Title: Florida Entomologist
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Title: Florida Entomologist
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Creator: Florida Entomological Society
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Place of Publication: Winter Haven, Fla.
Publication Date: 1985
Copyright Date: 1917
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Insects -- Periodicals
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FLORIDA ENTOMOLOGIST

(An International Journal for the Americas)

Volume 68, No. 3 September, 1985

TABLE OF CONTENTS
10th Congress of Brazilian Entomology Announcement ..................... i

SYMPOSIUM: BIOLOGY AND CONTROL OF WEEVILS
ASSOCIATED WITH CITRUS IN FLORIDA AND
THE WEST INDIES
McCoY, C. W.-Preface .- .......-. .... --------..- ......-.... 367
KNAPP, J. L.-The Citrus Root Weevils in Florida: An Extension
Service Perspective ....--.......----..------------......--..-.-..- 368
WOODRUFF, R. E.-Citrus Weevils in Florida and the West Indies: Pre-
liminary Report on Systematics, Biology, and Distribution
(Coleoptera: Cucurlionidae) --............ .......... ------... .. -.. ..... .... 370
McCoY, C. W., C. SEGRETAIN, G. M. BEAVERS, AND C. TARRANT-Labora-
tory Rearing and Some Aspects of the Biology of Artipus
floridanus Horn (Coleoptera: Curculionidae) --------......-..--..--.- 379
SYVERTSEN, J. P., AND C. W. McCoY-Leaf Feeding Injury to Citrus
by Root Weevil Adults: Leaf Area, Photosynthesis, and Water
Use Efficiency ......-... --....- --- ------ ----........-....-.......... 386
TARRANT, C. A., AND C. W. McCoY-Sampling and Distribution of
Artipus floridanus Corn (Coleoptera: Curculionidae) on Citrus
and Weed Hosts -. -...... -------.......-..- ...... 393
SCHROEDER, W. J., AND J. B. BEAVERS-Semiochemicals and Diaprepes
abbreviatus (Coleoptera: Curculionidae) Behavior: Implica-
tions for Survey .................... -- ------.......--...-.. 399
McCoY, C. W., G. M. BEAVERS, AND C. A. TARRANT-Susceptibility of
Artipus floridanus to different isolates of Beauveria bassiana .... 402
OSBORNE, L. S., AND D. G. BOUCIAS-A Review of Chemical Antagonists
to Mycopathogens of Citrus Root Weevils -.......... .... .... .--..-.----- 409
BULLOCK, R. C.-Potential for Controlling Citrus Root Weevil Larvae
and Adults with Chemicals ........-..........-.......... --..... ... 417

GRANT, P. M., AND K. G. SIVARAMAKRISHAN-A New Species of
Thraulus (Ephemeroptera: Leptophlebiidae) from Southern
India --.....---- ..---..------.. -------------.---- 424
PESCADOR, M. L.-Systematics of the Neartic Genus Pseudiron (Ephe-
meroptera: Heptageniidae: Pseudironinae) ...... ..... ....... 432
SLAFF, M., AND J. D. HAEFNER-The Impact of Phosphate Mining on
Culex nigripalpus and Culex salinarius (Diptera: Culicidae)
Populations in Central Florida ----...... --.. --..-........... .- ..... 444
Continued on Back Cover
Published by The Florida Entomological Society












FLORIDA ENTOMOLOGICAL SOCIETY



OFFICERS FOR 1984-85
President ...-.........------- - --_ ............................. D. H Habeck
President-Elect ..................--.....--- .. ........ ..... __ D. J. Schuster
Vice-President --.. .. -.. -- -- .... -...... . - .. -.. _ Vacant
Secretary .-...........--.... -.- ... ........... ... .. E. R. Mitchell
Treasurer ...........-------.... -.....................-.. A. C. Knapp


M. L. Wright, Jr.
J. E. Eger, Jr.
R. C. Bullock
Other Members of the Executive Committee .--...... G. Mathurin
A. Gettman
J. R. McLaughlin

PUBLICATIONS COMMITTEE


Editor .----.---- ...... ..... -----................................ J. R. McLaughlin
Associate Editors ............ ......... --................................................. W .C. Adlerz
A. Ali
J. B. Heppner
M. D. Hubbard
O. Sosa, Jr.
H. V. Weems, Jr.
W. W. Wirth
Business M manager ........................................................ ................ A. C. Knapp

FLORIDA ENTOMOLOGIST is issued quarterly-March, June, September,
and December. Subscription price to non-members is $20.00 per year in
advance, $5.00 per copy. Membership in the Florida Entomological Society,
including subscription to Florida Entomologist, is $15 per year for regular
membership and $5 per year for students. Inquires regarding membership,
subscriptions, and page charges should be addressed to the Business Man-
ager, P. O. Box 7326, Winter Haven, FL 33883-7326. Florida Entomologist
is entered as second class matter at the Post Office in DeLeon Springs and
Winter Haven, FL.
Authors should consult "Instructions to Authors" on the inside cover of
all recent issues while preparing manuscripts or notes. When submitting a
paper or note to the Editor, please send the original manuscript, original
figures and tables, and 3 copies of the entire paper. Include an abstract and
title in Spanish, if possible. Upon receipt, manuscripts and notes are ac-
knowledged by the Editor and assigned to an appropriate Associate Editor
who will make every effort to recruit peer reviewers not employed by the
same agency or institution as the authors(s). Reviews from individuals
working out-of-state or in nearby countries (e.g. Canada, Mexico, and others)
will be obtained where possible. Page charges are assessed for printed
articles.
Manuscripts and other editorial matter should be sent to the Editor,
JOHN R. MCLAUGHLIN, 4628 NW 40th Street, Gainesville, FL, 32606.


This issue mailed September 20, 1985











10TH CONGRESS OF BRAZILIAN ENTOMOLOGY
The 9th Congress of Brazilian Entomology was held in Londrina, Parana
in July 1984 with more than 600 participants. It was a very special meeting
with round tables, feature speakers, panels, hundreds of research papers
covering all aspects of Entomology. There was great interest in the competi-
tion of papers presented by graduate students.
The newly elected President is Jocelia Grazia, researcher from the Federal
University of Rio Grande do Sul, Porto Alegre; Vice-President is Euripedes
B. deMenezes; both well known in international circles.
The next Congress will be held in Rio de Janeiro 26-31 of January in
1986 in the Hotel Gloria. Plan to attend. For more information on member-
ship and future meetings, write to:
Sociedade Entomologicaide Brasil
A/C Ruth H. Mocellin
Depto. de Zoologia-UFRGS
Av. Paulo Gama, S/N
90.000 Porto Algre-RS
BRASIL










367


SYMPOSIUM: BIOLOGY AND CONTROL
OF WEEVILS ASSOCIATED WITH CITRUS IN
FLORIDA AND THE WEST INDIES

Preface

Numerous species of root weevils are associated with citrus in Florida
and the West Indies. In the last decade, certain species have increased in
importance particularly on Florida citrus. Currently, one or more species
infest about 30% of the total citrus acreage.
A one day symposium on citrus root weevils under the sponsorship of the
Institute of Food and Agricultural Sciences, University of Florida and the
Caribbean Basin Advisory Group (CBAG) was held at the Citrus Re-
search and Education Center, Lake Alfred, Florida, on December 5, 1984,
to address the status of root weevil research in Florida and the West
Indies and identify needed areas for research in the future. The papers
presented herein represent either subject reviews or new data on various
aspects of root weevil biology.


