leafminer occurrence on sicklepod and dayflower during the sampling period was slight. Of 87 mines found on sicklepod foliage only two contained living larvae. Neither larva developed to pupation. Although no adult leaf miners were reared from sicklepod, most, if not all, mines may have been those of Lir iomyza since they were serpentine in appearance and the majority of them (62%) occurred during the first two weeks of sampling when Lir iom y za Wcis most abundant on castorbean. Thus, damage inflicted upon these two plant species, particularly during this time, may have

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39 been caused by the same leaf miner infestation (i.e. species ) Only 15 mines were collected from dayf lower; four we reactive and one L. comme 1 inae adult and one pupal parasitoid were reared from them. The parasitoid was a Cynipid, possibly of the genus Ganasp i dium as it was very similar, if not the same, as that reared from Lir iomyza on castor bean. The specimen, however, was not sent for identification. Stegmaier (1966c) reared only one parasitoid from L. comm el in ae in south Florida, Chrysochar is maioriana (Girault) a neotropical eulophid. If the cynipid reared is the same as that attacking L. trifolii, dayflower may be considered beneficiial in that it harbors a natural enemy of the pest. Genung (1981) found dayflowet to contain significantly more chalcidoid parasitoids than other weeds (e.g. Spanish needle, Bi dens pilosa L Virginia pepperweec, Lepidium vir gi nicum L., spiny amaranth, A maranthu s spinosus L. and others) sampled near celery fields with sticky traps. Flower nectar, however, rather than the presence of leaf miner larvae is believed the major attractant of these parasitoids to dayflower (G.I. Leibee, personal communication, 1586). Lir io myza populations on castor bean were much greater than those on sicklepod or dayflower. Populations peaked the first week of sampling with more than 22 active mines collected per 5000 sq. cm leaf surface area (Figure 3.]).

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Figure 3.] Mean number of old and active rain vae and L. trifolii collected per 5000 so, en foliage, Belle Glade, FL (1984).

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Active mine density decreased significantly (P<0.C5) after the second sampling period and, except for a slight increase during the fourth sampling period, were less than one active mine per 5000 sq cm. As leaf miners continued to attack castor bean, old mines continued to accumulate and did not peak until the third sampling period at greater than 162 mines per 5000 sq cm (Figure 3.1). The almost complete cessation of leaf mirier activity and subsequent senescence of lower leaves decreased foliage area containing old. mines. Although not an indicator of present infestation levels, old mines can be used to determine the extent of recent leafminer attacks, and the potential of plant species as hosts in the future. All leafminer adults reared from castor bean foliage were either L. sati vae or L. t rifolii with the former comprising 63.3% of the specimens. More than 4.2 adult Lir iomyza per 5000 sq cm of foliage were reared during the first week of sampling (Figure 3.2) but numbers declined steadily with the decrease in active mines. No L. tr i f oli i were reared after Kay 30 and L. sati.yae was collected only twice (weeks of June 19 and July 18) during the same period. The disparity between number of active mines collected and adults reared from these mines resulted in part from the dessication of foliage within cardboard rearing containers. Larvae collected as first and early to mid-second instars probably lacked sufficient time to complete development although foliage, when held in adequate amounts, remained.

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42 3 a Figure 3.2. Mean number of L. sativae and L. trif olii reared per 5000 sq cm of castor bean foliage collected, Felle Glade FL (198 4)

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relatively moist several days after sampling. Tryon (1979) found that fewer celery trifoliates per rearing container resulted in accelerated dessication and fewer adults reared per trifoliate. Filling containers three quarters full with castor bean leaves was normally sufficient for rearing adequate numbers of adults. Completely filling a container usually promoted leaf tissue decay resulting in death cf developing leafminers and parasitoids. High levels of parasitism also accounted for reduced leafminer emergence. More than 9.6 adult parasitoids per 5C00 sq cm were reared from Lir iomy za collected during the first sampling period (Figure 3.3). The majority of parasitoids (9.5) were larval-pupal species in which females parasitize the larvae and adults emerge from the puparia. Although larval parasitoid (i.e. those that utilize onlv the larval stage for development) incidence increased during the week of May 30, the total number of parasitoids decreased corresponding with the decrease in leafminers. Levels never exceeded 0.65 per 5C00 sq cm for the remainder of the study Eleven species of parasitoids representing four families of Hymenoptera were reared fiom Lir io my za on caster bean (Table 3.1). Ail braccnids plus Hai t icoptera circulus (Walker), Chrysoc har is park si Crawford and Can as p i di urn sp. are larval-pupal parasitoids while the remaining are larval parasitoids. Larval-pupal species accounted for over 82.0% of all parasitoids reared for the entire sampling period

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Figure 3.3. Mean number of adult parasitoids reared per 5000 sq. cm foliage collected from L sativse and L. trifplii on castor bean, Belle Glade. FL (1964).

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43 Table 3.1. Bymenopteran parasitoid species reared from L. trifolii and L. sati vae on castor bean in Belle Glade, FL (Kay-July 1984). Family Eraconidae Species Opius dimidiatus (Ashme ad ) 0 dissitus Muesebeck 0 brun e ipes Gahan Abundance (% ) 31.8 21.2 2. ] Eulophidae Qenon oga st ra micr or hophala e (Ashme ad ) Diqlyphu s intermedius (Girault ) 4.2 Pter omal idae Cynipidae Ch rysono t omyia puncti ve ntr is (Crawford) 5.3 Chrysocha r is parksi Cr awf o rd 2.1 Clcster oc erus sp. 1.8 Pr.i gal i o f lav i pes (Ashme ad) 1.8 Hal t iccptera ci rc uius (Walker) 2 0.6 Gail as pidi urn s p 0.3

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46 with species in tbe genus Opius the most prevalent (Table 3.1). Opius spp. also accounted for the majority of adult parasitoids emerging from weed foliage adjacent to tomato fields in central western Florida (Schuster et al 1982). Percent parasitism, calculated by dividing the number of adult parasitoids reared from foliage by the number of adult leafminers plus parasitoids reared, was 10C% for larval and larval-pupal parasitism combined for the third, fifth and sixth sampling dates (Figure 3.4) when only eleven, three, and two parasitoids, respectively,, were collected. (No leafminer or parasitoid adults were reared the week of July 1C and this is represented by 0% parasitism.) Genung et al (1978) found over 90% parasitism of mines occurring on castor bean ir the Belle Glade area. 0. dim i ciatu s accounted for all parasitism the fifth and sixth sampling dates while only two L. sativae were collected during the final sampling period when no parasitism occurred. All parasitoids in general and Cpius spp. in particular apparently exhibited exceptional searching ability, attacking the majority, and sometimes all, leafminer larvae collected and reared even when populations were extremely low. Parasitism rates for tie four ivcst prevalent species are presented ir Table 3.2. Mortality due to the majority of larval-pupal parasitoids appears to be density independent, (i.e. its effect dees not vary v:itb the occurrence or population density of the species regulated

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47 MAY24 MAY30 JUN8 JUN19 JUN26 JUL4 JUL1 0 JUL18 Figure 3.4. Mean percent parasitism of L. sativae era L. trif oli i on castor bean by larval and larval -pupal parasitoids, Belle Glade, FL (1984).

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48 Table 3.2. Mean percent parasitism of L. t rif oli i and L. sati v ae on castor bean by the four most prevalent species of parasitoids, Belle Glade, FL (1984). Date n 0. dimidi atus O. dissitus H ci rculus D intermedius May 2 4 567 33 .8a 18.6ab 12 .6a 1.0a May 3 0 220 27.3a 9.4ab 1.9b 23.1a Jun 8 11 3 0.1a 34.0a 0.0b 14.0a Junl9 33 19.3a 16.4ab 6.7ab 14.3a Jun26 4 10 0 .Ob 0 .0b 0.0b 0 .0a Jul 4 2 100.0b 0.0b 0.0b 0. 0a JullO C Jull8 2 0.0a C.Ob 0. 0b 0. 0a Means in columns followed by same letter not significantly different by Duncan's new multiple range test (P<0.05). Data transformed by arcsine (v/T) transformation before analysis; unt ransformed date presented.

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(van den Bosch et al 1982)) since percent parasitism due to these species remains relatively high despite changes in leaf miner density. Larval parasitoids, however, perhaps exhibited a delayed density dependence, first inflicting significant mortality a week after Lir iomy za populations had peaked and becoming relatively ineffective as leaf miner densities decreased. Li riomyza adults apparently preferred to oviposit on castor bean foliage occupying the mid-canopy region (Table 3.3) which, for the first two sampling periods when the majority of active larvae were collected, was ca 55-130 cm above the ground. Mean plant heights were 166.2 and 191.4 cm for periods one and two (Figure 3.5), respectively. The mid-canopy regions, calculated as the middle third of these heights, were ca 55-110 and 64-128 cm for the two periods. Most adult parasitoids were also reared from midcanopy foliage (Table 3.4) which was to be expected as most leafminers occurred there. Larval parasitoids, however apparently exhibited a preference, although not significant, for hosts in the lower canopy. These species, all smalJ eulophids, may be more effective nearer the ground where lower wind speeds may allow for a more stable environment in which to search for hosts. Percent parasitism was significantly greater in the better., canopy layer for larval parasitoids (Table 3.5) again demonstrating the lower canopy's possible enhancement of efficient host-finding for these smaller species. In contrast, larval-pupal

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Table 3.3. Mean number of old and active mines collected and L. tri folii and L. sativae adults reared per 5000 sq cm of castor bean foliage, Belle Glade, FL (May-July 1984). Canopy layer Old Active L. trifolii L. sativae Top 2.5a 0.5a <0. la
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g 250 200 1 150 MAY24 MAY30 JUN8 JUN19 JUN26 1 JUL4 1 JUL10 JUL18 Figure 3.5. Mean growth of castor bear at EREC, Be] ie Glac FL (1984).

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52 Table 3.4. Mean number of total, larval and larvalpupal parasitoids reared per 5000 sq. cm foliage from L. tr if olii and L. sa ti vae on castor bean, Belle Glade, FL (May-July 1984). Canopy layer Top Middle Eottom Total 0.07a 4.19b 1.2 4a Larval 0.01a 0.38ab C.5 4b Larval -Pupal 0.06a 3 .82b 0.70a Means in columns followed by same letter net significantly different by Duncan's new multiple range test (F<0.05)

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Table 3.5. Mean percent total, larval and larvalpupal parasitism of L. trifolii and L. s ativa e on castor bean, Belle Glade, FL (Fay-July 1984). Canopy layer Total Larval Larval-pupa Top 65.2a 18.7a 46.4a Middle 78. Sab 11.2a 6 7.5a Bottom 93.4b 54.5b 38.9a Means in columns followed by same letter not significantly different by Duncan's new multiple range test (F<0.05). Data transformed before analysis by arcsine (i/x) transformation; un transformed data presented.

