• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Abstract
 Table of Contents
 Introduction
 Basic biology
 Environmental factors
 Control
 Appendices
 References
 Acknowledgement
 Back Cover














Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Biology, plant-insect relations, and control of the citrus blackfly
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Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00026781/00001
 Material Information
Title: Biology, plant-insect relations, and control of the citrus blackfly
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Alternate Title: Biology, plant insect relations, and control of the citrus blackfly
Physical Description: 49 p. : ill. (some col.) ; 23 cm.
Language: English
Creator: Dowell, Robert V
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Agricultural Experiment Station, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1981
Copyright Date: 1981
 Subjects
Subject: Citrus black fly -- Florida   ( lcsh )
Citrus black fly -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
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Bibliography: Includes bibliographical references (p. 45-48).
Statement of Responsibility: Robert V. Dowell ... et al..
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Bibliographic ID: UF00026781
Volume ID: VID00001
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Holding Location: University of Florida
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Resource Identifier: ltuf - ACF0949
oclc - 08394437
alephbibnum - 000404734

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Title Page
        Title Page
    Abstract
        Abstract
    Table of Contents
        Table of Contents
    Introduction
        Page 1
    Basic biology
        Page 2
        Page 3
        Page 4
        Page 5
    Environmental factors
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
    Control
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
    Appendices
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
    References
        Page 45
        Page 46
        Page 47
        Page 48
    Acknowledgement
        Page 49
    Back Cover
        Page 50
Full Text



February 1981 Bulletin 818 (technical)

Biology, Plant-Insect Relations,

and Control of the Citrus Blackfly






',. .













Robert V. Dowell, Ronald H. Cherry, George E. Fitzpatrick,
James A. Reinert, and Joseph L. Knapp





; -Florio,
Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
F. A. Wood, Dean for Research


















































Cover. Delphastus sp. larva (Coleoptera: Coccinellidae) (arrow) feeding on an
immature citrus blackfly.











Biology, Plant-Insect Relations
and
Control of the Citrus Blackfly,
Aleurocanthus woglumi Ashby
(Homoptera: Aleyrodidae)

Robert V. Dowell, Ronald H. Cherry,
George E. Fitzpatrick, and
James A. Reinert
Agricultural Research Center,
Fort Lauderdale

and

Joseph L. Knapp
Agricultural Research and Education Center,
Lake Alfred



















ABSTRACT
This technical bulletin summarizes the research done on the citrus
blackfly by researchers of the Institute of Food and Agricultural
Sciences, University of Florida, from 1976 to 1980. We found that the in-
troduction of two parasites specific to the citrus blackfly has resulted in a
permanent 98% reduction in pest numbers, and that the citrus blackfly is
now under complete biological control. We feel that current citrus grove
spray practices are compatible with continued biological control, as a
number of insecticides do not kill parasites pupated inside their hosts.
Additional information is provided on life history, plant-insect rela-
tions, survey techniques, and chemical control.
I






I




'I














CONTENTS
Page
ABSTRACT .............. ........................ ............ ii

INTRODUCTION ............................................... 1

BASIC BIOLOGY ................................. ........... 2

Taxonomy ................. ................................. 2
Life History ............. .................................... 2

ENVIRONMENTAL FACTORS............................................... 6

Temperature and Humidity ...................................... 6
Plant-Insect Relations ................. .......................... 11
Dispersal ....................................................... 17
Damage to Tree .................................... .......... 19

CONTROL .................... ................................ 20

Survey and Detection ............................................. 20
Chemical Control ............................................... 24
Biological Control ............................................. 29
Integrated Management .......................................... 34

APPENDICES ............. ...................................... 39

1. Plants Tested by IFAS Personnel .................. ............... 39
2. List of Selected County Agents .................. ................ 41
3. Metric Measures and Conversion Factors ........................... 44

REFERENCES ................................................. 45

ACKNOWLEDGMENT ............................................ 49
















INTRODUCTION

The citrus blackfly, Aleurocanthus woglumi Ashby (Homoptera:
Aleyrodidae), is a citrus-feeding whitefly of Asian origin (Dietz and
Zetek, 1920). It was first found in the New World in Jamaica in 1913.
Since that time, it has spread to most of the citrus growing regions of the
Western Hemisphere (Table 1).
Since its discovery on Jamaica, the citrus blackfly has been considered
a potential economic threat to the citrus industry of Florida (Weems,
1962). Plant board inspectors reported the continual interception of
infested plant material from 1918 to 1922 (Florida Department of Agri-
culture, 1922). The citrus blackfly was discovered in Florida in 1934 on
Key West. It was confined to citrus and mango trees located in dooryards
on the island, and was eradicated by 1937 through the use of oil sprays
(Newell and Brown, 1939). A second infestation, discovered in the Ft.
Lauderdale area on January 28, 1976, was soon found inhabiting virtual-
ly all the urban areas of Broward County and the adjacent portions of
Dade and Palm Beach counties. In response to this threat, the University
of Florida Institute of Food and Agricultural Sciences established a
research team to study the biology, host plant spectrum, and control
(both biological and chemical) of the citrus blackfly in Florida. The in-
formation gathered by this research team, supplemented by data from
federal, state, and regulatory personnel, is presented herein.
In this bulletin all plant species are referred to by their common
names. Both the common and scientific names of plants mentioned in the
bulletin are given in Appendix 1, except for those plant species referred
to only in specific tables.
Measurements are given in the metric system. For information on con-
version of these units to customary units of measure, see Appendix 3.
The first time a chemical is mentioned, both its common name and
chemical name are given; thereafter, only the common name is used.
Trade names are also used in some instances for clarity. The mention of
any trademark or brand name is to provide specific information, and
does not imply any endorsement by the University of Florida.
Symbols and abbreviations used include the following:
g AI/ha = grams of active ingredient per hectare
g AI/L = grams of active ingredient per liter
x = average number (mean)
9 = female

1









Table 1. History of discoveries of citrus blackfly infestations in the Western
Hemisphere.

Location Date Discovered Reference

Jamaica 1913 Dietz and Zetek, 1920
Bahama Islands 1916 Dietz and Zetek, 1920
Cuba 1916 Dietz and Zetek, 1920
Panama 1917 Dietz and Zetek, 1920
Costa Rica 1919 Dietz and Zetek, 1920
Key West, Fla. 1934' Newell and Brown, 1939
Mexico 1935 Baker and Dampf, 1937
Ecuador 1954 Yust and Cevallos, 1954-55
Texas 1955' Smith et al., 1968
Barbados 1962 Russell, 1962
Bermuda 1962 Russell, 1962
Cayman Islands 1962 Russell, 1962
Columbia 1962 Russell, 1962
Dominican Republic 1962 Russell, 1962
Haiti 1962 Russell, 1962
Nicaragua 1962 Russell, 1962
Argentina 1965 Angeles et al., 1971
El Salvador 1965 Quezada, 1974
Texas 19712 Hart et al., 971
Venezuela 1971 Angeles et al, 1971
Fort Lauderdale, Fla. 19762 Reinert, 1977
1. Eradicated
2. New infestations




BASIC BIOLOGY

Taxonomy
The citrus blackfly is one of 69 species of whitefly in the genus
Aleurocanthus. Most Aleurocanthus species are known from the Old
World, with 29 species found in the Orient (China, India, and Southeast
Asia), 23 species in Africa, and 17 species in the Australian region of the
Pacific (Mound and Halsey, 1978). The only widespread species, the
citrus blackfly and A. spiniferus (Quaintance), are both closely


2









associated with citrus. In all, nine Aleurocanthus species are reported
from citrus trees (Mound and Halsey, 1978).
The citrus blackfly is native to Asia and was first described by Ashby
in 1915, with additional details being supplied by Quaintance and Baker
(1916). Aleurocanthus punjabensis (Corbett, 1935) and A. woglumi var.
formosana (Takahashi, 1935) are synonyms of A. woglumi Ashby. The
species has acquired a series of common names throughout the years, in-
cluding "mosca prieta," "citrus bluefly," and "spiny citrus whitefly."


Life History

The female citrus blackfly will lay two or three egg spirals (28 to 34
eggs per spiral) usually within three or four days after emergence as an
adult (Fig. 1). All eggs are laid on the underside of leaves and average
0.03 x 0.013 millimeters (mm). Eggs hatch in 7 to 55 days, depending
upon the temperature (Table 4). The first instar is the only mobile stage
(Fig. 1) besides the adult. The majority of the first instars settle down to
feed within several centimeters (cm) of the egg spiral in less than 1 hour.
The remainder of the population (less than 1%), however, may move as
much as 10 cm from the eggs in a 3 to 4 hour period (Dowell et al., 1977).
The first instar is elongate-ovate in shape, and is brown with a tan
margin. There are two filaments curving over the body that originate at
the ends of the insect (Fig. 1). The nymphs tend to line up along the leaf
veins. The first instar averages 0.3 mm long and 0.15 mm wide.
The second instar (0.41 x 0.2 mm) is more ovate than the preceding in-
star, and is dull black with the exception of a large, somewhat circular
spot on the anterior part of the dorsum, which remains a dull green (Fig.
2). The insect at this stage is also decidedly more convex than the
preceding instar, with the spines more numerous and prominent.
In the third instar (Figs. 3 and 4) sexes can be distinguished with cer-
tainty for the first time. Males average 0.59 x 0.18 mm and are smaller
than the females, which average 0.68 x 0.24 mm. The only portion of the
third instar that does not become black is a more or less circular dull
green spot on the anterior dorsum, situated over most of the thorax and
the anterior abdomen. The spines are more numerous and stouter than in
the second instar. The cast skin of the preceding stage often remains at-
tached or entangled in the spines of the mid-dorsum. The convexity of
the individuals becomes pronounced, and the insect is distinctly ovate.
The fourth instar is ovate, with the anterior being the smaller end. This
instar is convex and covered with numerous long, stout, conspicuous
spines. The sexes are readily distinguished; the female averages 1.24 x
0.71 mm and is much larger than the male at 0.99 x 0.61 mm. Further,
filamentous white wax is secreted around the margin of the body; the
males usually secrete noticeably more wax than do the females (Fig. 5).