En la Florida y las Indias Occidentales hay numerosas species de gorgo-
jos de raices asociadas con los citricos. En la iltima decada, ciertas species
han aumentado en importancia, particularmente en los citricos de la Florida.
Una o mAs species infestan actualmente como un 30% del Area total de
citricos.
Un simposio de un da sobre gorgojos de raices deitricos fue auspiciado
por el Institute of Food and Agricultural Sciences de la Universidad de la
Florida y el Caribbean Basin Advisory Group (CBAG) y convocado en el
Citrus Research and Education Center en Lake Alfred, Florida, el 5 de
Diciembre de 1984, para tratar sobre el estado de las investigaciones en la
Florida y en las Indias Occidentales sobre el gorgojo de races e identificar
areas para investigar en el future. Los trabajas presentados aqui representan
revisiones del sujeto o datos nuevos sobre various aspects de la biologia de los
gorgojos de raices.
CLAYTON W. McCoY
University of Florida, IFAS
Citrus Research and Education Center
700 Experiment Station Road
Lake Alfred, FL 33850 USA










Florida Entomologist 68 (3)


September, 1985


THE CITRUS ROOT WEEVILS IN FLORIDA:
AN EXTENSION SERVICE PERSPECTIVE

J. L. KNAPP
Department of Entomology and Nematology
University of Florida
Citrus Research and Education Center
Lake Alfred, FL 33850 USA

ABSTRACT
There are 5 species of root weevils that infest citrus in Florida. A ban
on the use of existing effective persistent insecticides in the soil limits
recommended Cooperative Extension Service control practices to: 1)
maintenance of sound agronomic programs for vigorous growth of trees;
2) concentration of efforts on resets; 3) elimination of alternate hosts in
or near groves; 4) use of 0.5 to 1.0% FC-435-66 spray oil in normal spray
applications; and 5) use of Carzol SP as the miticide of choice when
needed.

RESUME
En la Florida hay 5 species de gorgojos de raices que infestan los
citricos. Debido a que se ha prohibido el uso en los suelos de insecticides
persistentes efectivos, las recomendaciones de control del Cooperative Ex-
tension Service se han limitado a: 1) mantenimiento de s6lidos programs
agron6micos para el vigoroso crecimiento de los Arboles; 2) concentrar los
esfuerzos hacia los replantes; 3) eliminar hospederos alternos dentro o
cerca de las arboledas; 4) usar rocios de aceite de 0.5 a 1.0% FC-435-6 en
aplicaciones normales de rocio; 5) cuando es necesario usar Carzol SP
como el acaricida preferido.



Presently, five species of root weevil are known to infest citrus in
Florida (Table 1). These are Diaprepes abbreviatus (L.), the West Indian
sugarcane root stalk borer weevil; Pantomorus cervinus (Boheman), Fullers
rose beetle; Pachnaeus litus (Germ.), the citrus root weevil; Pachnaeus
opalus (Oliv.), blue-green weevil; and Artipus floridanus Horn., the little
leaf notcher.
Pachnaeus and Artipus were observed feeding on citrus foliage by
Hubbard (1885). It was recommended that adults be hand picked from
the trees. Watson (1926) noted that larvae of Pachnaeus fed on citrus roots
and recommended adults be controlled by lead or calcium arsenate. Pachnaeus
litus was first mentioned by Watson and Berger (1937) as being a pest
of Florida citrus. Adults were controlled by spraying trees with fluosili-
cate. In 1957, the list of root weevils was expanded to include P. cervinus,
A. floridanus, and P. opalus. (Griffiths and Thompson 1957.) No recom-
mendations were given for control of these species. Brogdon and Lawrence
(1960) mentioned P. cervinus as only a minor pest of citrus which could
be controlled chemically by mixing 5 pounds a.i. per acre of aldrin, chlor-
dane, dieldrin or heptachlor with fertilizer. Two applications of 2.5 pounds
a.i. mixed with fertilizer applied in the spring and fall appeared better
than a single application of 5 pounds per acre. In addition, cultural weed


368










Knapp: Citrus Weevil Symposium 369

TABLE 1. GENERALIZED DISTRIBUTION OF CITRUS ROOT WEEVIL COMPLEX
SPECIES IN FLORIDA.

Species Distribution

Diaprepes abbreviatus Concentrated in the Lake to Orange County
areas with smaller population pockets in St.
Lucie and Palm Beach counties.
Pantomorus cervinus Northern half of citrus belt from Lake Okee-
chobee north including both coastal areas and
the ridge. Also collected in Homestead area.
Pachnaeus litus Southern half of citrus belt from Highlands
county south.
Pachnaeus opalus Northern half of citrus belt roughly from
Highlands county north.
Artipus floridanus Primarily along the east coast from Daytona
Beach to Key West. Specimens also collected in
Glades, Hendry, Polk, Lake and Orange
counties.

control by frequent mowing, chopping or cultivation, or a combination
were suggested to reduce weevil damage. Brogdon and Lawrence (1974)
mentioned P. cervinus and P. litus as pests of citrus but no control recom-
mendations were mentioned.
Prior to 1974, aldrin 5G was applied with fertilizer about every five
years for weevil control (Brooks personal communication). In 1974, the
U.S. Environmental Protection Agency (EPA) cancelled all agricultural
uses of aldrin/dieldrin in the U.S. leaving heptachlor as the only registered
treatment for root weevil. In 1978, EPA and USDA approved phasing out
the use of heptachlor over a two year period and limited the amount sold
in Florida for root weevil control to 20,000 pounds a.i. in 1978 and 1979.
From 1979 to 1981, two attempts were made by the Cooperative Extension
Service to get EPA to reopen the aldrin cancellation hearings. Both re-
quests were denied, citing "lack of substantial new evidence which
materially affected the cancellation order of this chemical". EPA requested
distribution and economic analysis information, which was not available.
In 1980, an application was submitted for an Experimental Use Permit to
evaluate Vydate 2L, FMC-35,001 5G, and aldrin 5G for citrus root weevil
control. EPA requested additional data on Vydate and FMC 35,001 relating
to ecological effects, environmental chemistry and residue chemistry. These
data were not available and industry terminated further development of
FMC 35,001 as a soil insecticide. A Section 18 request was filed through
the Florida Department of Agriculture and Consumer Services (FDA&CS)
in 1982 for the use of 500,000 pounds a.i. of chlorpyrifos (=Lorsban 5G)
to treat 50,000 acres at 10 pounds a.i./acre. EPA approved the request
but little material was purchased. The request was approved again in
1983. Usage was greater than in 1982, mostly on the east coast. Dow
Chemical Company requested full EPA registration for Lorsban 5G and 4E
for use on the citrus root weevil complex in 1983. In addition, Dow Chemical
filed for a 24(c) with FDA&CS which was denied. FDA&CS requested a
protocol for environmental fate studies before it would act on the 24(c)
request. No chemical was approved for use in 1984.









Florida, Entomologist 68 (3)


According to general observations, it would appear that: (1) the citrus
root weevil problem is more common in bedded groves on the east coast
and/or in the flatwoods where groves have limited root systems and are
grown under permanent sod culture; and (2) many of the groves showing
heavy feeding by adult weevils are adjacent to woods, swamps, or pastures.
Since no registered pesticides are available at this time for larval
control of root weevils, the Cooperative Extension Service is limiting their
recommendations to the grower with a problem to: (1) maintaining sound
fertilizer and water management practices, (2) paying more attention to
resets than mature trees as the potential for economic loss is greater, (3)
eliminating alternate hosts in and around the grove through sound weed
management practices, (4) using 0.5 to 1.0 percent FC-435-66 spray oil
in normal spray applications to slough off root weevil egg masses making
them more susceptible to dessication and predation, (5) using Carzol SP
according to the supplemental label for concentrate application when a
miticide is required. Carzol will kill adult D. abbreviatus.
Florida Agricultural Experiment Station Journal Series No. 6182.

REFERENCES CITED
BROGDON, J. E. AND F. P. LAWRENCE. 1960. Control of Minor Pests of
Commercial Citrus in Florida. Fla. Coop. Ext. Ser. Cir. 200. 16 p.
BROGDON, J. E. AND F. P. LAWRENCE. 1974. Insects and Mites of Florida
Citrus. Fla. Coop. Ext. Ser. Cir. 137.
GRIFFITHS, J. T. AND W. L. THOMPSON. 1957. Insects and Mites Found on
Florida Citrus. Univ. of Fla. Agri. Exp. Sta. Bul. 591. 96 p.
HUBBARD, H. G. 1885. Insects Affecting the Orange. Govern. Printing
Office, Washington, D.C.
WATSON, J. R. AND E. W. BERGER. 1937. Citrus Insects and Their Control.
Fla. Coop. Ext. Ser. Bul. 88. 134 p.
WATSON, J. R. 1926. Citrus Insects and Their Control Bul. 183. Univ. of
Fla. Agri. Exp. Sta. Gainesville, FL.