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parasitoids, most several times the size of the aforementioned species, performed equally well within all canopy layers. Seasona l Abundance Leaf miner occurrence on castor bean was negligible for the remainder of the summer of 1984 as populations never exceeded one mine per plot (Figure 3.6). From September 9 to November 4, no mines were found in castor bean foliage; however, populations increased slightly from late November until mid-January when several frosts destroyed all foliage. F.egrowth appeared by early March and populations increased rapidly to peaks of greater than 3 6 and 3 7 mines on March 25 and April 22, respectively. Leafminer density decreased steadily from early May until the end of sampling. Parasitoids possibly regulate Lir iomyza numbers in late spring and early summer. Increased temperature.'and rainfall of midto late summer may inf J ict mortality by increasing incidence of funga] diseases of larvae and pupae. Muck soils like those of the Belle Glade region can stay moist for days during this season and drowning of newly exited larvae and pupae may possibly occur. Charlton and Allen (1981) found submergence in water for 50 h caused 96% mortality of L. t-rifolii pupae. L. sativae comprised 74.5% of Liriomyzs adults reared from foliage (Figure 3.6) and only once (March 12) did L. trif olii adults reared exceed those of L sat iva e Although

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55 40 Figure 3.6. Mean number of mines collected and Li ri omyzs adults reared per 3 m x 3 ir. plot of castor bean, Belle Glade, PL (1984-85)

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Li r iomyza was most abundant at approximately the same times for both the host preference study and this study, population densities encountered during the latter were extremely low compared with those of the former study. Foliage during the host preference study was younger with a thinner epidermis and may have been more suitable as an oviposition substrate. Also, ricin, the proteinaceous toxin found in all plant parts, may accumulate as the plant ages, thus possibly decreasing the plants' attractiveness to ovipositing females and/or increasing mortality of eggs and/or young larvae. Again, larval-pupal parasitoid species comprised the majority (96.3%) of parasitoids attacking Li r iomyza (Table 3.6). C. parksi was reared in the previous study but was not reared from foliage in this experiment. Abundance of parasitoids (Figure 3.7) closely followed that of leaf miner hosts. Larval-pupal parasitoid density followed that of Lir i omyza while larval parasitoids occurred at relatively low, but steady levels. This contradicts the observation from the previous study that these species were more density dependent than larvalpupal species. Fercent parasitism peaked at 94.8% on April 8 and 100% on July 16 (Figure 3.3), although the percentage for the latter date represents the occurrence of only one individual. Larval-pupal parasitoids accounted for all species reared on these two dates.

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57 Table 3.6. Hymenopteran parasitoid species reared from Liriorayza trifolii and L. sati vae on castor bean, Eelle Glade, FL (Aug 1984-July 1985). Family Braconidae Euiophidae Pteromalidae Cynipidae Species Abundance ( % ) Cpius dim i diatus 0 dissitus 0 b runeipes Oenonogas tra micror h ophaiae Diqlyphu s interm edins Ch rysonotomyia pu ncti ventr is Clost erocer us sp. P nigalio f lavipe s Halticoptera ci rculus Ganaspidiurn sp 47.7 29.4 2.] 6.1 1.5 1. ] 0.8 0.4 9.7 ] .?

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25 cjure 3.7. Mean nun.be r of larval and larval-pupal adult rasitoids reared per 3 m x 3 it plot from L. sativae and ifolii on castor bean, Belle Glade.FL (1984-85).

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Figure 3.8. Mean percent larval and larval-pupal parasit.i of L. sativae and L. trifolii on castor bean, Felle Glade FL (1984-35)

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60 Results indicate castor bean, particularly young plants, can harbor considerable numbers of Lirio myza and their parasitoids. The high incidence of parasitism imparts a beneficial aspect to castor bean as part of the celery agroecosystem as it probably serves as a reservoir for these natural enemies; however the occurrence of the pest L. trif olii may negate any positive effects of the weed. Considering the report of Stegmaier (1981), the abundance of L. trif oli i on this host plant is surprising although Genung and Janes (1975) believed it to be the species attacking castor bean during their study and Spencer (1985) found it on the same host in Kenya. The extent to which castor bean can affect leafminer and parasitoid occurrence is uncertain. Eased on this study and reports of others on the "edge" effects cf weeds on Lir iomyz a and parasitoid incidence in celery (Genung et al 1978, Genung 1981), the plant probably does play a roJe in pest abundance and regulation under certain circumstances. Only further studies examining this specific phenomenon can begin to elucidate this weed's impact within celery.

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CHAPTER IV EFFECTS OF CASTOR BEAN ON LEAFMINER AND LEAFMINER PARASITOID POPULATIONS IN ADJACENT CELERY Introduc t ion The leaf miner Lir i o myza trifolii (Burgess) is considered the major insect pest of celery in south Florida (Guzman et al 1973). It is highly polyphagous attacking over 140 host plants in 32 families worldwide (Fate! 1S86) The capacity of these hosts, many of which ere considered weeds, to affect the population dynamics of L. trifoli i end its parasitoids is potentially considerable (Genung and Janes 1975, Genung et al 1978). Weeds adjacent to celery and tomato fields are known to act as reservoirs for leafminers and their natural enemies in Florida (Genung 1981, Schuster et al 1982). Increased rates of parasitism have been reported for celery at field borders nearest weeds (Genung and Janes 1975, Genung et al 1978). No experiments have been conducted to attempt to quantify the effect weeds have on leafminer and parasitoid population numbers in adjacent celery. Sue!: knowledge may enable growers to utilize insecticides and herbicides more effectively and efficiently and perhaps increase leafminer mortality in celery by manipulating weed species harboring natural enemies. 61

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62 Detection and quantification of movement of leafminers end parasitoids from, weeds to adjacent celery could be inferred from, data obtained by sampling celery nearest the weeds and at set intervals into the field. However, another method is required to detect and analyze these phenomena conclusively. If leafminers and parasitoids could be marked via the weed host and if such marked insects and/or their progeny could be collected in adjacent celery, the origin of these individuals could not be questioned. Radioactiveisotopes are ideal labels for such a study. Radioactive isotopes have been used as markers or labels in studies to estimate population numbers, dispersal and mortality factors and study behavior and other aspects of the biology of various organisms. They are relatively easy to apply and detect and, when utilized correctly, dc not affect normal behavior of labelled individuals (Southwooc 1978) The incorporation of isotopes into host plants has been used to label lepidopterous larvae on deadnettle, L ami urn spp., (Cook and Kettlewell I960) and balsam fir, A bie s balsamea L (Krall and Simmons 1977) and the mirid Orth otylus vi i escens (Douglas and Scott) cn broom, Sa rothamous scopar ius (L ) (Levis and Walcff 1964). The radionuclide of phosphorous, P, has been the most widely used isotope; however, ~ S, due to its longer half Life (67 3 2 d vs 14.2 d for ~P), is better suited for a study conducted over several weeks.

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63 The purpose of this study was to determine if castor bean ( Ricinus c ommunis L.), a major weed host of L. trifolii and sativae contributes to the occurrence of L. trifolii in celery and if parasitoids attacking both leafminer species in castor bean disperse and attack L. trifolii in celery. 35 Celery transplanted adjacent to S labelled castor bear in the field was sampled with the goal of collecting labelled individuals. Oviposit ional preference of L. trif olii and L. sativae females for castor bean and celery was quantified in a laboratory study. Meth ods a nd Mater ials Migrat ion Study Ten day-old castor bean seedlings were labelled by placing them in aluminum trays containing the isotope ~"^S in Hoagland's solution at 0.1 micr ocur ie/ml The bare real systems were placed within the solution and plants were held upright by 2.54 cm diameter chicken wire covering the tops of the trays. Girdling of seedlings by wire was prevented by ringing stems with cotton. Thirty plants were placed in each tray and trays contained 3C0 microcuries of """S each. Seedlings were held in this manner for 72 h. A preliminary autoradiography study determined 72 h was adequate time for uptake and translocation of the isotope to all seedling parts

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Seedling roots were washed twice in a magnesium sulfate and water mixture (.0083 M MgSO = 1 g/1) to remove the isotope-containing solution from the plants' outer surfaces. The plants were then transplanted to two field sites at EREC in two 50 plant rows spread 0.5 m apart and 25 m in length. Four days later, celery was transplanted at each site in two plots, one on either side and adjacent to the labelled plants. Plots, which were approximately three meters from the castor bean, were 18.5 m in length and 20 itwide at site one and 26 m in length and 15 m wide at site two. Sampling in celery began 12 d after transplanting. This was approximately one week after mines began appearing in the labelled castor bean plants. Two trifoliates were randomly selected from each of two sites along the two rows closest to the castor bean and from rows every five meters away from the castor bean thereafter. Therefore, trifoliates were sampled at four distances from castor bean at site one (3, 8, 13 and 18 m) and six distances (3, 8, 13, 18, 23 and 28 m) at site two. Collected trifoliates were placed in 0.47 1 cardboard rearing containers and held at 25 + 3 C and 65 + 10% FH until all leafminer and parasitoid adults had emerged and died (ca. two weeks). Adults were identified, counted and examined by autoradiography and liquid scintillation analysis for possible incorporation of ~ 5 S. Sampling was conducted weekly for 10 weeks from April 18 to June 20.

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65 Adults were examined for isotope uptake by attaching dead individuals to blotter paper with clear finger nail polish. Blotter paper was taped to 17.5 cm x 12.5 cm Kodak X-omat v^* AR x-ray film so that specimens were in direct contact with the film. Blotter paper with specimens and film were placed in light-tight wooden boxes which were Then the film was developed and examined for darkened areas where individuals were in contact with film signifying occurrence of the isotope. All handling of film pricr to development was conducted in a darkroom under red light. Adult leafminers and parasitoids were also sampled in celery using 7.6 x 12.7 cm Tangle Foot ^ -coatee yellow cards stapled to the tops of 3 0.5 cm stakes. These sticky traps were placed in the field on the same rows from which trifoliates were sampled. Two traps were placed in each row. Adults collected were identified and counted, then cleaned of Tangle Foot ^ with alcohol and examined for isotope incorporation in the same manner as those reared from trifoliates. Sticky trap sampling was conducted concurrently with trifoliate sampling. Selected adult leafminers and parasitoids reared from trifoliates and collected on sticky traps were also examined for containment of tie isotope by liquid scintillation analysis. Specimens were placed in a standard fluor cocktail solution for counting with a Tr acor Anal yt ic placed in an ultra-cold freezer at ca. -75 C for 16-20 d.

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Delta 300 Series liquid scintillation counter. Counts were made at the University of Florida campus, Gainesville. Host Preference To determine L. trifolii and L. sativae female preference for castor bean and celery as oviposition substrates, four females and two males (3-4 d old) of one species were placed in 66 cm high x 36 cm wide x 36 cm deep wooden, screened cages containing two castor bean and two celery seedlings each. After 48 h, the flies were removed and plants were monitored for leafmine development. When resulting la rvae had matured to mid— third instars (approximately 9-12 d after exposure) infested foliage was excised and placed in petri dishes containing moist filter paper to allow for emergence and pupation of mature larvae. Fuparia were collected into small plastic cups where adults emerged and died. Numbers of larvae, puparia and adults produced per cage were noted and recorded. This procedure was replicated 15 times for L. sativae and 16 times for L. trifolii and was conducted at 25 + 3 C, 65 + 10% RH and a photoperiod of L:D 14:10.