3



























Figure 1. Egg spiral and first instars of citrus blackfly on underside of citrus
leaf (24X).
Figure 2. Four citrus blackfly second instars. Note spines, characteristic color,
and alignment along vein of leaf (24X).










Figure 3. Visual com-
parison of first (a),
second (b), and third (c)
instar citrus blackflies
(35X).









F Id' .+




:a~

















Figure 4. Group of

stars. The clear insect (a)
has just molted. Another
instar (b) is about to
molt. The smaller third
instars (c) are males, the
,larger (d) are females
S(9X).



















.,5
I W
I
















Figure 5. Male (a) and female (b) fourth instar citrus blackfly. The female is
much larger. Emergence slits can be seen in two of the male fourth instars (c)
(26X).

5









At adult emergence, a T-shaped split (Fig. 6) appears anteriorly, the
stem of which arises at the middle of the anterior margin and extends
caudally along the median dorsal line to the junction of the thorax and
abdomen. The arms of this T-shaped split extend to the right and left
along the suture separating the thorax and abdomen. This split is visible
from 0.5 to 1 hour before the adult begins to emerge. The pharate adult
pushes against the split in the fourth instar skin, causing it to spread
wider. Adults emerge by using a wriggling, up-and-down movement, in-
terspersed with numerous rests. Some hardening of the various body
parts begins during these rests. Often, despite efforts to cling to the leaf,
the emerging insect falls to the ground, where many probably die or fall
victims to predators such as ants. The time taken for normal emergence
is from 14 to 30 minutes; under dry conditions, emergence may take as
long as 1.5 hours, or the insect may die without being able to escape.
When the adults first emerge, the head, thorax, and abdomen are a
bright brick-red, with the front of the head (the vertex) pale yellow, the
antennae and legs whitish, and the eyes a dark red or reddish brown (Fig.
7). The wings are expanded to full size 18 to 30 minutes after the insect
has emerged (Fig. 8). When the adult has trouble freeing itself from the
fourth instar, the wings begin filling out, nevertheless, and thus the insect
may become crippled. After about one hour, the head, thorax, wings
(with the exception of the colorless or whitish areas), and legs become
brown; the sutures on the thorax and the entire abdomen remain brick-
red, but the antennae become reddish brown.
Within 24 hours after emergence, the insects become covered with a
heavy pulverulence so that they have a slaty blue appearance. When the
insect is at rest, colorless spots on the wings form a white band across the
middle of the dorsum.
Adult citrus blackflies may live for up to 14 days, but virtually all
/ oviposition is completed in the first 4 days after emergence. Although
maximum fecundity per female is 100 to 110 eggs, the average number of
S eggs laid per female is 65 to 70. Unmated females lay viable eggs that give
rise to only male offspring. The sex ratio is about 1:1.

ENVIRONMENTAL FACTORS
Temperature and Humidity
As with all insects, the growth rate of immature citrus blackflies is
directly dependent upon the temperature of their surroundings. Dowell
and Fitzpatrick (1978) studied the effects of temperatures on the
developmental rate and survival of immature citrus blackflies (Table 2).
Fifty-seven degrees F (equal to 13.7 OC) is the threshold temperature for
citrus blackfly development; no development occurs at or below that
point.

6









Table 2. Number of degree-days required for completion of each development
stage of the citrus blackfly.
Observed at
Calculated Fort Lauderdale
Stage Degree-days ('C)' Degree-days (x)

Egg 161 164
First instar 121 122
Second instar 98 98
Third instar 117 112
Fourth instar 487 480
Life cycle 984 976
Taken from Dowell and Fitzpatrick, 1978.

1. Calculated as high + low temperature 13.70C for each day.
2


By describing citrus blackfly development in degree-days ([high + low
temperature 2] 13.7 C), the number of generations possible in any
given location can be calculated by use of weather data. For example,
weather data collected at the Agricultural Research Center, Fort Lauder-
dale, and Agricultural Research and Education Center, Lake Alfred,
from 1976-1978 were used to calculate the number of degree-days ac-
cumulated each month at both locations (Table 3). These figures can be
summed and divided by 984 (the number of degree-days needed for one
complete life cycle) to estimate the number of generations possible per
year at each site. At Fort Lauderdale, 3.6 to 3.8 generations were possi-
ble yearly, and temperatures were warm enough for citrus blackflies to
grow year-round. At Lake Alfred, however, there would be 3 to 3.2
generations possible per year. This reduction is due to the much colder
weather during the period November to March. Because of this colder
weather, probably citrus blackfly development would stop during the
winter months in the Lake Alfred area, should the insect become
established there. This information will be used later in this bulletin in
designing a survey scheme for citrus blackfly in groves in central Florida.
The number of days required for completion of each developmental
stage at five different constant temperatures is given in Table 4.
Temperature also affects citrus blackfly survival. Dowell and Fitz-
patrick (1978) found that survival of immature citrus blackflies held in
constant temperatures was greatest at 25.6C and decreased with a
change in either direction from that figure (Table 5). They were unable to
rear citrus blackflies successfully at constant temperatures of 31 or
34 C.

7















CA. '.












I ,.. . .
















Figures 6-8. Emergence of adult male citrus blackfly from fourth instar, the
pumping-up of its wings, and final color pattern (22X).






8










Table 3. Monthly total degree-days accumulated at Fort Lauderdale and Lake
Alfred, Florida, 1976-78.

Fort Lauderdale Lake Alfred
Month
Month 1976 1977 1978 1976 1977 1978

January 122 96 120 46 21 46
February 149 143 84 98 47 19
March 269 284 200 233 205 129
April 251 254 265 216 216 234
May 350 315 372 307 291 341
June 345 395 400 357 404 404
July 412 412 435 419 422 426
August 408 417 416 417 427 427
September 375 391 395 347 404 391
October 294 253 286 223 242 291
November 243 253 286 210 190 242
December 191 179 253 73 160 144

Total 3410 3392 3512 2946 3029 3094

Generations
per year 3.5 3.5 3.6 3.0 3.0 3.1


Table 4. Comparison of the number of days required for development of the im-
mature stages of citrus blackflies at selected constant temperatures.

Instar
Average Life
Temp. (oC) Eggs First Second Third Fourth Cycle

10 Never Never Never Never Never Never
16 97 73 55 70 272 567
21 22 17 13 16 63 133
27 13 9 7 9 36 74
32 9 7 5 6 25 52'

Taken from Dowell and Fitzpatrick, 1978.
1. This is a hypothetical value, since no adults emerged from nymphs held at constant
temperatures above 31 C.





9









Table 5. Survival of immature citrus blackflies at various constant temperatures.

Total Eggs Number Surviving
Temperature (C) Exposed Adults/1000 Eggs

20 400 275
23 1100 363
26 800 525
28 500 457
31 250 0
34 400 0
Taken from Dowell and Fitzpatrick, 1978.


Cherry (1979) studied the effects of short-term (3-hour) extreme
temperatures on citrus blackfly survival. Temperatures in excess of 45 C
for 3 hours are required before more than 50% of the immature citrus
blackflies exposed are killed (Table 6). Temperatures this high seldom
occur in Florida. Low temperatures of less than 10"C for a short dura-
tion are required before more than 50% of the immature stages are
killed, although temperatures between -5 C and 10 "C will kill most
of the eggs and adults (Table 7). For comparison, citrus seedlings are
killed by temperatures of 5 "C for 3 hours. Thus, citrus blackfly could
easily survive any temperatures found in citrus-growing regions of
Florida.



Table 6. Average survival of citrus blackfly after high temperature exposures for
3-hour periods in constant (+ 0.1 C) temperature cabinets.

Percent Survival'

Control
Stage (ca. 22 C) 35 C 40 C 45 C 50 C

Egg 100 90 90 70 45
First instar 70 65 60 30 10
Second instar 85 80 80 65 45
Third instar 80 80 80 65 40
Fourth instar 90 95 80 75 40
Adult (both sexes) 95 90 90 5 0

Taken from Cherry, 1979.
1. N = 40 citrus blackflies per exposure.

10









Table 7. Average survival of citrus blackfly after low temperature exposures for
3-hour periods in constant (+ 0.1 C) temperature cabinets.

Percent Survival'

Control
Stage (ca. 220C) 0C -5C -10C -15C

Egg 90 90 65 0 0
First instar 80 90 85 65 15
Second instar 90 85 90 70 10
Third instar 95 95 90 95 0
Fourth instar 100 90 90 85 10
Adult (both sexes) 90 90 85 15 0
Taken from Cherry, 1979.
1. N = 40 citrus blackflies per exposure.