CITRUS WEEVILS IN FLORIDA AND THE
WEST INDIES:
PRELIMINARY REPORT ON SYSTEMATICS, BIOLOGY,
AND DISTRIBUTION (COLEOPTERA: CURCULIONIDAE)
R. E. WOODRUFF
Div. of Plant Industry, Florida Dept. of Agriculture and
Consumer Services, Gainesville, FL 32602

ABSTRACT
The following 11 genera of weevils are associated with citrus in Florida
and the West Indies: Artipus, Cleistolophus, Compsus, Diaprepes, Epi-
caerus, Exophthalmus, Lachnopus, Litostylus, Pachnaeus, Pantomorus, and
Tanymecus. This paper is a compilation, listing the known species on
citrus, their biology, distribution, taxonomic status, economic importance,
and selected references.


370


September, 1985










Woodruff: Citrus Weevil Symposium


371


RESUME
Los 11 siguientes generos de gorgojos son asociados con citricos en la
Florida y las Indias Occidentales: Artipus, Cleistolophus, Compsus, Dia-
prepes, Epicaerus, Exophthalmus, Lachnopus, Litostylus, Pachnaeus,
Pantomorus, y Tanymecus. Este ensayo es una compilaci6n donde se listan
las species conocidas en citricos, su biologia, distribuci6n, estado taxo-
n6mico, importancia econ6mica, y seleccionadas referencias.



In a series of papers (Woodruff 1962-1982), I treated the Florida
weevils associated with citrus. Because one of these weevils, Diaprepes
abbreviatus (L.), was introduced from the West Indies (Woodruff 1964),
considerable effort has been made to learn what other species occur there.
This effort has opened a "Pandora's Box" of taxonomic confusion, but it
has also provided specimens and data for the following remarks.
The current emphasis on biological control of these weevils has re-
newed the interest in all aspects of their systematics, distribution, hosts,
and biology. This paper is the result of my own experiences over the past
20 years, combined with a preliminary literature search for these data.
Weevils belong to the beetle family Curculionidae (perhaps the largest),
containing about 7,500 species in North America (including the West Indies
and Central America) and over 3,000 in the U. S. Less than a dozen have
been considered pests in all citrus areas of the U. S. However, there are
more than double that number in the West Indies. The fauna there is in-
completely known and considerable basic data are needed. Because many
are abundant and most are serious pests in their native islands, there
is potential for introduction to other areas.

ANNOTATED LIST OF GENERA
No thorough study has been made of the entire literature, but the
following list is thought to be fairly complete at the generic level. Species
listed are those for which specific citrus records are known; this does not
preclude other species becoming pests or new species being found on citrus.
Because the higher categories (tribes and subfamilies) of weevils are not
clearly defined and await a more consistent treatment, I have listed the
genera alphabetically here. The numbers of species and their status follow
that in the checklist of weevils by O'Brien and Wibmer (1982).

Artipus Sahlberg 1823
Nine species are known: only A. floridanus Horn (in LeConte & Horn
1876) is known in the U. S., confined there to peninsular Florida (although
it is also known from the Bahamas). Other papers in this symposium
(Tarrant and McCoy 1985a, b) treat the biology, ecology, and control of
this species. The other 8 species are West Indian: 2 from Jamaica, 2 from
Hispaniola, 1 from Cuba, 1 from St. Barthelemy, 1 from Mona, and 1 from
the Bahamas. The Bahamian and Floridian species are both recorded
from citrus, but they also have a great diversity of host plants. There
is no modern revision, and some synonymy is suspected. Although many
other genera in the Naupactini are wingless and parthenogenetic, A.











372 Florida Entomologist 68 (3) September, 1985

floridanus is neither. Selected References: Rowan 1976; Tarrant and
McCoy 1985; Woodruff 1982.

Cleistolophus Sharp 1891

Four species are known, all Central American; 1 only from Belize and
Honduras, 1 only from Guatemala, the other 2 widespread in Central
America. Several of these are possibly found on citrus, but I have specific
records of damage from Honduras and Belize only for C. viridimargo
Champion. Specimens of this species were recently intercepted on Dra-
caena plants brought into Florida from Honduras. The species resemble
those of the genus Epicaerus. No information is available on their biology.
Selected References: Champion 1911.

Compsus Schoenherr 1823

Eleven species are known from Central America and the West Indies,
with only 1 (C. auricephalus Say) extending to the U.S., where it is re-
corded from AR, GA, LA, MS, TX, CO. It is also known from Costa Rica,
Guatemala, Mexico, Nicaragua, and Panama. Two species are found only
in Puerto Rico, and 2 others are recorded from Guadeloupe, 1 (C. lacteus
Fab.) is also known from Jamaica.
Little is known about most of the species, but C. auricephalus was found
commonly on citrus in Texas after the 1983 freeze (French 1984). Selected
References: Champion 1911; Marshall 1922; Wolcott 1924, 1951.

Diaprepes Schoenherr 1823

Nineteen species are currently recognized, 17 West Indian, 1 from Hon-
duras, and 1 from Nicaragua. Only D. abbreviatus (Linn.) has been found
in the U. S., and it is one of the most destructive known. It is also one
of the most variable species, resulting in many synonyms and varietal
names. Clarification of many of these names is underway, with large series
of specimens and pending type comparisons. D. famelicus (Olivier), re-
corded from Dominica, Guadeloupe, Martinique, Barbados, Cuba, Antigua,
Montserrat, St. Barthelemy, and St. Kitts, is listed as a citrus pest.
D. balloui Marshall is known only from Dominica where I collected it
damaging young citrus. Surprisingly, no Diaprepes are known from Jamaica
where the related genus Exophthalmus has numerous species on citrus.
Selected References: Beavers, et al. 1979 (bibliography); Hustache 1929;
Pierce 1915; Woodruff 1964, 1968, 1979.

Epicaerus Schoenherr 1834

This is one of the larger genera involved, with 91 N.A. species, nearly
all Mexican or Central American. Eleven species are known from the
U. S., but only E. mexicanus Boheman has been found on citrus (es-
pecially in Texas after the 1983 freeze, French 1984). Selected References:
Pierce 1913.

Exophthalmus Schoenherr.1823

This large genus contains 76 species, about equally distributed between


___


__ __










Woodruff: Citrus Weevil Symposium 373

Central America and the West Indies; none is known from the U. S. In
the Greater Antilles, species are distributed as follows: Hispaniola (17),
Cuba (11), Jamaica (5), and Puerto Rico (3). These are called "fiddler
beetles" in Jamaica, where all the species are known to feed on citrus.
E. quadrivittatus (Olivier) is a pest of many plants, including citrus in
Hispaniola. Along with Diaprepes abbreviatus it causes serious root dam-
age; the 2 have similar habits, hosts, and parasites.
Great confusion exists about the status of this and several related
genera (Vaurie 1961). Synonyms include Prepodes and Exophthalmodes;
the latter was an unjustified replacement name for Exophthalmus. Selected
References: Champion 1911; Cotton 1929; Cockerell 1893; Dixon 1954;
Fleutiaux & Salle 1889; Marshall 1934; Vaurie 1961; van Whervin 1968;
Wolcott 1929, 1951.

Lachnopus Schoenherr 1840
This name has long been used for a genus of weevils which contains
West Indies species feeding on citrus. According to O'Brien and Wibmer
(1982) the correct name should now be Menoetius Dejean 1821, because it
erroneously had been considered as a nomen nudum. However, in a later
paper (O'Brien & Wibmer 1983) they mention that they had petitioned
the International Commission on Zoological Nomenclature to conserve
Lachnopus.
It appears to be strictly a West Indian genus of 57 known species, 3
recorded in the U.S.: argus (Reiche) from Cuba and Florida; floridanus
(Horn) from Florida only; and hispidus (Gyllenhal) from Cuba and
Florida. Of these, I am familiar only with the Florida records of floridanus,
which is known from Homestead (Dade Co.) south, on Solanaceae. Only 2
species, aurifer and gowdeyi (Marshall), are recorded from Jamaica and
apparently both feed on citrus. Because it is such a large genus (57 spp.)
and there has not been a modern revision, most literature records refer
only to Lachnopus spp. Perhaps several other species are citrus pests in
the West Indies, but I have personally collected only inconditus (Rosen-
schoeld) feeding extensively on citrus in the Dominican Republic.
The biology of most species is unknown; those in Jamaica are treated
by Van Whervin (1968). Selected References: O'Brien & Wibmer 1982;
Marshall 1922, 1926, 1933; van Whervin 1968; Wolcott 1941, 1951.