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67 Results and Discussion Migration Study No adult leafminers and parasitoids reared from. foliage or trapped on sticky traps within celery during the entire sampling period were found to contain the radioactive isotope by either autoradiography or liquid scintillation counting. Yellow sticky traps are considered a reliable method for immediate detection of leafminer adults (Tryon et al 1980, Musgrave et al 1975a). If adults are moving into the celery after developing in isotope-containing castor bean some of these labelled individuals should have been collected in the traps. Also,any progeny of these adults which developed in and were reared from celery should 35 contain detectable traces of S within body tissues (E.L Cromroy, personal communication, 1985). Although the initial results possibly indicate no migration of leafminers and parasitoids from castor bean to celery, another conclusion is possible. The isotope may have dispersed within the castor bean and became too diluted for developing leafminers and parasitoids to incorporate in detectable amounts. Preliminary autoradiography analysis 35 found S was absorbed and distributed to all plant parts and L. sativae adults reared from labelled plants shortly after isotope exposure contained detectable amounts of the element. Mines were first noticeable in the transplanted castor bean more than two and one half weeks after

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labelling. Therefore, these larvae were exposed to the isotope at least ca two weeks after labelling. Given the extraordinary growth rate of castor bean (Chapter Three), 35 the S may have dispersed throughout plant tissues to concentrations too low to be incorporated into developing individuals and/or to be detected. Liquid scintillation counts of leafminer and parasitoid adults reared from labelled castor bean foliage collected May 7 and May 29 from 35 site two indicated no occurrence of S within insect tissues. Despite these findings, some of the collection data suggest castor bean perhaps does affect leafminer and parasitoid population numbers in adjacent celery. Liriomyza trifolii was the only Lir icmy za species reared from celery foliage during the entire ten weeks of sampling. Although L. sati vae was reported as a pest of celery in Florida until the late 1970s, L. trifolii is new considered the predominant, if not only, Lir icmy za species attacking celery in this region (Leibee 1984). However, both species have recently been reported on the crop in California (Trumble and Makakihara 1983, Zehnder and Trunble 1984) Greatest number of adults reared per t\vo trifoliates (11.8) occurred on May 15 (Figure 4.1). Pee et al (1978) reported rearing 17.2 to 114.5 adult L. s ativae per 1C trifoliates from control (untreated) celery plots near Belie Glade. In California Zehnder and Trumble (1984) reared 4.1

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69 12 Figure 4.1. Mean nunber of L. trifolii and total end larval parasitoids reared per two trifoliates of celery adjacent to castor bean, from two sites at Belle Glade, FL (1985).

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70 L. trifolii per two trifoliates of celery while Trumble and Nakakihara (1983) reared 3.6 L. t rif oli i and sativae adults per two trifoliates. The number of parasitoids reared, from foliage followed closely those of L. trifolii peaking one or twc weeks after those of their host (Figure 4.1). Larval parasitoids of the family Eulophidae constituted the majority of species collected (Table 4.1) in contrast to results of rearings from Lir iomyza on castor bean (Chapter Three) where the braconid larval-pupal parasitoids predominated. (Percent abundance of Oenonoqastr a micror h o phalae (Ashmead) appears as a portion of that for Opi us dimidiatus (Ashmead) Morphological characters used to distinguish between these two species were obscured by autoradiography and liquid scintillation analyses techniques. Species determinations were not made until after these analyses were conducted.) Diglyphus intermedius (Girault) and Chrysonotomyia punc ti ventr i s (Crawford) were the most abundant species reared from L. t rifolii in celery. Members of these genera have previously been reported as the most numerous parasitoids from celery foliage in Florida and California (Tryon and Poe 1981, Trumble and Nakakihara 1983). Mean number of L. trifolii and parasitoid adults reared per tv/o trifoliates sampled at set distances from the castor bean do not indicate that the weed influenced population numbers in celery (Table 4.2). Although L. trifoli i collection results indicateperhaps infestations

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Table 4.1. Hymenopteran parasitoid species reared from L. t rif oli i on celery adjacent to castor bean, from two sites at Belle Glade, FL, 1985. Family Species Abundance (% ) Braconidae Eulophidae Pteromal idae Opius dimidi atus (Ashmead ) 0 d is situs Muesebeck 0 bruneipes Gahan Diql yphus inter m ediu s (Girault) Chrysonot o myia puncti ve ntr is (Cr av/f ord ) Chrysochar is pa r k s i Crawford Hal ticoptera ci rc ulus (Walker) 17.0 14 .6 7.1 42.7 17.6 0.3 0.6 Abundance of Oenpnogas tra micr or ho p h alee (Ashmead) included as portion of that for 0. dimidiatus.

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72 Table 4.2. Mean number of L. tr if olii and total, larval and larval-pupal parasitoids reared per two trifoliates of celery adjacent to castor bean, from two sites at Belle Glade, FL, 1985 a h — c Distance (m) trifo lii 3 4.57 8 5 .] 5 13 4.05 18 3.57 23 3.10 28 3.10 Para sitoids LarvalTotal Larval pupal 1.58 1.08 0.50 1.55 0.93 0.62 1.60 0.80 0.80 1.45 0.82 0.63 1.60 1.00 C.6 0 2.20 1.50 0.70 All means in columns not significantly different by Duncan's new multiple range test (P<0.053. c Distance from castor bean at which samples taken. Logl0(x+1) transformation before analysis; untr ansf ormed data presented.

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73 were greater, though not significantly, near castor bean, parasitoid abundance exhibited no such trend and, in fact, appeared greatest at distances farthest from the weed. Analysis of percent parasitism of mines also failed to indicate any significant influence of castor bean on natural enemy occurrence (Table 4.3.). Approximately midway through the study (ca. May 15) almost all labelled castor bean plants at one site had been severely defoliated by an unknown disease. Therefore, results derived from data produced at both sites may not adequately estimate the effect of castor bean as the plants at the affected site (site one) contained considerably less foliage than those at the unaffected site (site twc). Thus, data from site two were analyzed separately to perhaps better ascertain castor bean's role. Number of adult L. trif olii and parasitoids reared per two trifoliates from site two did not vary significantly with distance from castor bean (Table 4.4). However, movement of parasitoids from the weed to celery is implicated as percent parasitism by larval-pupal species nearest castor bean was significantly greater than that occurring 23 m away (Table 4.5). As these parasitoid species are the most abundant reared from Lir iomy za on castor bean, the higher rates at which L. Lrifplii is attacked by them in adjacent celery may indicate the potential of castor bean as a harborage for these natural enemies

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Table 4.3. Mean percent total, larval and larval-pupal parasitism of L. trifoli i per two trifoliates of celery adjacent to castor bean from two sites at Belle Glade, FL, 1985 Distance (m) c Total Larval Larval-pupal 3 36.4 22.7 13.7 8 33.0 16.7 16.3 13 31.9 16.8 15.1 18 31.7 19.7 12.0 23 38.3 29.8 8.5 28 34.8 23.7 1] .1 All means in columns not significantly different by Duncan's new multiple range test (P
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75 Table 4.4. Mean number of L trifolii and total, larval and larval-pupal parasitoids reared per two tr ifoliates.of celery adjacent to castor bean, Belle Glade, FL, 1985 P arasi toids L. LarvalDistance(m) c trifolii Total G Larval pupal 3 3 .25 2.00 1.45 0.55 B 3.50 1.85 1.30 0.55 13 3.85 1.75 1.05 0.70 18 3.10 2.00 1.25 0. 75 23 3.10 1.60 1.00 0.60 28 3.10 2.20 1.50 0.70 ^Site two only. All means in columns not significantly different by Duncan's new multiple range test (P<0.05). ^Distance from, castor bean at which samples taken. Logl0(x+1) transformation before analysis; unt r ansf ormed data presented.

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Table 4.5. Mean percent total, larval and larval-pupal parasitism of L. t rif oli i per two trifoliates gf celery adjacent to castor bean, Belle Glade, FL, 1985 Distance (ir. ) c Total^ Larval 0 Larval-pupal 3 48.6 24.1 24.5 a 8 45.7 24.9 20.8 ab 13 27.9 16.1 11.8 ab 18 34.3 20.6 13.7 ab 23 38.3 29.8 8.5 b 28 34.8 23.7 11.1 ab j^Site two only. Arcsine (V/T) transformation before analysis; untransformed data presented. ^Distances from castor bean at which samples taken. Means in columns not significant] y different by Duncan's new multiple range test (P<0.05). Means followed by same letter not significant] v different by Duncan's new multiple range test (P<0.05).

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77 Populations of adult leafminers and parasitoids in celery based on sticky trap collections did not peak until the eighth week of sampling, ca June 6 (Figure 4.2). The greatest mean number of L. tr i f olii collected per trap was 7.75 while a mean of 8.95 parasitoids were trapped the same sampling period. (Traps at site two were covered with dust blown from an adjacent disked field on the last sampling date, June 20, making collection and identification of adults impossible. Results of catches for this date, therefore, were obtained only for site one.) Musgrave et al (1975a) trapped a maximum mean per sticky trap of 10.05 L. sat ivae adults in cucurbits and 9.69 parasitoids in legumes. They believed yellow sticky trap cards were the preferred method of estimating leafminer populations due to speed and ease of handling. Other maximum catches per trap of Lir i om y za species reported are 22.4 (Chandler 1981) in alfalfa and 44.0 (Tryor. et al 1980) in tomatoes. Genung (1981) trapped 13.8 parasitoids per daylight hour (over six h) per trap in the weed creeping cucumber, M.el oth r i a pendula I. All Liriomyza trapped during the entire study were L. t rif o lii except for one L. sativae. trapped on May 30. .At least six species of parasitoids, the vast majority of them larval, were collected representing fouj families of Hymenoptera (Table 4.6). Although, nest species were identifiable, sticky material used to trap adults often

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10 r r 1 1 r 1 1 1 APR18 APR25 MAY2 MAY9 MAY15 MAY22 MAY30 JUN6 JUN13 JUN20 Figure 4.2. Mean number of L. trifolii and total and larval parasitoids collected per yellow sticky trap in celery adja cent to castor bean, from two sites at Belle Glade, FL (1985)

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Table 4.6. Hymenopteran parasitoids of L. tr if o lii collected on sticky traps in celery adjacent to castor bean, from two sites at Belle Glade, FL, ]985. Family Species Abundance (% ) Er aconidae Cynipidae Eulopbidae Pteromalidae Opius spp. and Oenonogas tra micror hophalae G anaspidium. sp. Digl yphus intermedius C hrysonotornyia pun cti vent r i s Chrysoc bar is parks! Halt icoptera circulus 7.4 C.3 43 .6 47.2 C.2 1.3 Includes Cpiu s dim.idi a tus 0. dissitus and 0. br nne ipes

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covered the individuals and made discrimination between species of Braconidae virtually impossible. However, specimens of Braconidae trapped may include all species reared from trifoliates. Although the majority of parasitoids caught in traps were eulophids, this result may not reflect the true composition of adult parasitoids in celery adjacent to castor bean. Over 38% of parasitoids reared from trifoliates were braconids compared to less than eight percent found on sticky traps. This disparity may result from a greater attraction to yellow cards of eulophids than braconids. Genung (1981) reported the majority of parasitoids caught on yellow sticky traps in weeds adjacent to celery were chalcids including eulophids, however no studies have been conducted to determine the relative attractiveness of leafminer parasitoids to various colored traps Significantly more adult parasitoids, particularly larval species, were caught in traps closest to castor bean than those occurring 23 and 28 m away (Table 4.7). Occurrence of larval -pupal species, the densities of which were too low to affect patterns of total parasitoid abundance, did not differ with distance from castor bean. Catches of L. trifolii exhibited a pattern of decreasing abundance with increasing distance, although not a significant one.