Wind, rain, and low humidity have also been given as important en-
vironmental factors for the citrus blackfly. Flanders (1972) reported that
high winds and heavy rains were able to dislodge and kill adult citrus
blackflies. While this will happen in Florida, storms are too sporadic to
greatly influence citrus blackfly populations.
The hot, dry weather of Mexico greatly reduces citrus blackfly survival
(Flanders 1972). In Florida, however, these two factors are seldom found
together. Florida's hot weather coincides with high humidity, while the
low humidity season is also the coldest. It is unlikely that humidity will
be an important factor in limiting citrus blackfly spread or survival.


Plant-Insect Relations

Host plant studies had the following goals: (1) to determine the host
ranges of citrus blackfly with respect to oviposition and development, (2)
to rank host plants in terms of citrus blackfly productivity, (3) to look
for potential attractants for use in citrus blackfly surveys, and (4) to
determine if any common native plant species could support a high
enough level of citrus blackfly survival to aid dispersal of citrus
blackflies from infested area into central Florida.
Not all of the plants studied are equally attractive to citrus blackfly as
egg-laying sites (Tables 8 and 9). Citrus blackflies prefer to oviposit upon
citrus, mango, kumquat, orange-jessamine, and pink trumpet. Another
group of plants, including loquat, Surinam-cherry, ardisia, Brazilian-
pepper, and avocado, are considerably less preferred for oviposition but
are still utilized to some extent (Tables 8 and 9 and Appendix 1). Citrus

11










Table 8. Average number of egg spirals laid on potted plants by female citrus
blackflies in dooryard exposures.
x Citrus Blackfly
Plant' Egg Spirals/Plant

Lime 10
Mango 7.5
Pink trumpet 7.3
Kumquat 6.7
Wampi 2.8
Loquat 2.5
Marlberry 1.0
Brazilian-pepper 0.5
Chinese box-orange 0.3
Silver trumpet 0.3
Myrsine 0.3
Limeberry 0.3
Ardisia 0.3
Black sapote 0.1
Surinam-cherry 0.1
Toog 0
Avocado 0
Sapodilla 0
Coffee 0
Prickly-ash 0
Modified from Dowell et al., 1979b.
1. Refer to Appendix 1 for scientific names of plants.


blackflies never deposited eggs on other plants used in our tests (e.g.,
castor bean and cherimoya). As indicated in Table 9, the number of plant
species used for oviposition by citrus blackflies varies directly with the
size of the adult population. At very low densities, only citrus, mango,
and Murraya paniculata are commonly used.
Table 10 lists 12 plants surveyed in home yards in Broward County in
the order of the percentage of these plants found infested with citrus
blackflies. Oviposition preferences in the field agree closely with lab
studies, lending further support to the ideas that citrus blackflies
preferentially oviposit on certain plants and that the number of plants
oviposited upon directly varies with the number of citrus blackflies. At

12









the time of the survey, northern Broward County had more citrus
blackflies than the southern portion.
The survival of the immature citrus blackflies on all plants oviposited
upon is not equal. Only a few (20 to 30) plant species are capable of sup-
porting complete development of citrus blackflies from egg to adult (Ap-
pendix 1). The ability to support complete citrus blackfly development is
our definition of a "host plant" of this insect. All plants incapable of
this are not considered as host plants. Survival of immature citrus
blackflies was as high on black sapote, ardisia, and wampi as it was on
citrus (Table 11).
Plants in Table 11 were ranked in terms of a replacement value; that is,
the number of eggs each citrus blackfly female must lay in order to exact-
ly replace the initial egg number tested. In theory, any plant with a
replacement value less than the average fecundity of a female citrus
blackfly (67 eggs per female) (Riviello, et al. 1978) is capable of support-
ing a population of citrus blackflies indefinitely. Seven plant species were
rated as capable of doing this (ardisia, avocado, black sapote, citrus,
Surinam-cherry, toog, and wampi) (Table 11). In these tests, however,
only ardisia, black sapote, citrus, Surinam-cherry, and wampi were ac-
tually able to do so. The very low ovipositional attractiveness of


Table 9. Field host selection by citrus blackfly at three different densities of
ovipositing adults.

x Citrus Blackfly Egg Spirals/Plant

Plant' Test 1 Teat 2 Test 3

Citrus 11.8 415.3 4521
Mango 13.0 314.7 1128.7
Orange-jessamine 10.2 40 298.0
Loquat 1.2 0 14.0
Wampi 0.3 2.7 12.0
Brazilian-pepper 0.2 3.3 5.0
Papaya 0 1.0 3.0
Avocado 0 0 2.3
Natal-plum 0 0 0.5
Sugar-apple 0 2.0, 1.7
Wild-coffee 0 0 1.0
Castor bean 0 0 0
Taken from Dowell et al., 1979b.
1. Refer to Appendix 1 for scientific names of plants.

13









Table 10. Survey of plants infested with citrus blackfly in yards adjoining
nurseries in Broward County, Florida, from July to December, 1977.'

Northern Broward Co. Southern Broward Co.

Number Percent Number Percent
Plant2 observed infested observed infested

Citrus 4,437 57.1 4,452 3.4
Mango 843 33.8 1,302 0
Kumquat 36 19.4 10 0
Limeberry 33 24.2 121 0
Pink trumpet 21 19.0 2 0
Surinam-cherry 6,372 5.7 9,460 0
Loquat 192 3.6 237 0
Sapodilla 36 2.8 28 0
Brazilian-pepper 1,304 2.6 1,327 0
Gardenia 762 1.4 297 0
Ixora 18,236 0.2 7,303 0
Toog 104 0 96 0
Taken from Dowell et al., 1979b.
1. In late 1977, there were more citrus blackflies in northern Broward County than in
southern Broward County. The survey data is therefore reported separately for the two
areas.
2. Refer to Appendix 1 for scientific names of plants.



avocado and toog preclude their sustaining a population of citrus
blackflies. In theory, all the other host plants are incapable of supporting
a population of citrus blackflies indefinitely, and laboratory tests
verified this.
A number of native and naturalized plants of southern Florida were
hosts of citrus blackfly (Table 11). We found that any park having large
numbers of ardisia, marlberry, and/or myrsine, plus some citrus trees,
could harbor native plants which were infested with citrus blackfly,
(Steinberg et al., 1978). Howard (1979b) presented further data on the
suitability of Ardisia spp. as hosts for citrus blackfly.
We feel that the citrus blackfly is incapable of utilizing native and
naturalized vegetation as an aid in dispersal from the infested area.
Howard and Neel (1978) surveyed the plants along the North New River
Canal as it extends from Ft. Lauderdale northward to Lake Okeechobee.
The six most commonly encountered plant species are listed in Table 12.
The first five are common enough that they could act as potential disper-

14









sal agents, but only Brazilian-pepper was capable of supporting complete
development of citrus blackfly. However, our data shows that it cannot
support a population of the citrus blackfly in the absence of an infested
citrus tree nearby.
Since citrus and mango are economically important hosts of the citrus
blackfly, more detailed studies were done on these plants. All Citrus spp.
tested were equally attractive to ovipositing citrus blackflies (Dowell and
Steinberg, 1979), and all supported complete development of the insect.
However, survivorship varies among the plant species in the genus (Table
13) (Dowell et al., 1978; Howard, 1979a). In general, citrus blackfly sur-



Table 11. Number of eggs required per female citrus blackfly to replace initial
number of eggs laid on 20 host plants.

Plant' Replacement Value2

Ardisia 8
Citrus 8
Black sapote 8
Wampi 9
Toog 35
Surinam-cherry 38
Avocado 55 below reported fecundity of 67 eggs/ 9
Limeberry 79 above reported fecundity of 67 eggs/ 9
Myrsine 109
Mango 111
Brazilian-pepper 119
Kumquat 130
Loquat 134
Chinese box-orange 215
Pink trumpet 228
Silver trumpet 285
Marlberry 296
Prickly Ash 508
Coffee 522
Sapodilla 520
Taken from Dowell and Steinberg, 1979.
1. Refer to Appendix 1 for scientific names of plants.
2. The number of eggs each female must lay to replace initial number begun with.

15









Table 12. Frequencies of shrubby plant species along the North New River
Canal, Broward County, May 1976.

Percent of 25 Transects in
Species' which Species Occurred

Elderberry 60.0
Australian-pine 40.0
Groundsel 36.0
Florida-holly 32.0
Castor-bean 20.0
Guava 12.0

Taken from Howard and Neel, 1978.
1. See Appendix 1 for scientific names.


Table 13. Laboratory survivorship of citrus blackflies on six species of citrus.

No. of Citrus Blackfly Adults
Citrus Species' Emerging/1000 Eggs

Lemon 646
Orange 457
Lime 427
Tangerine 417
Tangelo 417
Grapefruit 316
Taken from Dowell et al., 1978.
1. See Appendix 1 for scientific names.



vival is greatest on lemons and limes and poorest on grapefruit. These
differences are generally unimportant, since a population of citrus
blackfly will thrive on any of them.
The inter-relationship between the citrus blackfly and mango was
detailed by Dowell (1978) and Dowell and Steinberg (1979). Citrus
blackfly survival on mango (Table 14) was too poor to allow a popula-
tion of citrus blackfly to exist on it without the constant immigration of
gravid females from nearby citrus trees. It is highly unlikely that the
citrus blackfly will be able to maintain itself in mango groves. No reduc-
tion in mango yields due to citrus blackfly has been reported.
We failed to find any long-range chemical attractants for adult citrus
blackflies in citrus leaves. It appears that citrus blackfly adults are only

16









Table 14. Survival of citrus blackfly nymphs on mango as compared to citrus.