Litostylus Faust 1894
A small genus of 5 species: bovelli (Marshall) from Barbados and
Dominica; diadema (Fabricius) (=juvencus (Olivier)) from C. A. and
S. A.; leucocephalus (Chevrolat) from Guadeloupe; pudens (Boheman)
from Antigua, Montserrat, St. Barthelemy, and St. Vincent; and strangu-
latus (Chevrolet) from Dominica, Guadeloupe, and Montserrat. L. pudens
is often recorded on citrus in the West Indies. Little is known of the
biology or economic importance of the genus. Selected References: Champion
1911; Marshall 1922.

Pachnaeus Schoenherr 1826
Seven species are listed in the genus, 2 in the U. S.: litus (Germar) and











Florida Entomologist 68 (3)


opalus (Olivier). The other 5 are West Indian: azurescens Gyllenhal from
Cuba; citri Marshall from Jamaica; costatus Perroud from Cuba; mar-
moratus Marshall from Jamaica; and psittacus (Olivier) from Cuba and
Puerto Rico.
All those whose habits are known feed on citrus and are among the
earliest recorded pests in Florida and the West Indies. They are often re-
ferred to as "blue-green notchers" or "citrus root weevils". I have treated
the 2 U. S. species in detail (1981b) and van Whervin (1968) has published
on the biology of P. citri in Jamaica. There is little information on the
other species. Selected References: Bruner 1934; Marshall 1916; Schwarz &
Barber 1922; van Whervin 1968; Wolfenbarger 1952; Wolcott 1951; Wood-
ruff 1981b.

Pantomorus Schoenherr 1840

This huge genus has many species in Central and South America; 44
are recorded from North America, with 11 known from the U. S. (3
introduced). Only one, P. cervinus (Boheman), is a regular pest of citrus
and is commonly called "Fuller's rose beetle or weevil". Woodruff &
Bullock (1979) treated it in Florida, and there is a wealth of economic
literature on the species. Selected References: Buchanan 1939; Champion
1922; King 1959; Woodruff & Bullock 1979.

Tanymecus Germar 1817
Four species are listed from North America and none from the West
Indies. Tanymecus lacaena (Herbst), which is recorded from AL, FL, GA,
SC, and TX, is an occasional pest of Florida citrus (Woodruff 1981a). This
is a complex species (D. R. Whitehead, pers. comm.) some are flightless
and may be parthenogenetic.

HOST PLANTS
Since the plant we are most concerned about is citrus, its history is of
significance in relation to the weevils in Florida and the West Indies. The
origin of citrus has not been positively traced, although it is definitely an
Old World plant of the family Rutaceae. Swingle and Reece (1967) stated
that it was introduced into the Mediterranean area about 325 B.C., but
whether from India or China was questionable. In fact, they suggest that
it may be native to southern Arabia (possibly between eastern Hadhramaut
and Oman).
Regardless of its origin, none of the known weevil pests in the New
World appear to have been introduced with it. The history of citrus in
the West Indies was treated by Webber (1967). It appears that Columbus
brought seeds from the Canary Islands on his second voyage to the New
World, when he established the settlement in Haiti in 1493. Because there
are so many weevils in the W.I. which feed on the introduced genus Citrus,
it is of interest to know what the native hosts are. Some seem to be more
abundant on citrus than any other plants, and thus native hosts are diffi-
cult to establish. Some of the weevils involved (e.g., Pachnaeus spp.) seem
to be so commonly associated with citrus that it would appear to be their
natural host.


September, 1985


374










Woodruff: Citrus Weevil Symposium 375

Without a thorough search, I have made some notes on the botany of
the Rutaceae in the West Indies and on the taxonomic relationships of some
of the known native hosts. In Jamaica, Adams (1972) listed 7 genera of
Rutaceae (in addition to citrus): Ravenia with 2 species, 1 endemic and
the other introduced from Cuba and Hispaniola; Spathelia has 2 species (one
called mountain pride); Fagara (=Zanthoxylum) has 14 species, among
which are bastard ironwood, prickly yellow, Jamaica satinwood, yellow
sanders, Caesarwood, rosewood, toothache tree, satinwood, licca tree, and
Lignum rorum; Esenbeckia has a single endemic species (pentaphylla), the
wild orange; Peltostigma has one species (pteleoides), candlewood or cantoo;
Amyris contains 3 species, commonly called torchwood, candlewood, and
W.I. sandalwood; and Glycosmis has a single introduced species.
Since the 5 species of Exophthalmus in Jamaica are all known to feed
on citrus, and 4 are serious pests, one would expect some of the above
to be the native hosts. However, the literature (Dixon 1954, Vaurie 1961,
van Whervin 1968) indicates mostly introduced, cultivated plants as hosts,
and only one of the above (Zanthoxylum flavum) is listed. Other native
host plants mentioned include: Comocladia (4 spp.) or "maiden plums"
in the family Anacardiaceae (the family of akee, Blighia sapida, an intro-
duced host) and the primary host for the pink-spotted variety of E. im-
pressus; bastard cedar, Guayuma ulmifolia; red bullet, Dipholis nigra;
blue mahoe, Hibiscus elatus; seagrape, Coccoloba uvifera; dogwood, Lon-
chocarpus latifolius; and wild coffee, Casearia hirsuta. This is a small
number compared to the 23 introduced hosts listed. One of the Jamaican
species (E. farr Vaurie) is primarily found on the native leguminous tree
Acacia macracantha.
For Pachnaeus citri, an endemic Jamaican species, van Whervin (1968)
listed the following hosts: citrus, star apple, avocado, mango, Pithecellobium
dulce, cherry (Malphigia punicifolia), and guava. No native hosts were
listed.
In the Bahamas, where Pachnaeus, Artipus, and Litostylus occur, 5
genera of Rutaceae are known (Correll & Correll 1982) (including the
introduced Citrus and Triphasia): Amyris contains a single species
(elemifera), torChwood; Spathelia with the endemic bahamensis; and
Zanthoxylum which has 5 species, 3 of which also occur in Florida.
One of the most common hosts of species of Exophthalmus and Dia-
prepes, based upon literature and personal experience, is Gliricidia sepium
or "quick stick". Adams (1972:347) stated that it is a native of tropical
America, now widespread. Other common names include "Aaron's rod" and
"grow stick". It is often used as a living fence, and, as the name implies,
it grows easily and fast, making it a favorite wind-break. Since it is often
the preferred host, it serves as an attractant to the vicinity of other more
commercial crops. When weevil eggs are laid high in these trees, wind
dispersal of the first instar larvae may spread an infestation. One cultural
practice that might be beneficial, would be to eliminate this host near
citrus plantings, or at least keep it trimmed low to avoid wind dispersal
of the larvae. This problem has been seen in Jamaica, Puerto Rico, the
Dominican Republic, and in many of the Lesser Antilles.
From the above, it is obvious that none of the pests is host specific,
and they appear to be adaptable to many introduced plants. More effort










Florida Entomologist 68 (3)


September, 1985


should be made to obtain specific native host records in order to suggest
cultural controls.

RECOMMENDATIONS
The identity of any pest is basic to an understanding of its biology,
ecology, and behavior. It is essential before an efficient pest management
strategy can be developed. In biological control, host specificity and dis-
tribution cannot be established without knowing specifically the organisms
involved.
Unfortunately, several genera mentioned here (e.g., Diaprepes, Exo-
phthalmus, Lachnopus) are large, and many of the species show great
variability in color, morphology, and biology. It appears that many are
in a state of evolutionary and genetic plasticity, making interpretation
of their variability difficult.
Nevertheless, modern taxonomic studies should be of high priority so
that a firm foundation is established for other studies (especially parasite
specificity and regulatory considerations). This will require large series
of specimens from all geographic areas, from different hosts, and all
seasons. These must be properly prepared, studied, and vouchered. Taxo-
nomic studies must involve comparisons with all the relevant holotypes-
many of which are scattered and located in European museums.
All modern techniques must be employed to clarify the relationships of
known variants. Cytology and electrophoresis have both provided aid in
some previous taxonomic studies. However, studies of such a complex and
interesting group will require a concerted effort by all specialists involved
with these weevils.