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81 Table 4.7. Mean number of L. tr if olii and total, larval and larval-pupal parasitoids collected per sticky trap in celery adjacent to castor bean, from two sites at Belle Glade, FL, 1985 Parasitoids Distance(m) trifolii Total Larval pupal 3 3.34 a 2.44 a 2.28 a 0.16 a 8 3.35 a 1.67 ab 1.56 ab 0.11 a 13 3.23 a 1.64 ab 1.41 ab 0.2 3 a 18 2.94 a 1.35 ab 1.19 ab 0.16 a 23 2.22 a 0.58 b 0.50 b C.CC a 28 1.78 a 0.53 b 0.44 b 0.0 9 a Means in columns follov/ed by same letter not significantly b different by Duncan's new multiple range test (P<0.05). c Distance from castor bean at which collections were mace. LoglO (x+1) transformation before analysis; unt ransf or med ^ data presented Vx+.5 transformation before analysis; untransf or med data presented

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Results from samples taken at site two failed to reveal any possible effect of the weed on adult numbers in celery (Table 4.8). Significantly fewer larval parasitoids were caught at site two than at site one (Table 4.9) for those dates when populations were greatest (June 6 and 13) Castor bean may have attracted parasitoids from the celery, thus affecting trap catches. Also, rows within celery were generally more weed-free at site one, therefore, the yellow traps may have been more visible and, thus, more attractive to parasitoids there than at site two. Or perhaps other factor (s) such as site location affected number and composition of parasitoids occurring or their susceptibility to being trapped. Mean number of larval-pupal species trapped die not differ significantly for plots at site one and site two during the entire study (Table 4.9). Their generally low abundance in celery was apparently unaffected by abundance or scarcity of adjacent castor bean or other factors mentioned above which may have influenced larval parasitoid population numbers. Results of this study remain largely inconclusive. Clearly, radiation dosages greater than that used (0.1 microcurie per ml) should be incorporated in castor bear to sufficiently label, for several weeks, leefminers and parasitoids developing within foliage. However, transplanting plants exposed to higher dosages to the field is potentially environmentally unsound (H.L. Cromroy

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Table 4.8. Mean number of L. t rifolii and total, larval and and larval-pupal parasitoids collected per sticky trag. in celery adjacent to castor bean, Belle Glade, FL, 1SB5 Paras itoids L. LarvalDistance (m) trifolii Total 6 Larval 6 pupal e 3 2 .25 0.91 0.72 0 19 8 3.05 0. 69 0.58 0.11 13 2.39 1.11 0.86 0 .25 18 1.69 1.08 0.89 C.19 23 2.22 0 .58 0 .50 0 .08 28 1.78 0.53 0.44 0.09 Site two only. All means in columns not significantly different b^ Duncan's new multiple range test (P<0.05). ^Distance from castor bean at which collections were made. Logl0(x+1) transformation before analysis; untransf ormed data presented Vx+ 5 transformation before analysis; untransf ormed data presented

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84 Table 4.9. Mean number Of L t r if oli i (LT) and total (TP), larval (LP) and larval-pupal (LPP) paras itoids collected per sticky trap in celery adjacent to castorbean Belle Glade, FL, J 9 8o Site Date Species One Two Apr 18 LT 0.46 TP ft nn 0.00 LP n ft ft u u u 0.00 LPP r\ ft ft 0.00 Apr 25 LT ft ) l U • j 1 0.12 TP ft ft n u u u 0.04 LP ft ft ft u u u 0.04 LPP U U U 0.00 May 2 LT 1 -} 1 2.41 TP ft a r\ 0.08 LP 0.00 0.08 LPP 0.00 0.00 May 9 LT 2.4 4 4.00 TP 0.12 0.00 LP 0.06 0.00 LPP 0.06 coo May 15 LT 0 .75 0.83 TP 0.50 0.83 LP 0.50 0.83 LPP O.CO 0.00

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Table 4.9 continued. Site Date Species One Two May 22 LT 7 4 4 £ r n TP X VJ u n so LP LPP fi 0 6 Utl'U May 3 0 LT ft 7R J • X z TP 1 1 Q i n 1 • uo LP i no LPP 0 1 9 Jun 6 LT 15.81 2.37 TP 15. 44 4.71 LP 14.94 3.66 LPP 0.50 1.05 Jun 13 LT 2.5 0 0 .25 TP 5.56 0.2 5 LP 5.25 0.16 LPP 0.31 0.09 Means in these rows significantly different by ttest (P<0 .05)

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personal communication, 1985) Therefore, other methods of detection such as activation analysis or X-ray micropoble elemental analysis may need to be implemented to determine castor bean's effect. Analysis of collection data also failed to detect any such effect. Although some data suggest leafminer and parasitoid abundance is greater in celery nearest castor bean, further studies entailing several years of sampling, not only from celery but from castor bean, are required before the role of this weed within the celery agroeco system of southern Florida can be adequately assessed. Host Preference Liriomyza s a tivae preferred castor bean over celery for oviposition, as a total of only two larvae were observed on all celery seedlings offered (Table 4.10). Liriomyza trif olii females preferred celery as a host, although they produced more progeny on their less preferred host (castor bean) than L. satiyae females did on celery. Progeny production of these individuals is less than that of females in previous studies. Leibee (1984; found L. trif olii females produced an average of greater than 16 eggs per day at 4.5 d of ace while Parrella et al (1983b) recorded a mean daily viable egg production of 17.3 for L. tr if olii, on celery. Low mean progeny production resulted in part from extreme variability in oviposition by individual females. Egg deposition (based on larval counts) by L.

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87 Table 4.10. Mean number of larvae, pupee end adults of Lir iomyza spp. produced on celery and castor bean offered simultaneously to females for oviposition L. sativae L trifolii celery castorbean celery castorbean larvae 0.13 a 22.33 b 23.19 a 5.38 b pupae 0.00 a 19.33 b 16. 0G a 4.13 b adults 0.00 a 15.73 b 12.56 a 3.06 b Mean number per four females in 48 h. Means in rows for each Liriomyza sp. followed by same letter not significantly different by t-test (P<0.05). life stage

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sativae in castor bean occurred in only eight of the 15 cages as a mean of 41.9 larvae per four females were produced in these cages. Four L. trifolii females produced a mean of 33.7 larvae in the 11 cages where oviposition occurred Leibee (1984) and Parrella et al (1983b) however, followed female oviposition over entire lifetimes. The exposure period of only 48 h used in this study may not have allowed females enough time to produce or begin producing progeny at their maximum rates. Leibee (1984) and Parrella et al. (1983b) also used smaller cages to expose plants to flies. Female Li riomy za contained in closer proximity to host plants may oviposit sooner and more often than those in a larger cage. Also, females may not have adequately acclimated to cage conditions within 48 h to begin ovipositing at rates representing their normal potential on these host plants. Lir iomyza species' preference in the laboratory for celery and castor bean as host plants for oviposition may provide insights into factors affecting field populations where celery and castor bean are in close proximity to one another. Rejection of celery for ovipositon by L. sativae is not surprising as it was not collected from celery in the preceding field study and has not been found on this crop in recent years in Florida (Leibee 1984). Considering L. sativa e is the most abundant Lir iomy za species found on castor bean and the same complex of parasitoids attacks L.

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89 sati vae and L. trifolii castor bean, in certain situations, could be considered beneficial as a source of natural control agents for L. trifolii in celery.

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CHAPTER V BIOLOGY OF Liriomvza sativae BLANC HARD ON CASTOR BEAN Introduction Lir iomyza trif olii (Burgess) has recently emerged as the dominant leafminer species affecting celery in Florida and California (Leibee 1984, Trumble and Toscanc 1983) Weeds adjacent to celery fields of south Florida are reported to affect leafminer and leafminer parasitoid abundance in celery nearest weeds (Genung and Janes 1975, Genung et al 1978, Genung 1981). Stegmaier (1981) cited castor bean, Ricinus communis L as an important host of Lir iomyza in south Florida. This weed was found to harbor large numbers of L. trif oli i L. sativae (a very similar species) and several species of parasitoids known to attack both leafmining pests (Chapter Three). Castor bean is fairly common to the celery -growing region of south Florida. Since L. sat ivae is the predominant Lir iomyza species occurring on this weed (Chapter Three) an understanding of the biology of the species on this weed may help in understanding the factors affecting L ir iomyza population dynamics within the celery agroecosystem This is especially true since certain parasitoids are known to attack both L. sativae and L. trifolii (Chandler 1982) Objectives of this study were to 90

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91 determine development times for egg, larval and pupal stages at 20, 25, 30 and 35 C and oviposition rate and fecundity of L. sati vae on castor bean. Methods and Materia ls Development at Constant Te mp eratures Four groups of 50 female and 20 male L. sati vae three to four days old, were taken from the colony maintained at EREC and each placed in 66 cm high x 3 6 cm wide x 36 cm deepwood and screen cages, each containing nine 10-14 day-old castor bean plants. The plants were held in Ehrlenmeyer flasks containing Hoagland's solution and were plugged around the plant stems with cotton. After being exposed to adult leafminers for 24 h, the plants were placed into fcur separate environmental chambers maintained at 20, 25, 30 and 35 C, 55 + 10% RH and a phot ope riod. of L:D 14:10. Groups (cages) of plants were not exposed simultaneously and all plants within a cage were placed in the same chamber, i.e. maintained at the same temperature. Development of resulting leafminer progeny was observed and noted daily. No more than eight larvae were allowed to develop per leaf as excess larvae were destroyed within their mines with an insect pin. When the majority cf larvae within a leaf had developed to third, instar, the leaf was excised and placed in a petri dish containing moist

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filter paper. Inspection for development was then increased to twice daily. After all larvae within a leaf had completed development, puparia were placed individually into gelatin capsules for adult emergence. Occurrence of leaf-exit bymature larvae, pupation and adult emergence for each progeny was noted to determine mean development times for egg-larval (combined egg and larval stages) and pupal stages. Lifetime Oviposition A female and two males (<24 h old) were confined in a 23 cm high x 20 cm wide x 20 cm deep plexiglass and screen cage containing two castor bean plants (five to seven d old) for ovipostion. Plants were held in the same manner as those in the previous study. Honey water was smeared on the screen sides as a source of carbohydrates for the flies, Exposed plants were replaced every two days until death of the female. If both males died before the female, another one less than 24 h old was provided. Number of resulting larvae, puparia and adults and sex of adults was noted. A cage with adult flies was replicated 11 times and maintained at 25 C, 55 + 10% RH and a photoperiod of L : D 14:10.