Mango Mango
Test 1 Citrus2 Test 2

Initial egg number 17061 1706 17063
Number of adults 40 855 42
Number of 9 citrus blackfly 16 342 15
Number of eggs/ 9 citrus blackfly needed
to replace initial egg number 106 5 111
1. Taken from Dowell, 1978.
2. Taken from Dowell et al., 1978; represents a composite figure of six citrus species.
3. Taken from Dowell and Steinberg, 1979.


Table 15. Time spent by adult female citrus blackflies on leaves of various plants
per 10-minute observation period.

Plant2 Median Sec/10 Min

Orange 215.0
Surinam-cherry 49.5
Gardenia 13.0
Boston fern 1.5
Taken from Dowell, 1979a.
1. Ten females tested per plant.
2. See Appendix 1 for scientific names of first three plants.



capable of identifying and evaluating a plant after first making contact
with it (Table 15). Figure 9 is a flow-diagram describing the ovipositional
process in citrus blackfly. The insects are attracted to any object reflect-
ing light of the proper wavelength. After that, all selection is done after
landing on the leaves.

Dispersal

There are three routes by which the citrus blackfly can disperse: adult
flight, passive movement on excised leaves, or the transport of infested
plants.
Researchers in Florida (Dowell, 1979) and Texas (Hart et al., 1978)
have studied the dispersal of adult citrus blackflies. Overall, it appears
that the citrus blackfly is capable of moving 400 to 600 meters (m) per
generation unaided by man. Adult dispersal from infested plants is a

17











ADULTS EMERGE
AND MATE






ACCEPTED FOR
FEEDING



NO
LEAF
DISPERSE ITO NO ACCEPTED FOR
ANOTHER LEAF) OVIPOSITION?




YES

AFTER FEMALE
OVIPOSITION OVIPOSITS


PROPER
PHOTO-
STIMULI


NO
LEAF
ACCEPTED FOR
n f b OVIPOSITION?19





(Table 16). In Mexico citrus EAF HAS ckfly disp YESal through flight was less









INSthan 400 m per generation (Smith et al., 1968).INSECT
ISETPROPER CONTACT STAYS
LANDS STIMUAYS


NO





Figure 9. Flow diagram of oviposition by the citrus blackfly. Rectangles are ac-
tions, diamonds are decision points, and the trapezoid is the point where en-
vironmental factors become important. (Dowell, 1979a)



continuous process, but few insects fly beyond 50 m from any given host
(Table 16). In Mexico, citrus blackfly dispersal through flight was less
than 400 m per generation (Smith et al., 1968).
Live adult and immature citrus blackflies have been found on leaves
with packed fruit and as parts of corsages (Florida Department of
Agriculture, 1922). Shaw and Ortiz (1951) observed emergence of adult
citrus blackflies from fourth instars on excised lime leaves after 12 days


18









Table 16. Average number of adult citrus blackflies caught on yellow sticky
traps at different distances and exposure periods.

Distance from Traps Changed Traps Changed
Infested Citrus Tree (m) Daily x/Trap Weekly x/Trap

<1 276.0 1,000.0
5 23.0 126.0
10 3.2 13.0
15 4.5 17.3
20 1.4 12.0
25 1.8 9.8
50' 0.5 -
Taken from Dowell, 1979a.
1. Only four traps survived vandalism at this distance.


of storage at room temperature. Cherry et al. (1978) found that under
screenhouse conditions all adult citrus blackflies emerged from excised
leaves within 4 days. When the excised leaves were sealed in plastic bags
sprayed with water, emergence was 19% and extended 10 to 13 days after
leaf excision. Between the low survival of citrus blackflies on excised
leaves and the 1979 containment regulations, it is unlikely that the citrus
blackfly will spread beyond its 1979 boundaries on excised host leaves.
We believe that the citrus blackfly came to this hemisphere on either
infested citrus or mango plants (Dietz and Zetek, 1920). This is probably
the avenue by which the citrus blackfly entered Florida and the method
by which it has escaped the containment procedures instituted in 1976.
The proper inspection and treatment of all regulated plants will reduce
the possibility of man-induced dispersal. If the citrus blackfly is even-
tually found in central Florida, it probably will have been brought in on
infested potted plants.


Damage to Tree

Feeding by immature citrus blackflies can damage a plant in two rather
distinct ways: first, through the direct feeding of nymphs on "the leaves;
second, through the production of honeydew, on which various sooty
molds develop. Under moderate to heavy infestations, leaves will be
black on the underside with immature citrus blackflies and black on the
upper surface with sooty mold.
After hatching, the first instar citrus blackfly soon settles down over a
leaf vein and inserts its mouthparts into the plant to feed on plant fluids.
Thenymphsmaycause extensive cellular damage to the leaf (much like

19









that done by rust mites); they remove plant nutrients and/or inject toxins
into the leaf.
Cellular damage was evaluated by measuring the amount of ethylene
gas produced by leaves on which third and fourth instar citrus blackflies
were feeding. Ethylene is produced by the leaves in direct response to
damage; the greater the damage, the greater the amount of ethylene pro-
duced daily. Dowell and Selhime (unpublished data) found that citrus
blackflies produce less than 1/2Q theamunof cellular damage
(ethylene) caused by rust mites at the same density (McCoy and Albrigo
1975). rom these obser\ation,-; i- appears that the citrus blackfly,
feeding on citrus leaves, does relatively little cellular damage as_ cm-
pared.to the citrus risftffite:."
Organic nitrogen levels were measured in orange leaves infested with
several citrus blackfly population densities to determine nutrient loss.
Other organic materials may also be removed during citrus blackfly
feeding, and changes in nitrogen levels are indicative of this. It takes
from 5 to 10 citrus blackflies per square centimeter (cm2) to reduce the
nitrogen levels below the 2.2% needed in orange for successful fruit set
(Chapman, 1968; Reitz et al., 1972). Shortly after insect density was
reduced to less than two per cm2, nitrogen levels quickly rose to 2.3%.
Investigators in Mexico (Smith et al., 1968) reported over 90% reduction
in fruit production occurred with citrus blackfly infestations exceeding
five to seven nymphs per cm2 on virtually all leaves. Fifty to 100 citrus
blackfly nymphs are required on a leaf before the nitrogen level in that
leaf will drop below 2.2%; infestations of up to 20 to 30 per leaf appear
to cause no measurable loss of nitrogen. Imported parasites of the citrus
blackfly are holding the insect at densities well below this level. Observed
reductions in fruit yield at high citrus blackfly densities can be explained
through the loss of at least organic nitrogen and probably other organic
materials from the leaves via feeding by the nymphs. This deficiency can
reduce bloom and fruit set.
Although it is possible that citrus blackfly nymphs could be injecting
toxins into the leaves as they feed, this has not been confirmed. During
their feeding, nymphs excrete honeydew which falls onto the surface of
leaves below. Sooty-mold fungi grow on this honeydew; and the fungi
are reputed to interfere with photosynthesis and reduce yields.


CONTROL
Survey and Detection
We are concerned with detection of the citrus blackfly in a range of
settings from urban, with small groups of virtually isolated trees, to the
large citrus grove.

20









Dowell et al. (1979) and Dowell and Cherry (1979) studied several
aspects of citrus blackfly detection in the urban setting. They found that
yellow traps like those used by Stone (1950) in Mexico, and reflecting
light at the wavelength 550 nanometers, caught the most adult citrus
blackflies.
To determine whether these yellow traps (plastic coffee can lids
covered with Tanglefoot) are as effective in an urban setting as in a
grove (Harlan et al., 1979; Hart et al., 1978), individual traps were hung
on 160 trees in a lightly infested urban area from March 22 to July 5,
1977, for 1 to 7 day intervals (Fig. 10). After this, the presence or absence
of adult citrus blackflies on the traps was noted, and each tree was visual-
ly examined for live citrus blackflies. The visual survey (10 man-minutes
per tree) consistently detected more citrus blackfly infested trees than
were indicated by the traps (Table 17). On the basis of these data, we feel
that a periodic visual survey of urban areas is the more discriminating
method of detecting citrus blackflies.
For the homeowner, a visual inspection of his trees two or three times
a year will be sufficient to detect any potentially damaging level of citrus
blackflies. Any leaves suspected by the homeowner of having citrus
blackflies on them should be taken to a County Extension Office for ex-
amination. (See Appendix 2 for addresses and phone numbers.)



Table 17. Comparison of visual observations vs. yellow sticky traps (exposed I
and 7 days) in detecting light citrus blackfly infestations in an urban environment.

1 Day Trap Exposure 7 Day Trap Exposure

Date Ties' Trap2 Visual3 Ties' Trap2 Visual3

March 22-28, 1977 14 1 5 14 1 5
April 6-14 9 0 11 9 0 11
April 19-27 9 0 11 5 1 14
April 28-May 5 4 0 16 3 0 17
May 13-21 6 0 14 5 1 14
May 27-June 3 13 0 7 17 0 3
June 14-22 8 0 12 9 1 10
June-July 5 6 0 14 8 0 12
Total 69 1 90 70 4 86
Taken from Dowell and Cherry, 1979.
1. Both traps and visual survey had the same result.
2. Number of trees in which the trap detected citrus blackflies while visual survey did not.
3. Number of trees in which visual survey detected citrus blackflies but traps did not.

21

















































Figure 10. IFAS technician Steven Pastor hanging a yellow sticky trap.