ACKNOWLEDGMENTS
I thank all those who have provided specimens for my studies and for
assistance in the field; the following for reviewing the manuscript: R. H.
Arnett, Jr., H. A. Denmark, J. J. McRitchie, C. W. O'Brien, L. A. Stange,
and D. R. Whitehead. This is Contribution No. 607, Bureau of Entomology,
Division of Plant Industry, Florida Dept. of Agriculture and Consumer
Services.

REFERENCES
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Mona, Jamaica. 848 p.
BEAVERS, J. B., AND R. E. WOODRUFF. 1971. A field key for separating
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Curculionidae). Florida Dept. Agric., Div. Plant Ind., Ent. Circ.
112: 1-2; 4 fig.
BEAVERS, J. B., R. E. WOODRUFF, S. A. LOVESTRAND, AND W. J. SCHROEDER.
1979. Bibliography of the sugarcane rootstalk borer weevil, Diaprepes
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BLACKWELDER, R. E. 1947. Checklist of the coleopterous insects of Mexico,
Central America, the West Indies, and South America. Part 5. Cur-
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BLATCHLEY, W. S., AND C. W. LENG. 1916. Rhynchophora or weevils of
north eastern America. Nature Publ. Co., Indianapolis, Indiana.
682 p.


376










Woodruff: Citrus Weevil Symposium 377

BRUNER, S. C. 1934. Observaciones sobre el picudo verde-azul de los
naranjos. Rev. Agr. Comer. Trabajo (Cuba) 14: 35-40.
BRUNER, S. C., AND L. C. SCARAMUZZA. 1929. Resena de los plagas del cafeto
en Cuba. Circ. Estac. Exp. Agron. 68: 1-38 (Santiago de las Vegas).
BUCHANAN, L. B. 1939. The species of Pantomorus of America north of
Mexico. USDA Misc. Publ. 341: 1-39.
CHAMPION, G. C. 1911. Biologia Centrali-Americana. Otiorhynchinae
Alatae. 4(3): 178-317. London.
CHAMPION, G. C. 1922. The synonymy and distribution of Pantomorus
godmani Crotch, a cosmopolitan weevil attacking roses, greenhouse
plants, etc. Ent. Mon. Mag. 58: 161-162.
COCKERELL, T. D. A. 1893. The Jamaican species of Praepodes, Schon. Jour.
Inst. Jamaica 1: 374-375.
COOK, M. T., AND W. T. HORNE. 1908. Insects and diseases of the orange.
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CORRELL, D. S. AND H. B. 1982. Flora of the Bahama Archipelago. J.
Cramer, Publ., Vaduz (Germany). 1692 p.
COTTON, R. T. 1929. The larva of the weevil Exopthalmus (sic) quadrivit-
tatus Olivier (Coleoptera:Rhynchophoridae). Proc. Ent. Soc. Wash-
ington 31: 27-31; 1 pl.
DIXON, W. B. 1954. Fiddler beetles. Nat. Hist. Notes, Nat. Hist. Soc.
Jamaica (mimeogr.) 69: 157-183.
VAN EMDEN, F. I. 1944. A key to the genera of Brachyderinae of the
world. Ann. Mag. Nat. Hist. (Ser. 11) 11(80): 503-532; 11(81):
559-586.
FLEUTIAUX, E., AND A. SALLE. 1889. Liste des Coleopteres de la Guadeloupe
et descriptions d'especes nouvelles. Ann. Soc. Ent. France (Ser. 6) 9:
351-484.
FRENCH, J. V. 1984. Post freeze survey for citrus pests. Texas A & I
Univ., Citrus Center 2(2): 3.
GOWDEY, C. C. 1926. Catalogus insectorum Jamaicensis. Dept. Agr. Jamaica,
Ent. Bull. 4(1) : 1-114.
HUSTACHE, A. 1929. Curculionides de la Guadeloupe. In Gruvel, A., Fauna
des colonies francais. Paris. Vol. 3: 165-267, fig. 1-8.
KING, J. R. 1959. Occurrence, distribution, and control of Fuller's rose
beetle in Florida citrus groves. Proc. Florida State Hort. Soc. 71:
146-152, 6 fig.
KISSINGER, D. G. 1964. Curculionidae of America north of Mexico. Taxo-
nomic Publ., South Lancaster, Mass. 143 p., 59 fig.
LECONTE, J. L., AND G. H. HORN. 1876. Rhynchophora of America north
of Mexico. Proc. Amer. Philos. Soc. 15(96): 1-455.
LENG, C. W., AND A. J. MUTCHLER. 1914. A preliminary list of the Coleop-
tera of the West Indies, as recorded to January 1, 1914. Bull. Amer.
Mus. Nat. Hist. 33: 391-493.
MARSHALL, G. A. K. 1916. On new neotropical Curculionidae. Ann. Mag.
Nat. Hist. (Ser. 8) 18: 449-469.
MARSHALL, G. A. K. 1922. On new genera and species of neotropical
Curculionidae. Trans. Ent. Soc. London 1922: 181-224; fig. 1-4, pl. 3-4.
MARSHALL, G. A. K. 1926. Two new species of Curculionidae (Col.) from
Haiti. Bull. Ent. Res. 17(1)53-54.
MARSHALL, G. A. K. 1933. New neotropical Curculionidae (Coleoptera).
Stylops 2(3): 59-69.
MARSHALL, G. A. K. 1934. New West Indian Curculionidae (Coleoptera).
Ann. Mag. Nat. Hist. (Ser. 10) 14: 621-631.
O'BRIEN, C. W., AND G. WIBMER. 1982. Annotated checklist of the weevils
(Curculionidae sensu lato) of North America, Central America, and
the West Indies (Coleoptera:Curculionidae). Mem. Amer. Ent. Inst.