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Results and Discussion 93 Development at Constant Temperature s The development times for the combined egg and larval stages were inversely proportional to temperature for a3 1 temperatures (Figure 5.1 and Table 5.1), however, development times at 30 and 35 C were essentially equal. Charlton and Allen (1981) reported similar effects on development of L. t rifoli i on eggs and larvae on pink beans. Leibee (1984) found egg development time varied little from 25 to 35 C for L. t rifolii on celery noting evaporative cooling of leaves may have negated any effects of increased ambient air temperature. Evaporative cooling by castor bean leaves may explain why development times of combined egg and larval stages of L. sati vae at 30 and 35 C were approximately equal. Pupal development times were also inversely proportional to temperature (Figure 5.1 and Table 5.1). None of the 27 pupae formed at 35 C completed development indicating this temperature is approximately the upper lethal temperature for the pupal stage of L. s ativae Leibee (1984) reported only 9.4% survival of L. trifolii pupae at 35 C and Parrella et al (1981b) found no adult emergence at 37.8 C for L. trifolii Pupal survival of L. sa tivae at lower temperatures, however, was somewhat less than reported for L. t ri fo li i at similar temperatures (Leibee 1984, Parrella et ai 1981b). Tryon and Foe (1981)

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94 Figure 5.1. Relationship of development time to temperature ( C) for the combined egg and larval (egg-larval) stage and the pupal stage of L. sativa e on castor bean,

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95 Table 5.1. Development time (DT) development rate (DR) thermal units in degree days (TU) and development threshold (D Th) for life stages, and pupal survival for L. sat ; vae on castor bean at 20, 25, 30 and 35 C. Tgmp Egg-larva Pupa Total Pupal ( C) (days) (days) survival (%) 20 DT+S (n) 13 .22 + 0. 12(38) 15. 33 DR 7 .56 6. 52 TU 192 .15 121. 59 25 DT + S (n) S .75 + 0 10 (65) 9. 61 DR 11 .43 10. 41 TU 170 .93 124. 27 30 DT+S (n) 6 .31 + 0. 04 (66) 6. 81 DR 15 .84 14. 68 TU 154 .82 122. 11 35 DT+S (n) 6 .17 + o 10(27) DR 16 .21 TU 182 .23 D Th 5. 47 12. 07 313.74 295 .20 276.93 71.1 71.0 65. CO

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reported 75% emergence for L. sativae and its parasitoids on celery at temperatures above 21.1 C, a survival rate very similar for this species on castor bean (Table 5.1). This indicates that the adult emergence rate of L. sativae may be lower than that for L. trif olii which has been reported as high as 92.5% at 26.7 C (Parrella et al 1981b). Regression equations for linear relationships between temperature and development rate (Figure 5.2) are presented in Table 5.2. Although the equation for pupal development is similar to those reported by Leibee (1984) (y = 0.76X 7.79) and Tryon and Poe (1981) (y = 0.78X 7.45) for L. trif olii and L. sativae pupae, respectively, on celery, the differences are great enough to indicate a possible host plant effect on development biology. Likewise, the development thresholds predicted from the regression equations (Table 5.1) were dissimilar from that found by Leibee (1984) Host plant effects on immature leafminer biology were evident in studies by Parrella et al (1983b) who found significantly greater survival for L. trif oli i larvae on chrysanthemum and celery than on tomato and Charlton and Allen (19 81) who reported slower development times for L. trifolii on v Show-off chrysanthemums than on pink beans. Lifetime Ovi pos ition Daily oviposition rate measured as mean number of larvae produced per female peaked at 25.5 when females were

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rEMPERATURE (C) 5.2 Figure to larval) stage and the pupal bean Relationship of development rate (1/days x 100) temperature ( C) for the combined egg and larval (eggstage of L. sat i vae on castor

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98 Table 5.2. Linear regression equations and r values for development rate and temperature ( C) for egg-larval and pupal stages of L. sativae on castor bean Stage Temp (C) used in regression equation r Egg-larva 20, 25, 30, 35 y = 0.58X 3 .18 0.96 Pupa 20, 25, 30 y = 0.82X 9 .86 0.98 y = 1/days x 100.

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99 five days of age (Figure 5.3). Total average fecundity + SE of females was 164.5 + 45.7 resulting in 98.6 + 25.7 adults with a male to female sex ratio of 1.0:1.1. Average longevity of females was 13.4 + 2.3 d; one individual died at one day of age while two survived to 19 d. Female age apparently had no effect on survival and sex ratio of progeny (Table 5.3) although pupal survival appears greatest when females were 13 d of age and older. Older females were less fecund (Figure 5.3); therefore developing larvae had less competition for food resources possibly resulting in increased fitness and survival of the subsequent (pupal) stage. Average total pupal survival (86.1%) was somewhat greater than that for pupae at 25 C in the preceding study (71.0%). All puparia produced during one exposure period for one female were held in petri dishes containing moistened filter paper opposed to puparia formed in the previous study which were held individually in gelatin capsules. The wet paper may have increased humidity within the petri dishes and this may have enhanced pupal survival whereas some dessication of puparia may have occurred in the gelatin capsules. Leibee (198 4) found L. t r i f oli i at 25 C to produce an average of 288.3 eggs during a lifespan of 16.8 d utilizing celery as a host. Chariton and Allen (1981) reported a lifetime fecundity per L. trifolii female of 439 eggs on blackeye peas. The superior reproductive potential of L.

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30 25 Q ^ 20 LU \ 15 10 5 1 1 13 FEMALE AGE (DAYS) 15 1 7 19 Figure 5.3. Mean number of larval progeny produced per female per day throughout the life of L. sati vacon castor bean at 25 C.

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101 Table 5.3. Percent survival of larval and pupal progeny and sex ratio of resulting adults for L. s ativae on castor bean at 25 C. % Survival Age a h Larvae Pupae Sex ratic (fem 1 11 73.4 82.5 1:0.9 3 10 64.2 86 .5 1:0.9 5 10 61.7 80.2 1:0.9 7 10 65 .2 82.0 1:0.9 9 10 83.3 86.3 1:0.9 11 10 80 .1 86 .9 1:1.0 13 6 90.4 89.4 1:1.2 15 6 89.1 89.7 1:0.9 17 A 75.0 100.0 1:1.2 19 z 80. C 10 0.0 1:0.3 Cumulative ace of females in days. Number of females surviving.

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102 trifolii compared to that of L. sati vae and other Liriomyza species may explain the former species evolution of pesticide resistance and adaptability to a wide range of host plants resulting in its current pest status (Farrella and Keil 1984) The reproductive biology of L. sat i va e on castor bean, however, may not represent this leafminer's true potential as would occur on a more suitable host. Although castor bean is readily attacked by L. sati v ae certain characteristics of the plant, such as the presence of the proteinaceous toxin ricin in plant tissues (Weiss 1971) may inhibit and reduce progeny development and survival Results of this study indicate castor bean to be a suitable host for L. sati vae Although its reproductive performance is not as great as that of L. trifolii its potential, at least on young castor bean plants, is still considerable. Based on this study, maximum population growth of L. sati v ae on castor bean should occur at cir temperatures from 25 to 30 C. Laboratory studies conducted under ideal conditions, however, can only approximate field situations. fore research is needed to better quantify factors, especiallly parasitism, which affect and regulate Li riomyza populations on wild and crop hosts to adequately predict future leafminer population dynamics.

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CHAPTER VI CONCLUSIONS The preceding studies should help elucidate the potential of castor bean as a host for Lir i omyza species in the celery-growing region of south Florida and the weed's possible effects on leafminer and leafminer parasitoid population dynamics within celery where it occurs adjacent to the crop. Even where stands of castor bean are not in close proximity to celery fields, mid to long distance migration of leafminers and parasitoids may still occur particularly if prevailing winds, found to facilitate leafminer movement (Tryon et al 1980), move from the weed in the direction of fields. Castor bean, particularly young plants, was readily attacked by L. sati vae and L. tr if olii with the latter comprising over 36% of adults reared from foliage during late spring and early summer 19 84. This supports Genung and Janes (1975) who reported the possible occurrence of this pest on the weed near Belle Glade. The harborage of L. trif olii by castor bean rray expand the pest status of this weed to include not: only those plants invading fields but those occurring outside of,but near, fields which can serve as sources cf the pest. The occurrence of a large parasitoid complex (11 species) found to attack Lir iomyza on 103

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104 castor bean, however, does impart a beneficial role to the we ed Except from late summer to mid-fall and during the coldest weeks of winter, Li r iomy za was found on castor bean year-round (August 1984-July 1985) in the Belle Glade area. Population density, determined during this period on older plants, however, never approached that occurring earlier in 1984 on younger ones (< four months old). Regrowth on older plants, which appeared in late winter, probably had a thicker epidermis than foliage of young plants. Li r iomy females may have found the regrowth unsuitable as ovipositon substrates or less desirable than other available hosts. Established stands of castor bean near celery fields in south Florida generally occur on canal ditcbbenks and consist of older plants which may contain relatively few Lir iomyz a Younger foliage is present, however, as seedlings constantly appear, especially in spring, under and around the mature plants (personal observation). Thus, even cider stands of castorbean can serve as sources of Li r iom y zo and their parasitoids. Although sampling data suggest leafminers and parasitoids may migrate from castor bean to adjacently planted celery, study results were inconclusive in quantifying the extent of the weed's effect on populations within the crop. Attempts to detect migration by labelling developing Lir iom y za and parasitoids within castor bear: by •35 incorporating the isotope ~ S in the plants were

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unsuccessful. Rapid plant growth possibly dispersed the isotope to concentrations too low to be encountered by 35 developing individuals. If S was incorporated in insect tissues, the concentrations were at such levels as to be undetectable by autoradiography or liquid scintillation analysis. Possible dilution of isotopes and other tracer compounds by rapid plant growth should be considered when utilizing this method for labelling insects. Lir iomy za females exhibited definite host preferences for either castor bean or celery in the laboratory. Although females attacked castor bean, L. tr if olii preferred celery as an oviposition substrate while celery was virtually rejected by L. sati vae as a host plant. Though once considered the major leafminer species attacking celery in Florida (Musgrave et al 1975b), L. sativa e may have recently developed a nor. preference for this plant, perhaps as a result of its displacement from the celery "niche" by L. trif olii L trif olii s propensity to develcp resistance to insecticides (Leibee 1981) and its superior reproductive potential (Parrella and Keil 1984) have possibly giver: it a selective advantage over L. sativae thus allowing it to outcompete and displace the latter in celery in Florida (Foe and Montz 1981) and, apparently, in California (Trumble 1981) The biology of L. sati vae on castor bean in the laboratory proved different from that of L. t rif oli i reported on other hosts (Charlton and Allen 1981, Parrella

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106 et al 1983b, Leibee 1984). The reproductive potential cf L. sati vae was less than that previously reported for L. tr if oli i but was still considerable since a female could produce ca 90 female progeny during her lifetime on castor bean. Even under the most ideal conditions, however, reproductive capabilities for L. sat ivae in the field are probably considerably less than that found in the laboratory as the majority of stands of castor bean consist of older plants, the foliage of which, as noted above and in Chapter Three, does not appear as suitable for leaf miner oviposition and development as younger foliage. Although the preceding studies have expanded our knowledge of castor bean's potential as a host and reservoir of Liriomy za and their parasitoids in the Belle Glade area, more field research is needed to fully understand the weed's role within the celery agroecosystem Several yearsof sampling are required before adequate determinations can be made about the exact composition and abundance of leafminers and parasitoids throughout the seasons. This information is necessary to predict leafminer infestation levels and tc develop a broad-ranging celery pest management progran Determination of the extent of migration of Li r icm y za and parasitoids from chemically or mechanically destroyed castor bean stands into nearby celery would also be worthwhile since our understanding of how a weed, species might be manipulated to influence arthropod populations within host crop fields would be increased. Equally worthwhile is the

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education of commercial growers, ideally the primary beneficiaries of such research, on the role weeds such as castor bean can play within the crop ecosystem and how these plants can potentially be utilized as an integral component of a pest management program.