Detection of citrus blackflies in a citrus grove is complicated by the
size and number of trees present. However, two factors make the prob-
lem more easily solved. The first is that at economically damaging levels
of citrus blackflies, large numbers of leaves will be covered by sooty-
mold. The second concerns the physical distribution of citrus blackflies
within infested trees.

22









Cherry and Fitzpatrick (1979) found that leaves infested with live
citrus blackflies are consistently more common on the lower half of
citrus trees (Table 18). In addition, Dowell and Cherry (1980) found that
citrus blackfly egg spirals are clumped on leaves and that these infested
leaves occur in clusters. Thus, at economically damaging levels of citrus
blackfly, infested leaves are easily seen.
Hart et al., (1979) have shown that yellow traps will detect citrus
blackflies in groves where manpower for visual examination of leaves is
not available. An alternative way to check for economically damaging
levels of citrus blackflies is to examine any tree with heavy sooty mold at
periodic intervals. Since dispersal and population build-up of citrus
blackflies are slow, two visual inspections per year (in June and again in
September) should suffice. In those areas south of Palm Beach County,
we suggest looking in May and August. Any leaves thought to be infested
with citrus blackflies should be taken to the local County Extension Of-
fice for examination (Appendix 2). Since sooty molds will also grow on
the honeydew excreted by other insects, such as whiteflies, aphids, soft
scales, and mealybugs, this procedure is not specific to the citrus black-
fly.


Table 18. Intra-tree dispersion of citrus blackflies based on leaves infested with
live insects.

Tree Section Leaves Infested Percent of Total

North quadrant 160 24.39
South quadrant 152 23.17
East quadrant 164 25.00
West quadrant 180 27.44
656 100.00


Upper half 188 28.66
Lower half 468 71.34
656 100.00


Within tree 405 51.59
Outer tree 380 48.41
785 100.00
Taken from Cherry and Fitzpatrick, 1979.
1. Fifteen trees were sampled with 4,000 leaves examined per tree.

23









Chemical Control

Although the citrus blackfly is under complete biological control,
which makes insecticide treatments unnecessary, we have included this
section for completeness and to summarize other available control
measures.
Prior to our research, most available data on chemical control was
either generated many years ago or developed in foreign countries under
conditions not necessarily comparable to those in Florida. Reinert and
Neel (1978) reviewed chemical controls used against the citrus blackfly
prior to 1976, including the use of malathion and dimethoate in Texas.
Chemical control research conducted since 1976 has focused on screening
a number of compounds and formulations for efficacy and photo-
toxicity; determining the fate of sprayed compounds; testing the use of
surfactant formulations to reduce the amount of insecticide needed to
achieve effective control; and developing alternative treatment pro-
cedures. Twenty-nine compounds have been screened for efficacy against
the citrus blackfly as foliar sprays. Generally, compounds that are effec-
tive against whiteflies worked well against the citrus blackfly (Table 19).
Of the compounds tested, 18 were demonstrated as effective for control-
ling the citrus blackfly (Reinert, 1976, 1978; Reinert and Fitzpatrick,
1977; Fitzpatrick et al., 1979a).


Table 19. Insecticides that have been screened for efficiency as dilute sprays
against the citrus blackfly in Florida since 1976.

Application Effective in
Insecticide Rate Method2 Controlling
(g AI/100 L)' Citrus Blackfly3

Diazinon' 60 L,F Yes
Naled (Dibrom) 60 L Yes
Carbaryl (Sevin) 60 L Yes
Chlorpyrifos (Dursban) 60 L,F Yes
Ethion' 60 L,C,F Yes
Ethion + oil 72 C Yes
Oxydemetonmethyl
(Meta-Systox R) 60 L,C Yes
Methamidophos (Monitor) 60 L Yes
Fenitrothion (Smithion) 60 L No
Temphos (Abate) 60 L No
Dimethoate (Cygon) 60 L,C Yes


24










Table 19. Continued.

Application Effective in
Insecticide Rate Method2 Controlling
(g AI/100 L)' Citrus Blackfly'

Carbophenothion'
(Trithion) 60 L,F Yes
Malathion (Cythion) 60 L,F Yes
Methidathion' (Supracide) 30 L,F Yes
Acephate (Orthene) 60 L,C,F Yes
Chlorpyrifos-methyl
(Reldan) 60 F No
Permethrin 30 L,C,F Yes
Resmethrin 30 L,C,F Yes
Butocarboxime
(Drawin 755) 72 L,C Yes
Heptenophos (Hostaquick) 60 C No
HOE 25682 60 C No
Azinphosmethyl (Guthion) 60 C Yes
Phosmet (Imidan) 60 F Yes
Endosulfan (Thiodan) 60 L No
Diflubenzuron (Dimilin) 60 C No
Diflubenzuron + oil 60 C No
Kinoprene (Enstar) 90 C No
Methoprene (Altosid) 90 C No
FC-435 oil' 1% L,F Yes

1. For the compounds that are effective, the lowest effective rate is given.
2. L =laboratory test; C =test conducted on container grown plants;
F=test conducted in the field.
3. Yes = > 90+% kill
No = < 80+% kill
4. Listed in Florida Insect Control Guide, Florida Cooperative Extension Service.
5. 4 (N,N-dimethyl carbamoyloxy-) -2-methyl-5,6,7,8-tetrahydro-chinolin


Soil drenching insecticides is an application technique well suited for
use on potted plants. Reinert (1979) has demonstrated that several com-
pounds are effective against the citrus blackfly when used in this manner
(Table 20).
Since the citrus blackfly is currently (March 1980) confined to urban
areas, we investigated the possibility that four insecticides available to
homeowners might have phytotoxic properties (Table 21). Generally, all

25









Table 20. Percent kill of immature citrus blackflies on potted trees treated with a
soil drench.'
Percent Kill
Rate
Compound (g AI/ha) 1 week 2 week 3 week

Acephate 75WP 5.6 34 94 95
11.2 85 94 100
Aldicarb 10G 5.6 12 59 90
11.2 60 99 100
Dimethoate 2.67EC 5.6 56 72 69
11.2 91 96 96
Oxydemeton-methyl 2EC 5.6 7 14 0
11.2 9 0 10
Oxamyl 2EC 5.6 13 0 10
11.2 32 12 14
Azinphos-methyl 2EC 5.6 8 0 0
11.2 1 0 0
Untreated 0 0 0
Taken from Reinert, 1979.
1. There were five replicates per treatment.


four insecticide formulations tested appear safe and effective for use in
dooryard situations (Reinert and Neel, 1978).
Other studies have dealt with the possible use of soil-infested systemic
insecticides to control the citrus blackfly (Fitzpatrick et al., 1979b), and
how long acephate and malathion residues remained detectable on urban
citrus trees (Nigg et al., 1979a, 1979b). Addition of the surfacant Atplus
411F resulted in maintenance of efficacy when rates of active ingredient
were reduced considerably. When acephate and malathion were tested
with this surfactant, there was no significant difference in efficacy be-
tween the recommended rates without surfactant, and half rate or less of
the recommended rate with the surfactant (Vaughan and Fitzpatrick,
1978) (Table 22).
Homeowners desiring to spray for the citrus blackfly should first con-
firm that they do, in fact, have the insect on their trees and that it is pres-
ent in sufficient numbers to cause damage. If they then decide to spray,
they may use any material registered for whitefly control on citrus, at the
rates recommended, it is our consensus that no homeowner need spray
specifically to control citrus blackflies. The use of chemical sprays in
citrus groves will be discussed later.

26










Table 21. Phytotoxicity' of insecticides on 28 species of ornamental plants com-
monly grown in south Florida.

Insecticide2

Mala- Ace- Di- Di-
thion phate methoate azinon
Plant Name lx 2x Ix 2x Ix 2x lx 2x

Arecastrum romanzoffianum
Becc. 0 0 0 1 0 0
Asparagus densiflorus
(Kunuth) Jessup 0 0 0 0 0 0 0 0
Bougainvillea glabra Choisy 0 0 0 1 1 0
Brassaia actinophylla Endl. 0 0 0 0 2 3 1 1
Bucida bucerus L. 2 3 1 2 3 3 3 3
Carissa grandiflora
(E. H. Mey.) A. D. C. 0 0 0 0 0 0 0 0
Chrysalidocarpus lutescens
Wendl. 0 0 0 0 0 0 0 0
Coccoloba uvifera L. 0 0 0 0 0 0 0 0
Cocos nucifera L 0 0 0 0 0 0
Codiaeum variegatum Blume 0 0 0 0 0 0 0 0
Dizygotheca elegantissima
(Hort. Veitch)
Vig. & Guill. 0 0 0 0 0 1 0 0
Dracaena marginata Lam. 0 0 0 0 0 0 0 0
Ficus benjamin L. 0 1 0 0 1 3 0 0
Fiscus retusa L. 0 1 0 1 0 3 0 1
Hibiscus calycinus Willd. 1 3 1 2 0 2 2 3
Hibiscus rosa-sinensis L. 1 3 1 1 1 2 2 3
Ixora coccinea L. 0 0 0 0 0 0 1 1
Jasminum volubile Jacq. 0 0 0 0 0 0 0 0
Ligustrum japonicum Thumb. 1 2 0 0 0 0 0 0
Murraya paniculata
(L.) Jack 0 0 0 0 0 0 0 0
Philodendron selloum
C. Koch 0 0 0 0 0 0 0 0
Phoenix dactylifera L 0 0 0 0 0 0
Pittosporum tobira
(Thumb.) Ait. 0 0 0 0 0 0 0 0


27









Table 21. Continued.
.4
Insecticide'

Mala- Ace- Di- Di-
thion phate methoate azinon
Plant Name lx 2x lx 2x lx 2x lx 2x

Podocarpus macrophylla
(Thumb.) D. Don 0 0 0 0 0 0 0 1
Rhoeo spathacea
(Swartz) Stearn 0 0 0 0 0 0
Sinningia speciosa
(Lodd.) Hiern. 0 0 0 1 0 0
Viburnum suspensum
Lindl. 0 0 0 0 0 2 0 0
Veitchia merrillii
(Becc.) Moore 0 0 0 0 0 0

Taken from Neel and Reinert, 1975.
1. 0 = no damage; 1 very slight damage; 2 = moderate damage; 3= severe
damage; = not treated.
2. Rates of each chemical used at lx (manufacturer's recommended) rate in grams of active
ingredients per liter were: Malathion 57% EC, 1.5; Acephate 75 WP, 1.2; Dimethoate 2.67
EC, 0.6; and Diazinon 4 EC, 0.6. 2x means that chemicals were tested at twice the recom-
mended rate.