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34: 1-382.
O'BRIEN, C. W., AND G. J. WIBMER. 1984. Annotated checklist of the weevils
(Curculionidae sensu lato) of North America, Central America,
and the West Indies-Supplement 1. Southwestern Ent. 9(3): 286-
307.
PIERCE, W. D. 1913. Miscellaneous contributions to the knowledge of the
weevils of the families Attelabidae and Brachyrhinidae. Proc. U. S.
Nat'l. Mus. 45: 365-426.
PIERCE, W. D. 1915. Some sugar-cane root-boring weevils of the West
Indies. Jour. Agr. Res. 4(3): 255-263; pl. 25-27.
ROWAN, W. T. 1976. Florida host plants of Artipus floridanus (Coleop-
tera: Curculionidae). Florida Ent. 59(4): 439-440.
SCHWARZ, E. A., AND H. S. BARBER. 1922. The specific names of two
otiorhynchid weevils of Florida. Proc. Ent. Soc. Washington 24: 29-
30.
SWINGLE, W. T., AND P. C. REECE. 1967. The botany of citrus and its wild
relatives, p. 190-430, In The Citrus Industry. Vol. 1. Univ. California,
Berkeley. 611 p.
TARRANT, C. A., AND C. W. McCoY. 1985a. The natural history of the little
leaf notcher (Coleoptera: Curculionidae). Citrus Industry 66: 60-65.
TARRANT, C., AND C. W. McCoY. 1985b. Sampling and distribution of Artipus
floridanus Corn (Coleoptera: Curculionidae) on Citrus and Weed
Hosts. Florida Ent. 68: 393-398.
VALENTINE, B. D. AND B. S. 1957. Some injurious weevils in Haiti (Cur-
culionidae). Coleopterists Bull. 11: 29-32.
VAURIE, PATRICIA. 1961. A review of the Jamaican species of the genus
Exophthalmus (Coleoptera, Curculionidae, Otiorhynchinae). Amer.
Mus. Novit. 2062: 1-41.
WEBBER, H. J. 1967. History and development of the citrus industry, p.
1-39, In The Citrus Industry. Vol. 1. Univ. California, Berkeley. 611
p.
VAN WHERVIN, L. W. 1968. Citrus weevils of Jamaica. Univ. West Indies,
Tech. Bull. 1: 1-23.
WOLCOTT, G. N. 1929. Notes on the life history of Exopthalmus (sic)
quadrivittatus Olivier (Coleoptera). Proc. Ent. Soc. Washington
31: 21-26.
WOLCOTT, G. N. 1936. Insectae Borinquenses. Jour. Agr. Univ. Puerto Rico
20(1) : 1-627.
WOLCOTT, G. N. 1941. A supplement to "Insectae Borinqueneses". Jour.
Agr. Univ. Puerto Rico 25 (2): 33-158.
WOLCOTT, G. N. 1951. The insects of Puerto Rico. Coleoptera. Jour. Agr.
Univ. Puerto Rico 32: 225-416. (vol. for 1948, but publ. in 1951).
WOLFENBARGER, D. 0. 1952. Some notes on the citrus root weevil. Florida
Ent. 35(4): 139-142.
WOODRUFF, R. E. 1962. Some Florida citrus weevils. Florida Dept. Agr.,
Div. Plant Ind., Ent. Circ. 5: 1; 6 fig.
WOODRUFF, R. E. 1964. A Puerto Rican weevil new to the United States
(Coleoptera: Curculionidae). Florida Dept. Agr., Div. Plant Ind.,
Ent. Circ. 30: 1-2; 1 fig.
WOODRUFF, R. E. 1968. The present status of a West Indian weevil
(Diaprepes abbreviatus (L.)) in Florida (Coleoptera:Curculionidae).
Florida Dept. Agr., Div. Plant Ind., Ent. Circ. 77: 1-4; 7 fig.
WOODRUFF, R. E. 1972. The coffee bean weevil, Araecerus fasciculatus
(DeGeer), a potential new pest of citrus in Florida (Coleoptera:
Anthribidae). Florida Dept. Agr., Div. Plant Ind., Ent Circ. 117:
1-2; 11 fig.
WOODRUFF, R. E. 1979. Florida citrus weevils (Coleoptera:Curculionidae).


378


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Woodruff: Citrus Weevil Symposium


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Florida Dept. Agr., Div. Plant Ind., Ent. Circ. 202: 1-4; 20 fig.
WOODRUFF, R. E., AND R. C. BULLOCK. 1979. Fuller's rose weevil, Panto-
morus cervinus (Boheman), in Florida (Coleoptera:Curculionidae).
Florida Dept. Agr., Div. Plant Ind., Ent. Circ. 207: 1-4; 3 fig.
WOODRUFF, R. E. 1981a. Tanymecus lacaena (Herbst), an occasional
weevil pest of citrus in Florida (Coleoptera:Curculionidae). Florida
Dept. Agr., Div. Plant Ind., Ent. Circ. 225:1-2; 2 fig.
WOODRUFF, R. E. 1981b. Citrus root weevils of the genus Pachnaeus in
Florida (Coleoptera:Curculionidae). Florida Dept. Agr., Div. Plant
Ind., Ent. Circ. 231:1-4; 5 fig.
WOODRUFF, R. E. 1982. Artipus floridanus Horn, another weevil pest of
citrus (Coleoptera:Curculionidae). Florida Dept. Agr., Div. Plant
Ind., Ent. Circ. 237: 1-2; 3 fig.



LABORATORY REARING AND SOME ASPECTS OF
THE BIOLOGY OF ARTIPUS FLORIDANUS HORN
(COLEOPTERA: CURCULIONIDAE)

CLAYTON W. McCoY, CLAIRE SEGRETAIN,
GREGORY M. BEAVERS AND CHRISTINE TARRANT
University of Florida, IFAS Citrus Research and Education Center
700 Experiment Station Road, Lake Alfred, FL 33850 USA

ABSTRACT
Artipus floridanus Horn adults were reared in the laboratory for 4 years
on citrus leaves. Newly-expanded leaves were preferred over mature
leaves. Adult feeding was influenced by photoperiod; surface area leaf
consumption per adult in total darkness was significantly greater than in
a 12 h light/dark cycle, and in constant light. Survivorship of both mated
and virgin females averaged 161 days. The ratio of female to male in a
laboratory population was 6:4. Preoviposition period for mated and virgin
females varied from 11-20 days and 15-27 days, respectively. Virgin fe-
males laid 50% fewer eggs in their life span than mated females. Egg vi-
ability per mated female was 80-85% during peak production; virgin fe-
males laid nonviable eggs.
At 28 C, eggs hatched in about 9 days, larval development to pupation
on artificial diet averaged 45 days, and the pupal period lasted approxi-
mately 14-20 days. Total developmental time from egg to adult ranged
from 70-120 days. Six larval instars were observed; molting occurred every
5-10 days. Survivorship of larvae and pupae on an artificial diet averaged
30%. The moisture content of the medium was critical to survival.

RESUME
Adultos de Artipus floridanus fueron criados por 4 afios en hojas de
citricos en el laboratorio. Hojas nuevas fueron m6s preferidas que hojas
maduras. La alimentaci6n de los adults fue influenciada por el period de
luz; el consume por adults de areas de hojas en obscuridad absolute fue
significativamente mas alto que el consume durante el ciclo de 12 horas de
luz/obscuridad y de luz constant. El promedio de sobreviviencia de
hembras apareadas y hembras virgenes fue de 161 dias. La proporci6n de
hembras a machos en una poblaci6n de laboratorio fue de 6:4. El period
precedent a la puesta de huevos por hembras apareadas y de hembras
ivrgenes vari6 de 11-20 dias, y de 15-27 dias respectivamente. Durante su










380 Florida Entomologist 68 (3) September, 1985

vida, hembras virgenes pusieron un 50% menos huevos que hembras
apareadas. La viabilidad de los huevos puestos por hembras apareadas fue
de un 80-85% durante el period de minima production; los huevos puestos
por hembras virgenes no eran viables.
A 280C los huevos nacieron aproximadamente en 9 dias, en una dieta
artificial el desarrollo larval hasta el pupal dur6 45 dias, y el period pupal
dur6 aproximadamente 14-20 dias. El tiempo total de desarrollo de huevo
hasta adulto fue de 70 a 120 dias. Se observe 6 estadios larvales; mudas
ocurrieron cada 5 a 10 dias. El promedio de sobreviviencia de las larvas y
pupas en una dieta artificial fue de un 30%. El contenido de humedad de la
dieta fue critic para su sobreviviencia.


Artipus floridanus Horn occurs in Florida, the Bahamas, and the United
States Virgin Islands (Rowan 1976). In the U. S., the genus Artipus
contains only the species floridanus (Woodruff 1982) and has been placed
taxonomically in the subfamily Brachyderinae and tribe Naupactini, which
contains 26 other U. S. species. LeConte and Horn (1876) reported the
first collection of adult weevils feeding on lime tree foliage in the
Florida Keys. It is now distributed mainly along the Florida east coast
as far north as Daytona Beach (Woodruff 1982) and is the most common
weevil found on commercial citrus (Simanton 1976). According to
Woodruff (1982), A. floridanus can be found on at least 150 plant species
but prefers citrus to other plants on which it feeds.
Other than scattered information on distribution, host plants (Wood-
ruff 1982, Rowan 1976) and natural enemies (Bullock 1984, Beavers et al.
1983), no data is available on the biology and ecology of A. floridanus and
its effect on the citrus tree. Basic biological and ecological information are
essential to develop sampling methods and generate quantitative data on
the importance of larval and adult feeding on citrus. Furthermore, without
this information control strategies cannot be developed or justified for
either larvae or adults. This paper presents methods used to establish a
laboratory colony of A. floridanus, data on photoperiod effects on adult
feeding and ovipositional behavior, and describes the survival, fecundity,
sex ratio and larval developmental biology in the laboratory.