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LITERATURE CITED Aii, A.D., T.E. Reagan, and J.I. Flynn. 19 84. Influence of selected weedy and weed-free sugarcane habitats on diet composition and foraging activity of the imported fire ant (Hymenoptera :Formicidae) Environ. Entomol 13: 1037-1041. Altieri, M.A., C.A. Francis, A. v. Schoonhoven, and J.D. Doll. 1978. A review of insect prevalence in maize (Sea mays L.) and bean (Pha seolu s vul g ar is L.) polyculture systems. Field Crops Res. 1:33-49. Altieri, M.A., A. v. Schoonhoven, and J. Doll. 1977. The ecological role of weeds in insect pest management systems: A review illustrated by bean ( Phaseol us vulgaris ) cropping systems. PANS 23:185-206. Altieri, M.A., and W.H. Whitcomb, 1979a. The potential use of weeds in the manipulation of beneficial insects, fiortscience. 14(1):12-18. Altieri, M.A., and W.H. Whitcomb. ]979a. Predaceous arthropods associated with Mexican tea in north Florida, Fla. Entomol. 62:175-182. Altieri, M.A. and W.H. Whitcomb. 1980. Weed manipulation for insect pest management in corn. Environ. Fanag. 4(6'-: 483-489. Anonymous. 1977. New records. Quarterly Newsletter, FAC Plant Protection Committee for the EE Asian and Pacific Region 20(4) : 5-7 Anonymous. 1986. Florida Agricultural Statistics, Vegetable Summary. Florida Crop and Livestock Reporting Service, Orlando, FL. Baranowski, R.M. 1958. Serpentine leaf miner control on pole beans. Proc. Fla. St. Hort. Soc 71:29-31. Earanowski, R.M. 1959. Effects of combining hydrocarbon insecticides with parathion or diazinon for leaf miner control on tomatoes. Proc. Fla. St. Fort. Soc. 72:155-158. 108

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Bartlett, P.W., and D.F. Powell. 1981. Introduction of Amer ican serpentine leaf miner Liriomy za tr if oli i into England and Wales and its eradication from commercial nurser ies, 1977-1981. Plant Pathol. 30:185-193. Blanchard, E. 1938. Descr ipciones y anotaciones de dipteros argentinos. Agromyzidae. An. Soc. Cient. Argent. 126:352359. Burgess, E. 1880. The clover Oscinis ( Oscini s trifolii Eur gess (n. sp.)). Report of the Commission of Agriculture for the year 1879. USDA, Washington, pp. 200-201. Chandler, L.D. 1981. Evaluation of different shapes and color intensities of yellow traps for use in population monitoring of dipterous leaf miners. Southwestern Entomol. 6(l):23-27. Chandler, L.D. 1982. Paras it ization of cantaloup-infesting agromyzid leafminers in the lower Rio Grande Valley, Texas. Southwestern Entorcol 7(2): 94-97. Charlton, C.A., and W.W. Allen. 1981. The Biology of Liricmy za trifolii on Beans and Chrysanthemums, pp. 42-4 8 in D.J. Schuster (ed.) Proceedings of the IFAS-Indust ry Conference on the Biology and Control of Li r iomy za Leafminers. Institute of Food and Agriculture Sciences, University of Florida, Gainesville. 235 pp. Cook, L.M., and H.B.D. Kettlewell. 1960. Radioactive labeling of lepidopterous larvae: A method of estimating larval and pupal mortality. Nature. 187:301-302. Coquillet, D.W. 1898. On the habits of tre Cscinidae and Agromyzidae, reared at the United States Department of Agriculture. Div. Entomol Bull. 10 (r. ser.), : 70-79 110 pp. d'Aguillar, CM., and M Martinez. 1979. Sur la precerse en France de Lir i omy za tr i f ol j i Burgess. Bull. Entomol. Soc. France 84:143-146. deLima C.P.F. 1979. Li r iomy za tr if olii (E ipter a : Agromyzidae), an important new leafminer pest in Kenya. Kenya Ento mol Newsletter 10:8. de Hejiere, J.C.H. 1925. Die larven der Agromy zinen Tijdschr. Entomol. 68:195-293. Dempster, J. P. 1969. Some effects of weed control on the numbers of the small cabbage white Pie r is rapae (L.) on brussels sprouts. J. Appl Ecol 6 ( 2) : 339-405

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110 Dimetry, N.Z. 1971. Biological studies on a leaf -mining Diptera, Lir iomyza tr if oli i Burgess, attacking beans in Egypt. Bull. Soc Entomol Egypte 55:55-69. Doutt, R.L., and J. Nakata. 1973. The Rubus leaf hopper and its egg parasitoid: an endemic biotic system useful in grape-pest management. Environ. Entomol. 2:381-386. Emery, W.L. (ed.). 1985. Commodity Year Book. Commodity Research Bureau, Jersey City, N J p. 21. Fagoonee, J., and V. Toory. 1984. Contribution to the study of the biology and ecology of the leaf -miner Liriomy za trif olii and its control by neem. Insect Sci. Appl 5: 23-30. Feeny, P. 1976. Plant apparency and chemical defense, pp. 1-49 in J. Wallace and R. Munsell (eds.) Recent Advances in Phytochemistry 10. Biochemical Interactions Between Plants and Insects. Foster, R. W. 1986. Monitoring populations of Lir iomyza trif olii (Diptera :Agromyzidae ) in celery with, pupal drop counts. Fla. Entomol. 69:292-298. Freeman, C.C. 195 8. Lir iomyza guytona : a new species of agromyzid leafminer. Ann. Entomol. Soc. Amer. 51:344-345. Frick, K.F. 1952. A generic revision of tre family Agromyzidae (Diptera) with a catalogue of New World species. Univ. Calif. Publ Entomol. 8 (8) :339-452. Frick, K.E. 1955. Kearctic species in the Lir i omyza pusilla complex no. 3 L. ali i vora new name for the Iowa onion miner (Diptera : Agromy zidae ) J. Fans. Entomol. Soc. 28(3): 88-92. Frick, K.E. 1957. Nearctic species in the Li r io myza pusilla complex no. 2 L. mun da and two other species attacking crops in California. Pan-Pac. Entomol. 33:59-70. Frick, K.E. 1959. Synopsis of the species of agromyzid leaf miners described from North America. Proc U.S. Natl. Mus. 108:347-465. Frost, S.W. 1943. Three new species of Diptera related to Agromy za pusil la Meig. J. N.Y. Entomol. Soc. 51:253-260. Frost, S.W. 1954. A new record for Phy tomyza su bpusilla Frost (Diptera). Entomol. News 65:73. Frost, S.W. 1962. Lir iomyza archibolci a new species Dipt (Agromyzidae) Entomol. News 73:51-53.

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] 11 Genung, W.G. 1976. Flooding in Everglades soil pest management. Proc Tall Timbers Conf Ecolog. Animal Control by Habitat Mgmt 6:165-172. Genung, W.G. 1981. Weed Hosts of Lir iomy za and Parasite Incidence in the Celery Agro-ecosystem at Belle Glade, Florida, pp. 61-69 in D.J. Schuster (ed.) Proceedings of the IFAS-Industry Conference on the Biology and Control of Lir iomy za Leafminers. Institute of Food and Agricultural Sciences. University of Florida, Gainesville. 235 pp. Genung, W.G., V.L. Guzman, M.J. Janes, and T .A Zitter. 1978. The first four years of integrated pest management in Everglades celery: part I. Proc. Fla St. Hort. Soc 91:275284. Genung, W.G., and E.D. Harris, Jr. 1961. Notes on the biology and control of serpentine leafminer(s) in the Everglades. Proc. Fla. St. Hort. Soc. 74:137-143. Genung, W.G., and M.J. Janes. 1975. Host Range, Wild Host Significance, and In-field Spread of Lir iom y za t r if o lii and Population Build-up and Effects of Its Parasites in Relation to Fall and Winter Celery (Dipter a : Agromyzidae ) Belle Glade AREC Research Report EV-1975-5. Institute of Food and Agricultural Sciences, University cf Florida, Gainesville. 18 pp. Getzin, L.W. I960. Selective insecticides for vegetable leafminer control and parasite survival. J. Econ. Entcmol. 53:872-875. Griffiths, G.C.D. 1962. Breeding leaf -mining flies and their parasites. Entomol Res. 74:178-185. Guzman, V.L., H.W. Burdine, E. D. Harris, Jr., J. P. Orse nigo, R.K. Showalter, P.L. Thayer, J. A. Winchester, E.A. Wolf, R.D. Berger, W.G. Genung, and T.Z. Zitter. 1973. Celery Production on Organic Soils of South Florida. Bull. 757. Institute cf Food and Agricultural Sciences, University of Florida, Gainesville. 79 pp. Guzman, V.L., W.G. Genung, D.D. Gull, M.J. Janes, and T.A. Zitter. 1979. The first four years of integrated pest management in Everglades celery: Fart II. Proc. Fl St. Hort. Soc. 92:88-93. Harbaugh, B.K., J.F. Price, and CD. Stanley. 1983. Influence of leaf nitrogen on leafminer damage and yield cf spray chrysanthemum. HcrtScience 18 ( 6 ) : 8 8G-C 81 Harding, J. A. 1965. Parasitism of the leaf miner L ir iomy za rcuhda in the winter garden area of Texas. J. Econ. Entomol. 58:442-443.