Table 22. Insecticides and surfactant' formulations tested for controlling citrus
blackfly infestations.

No. Citrus Blackfly Nymphs/Leaf

Application Pre- 4 weeks
Insecticide Rate (per 100 liters) treatment after treatment

Acephate 60 g, no surfactant 22.6 0
Acephate 60 g, surfactant 33.8 0
Acephate 30 g, surfactant 39.0 0
Acephate 12 g, surfactant 36.7 0.1
Malathion 1 liter, no surfactant 42.0 3.7
Malathion 1 liter, surfactant 36.1 2.1
Malathion 0.1 liter, surfactant 34.3 0.1
Untreated -31.4 31.3

Taken from Vaughan and Fitzpatrick, 1978.
1. Surfactant (Atplus 411) was added at the rate liter per 100 liters.

28









Biological Control

Cherry and Dowell (1979) studied the seasonal abundance and feeding
preference of the citrus blackfly predators found on southern Florida
citrus (Tables 23 and 24). They found the little black lady beetle
(Delphastus pusillus Lee.) and the little tan lady beetle (Delphastus
pallidus Lee.) to be the most common ladybird beetles present on urban
citrus trees (Table 24). The predators killed between 50% and 67% of all
citrus blackfly eggs and nymphs, and up to 80% of all adults. A life-table
analysis of citrus blackflies in Broward County at several different times
(Dowell et al., 1979) showed that although predators can kill a large
number of citrus blackflies, predators alone are not capable of causing
citrus blackflies populations to decrease. This is because the natural
fecundity of the citrus blackfly is high enough to more than compensate
for the loss of offspring.
Early in 1976, officials of the Department of Agriculture and Con-
sumer Services decided to supplement native predators with imported
parasites specific to the citrus blackfly. Accordingly, the first shipment
of parasites from USDA-SEA researchers in Texas was hand carried by
W. G. Hart to Fort LaudeIdale, Florida, on April 7, 1976. The parasites
were then released at carefully selected release sites in Broward County
(Hart et al., 1978). Subsequent shipments were either hand carried or
sent to A. G. Selhime, USDA-SEA, Orlando, Florida, for release in the
Fort Lauderdale area.
Three parasite species were received from Texas. They were Amitus
hesperidum Silvestri (25,350), Prospaltella opulenta Silvestri (1,300), and
Prospaltella clypealis Silvestri (250). Of these, A. hespridum became
established very quickly and within 8 months had parasitized more than
90% of all available citrus blackflies at the release sites (Fig. 11). Disper-
sal of A. hesperidum was aided by regulatory personnel who took leaves
with parasitized fourth instar citrus blackflies from selected trees and
pinned these leaves on other trees throughout Broward County. Cherry
et al. (1978) showed that A. hesperidum will emerge from the parasitized
citrus blackflies on excised leaves for up to 4 weeks at room temperature,
and that cool storage can extend emergence up to 6 weeks (Table 25). By
the end of 1978, A. hesperidum had been spread throughout most of the
infested area.
Figure 12 shows the population trends of the citrus blackfly in
Oakland Park, Broward County, from June 1976 to December 1978.
A. hesperidum became numerous in the city in early 1977. Prior to this,
we observed between 40 to 60 live citrus blackfly nymphs per leaf. By
September 1977 (8 months later), this figure had been reduced by 98% to
about 1 nymph per leaf. Table 26 presents data from the same area show-
ing that parasite presence was the key factor responsible for this decline.

29










Table 23. Predators caught by fumigating branches of urban trees in Broward
County, Florida, during 1977 and 1978.
Season'
Taxon Winter Spring Summer Fall Total

Aranaea 1977 53 27 103 65 248
1978 41 34 55 59 189
Chrysopidae
Adults 1977 5 2 3 3 13
1978 9 5 15 8 37

Immatures 1977 0 1 1 2 4
1978 7 7 1 4 19

Coccinellidae-Adults
Azya luteipes Muls. 1977 0 0 0 0 0
1978 0 0 0 1 1

Chilocorus stigma (Say) 1977 4 4 4 1 13
1978 1 3 1 0 5

Cycloneda sanguine (L.) 1977 8 4 0 1 13
1978 5 2 2 0 9

Cryptolaemus montrouzieri 1977 0 3 5 0 8
Muls.

Delphastuspallidus Lec. 1977 1 0 9 5 15
1978 3 1 4 18 26

Delphastuspusillus Lec. 1977 64 15 38 21 138
1978 14 5 23 27 69

Unidentified 1977 5 11 13 7 36
1978

Coccinellidae-immatures
Cycloneda sanguine (L.) 1977 0 0 4 0 4
1978 4 0 0 0 4

Delphastus spp. 1977 0 1 4 0 5
1978 0 0 0 0 0

Totals 1977 531
1978 351
Taken from Cherry and Dowell, 1979.
1. One hundred branches sampled (one per tree) per season.





30









Table 24. Feeding tests to determine predators of citrus blackfly.

Citrus Blackfly Stage'
Taxa egg nymph adult

Araneae
Gasterocantha elipsoides (Wal.) +
Leucauge venusta (Wal.) +
Lyssomanes viridis (Wal.) +

Chrysopidae
Chrysopa bicarnea Banks-adults -
Unidentified immatures (trashbugs) + +

Coccinellidae-adults
Azya luteipes Muls. +
Chilocorus stigma (Say) +
Cycloneda sanguine (L.) + + +
Cryptognatha nodiceps Mshll. +
Delphastus pallidus Lec. +
Delphastus pusillus Lec. + +
Nephaspis gorhami Lec. -

Coccinellidae-larvae
Cycloneda sanguinea (L.) + +
Cryptognatha nodiceps Mshll. +
Delphastes pusillus Lec. +

Dolichopodidae
Condylostylus chrysoprasi +
(Walker) adults

Formicidae
Camponotus floridanus (Buckley) -
Crematogaster ashmeadi (Mayer) -
Paratrechina longicornis (Latreille) -
Pseudomyrmex mexicanus Roger -
Taken from Cherry and Dowell, 1979.
1. Minimum of 10 individuals tested per citrus blackfly stage; response considered + if
20% or more of individuals consumed the citrus blackfly stage.


Without parasites, the replacement rate (Ro) was 1.6; that is, for every
egg laid in the first generation, 1.6 eggs would be laid in the second. With
the parasites present, the replacement rate was reduced to 0.2; that is,
one-fifth egg laid in second generation for every egg in the first.
Prospaltella opulenta also became established, but its numbers grew
more slowly than those of A. hesperidum. We began to observe it in
Oakland Park in early 1978. By the end of that year, it was the prevalent
parasite, and citrus blackfly numbers, which had begun to rise in late


31









100


90


80


70
+
60 -60
I-
S-Y = 0.425 x
R2= 98.7
a-
Z
LU J
S 40 -
w +
a- T
30


20

+
10


0 II I I
40 80 120 160 200 240

DAYS PAST INITIAL RELEASE

Figure 11. Percent parasitism of citrus blackflies by Amitus hesperidum at
release sites in Broward County for 200 days postrelease (Hart et al., 1978).


1977, became stabilized at an average of 8 nymphs per infested leaf. At
this level, less than 10% of the leaves on any tree had live citrus
blackflies. Densities of citrus blackflies in Oakland Park have not ex-
ceeded 15 citrus blackflies per leaf since June 1977. This is far below the
50 to 100 nymphs per leaf required to reduce nitrogen levels below the
2.2% level and stop fruit production. Life-table data (representative of

32









Table 25. Weekly number of A. hesperidum emerging from citrus blackflies on
excised citrus leaves stored under different conditions.

Weeks after Citrus Leaf Excision
Storage
Treatment' 1 2 3 4 5 6 7 Total

Screenhouse 23 8 6 1 0 0 0 38
100C 1 wk.2 10 12 2 2 0 0 0 26
10C 4 wk.3 11 4 2 2 14 9 0 42
50C-l wk.2 0 21 12 11 0 0 0 44
50C-4wk.3 1 0 0 0 0 0 0 1
Taken from Cherry et al., 1978.
1. One hundred fifty citrus blackfly fourth instars exposed per treatment.
2. Removed to screenhouse after 1 week.
3. Removed to screenhouse after 4 weeks.


these three phases) were analyzed and are presented in Figure 12. A 4.5
times increase in egg numbers was possible at each generation before the
parasites were introduced. (See data for June 1976 to January 1977 in
Figure 12.) After Amitus became established, there was a 5-fold decrease
in citrus blackfly numbers at each generation. (This corresponds to the
period January to September 1977 in Figure 12.) Currently, P. opulenta
is maintaining the citrus blackfly population at a constant level of 8
nymphs per infested leaf. (This corresponds to February 1978 onward in
Figure 12.)