MATERIALS AND METHODS
LABORATORY REARING

The initial laboratory colony of A. floridanus was established from a
wild population of approximately 200 adults collected from citrus foliage
in a grove near Vero Beach in Indian River County, Florida. Adult weevils
infesting Australian pine, Casuarina spp., were present in the vicinity but
avoided during collection.
In the laboratory, the field-collected and subsequently laboratory-reared
adults were held in transparent polycarbonate jars (17-liter capacity) with
aluminum screen lids (1.43-mm mesh) and maintained at a constant
temperature of 26-280C. A maximum of 250 adult weevils was maintained
in each jar to prevent overcrowding. Adult weevils were fed field-collected
newly-expanded citrus leaves as bouquets secured in 90-dram vials con-
taining deionized water. Three bouquets of fresh citrus leaves were added
to each holding jar twice weekly. During the 4-year rearing program, field-










McCoy et al.: Citrus Weevil Symposium


381


collected adults were periodically mixed with laboratory-reared adults to
maintain genetic vigor.
Female weevils laid their eggs between two wax paper strips (20-25
cm long) that were stapled together and suspended in the adult holding
cages. This method of egg collection is a modification of the method de-
scribed by Wolcott (1933) for Diaprepes abbreviatus (L.). Approximately
10 oviposition strips were placed in each holding unit and changed week-
ly. After collection, the paper strips, containing an average of 68 egg
masses/week, were placed in a funnel (12-cm diameter) attached to the
lid of a 90-dram plastic vial which served as a receptacle for hatched neo-
nate larvae. The egg masses were incubated at 26-270C and 65-70% R. H.
Hatching larvae were collected daily for transfer to the rearing medium.
Weevil larvae were reared successfully on the same artificial diet used
for rearing larvae of D. abbreviatus (Beavers 1982) with the following
modifications in the preparation procedures: formalin, Vanderzant's vitamin
mixture, ascorbic acid and sorbic acid (heat sensitive ingredients) were
added after autoclaving the diet mixture. Batches of diet were prepared
in a 5-liter blender by: a) melting the agar in water at 1000C, b) adding
heat tolerant ingredients and autoclaving for 20 minutes at 1500C at 18
psi, and c) adding above ingredients when the media cooled at 800C. Diet
was poured (ca. 35 ml) immediately into 35-ml clear, plastic creamers
and allowed to solidify at ambient temperature. The open cups of diet
were held for 3-4 days in a semi-aseptic condition until excess moisture
(50% of initial wet-weight) had evaporated before introducing the neonate
larvae. Twenty larvae were placed into punctures made in the media to
minimize cannibalism and assure immediate opportunity for larval feed-
ing. Creamers were capped, placed on large trays and incubated in total
darkness in a controlled-temperature cabinet at 280C and 60% R.H. After
the completion of larval and pupal development at 65-70 days, newly-
emerged adults crawled to the surface of the medium where they were
collected each week and placed in an adult holding cage with newly-
expanded citrus flush.

EFFECT OF PHOTOPERIOD ON ADULT FEEDING BEHAVIOR

Cohorts of 6 adult weevils (8-day-old) were confined to holding cages
(11 x 5 cm) containing a single newly-expanded citrus leaf. Units were
held for 48 h in plant growth chambers at a constant temperature of
250C and 60% R.H. at 1 of 3 photoperiods: 24 h light, 12 h light-12 h dark,
and 24 h dark. Each weevil cohort per photoperiod was replicated 5 times.
Leaf area was measured before and after weevil exposure with a LiCor
portable area meter (Model LI-3000) to determine leaf area consumption.


EFFECT OF PHOTOPERIOD ON FEMALE OVIPOSITIONAL BEHAVIOR
Cohorts of 10 male and 10 female adult weevils of approximately the
same age were confined to holding cages (18 x 14 cm) containing bouquets
of newly-expanded citrus leaf flush, and stapled wax paper strips were
attached to the side of each cage. Units were held in plant growth chambers
at a constant temperature of 250C and 60% R. H. in either total light or
total darkness for 35 days. At 5-day intervals, new flush was added to each










382 Florida Entomologist 68 (3) September, 1985

unit, waxpaper strips were collected, and the number of egg masses and
eggs per mass were counted for each container. Each treatment was
replicated 3 times.

DETERMINATION OF PREOVIPOSITION, REPRODUCTIVE POTENTIAL,
ADULT LONGEVITY AND SEX DETERMINATION

At the time of adult emergence in the laboratory, individual weevils
were placed into separate cages containing citrus flush and oviposition
strips as previously described for the experimentation. A cohort of 35
females was held until they laid their first egg masses. Twenty five of the
females were then caged individually with males (2 males/cage) for 1
week, after which time the males were removed. The remaining 10 females
were unmated. The number of eggs per female and the percent egg eclosion
for each day was recorded until females died or the experiment was
terminated after 190 days.

DETERMINATION OF LARVAL GROWTH AND DEVELOPMENT

Twenty-four-h-old larvae were placed individually into 24-cell tissue
culture plates containing a small quantity of artificial diet. Plates were
incubated at 280C. Each day larval body length was measured, and the
media was examined for exuvia and head capsules. Head capsules were
placed on microscope slides and capsule widths measured using phase
contrast microscopy. To determine weevil sex ratio, 70 newly-emerged
adults were randomly selected from the media, dissected, and the genitalia
examined under a stereomicroscope.

RESULTS AND DISCUSSION

ADULT FEEDING BEHAVIOR

In the field, A. floridanus adults normally feed by straddling the edge
of the leaf and eating straight down into the leaf to a depth of 5-10 mm.
Repetitive feeding results in a characteristic leaf notching (Rowan 1976).
In the laboratory, the same feeding behavior was observed. In addition,
adults always preferred newly-expanded citrus leaf flush of any variety to
mature foliage. As shown in Table 1, adult feeding behavior was also
influenced by photoperiod. Leaf consumption per adult weevil was sig-

TABLE 1. LEAF CONSUMPTION BY ADULT Artipus Floridanus DURING 48-HOUR
EXPOSURE TO NEWLY-EXPANDED CITRUS LEAVES AT THREE PHOTO-
PERIODS.

Photoperiod Mean leaf consumption/
(h light:h dark) weevil (cm2)1

24:0 0.60 0.2 a
12:12 0.69 0.1 b
0:24 0.97 + 0.2 c

'All treatment means are based on 5 replicates and are significantly different (p = 0.05)
using Duncan's multiple range test.










McCoy et al.: Citrus Weevil Symposium 383

nificantly greater in 24 h darkness than in 24 h light or 12 h light/12 h
dark. This apparent preference for darkness or subdued light while feed-
ing has been observed in the grove.

OVIPOSITIONAL BEHAVIOR

In the laboratory, female A. floridanus generally laid their eggs between
the wax paper strips, but on occasion, deposited them between two citrus
leaves supplied as food. Eggs were always laid in masses of irregular
shape. Each egg mass contained from 12-130 eggs. Eggs were white to
yellow, depending on age and were about 0.8 mm long by 0.35 mm wide.
Eggs generally hatched in 7-9 days at 25-280C. Although females appeared
to lay a few more egg masses per day in total darkness than light, the
difference was not significant and the actual number of eggs per mass
was not affected (Table 2).

PREOVIPOSITION, REPRODUCTIVE POTENTIAL, ADULT LONGEVITY AND
SEX DETERMINATION

The preoviposition period for newly-emerged adult females was ap-
parently influenced by mating. Virgin females (n = 40) began to lay eggs
between 15 and 27 days after emergence, while mated females began laying
eggs at 11-20 days. Egg production for mated females peaked at about
8.0 eggs per day about 60 days after adult emergence; they continued to lay
a few eggs beyond 165 days (Fig. 1). Mated females laid an average of
1,220 430 eggs in their life span compared to 683 446 eggs by virgin
females. None of the eggs laid by virgin females hatched. Egg viability
for mated females exceeded 80% during most of their life span but declined
abruptly after 120 days (Fig. 1). Adult female survival began to decline
sharply around 160 days (Fig. 1).