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112 Hills, O.A., and E.A. Taylor. 1951. Parasitizaticn of dipterous leaf miners in cantaloupes and lettuce in the Salt River Valley, Arizona. J. Econ. Entorr.ol 44:759-762. Horn, D.J. 1981. Effects of weedy backgrounds on colonization of collards by green peach aphid, Myzus persicae and its major predators. Environ. Entomol. 10:285-289. Jensen, G.L., and C.S. Koehler. 1970. Seasonal and distributional abundance and parasites of leaf miners of alfalfa in California. J. Econ. Entomol. 63:1623-1628. Johnson, M.W., E.P. Oatman, and J. A. Wyman. 1980a. Effects of insecticides on populations of the vegetable leafminer and associated parasites on summer pole tomatoes. J. Econ. Entomol. 73:61-66. Johnson, M.W., E.R. Oatman, and J. A. Wyman 19 8Cb. Natural control of Lir iomyz a sat i vae (Diptera :Agromy zidae ) in pole tomatoes in southern California. Entomophaca 25(2):19319 8. Knodel-Montz J.J., H.G. Larew, and R.E. Webb. 1985. Efficacy of Margosan-O, a Formulation of Neem, Against Lir iomyz a tri fo lii (Eurgess) on Floral Crops, pp. 33-44 in J.J. Knodel-Montz (ed.) An Informal Conference on Lir iomyza Leafminers. USDA, ARS Technical Information Bulletin United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 75 pp. Knodel-Montz, J.J., and S.L. Poe. 19 82. Oviposition Morphology of Three Economically Important Lir io myz a Species (Diptera :Agromy zidae ) pp. 186-195 in S.L. Pee (ed.) Proceedings of the 3rd Annual Industry Conference on the Leafminer. SAF The Center for Commercial Floriculture, Growers Division. Alexandria, VA 216 pp. Krall, J.H., and G..A. Simmons. 1977. Tree root injection of Phosphorous-32 for labeling defoliating insectst Environ, Entomol. 6:159-160. Larew, H.G., J.J. Knodel -Montz P..F. Webb, and J.D. Warthen. 1985. Lir iomyza trifol ii (Eurgess) (Diptera : Ac romyz idae ) control on chrysanthemum by neem seed ext ract "appl ied to soil. J. Econ. Entomol. 78:80-8 4. Leibee, G.L. 1981. Insecticidal Control of Liric myza spp. on Vegetables, pp. 216-220 in D.J. Schuster (ed.") Proceedings of the IFAS-Industry Conference on the Biology and Control of Lir iomyza Leafminers. Institute of Food and Agricultural Sciences. University of Florida, Gainesville. 235 pp.

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Leibee, G.L. 19 84. Influence of temperature on development and fecundity of Liriomyza tr i f oli i (Burgess) (Diptera: Agromyzidae ) in celery. Environ. Entomol 13:497-501. Leius, K. 1967. Influence of wild flowers on parasitism of tent caterpillar and codling moth. Can. Entomol. 99:444446. Lewis, C.T., and N. Waloff. 1964. The use of tracers in the study of dispersion of Orth oty lus vir escens (Douglas and Scott) (Miridae ,Heteroptera) Ent. Exp. et Appl 7:15-24. Halloch, J.R. 1913. A revision of the species in A gromy za Fallen and Cerodon tha Rondani Ann. Entomol. Soc Amer. 6:269-336. McClanahan, R.J. 1977. Biological Control of the Leafminer Lir iomy za sativae in Greenhouse Crops, pp. 45-48 in F.F. Smith and R.E. Webb (eds.) Pest Management in Protected Culture Crops. £RS-NE-85. United States Department of Agriculture, Beltsville, MB. Melander, A.L. 1913. A synopsis of the dipterous groups Agromyzinae, Milichiinae, Ochtiphilinae and Geomyzinae J. N.Y. Entomol. Soc. 21:219-300. Menken, S.B., and S.A. Ulenberg. 1986. Allozymatic diagnosi of four economically important Li r iomy za species (Diptere Agromyzidae). Ann. App. Biol. 109:41-47. Musgrave, C.A., S.L. Poe, G.H. Smearage, and W.D. Eshleroan. 1978. Analysis of the dynamics of insect populations in celery production. Proc Fla St. Hort. Soc. 91:271-275. Musgrave, C.A., S.L. Poe, and D.P. Bennett. 1975a. Leaf miner population estimation in polyculturec vegetables. Proc. Fla. St. Hort. Soc. 88:156-160. Musgrave, C.£., S.L. Poe, and H.V. We ems, Jr. 1975b. The Vegetable Leafminer, Lir io my za sativae Blanchard (Diptera Agromyzidae) in Florida. Entomol. Circ. No. 162. Florida Agriculture and Consumer Services, Division of Flant Industry, Gainesville, FL. 4 pp. Need ham, J.G. 1948. Ecological notes on the insect population of the f lower heads of Bicens pi l osa Ecclog. Monoar 18:433-447. Oatman, E.R. 1959a. Host range studies of the melon leaf miner, Liriomyza pictella (Thomson) (Diptera : Agromy zidae). Ann. Entomol. Soc. Amer. 52:739-741.

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114 Oatman, E.R. 1959b. Natural control studies on the melon leaf miner, Lir iomyza pictella (Thomson) J. Fcon. Entomol. 52:895-898. Oatman, E.R. 1960. Intraspeci f ic competiton studies of the melon leaf miner Liriomyza pictella (Thomson) (Diptera: Agromyzidae) Ann. Entomol Soc Amer. 53:131-132. Oatman, E.R. 1961. Crossbreeding studies with two closely related species of Liriomyza (Diptera : Agromyzidae ) PanPac. Entomol. 37:53-57. Oatman, E.R., and G.G. Kennedy. 1976. Methomyl induced outbreaks of Liriomyza sativae on tomato. J. Econ. Entomol. 69:667-668. Oatman, E.R., and A.E. Michelbacher 1958. The melon leaf miner, Lir iomyza pictell a (Thomson) (Diptera : Agromyzidae) Ann. Entomol. Soc. Amer. 51:557-566. Parrella, M.P. 1984. Effect of temperature on ovipositicn, feeding, and longevity of Lir iomyza trifolii (Diptera: Agromyzidae). Can. Entomol. 116:85-92. Parrella, M.P., W.W. Allen, and P. Morishita. 1983a. Leafminer species causes California mum growers new problems. Calif. Agric. 35:28-30. Parrella, M.P., G.D. Christie, and K.L. Pobb. 1983a. Compatibility of insect growth regulators and Chrysochar is park si (Hymenoptera : Eulophidae ) for the control of Lir iomyza tr i f oli i (Diptera -.Acrornvzidae) J. Econ. Entomol. 76: 949-951. Farrella, M.P., and C.B. Keil. 1984. Insect pest management: The lesson of Lir iomyza Bull. Entomol. Soc. Amer. 30(2): 22-25. Parrella, M.P., K.L. Pobb, and J. Bethke. 1983b. Ovipositicn and Pupation of Liri o myz a trifolii (Eurgess) pp. 5 0-55 in D.J. Schuster (ed.) Proceedings of the TFAS-Industry Conference on the Biology and Control of Liriomyza Leafmin-. ers. Institute of Food and Agricultural Sciences. University of Florida, Gainesville. 235 pp. Parrella, M.P., K.L. Robb, and J. Bethke. 1983b. Influence of selected host plants en the biology of Li r i omyza trifolii (Diptera : Agromyzidae ) Ann. Entomol. Soc Amer. 76: 112-135. Parrella, M.P., K.L. Pobb, G. D. Christie, and. J. A. Bethke. 1982. Control of Lir iorny za. trifo lii with biological control agents and insect growth regulators. Calif. Aoric. 26:17-19.

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115 Patel K.J. 1987. Paras itizaticn of Liriomyz a tr ifoli i (Burgess) by Diglyphus intermedius (Girault) PhD dissertation, University of Florida, Gainesville. 129 pp. Perrin, R.M. 1975. The role of the perennial stinging nettle Urtica dioica as a reservoir of beneficial natural enemies. Ann. Appl Biol. 81:289-297. Perrin, R.M. and M.L. Phillips. 1978. Some effects of mixed cropping on the population dynamics of insect pests. Entomol. Expl. et Appl. 24:385-393. Fimentel D. 1961. Species diversity and insect population outbreaks. Ann. Entomol Soc Amer. 54:76-86. Poe, S.L., R.J. Gouger, and L.N. Poe. 1978. Protection of celery from leafminers with permethrin. Froc. Fla. St. Hort. Soc. 91:2 67-271. Poe, S.L., J.L. Green, and C.I. Shin. 1976. Cultural practices affect damage to chrysanthemum by Liriomy z a satiyae Blanchard. Proc Fla. St. Hort. Soc. 89:299-301. Poe, S.L., and J.J. Montz 1981. Preliminary Results of a Leafminer Species Survey, pp. 24-34 in. D.J. Schuster (ed.) Proceedings of the IFAS-Indust ry Conference on the Eiology and Control of Li r iomy za leafminers. Institute cf Food and Agricultural Sciences, University cf Florida, Gainesville. 235 pp. Price, J.F. 198]. Ecologia, biologia y control de Lir i omyza trif olii (Eurgess) minador de hojas de crisantemo en America. Mem. VII Congr. Soc. Colombiana Entomol. 28 pp. Price, J.F. 1982. An assessment of leafminer management methods on export chrysanthemum enterprises in Colombia, South America. Proc. Fla. St. Hort. Soc. 95:146-148. Price, J.F., and S.L. Poe. 1976. Response of Liriomyza (Diptera :Agromy zidae ) and its parasites to stake and mulch culture of tomatoes. Fla. Entomol. 59:85-87. Risch, S.J., D. Andow.and M Altieri. 1983 Agrcecosystero diversity and pest control: Tata, tentative conclusions, and new research, directions. Environ. Entomol, 1-2: 625-629. Robb, K.L., and M.P. Parrella. 1984. Sublethal effects cf two insect growth regulators applied to larvae of Lir iomy z a trif olii (D iptera : Acromyzidae ) J. Ecop, Entomol. 77:1288-1292.