Table 26. Comparison of the potential population increase of citrus blackflies
under screen room, research station, and field conditions.

No. Eggs/9
Initial Final No. Required Ro at 100
No. Eggs 9 Adults for R= 1' Egg/9 2

Screenroom 7284 1665 4.4 22.9
Research station 1436 72 20 5
Field (with parasites) 1086 2 543 0.2
Field (without
parasites)3 21 68 1.6
1. Ro = 1 when initial egg number = number eggs laid by survivors. Taken from
Dowell, 1979.
2. Maximum fecundity of the citrus blackfly is 100 eggs/9 (Dietz and Zetek,
1920; Dowell, unpublished data).
3. Assuming that the 19 parasitized fourth instars had survived and that the
9 / 6 ratio was 2:1 (Dowell, unpublished data) for all adults.


33









180 -




LL 50


I 40
6 0--
30




S320

"" V
SlO
I 10
LU


6 9 12 3 6 9 12 3 6 9 12
1976 I1977 I1978

Figure 12. Graph of average number of live, immature citrus blackflies per in-
fested leaf by month from June 1976 through December 1978 in Oakland Park,
Broward County, Florida. The arrows mark the points of maximum adult
emergence. The standard deviations of the plotted means ranged from 33% to
50% of the mean with an average of 43%. (Dowell et al., 1979a)

Cherry (1979) has demonstrated that short-term extreme temperatures,
both hot and cold, will not inhibit the movement of A. hesperidum
throughout the state. While we have no comparable data for P. opulen-
ta, it is the most widespread parasite in Mexico (Flanders, 1972; Smith et
al., 1968) and should also easily survive Florida's weather.
We feel that the citrus blackfly is currently under biological control in
Florida through the combined action of A. hesperidum and P. opulenta.
This biological control is compatible with existing pest management
practices on commercial Florida citrus.


Integrated Management

The Florida Citrus Spray Guide (Extension Circular 393-E) recom-
mends a number of materials for the control of insects, mites, and
phytopathogenic diseases. Many of the insecticides included in this guide
provide acceptable levels of control (more than 90% kill) for citrus
blackfly infestations (Table 20). Generally speaking, any formulation

34









recommended for whitefly control will probably work well against citrus
blackfly.
One of the most important questions that must be addressed when
considering chemical control impact on citrus blackfly populations is the
acute and chronic effects of the sprays on the natural enemy complex of
citrus blackflies. The difference between acute and chronic effects can be
a reflection of the severity of the stress imposed. For example, malathion
has a significantly acute effect on both P. opulenta and A. hesperidum
by reducing adult emergence of these parasites (Table 27). However,
when malathion is applied as an insecticidal component of a post-bloom
spray, it does not cause any significant long-term disturbance to the
parasite's ability to keep citrus blackfly populations in check.
Research studies on chronic effects take a great deal more time to con-
duct, since longer periods of time are required to observe changes in
parasite and host numbers through successive generations. In one long-
term study already completed, a spray program selected from the Florida
Citrus Spray Guide was shown to be extremely effective in reducing


Table 27. Insecticides that have been assessed for acute negative effects on Pro-
spaltella opulenta and Amitus hesperidum, parasites of the citrus blackfly.

Significantly' Reduced Emergence
Application
Insecticide Rate (g AI/100 L) P. opulenta A. hesperidum

Carbaryl 60 Yes Yes
Carbophenthion 60 Yes Yes
Chlorphyrifos 60 Yes Yes
Diazinon 60 Yes Yes
Ethion 60 Yes Yes
Fenitrothion 60 Yes Yes
Methamidophos 60 Yes Yes
Naled 60 Yes Yes
Malathion 150 Yes Yes
Methidathion 30 Yes Yes
Acephate 60 Yes No
Temephos 60 No No
Dimethoate 60 No No
Oxydemeton-methyl 60 No No
1. Average number of parasitoids emerging per leaf on treated leaves significantly (P < 0.05)
less than untreated leaves.

35








U-
g 40-
o A TREATED
UL-
25 A UNTREATED
. 30-
Z
U3

20 -


| 10- 0
A-A 0

W A A *A A A
I I I
APR MAY JUN JUL AUG SEP OCT

T1 T2

Figure 13. Average number of citrus blackfly adults caught per trap on citrus
trees subjected to two pesticide treatments. Treatment dates are indicated by T1
and T2. (Fitzpatrick et al., 1979)


100
IO


> 80
I-


o A TREATED
.rr 60 0 UNTREATED
LU


z 40



20 -_- -
20 A -A
*V- \AA0AA


APR MAY JUN JUL AUG SEP OCT

T1 T2

Figure 14. Average number of citrus blackfly nymphs per infested leaf on citrus
trees subjected to two pesticide treatments. Treatment dates are indicated by T1
and T2. (Fitzpatrick et al., 1979)

36








levels of citrus blackfly infestations without causing any negative chronic
effect on the parasite's ability to reduce citrus blackfly infestations. In
this study two sprays were applied, a post-bloom spray of malathion (50
g AI/100 L) and copper sulfate (Kocide 101) (180 g AI/100 L), and a
summer spray of methidathion (30 g AI/100 L), chlorobenzilate (30 g
AI/100 L), benomyl (Benlate) (30 g AI/100 L), and oil (FC 435 at 1%)
(Fitzpatrick, et al. 1979). This spray program significantly lowered the
numbers of citrus blackfly nymphs and adults (Figs. 13 to 15), but still
allowed A. hesperidum to survive (Fig. 16). By November (8 months into
the program), A. hesperidum had reduced citrus blackfly numbers on
both treated and untreated trees to less than 1 nymph per leaf. Other
long-term research is currently in progress to determine chronic effects of
other compounds on the natural enemies of the citrus blackfly. Results
from these studies will be made available when completed.


U 40

z 30


"25
QC

S 20 A TREATED
O *0 UNTREATED
cc 15
UJ

D 10
2A

I I jU..-&
5 A\


APR MAY JUN JULT AUG SEP OCT

T1 T2
Figure 15. Average number of Amitus hesperidum observed per 20-minute
observation period on citrus trees infested with Aleurocanthus woglumi subjected
to two pesticide treatments. Treatment dates are indicated by T1 and T2. (Fitz-
patrick et al., 1979)

37









While there are certain spray combinations that have not yet been
tested for compatibility with biological control of the citrus blackfly,
most of the recommended sprays have been assessed for either their acute
or chronic effects on P. opulenta and A. hesperidum. Table 27 sum-
marizes the compounds that have been tested for negative acute effects
on citrus blackfly parasites. Additional compounds are being studied for
negative acute effects on biological control agents of the citrus blackfly,
and results of these tests will also be made available when complete.
Although the picture is far from complete, there are many pesticides
that already have been demonstrated to be compatible with parasites and
predators of the citrus blackfly (Fitzpatrick, et al. 1978, 1979). However,
all studies have been done on urban citrus trees. To date (December
1980) no citrus grove within the regulated area has been identified by
DPI or APHIS personnel as having an infestation of citrus blackflies.
While there are questions as to the acceptability of applying urban citrus
tree research to grove situations (Dowell, et al. 1979), the citrus blackfly
has shown little inclination to invade Broward or Dade County groves.
Considering all of our studies, we feel that the citrus blackfly will not
become a problem in Florida citrus groves.






























38














APPENDIX 1. Plants tested by IFAS researchers.


Table 1. Plants which were oviposited upon by the citrus blackfly, and which
supported complete development of citrus blackfly.
Common Name Scientific Name
Marlberry Ardisia escalloniodes Schlect. and Cham.
Ardisia A. solanacea Rosb.
Toog Bischofia javanica Blume
Citrus Citrus spp.
Wampi Clausena lansium (Laurciro) Skeels
Coffee Coffea arabica L.
Black sapote Diospyros ebenaster Ritz.
Loquat Eriobotrya japonica Lindley
Surinam-cherry Eugenia uniflora L.
Kumquat Fortunella sp.
Gardenia Gardenia thunbergii Ellis
Mango Mangifera indica L.
Sapodilla Manilkara sapota L.
Myrsine Myrsine guianesis (Auh L). Kuntz
Avocado Persea americana L.
Brazilian-pepper Schinus terebinthifolius Raddi
Chinese box-orange Severinia buxifolia (Poir) Tenore
Silver trumpet Tabebuia argentea (Bur. and K. Schum). Britt
Pink trumpet T. pallida (Lindley) Meirs
Limeberry Triphasia trifolia (Burm. f.) P. Wilson
Prickly ash Zanothxylum fagara (L.) Sarg.




Table 2. Plants which were oviposited upon by the citrus blackfly, but did not
support complete development of the insect.
Common Name Scientific Name
Allamanda Allamanda cathartica L.
Sugar apple Annona squamosa L.
Groundsel Baccharis halimifolia L.
Schefflera Brassaia actinophylla Edler
Japanese boxwood Buxus microphylla Siebold Zuccarini
Papaya Carica papaya L.
Natal-plum Carissa grandifolia A. DC
Sea-grape Coccoloba uvifera (L.) L.
Croton Codaeum variegatum Blume
Benjamin fig Ficus benjamin L.
Gardenia Gardenia jasminoides Ellis


39









Table 2. Continued.
Common Name Scientific Name
Hibiscus Hibiscus rosa-sinensis L.
Ixora Ixora coccinea L.
Crape-myrtle Lagerstroemia indicia L.
Orange-jessamine Murraya paniculata Jack.
Jaboticaba Myricaria cauliflora Berg.
Arrow arum Peltandra virginica (L.) Schott and Endlicher
Red bay Persea borbonia (L.) Spreng.
Japanese pittosporum Pittosporum tobira Aiton
Strawberry guava Psidium cattleianum Sabine
Guava P. guajava L.
Wild coffee Psychotria nervosa Sw.
Coast plain willow Salix caroliniana Michx.
Elderberry Sambucus simpsoni Rehder
Rose-apple Syzigium jambos Alston
Cacao Therbroma cacao L.





Table 3. Plants which were not oviposited upon by citrus blackfly, and which
did not support complete development of the insect.
Common Name Scientific Name
Women's tongue Albizza labbeck Bentham
Cashew Anacardium occidental L.
Cherimola Annona cherimola Mill.
Orchid-tree Bauhinia variegata L.
Royal poinciana Delonix regia Bljer
Moon flower Ipomoea alba L.
Lychee Litchi chinensis Sonnerat
Holly malpighia Malpighia coccigera L.
Philodendron Philodendron sp.
March fleabane Pluchea odorata Cassini
Poinsettia Poinsettia pulcherrima Willdenow
Southern sumac Rhus copallina L.
Castor bean Ricinus communis L.
Viburnum Viburnum suspensum Lindley
Wedelia Wedelia trilobata (L.) Hithcock











40













APPENDIX 2. Location of selected county extension
agents with addresses and phone numbers.



Brevard County: DeSoto County:
1125 W. King Street P. 0. Drawer 310
Cocoa, FL 32922 Arcadia, FL 33821
(305) 632-9505 (813) 494-0303

Broward County: Glades County:
3245 S. W. 70th Avenue P. 0. Box 398
Fort Lauderdale, FL 33314 Moore Haven, FL 33471
(305) 581-8010 (813) 946-2601


Charlotte County: Hardee County:
1922 Florida Street P. 0. Box 1288
Punta Gorda, FL 33950 Wauchula, FL 33873
(813) 639-6255 (813) 733-6954

Citrus County: Hendry County:
Route 1, Box 6 P. 0. Box 68
Inverness, FL 32650 Labelle, FL 33935
(904) 726-2141 (813) 675-2361

Collier County: Hernando County:
Collier County 608 W. Broad Street
Government Center Brooksville, Fl 33512
Naples, FL 33940 (904) 796-9421
(813) 774-8953


Dade County: Highlands County:
18710 S. W. 288th Street Route 3, Box 149-B
Homestead, FL 33030 Sebring, FL 33870
(305) 248-3311 (813) 385-5158

41








Indian River County: Monroe County:
7150 20th Street, Suite G P. 0. Box 2545
Agricultural Center Key West, FL 33040
Vero Beach, FL 32960 (305) 294-4641 Ext. 263
(305) 562-2160

Lake County: Okeechobee County:
P.O. Drawer 357 Rm. 200, Courthouse
Tavares, FL 32778 Okeechobee, FL 33472
(904) 343-4101 (813) 763-6469

Lee County: Orange County:
3406 Palm Beach Blvd. 2350 E. Michigan Avenue
Ft. Myers, FL 33905 Orlando, FL 32806
(813) 334-1292 (305) 420-3265

Levy County: Osceola County:
P. O. Box 218 P. 0. Box 639
Bronson, FL 32621 Kissimmee, FL 32741
(904) 486-2115 (305) 846-4181

Manatee County: Palm Beach County:
1303 17th Street 531 N. Military Trail
Palmetto, FL 33561 West Palm Beach, FL 33406
(813) 747-3007 (305) 683-1777

Marion County: Pasco County:
P. O. Box 511 1516 Highway 52 West
Ocala, Fl 32670 Dade City, FL 33525
(904) 629-8067 (904) 567-5167

Martin County: Pinellas County:
P. O. Box 416 P. 0. Box 267
Stuart, FL 33494 Largo, FL 33540
(305) 283-6760 (813) 446-7161 Ext. 771




42








Polk County: Seminole County:
P. O. Box 50 4320 S. Orlando Drive
Bartow, FL 33830 Sanford, FL 32771
(813) 533-7665 (305) 322-3233

St. Lucie County: Sumter County:
Route 5, Box 170 P. 0. Box 218
Ft. Pierce, Fl 33450 Bushnell, FL 33513
(305) 464-2900 (904) 793-2728

Sarasota County: Volusia County:
2900 Ringland Blvd. 3100 E. New York Avenue
Sarasota, FL 33580 DeLand, FL 32720
(813) 955-6239 (904) 736-0624































43












APPENDIX 3. Metric measures and conversion factors.
SApproximate conversions Approximate conversions
Metric uts from metric to customary from customary to metric

Length:
meter (m) im = 3.3 ft = 1.1 yd 1 ft = 0.3 m
centimeter (cm) 1 cm = 0.39 in 1 in = 2.5 cm
(1 cm = 0.01 m)
millimeter (mm) 1 mm = 0.039 in I in = 0.25 mm
(1 mm = 0.001 m)
nanometer (nm)
(1 nm = 0.000 000 000 0001 m)


Area:
square centimeter
(cm2) 1 cm2 = 0.16 in 1 in2 = 6.5 cm2
hectare (ha 1 ha = 2.5 acres 1 acre = 0.4 ha
(1 ha = 1000 m2)


Volume:
liter (L) 1 L = 1.1 qt = 0.26 gal 1 gal = 3.8 L
(1 L = 1000cm3)


Mass (weight):
gram (g) 1 g = 0.35 oz 1 6z = 28 g
kilogram (kg) 1 kg = 2.2 lb 1 lb = 0.45 kg


Rate of use for pesticides:
kg AI/ha 1 kg/ha = 0.89 lb/acre 1 lb/acre = kg/ha
(AI = active ingre-
dient)
g AI/L 1 g/L = 0.13 oz/gal 1 oz/gal = 7.4 g/L


Temperature:
degree Celsius (OC) C'= (OF -32) 5/9 OF = (C x 9/5) + 32








44












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45










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46









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47










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Stone, W. E. 1950. Prog. Rpt. 1st Qtr. 1950. (357-Q). USDA. Bur. En-
tomol. Plant Quarantine
Vaughan, A. W., and G. E. Fitzpatrick. 1978. Use of insecticide/surfactant
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61-62.
Weems, H. V., Jr. 1962. Citrus blackfly, Aleurocanthus woglumi Ashby
(Homoptera: Aleyrodidae). Div. Plant Ind., Fla. Dept. Agr. Entomol. Cir.
No. 9. 2 pp.
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425-442.

































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ACKNOWLEDGMENT
This was a cooperative effort and would not have been possible without the
help of many individuals.
We want to thank the following colleagues for their help, guidance, patience,
and advice: Drs. Reece I. Sailer, Robert F. Brooks, Herbert N. Nigg, John C.
Allen, W. H. Whitcomb, Forest W. Howard, P. L. Neel, F. G. Maxwell, W. B.
Ennis, Jr., and V. G. Perry.
Dr. Herman Reitz deserves special thanks for his steady guidance of the Citrus
Blackfly Technical Committtee and for his continual encouragement to all of us.
A group of technicians performed most of the field work reported herein. For
their cheerful execution of their duties, in spite of tedious tasks and uncomfort-
able heat, thanks go to Anne Brown, Mike Bogan, Linda Economou, Joseph
Fiore, Beth Fisher, Fay Fisher, Susan Gould, Martha Johnson, Jack Keller, Alex-
andria Cabrera Lotorto, James Lawrence, Guy Nelson, Stephen Pastor, DuVal
Puckett, Debbie Riggins, Sharlene Rutledge, Valerie Shank, Dennis Steele, Bryan
Steinberg, Donna Sweeney, Allen Vaughan, Karen Vaughan, and Bob Zumstein.
t-Ve convey a very special thanks to Allen G. Selhime (USDA-SEA-Orlando)
for his friendship, encouragement, advice, and steadying hand throughout the
research studies in Fort Lauderdale.
Special thanks are also due our friends and colleagues in the Division of Plant
Industry, Florida Department of Agriculture and Consumer Services, especially
Charles Poucher, Dr. Evert Nickerson, Jack McClusky, and Curtis F. Dowling,
Jr., and to USDA workers Carl Gaddis and Jerry O'Neal of APHIS, for their
assistance in providing equipment and research ideas throughout the cooperative
program.
S The successful biocontrol effort against the citrus blackfly was directly due to
the assistance given by William G. Hart of SEA-Welasco, and the state of Florida
"owes him a very special thanks.
Finally, we want to thank Mrs. Ann Berman for typing the many drafts of this
manuscript.
Portions of the research reported herein were supported by a cooperative
agreement (No. 12-14-7001-1148) between USDA SEA-AR and the University of
Florida.











49


































e FAI







All programs and related activities sponsored or assisted by the Florida
Agricultural Experiment Stations are open to all persons regardless of race, *
color, national origin, age, sex, or handicap.


This public document was promulgated at an annual cost of $4,588
or a cost of $1.53 per copy to provide information on the biology,
host plant spectrum, and control (both biological and chemical) of
the citrus blackfly in Florida.





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