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116 Schenck, E.T., and J.H. McMasters. 1936. Procedure in Taxonomy. Stanford Univ. Press, Palo Alto, CA 72 pp. Schoonhoven, A. v., C. Cardona, J. Garcia, and F. Garzcn. 1981. Effect of weed covers on Empoasca kraemeri Ecss and Moore populations and dry bean yields. Environ. Entomol. 10:901-907. Schuster, D.J., and P.H. Everett. 1983. New Chemicals for Control of Leafminer on Tomato. Eradenton AEEC Research Report BRA1983-12. Institute of Food and Agricultural Sciences, University of Florida, Gainesville. 6 pp. Schuster, D.J., and K.J. Patel 1985. Development of Li ric my za trif olii (Diptera :Agromyzidae ) larvae en tomato at constant temperatures. Fla. Fntomol 68:158-161. Schuster, D.J., and J.F. Price. 1985. Impact of insecticides on lepidopterous larval control and leafminer parasite emergence on tomato. Proc Fla. St. Hort. Soc. 98:248-251. Schuster, D.J., T.G. Zoebisch, and J. P. Gilreath. 1982. Ovipositional Preference and Larval Development of Li r iomy za tri f olii on Selected Weeds, pp. 137-145 in S.L. Poe (ed.) Proceedings of the 3rd Annual Industry Conference on the Leafminer. SAF, the Center for Commercial Floriculture, Growers Division, Alexandria, VA 216 pp. Shelton, M.D., and CP. Edwards. 1983. Effects of weeds en the diversity and abundance of insects in soybeans. Environ. Entomol. 12:296-298. Short, D.E., and J.F. Price. 1981. 3981-1982 Pest Control Guide for Commercial Flower Crops in Florida. No. 50. Institute of Food and Agricultural Sciences Cooperative Extension Service Report. University of Florida, Gainesville. 18 pp. Smith, J.G. 1969. Some effects of crop background on populations of aphids and their natural enemies on brussels sprouts. Ann. Appl Biol. 63:326-330. Smith, J.G. 1976. Influence of crop background on natural enemies of aphids on brussel sprouts. Ann. Aop] Bio]. 83:15-29. Southwood, T.R.E. 1978. Ecological Methods with Particular Reference tc the Study of Insect Populations. Chapman and Hall, New York. 5 24 pp. Spencer, K.A. 1965. A clarification of the status cf Lirionty za trif olii (Burgess) and some related species. Proc. Entomol. Soc. Wash. 67:32-40.

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117 Spencer, K.A. 1973. Agromyzidae (Diptera) of Economic Importance. Dr. Junk. The Hague. 418 pp. Spencer, K.A. 1981a. A Revisionary Study of the Leaf mining Flies (Agromyzidae) of California. Special Public. 3273^ University of California Division of Agricultural Sciences. Agricultural Science Publications, Berkeley, CA. 489 pp. Spencer, K.A. 1981b. Morphological Characteristics and Brief Taxonomic History of Lir iomyza pp. 12-23 in D.J. Schuster (ed.) Proceedings of the IFAS-Indust ry Conference or. the Biology and Control of Lir iomyza Leaf miners. Institute of Food and Agricultural Sciences, University of Florida, Gainesville. 235 pp. Spencer, K.A. 1985. East African Agromyzidae (Diptera): further descriptions, revisionary notes, and new records. J. Nat. Hist. 19:969-1027. Spencer, K.A., and C.F. Stegmaier, Jr. 1973. -Agromyzidae of Florida with a Supplement of Species from the Caribbear. Arthropods of Florida and Neighboring Land Areas. Vol 7. Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 205 pp. Stegmaier, C.E., Jr. 1966a. Host plants and parasites of Lir iomyza munda in Florida (Diptera : Agromyzidae ) Fla. Entomol. 49:81-86. Stegmaier, C.E., Jr. 1966b. Host plants and parasites of Liriomyz a trif olii in Florida (Diptera : Acromvzidae ) Fie. Entomol. 49:75-80. Stegmaier, C.F., Jr. 1966c. Li riomyz a cpmmelin a e. a leaf miner on Co m me] i na in Florida (Dipter a : Agromyzidae ) Flc Entomol. 49:147-149. Stegmaier, C.E., Jr. 1971. Lepidoptera, Diptera, and Hymenoptera associated with Ambrosia arte misiif o lia (Compcsitae) in Florida. Fia. Entomol. 54:259-272. Stegmaier, C.E., Jr. 1973. Some insects associated with joepye weed, Eupatorium coe lestinum (Compositae) from south Florida. Fla. Entomol. 56:61-65. Stegmaier, C.F. Jr. 1981. The Host Plant Ranges of Liriomyza sativae and Lir io myz a trif olii and Notes or Their Parasites, pp. 56-60 in D.J. Schuster (ed.) Proceedings of the Conference on the Biology and Control cf Liriomyza Leafminers. Institute of Food and Acjr icuitur al Sciences, University of Florida, Gainesville. 235 pp.

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118 Steyskal, G.C. 1964. Descriptions and synonomical notes on Lirioiny zs mu no a (Diptera : Agromy ziclae ) Ann. Entomol. Soc Amer. 57:388-389. Steyskal, G.C. 1973. The strange fate of the "serpentine leaf miner" ( Lir iomyza spp., Agromyzidae, Diptera). U.S. Dept. Agric. Crop Ins. Pep. 23 ( 43 ): 735-736 Syme P.D. 1975. The effects of flowers on the longevity and fecundity of two native parasites of the European pine shoot moth in Ontario. Environ. Entomol. 4:337-340. Tahvanainen, J.O., and R.E. Foot. 1972. The influence of vegetational diversity on the population ecology of a specialized herbivore, Phyl lo treta cruci f erae (Coleoptera :Chrysomel idae ) Oecologia 10:321-346. Taylor, T.G., and D. Locascio. 1985. Costs and Returns from Vegetable Crops in Florida, Season 1983-84 with Comparisons. Economic Information Report 205. Institute of Fcod and Agricultural Sciences, University of Florida, Gainesville. 24 pp. Trumble, J.T. 19 81. Lir iomyza trifolii could become a problem in celery. Calif. Agric. 35:30-31. Trumble, J.T. 1985. Integrated pest management of Lir ;.omy za trifolii : Influence of avermectin, cyromazine, and methomyl on leaf miner ecology in celery. Agric., Ecosyst., and Environ. 12:181-188. Trumble, J.T., and H. Nakakihara. 1983. Occurrence, parasitization.and sampling of Lir io my za species (Diptera tAgromyzidae) infesting celery in California. Environ. Entomol. 12:810-814. Trumble, J.T., and N.C. Toscano. 1983. Impact of me tbamidi phos and methomyl on populations of Lir iomy za species (Diptera : Agromy zidae ) and associated parasites in celery. Can. Entomol. 115:1415-1420. Trycn, E.B., Jr. 1979 Environmental, Cultural, and Ir.secticidal Effects on the Vegetable Leaf miner Lir io my za sativae Blancrard, and Its Parasites. PhD Dissertation, University of Florida, Gainesville. 94 pp. Tryon, E.H., Jr., and S.L. Poe. 1981. Developmental rates and emergence of vegetable leaf miner pupae and their parasites reared from celerv fcliace, Fia Entomol. 64 : 477483 Tryon, E.F., Jr., S.L. Poe, and H.L. Cromroy 198C. Dispersal of vegetable leafminer onto a transplant production range. Fla. Entomol. 63:292-296.

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lis van den Eosch, R., P.S. Messenger, and A. P. Guiterrez. 1982. An Introduction to Biological Control. Plenum Press, New York. 247 pp. Waddill, V. 1981. Effects of Insect icicles on Nontarget Organisms, pp. 186-189 in D.J. Schuster (ed.) Proceedings of the IFASIndustry Conference on the Biology and Control of Lir ioiny za Leafminers. Institute of Food and Agricultural Sciences, University of Florida, Gainesville. 235 pp. Waddill, V.H. 1978. Contact toxicity of four synthetic pyrethroids and methomyl to some adult insect parasites. Fla. Entomol. 61:27-30. Webb, R.E., M.A. Harbaugh, R.K. Lindquist, and M Jacobsen. 1983. Evaluation of aqueous solution of neem seed extract against Lir iomy za sati vae and L. trifolii (Diptera : Agromyzidae) J. Econ. Entomol 76 : 357-362 Webb, R.E., and F.F. Smith. 1973. Influence of reflective mulches on infestations of Li r iomy za mu no a on snap bean foliage. J. Econ. Entomol. 66:539-540. Webster, F.M., and R.H. Parks. 1913. The serpentine leaf miner. J. Agric. Res. 1:59-87. Weiss, E.A. 1971. Castor, sesame, and safflover. Barnes and Noble, Inc., New York. 9Ci pp. Wene, G.P. 1955. Effect of seme organic insecticides en the population levels of the serpentine leafminer and its parasites. J. Econ. Entomol. 48:596-597. Wolfenbarger D.O. 19 47. The serpentine leaf miner and its control. University of Florida Agricultural Experiment Station Press Bulletin 639:1-6. Wolfenbarger, D.O. 1958. Serpentine leaf miner: brief history and summary of a decade of control measures in south Florida. J. Fcon. Entomol. 51:357-359. Wolfenbarger, D.O., and W.D. Moore. 1968. Insect abundances on tomatoes and squash mulched with aluminum and plastic sheetings. J. Econ. Entomol. 61:34-36. Woltz, S.S., and E.G. Kelsheimer. 1958. Effect of variation in nitrogen on chrysanthemum attack by serpentine leafminer. Proc Fia. St. Hort. Soc 71: 404-406.

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120 Zehnder, G.W., and J.T. Trumble. 1904. Host selection of Liriomyza species (Diptera : Agromy zidae ) and associated parasites in adjacent plantings of tomato and celery. Environ. Entomol 13: 492-496. Zehnder, G.W., and J.T. Trumble. 1985. Impact of Currently Registered Insecticides on the Li riomyza /Parasite Complex in Celery, 1984. pp. 21-27 in J.J. Knodel-Montz (ed.) An Informal Conference on Liriomyza Leafminers. USDA, ARS Technical Information Bulletin. United States Department of Agriculture, Agricultural Research Service, Beltsville, MD. 75 pp. Zehnder, G.W., J.T. Trumble, and W.P. White. 1983. Discrimination of Lir iomy za species (Diptera : Agromy zidae ) using electrophoresis and scanning electron microscopy. Proc Entomol. Soc. Wash. 85 (3) :564-574. Zoebisch, T.G. 1984. Oviposition and Development of Liriomy za trif olii (Burgess) (Diptera : Agromy zidae ) on Foliage of Tomato and Selected Weeds. MS Thesis, University of Florida, Gainesville. 48 pp.

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BIOGRAPHICAL SKETCH James Patrick Parkman was born December 1. 1954 in Columbia, SC. He graduated from Saluda High School, Saluda, SC in 1973 and enrolled at Clemson University, receiving a B.S. in economic biology in 1977. In 1978 he entered the graduate program in entomology at Clemson with research interests in biological control of armyworms. Upon receiving his M.S. in 19 80 he was employed as a laboratory and field, technician at Clemson' s Edistc Experiment Stationconducting research on the control of soybean pests. In January of 1983 he enrolled at the University of Florida in the Department of Entomology and Mematology to pursue a doctoral degree in entomology. He is a member of the Entomological Society of America and the Florida Entomological Society. 121

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I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of/Doctor j>£ Philosophy. Van H. Waddill, Chairma Professor of Entomology and Nematology I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Joan A. Dusky, Cbchairman Associate Professor of Horticultural Science I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of-^Doctor of Philosophy. Dale H. Habeck Professor of Entomology and Nematology I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of^Doctor of Philosophy. David J. Schuster Professor'of Entomology and Nematology This dissertation was submitted to the Graduate Faculty of tne College of Agriculture and to the Graduate School and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy. ^ r M y 1987 ^^^/,^^Dean, College of Agriculture Dean, Graduate School