LARVAL GROWTH AND DEVELOPMENT
Larval development on the artificial diet required about 45 days at 280C.
Exuvial counts indicated that there were 6 larval instars with stadia
varying from 5-10 days (Table 3). Sixth instar larvae averaged 9.6 0.4
mm in length (Table 3). Maximum larval survivorship occurred when the
artificial diet was pre-dried to approximately 50% of its fresh weight.
Thirty-day-old larval survival reached 60.7% under these conditions. Ma-
ture larvae constructed pupation cells in the frass where they remained
for as long as 2 weeks before pupation.

TABLE 2. EFFECT OF PHOTOPERIOD ON THE OVIPOSITIONAL BEHAVIOR OF
Artipus Floridanus AFTER 35 DAYS.1

Photoperiod Mean number Mean number
(h light:h dark) egg masses/female eggs/mass

24:0 9.6 44.0
0:24 12.7 35.6

'All treatment means based on 3 replicates and are not significantly different (p = 0.05)
using "t" test.











384


Florida Entomologist 68 (3)


TIME (DAYS)
Fig. 1. Percent adult survival, fecundity and
female Artipus floridanus in the laboratory.


September, 1985


-* Survivorship p-
z
-~ Percent Egg Viabiliy oi
-0 Mean Eggs/Female W

100





z
60

z
4 0-

40>

0
I




cr

20 >



0
160 200


egg viability for mated


PUPATION

The pupal period lasted 14-20 days at 280C. Newly closed adults began
to turn grey while in the pupal cell while many emerged shortly after adult
eclosion. Some, however, remained in the medium for as long as 2 weeks.
Total developmental time from egg to adult ranged from 70-120 days and
averaged 101 days.


TABLE 3. LARVAL DEVELOPMENT
FICIAL DIET AT 280C.


IN TIME BY Artipus floridanus ON ARTI-


Mean larvel Head capsule
Time interval Larval length SD width SD
(days) instar (mm) (mm)


0-5 1st 1.2 0.2 0.2 0.01
5-10 2nd 2.0 0.4 0.3 0.01
10-15 3rd 3.4 0.2 0.4 0.02
15-20 4th 4.9 0.9 0.6 0.10
20-25 5th 6.0 0.4 0.9 0.04
25-30 5th 7.0 0.5 0.9 0.04
30-35 6th 8.2 0.5 1.1 0.03
35-40 6th 9.6 0.4 1.1 0.03
40-45 Prepupae 9.4 0.2 -

'n=24










McCoy et al.: Citrus Weevil Symposium


385


The generation time of 70-120 days at 260C implies that A. floridanus
is a multivoltine species. Mean annual temperatures measured over a 5-
year period in commercial citrus groves were approximately 20-220C at
depths of 12-36 inches, and generally remained near 260C from May to
September (Sites 1971). Theoretically, this would allow for more than one
generation per year.
The relatively short generation time and high fecundity make A.
floridanus an excellent laboratory model to serve as a host for the de-
development of biological control agents which may be applied to other
weevil species less amenable to laboratory culture.
A vigorous colony of A. floridanus may also provide the experimental
material necessary for determining its effect upon citrus under controlled
conditions and the development of experimental populations in the field
for life table studies.

ACKNOWLEDGEMENTS
The authors would like to express their appreciation to Mr. Charles D.
Jones and Ms. Cecile J. Zickefoose for their major contributions in the
rearing program and preparation of this manuscript. This study was
supported by Tropical and Subtropical Agriculture Research Grant 83-
CSRS-2-2141 under PL 89-808, Section 406.
Florida Agricultural Experiment Station Journal Series Number 6252.

REFERENCES CITED
BEAVERS, J. B. 1982. Biology of Diaprepes abbreviatus (Coleoptera: Cur-
culionidae) reared on an artificial diet. Florida Ent. 65: 263-9.
C. W. McCoY, AND D. T. KAPLAN. 1983. Natural enemies
of subterranean Diaprepes abbreviatus (Coleoptera: Curculionidae)
larvae in Florida. Environ. Ent. 12(3) : 840-3.
BULLOCK, R. C. 1984. Endoparasitic braconid (Hym: Braconidae) attacks
little leaf notcher, Artipus floridanus Horn (Coleoptera: Curculioni-
dae), in Florida. Florida Ent. 67(4): 571-2.
LECONTE, J. L., AND G. H. HORN. 1876. Rhynchophora of America north
of Mexico. Proc. Amer. Phil. Soc. 15(96): 1-455.
ROWAN, W. T. 1976. Florida host plants of Artipus floridanus (Coleoptera:
Curculionidae). Florida Ent. 59(4): 439-40.
SIMANTON, W. A. 1976. Populations of insects and mites in Florida citrus
groves. Florida Agric. Exp. Sta. Monogr. Ser. 7: 1-141.
SITES, J. 1971. Soil temperature in Florida citrus groves. Univ. of Florida,
IFAS, Tech. Bull. 747: 3-15.
WOLCOTT, G. N. 1933. Otiorhynchids oviposit between paper. J. Econ. Ent.
26: 1172-3.
WOODRUFF, R. E. 1982. Artipus floridanus Horn: another weevil pest of
citrus. Florida Dept. Agric. Consum. Serv., Div. Plant Ind., Ent.
Circ. 237: 1-2.










386 Florida Entomologist 68 (3) September, 1985

LEAF FEEDING INJURY TO CITRUS BY ROOT
WEEVIL ADULTS: LEAF AREA, PHOTOSYNTHESIS,
AND WATER USE EFFICIENCY

J. P. SYVERTSEN AND C. W. MCCOY
University of Florida, IFAS
Citrus Research and Education Center
700 Experiment Station Road
Lake Alfred, FL 33850 USA

ABSTRACT
The purpose of this study was to quantitatively determine citrus leaf
consumption by Artipus floridanus Horn, the little leaf notcher, and the
effect of feeding injury on net CO2 assimilation and water use efficiency.
Feeding by either male or female weevils began at the margin of the
citrus leaf and progressed inward. Male, female, and mixed adult popu-
lations of A. floridanus, when previously fed normally or starved, consumed
an amount of leaf tissue over time which was directly proportional to
population density. Populations of 1 or 5 weevils per leaf consumed less
than 5% of the total leaf area after 72 h whereas 15 weevils consumed
up to 40% of the leaf area during the same period. Feeding by female
weevils generally reduced leaf area more than that by males. Leaf area
consumed per weevil per day did not change with differing population
levels. There was no evidence of sexual interference with feeding behavior.
None of the leaves exposed to weevil feeding sustained injury to the mid-
vein and, therefore, no abscission was observed.
Net gas exchange was reduced by the amount of leaf area consumed.
CO2 assimilation, transpiration, and water use efficiency were evaluated
using the remaining tissue of injured leaves. Net gas exchange rates of
leaves injured by previously fed weevils did not change consistently with
percentage leaf area consumed. In leaves more severely injured by starved
female populations, water loss increased proportionally more than photo-
synthesis declined, resulting in up to a 20% decrease in water use efficiency.
Thus, interactions between feeding injury and drought stress may be es-
pecially important.

RESUME
El prop6sito de este ensayo fue para cuantificar el area de hojas de
citricos consumidas por Artipus floridanus Horn, y el efecto de este dafio
en la asimilaci6n neta de CO2 y la eficiencia del uso del agua. El consume
de las hojas de citricos por gorgojos machos o hembras, comenz6 en el
marjen, progresando hacia el interior de la hoja. Machos, hembras, y
poblaciones mixtas de adults de A. floridanus, cuando se alimentaron
normalmente o se dejaron sin comida, consumieron una cantidad de tejido
de hojas directamente proporcional a la densidad de la poblaci6n. Poblaciones
de 1 a 5 gorgojos por hoja consumieron menos de un 5% del Area de las
hojas despu6s de 72 horas, mientras que 15 gorgojos consumieron on 40% del
Area de las hojas durante el mismo period. La alimentaci6n de gorgojos
hembras generalmente reducieron el Area de las hojas mAs que los machos.
El Area de las hojas consumidas diariamente por los gorgojos no cambi6 con
distintos niveles de poblaciones. No hubo evidencia de interferencia sexual
con el comportamiento de alimentaci6n. Ninguna de las hojas expuestas a los
gorgojos sostuvieron dafios en la nervadura central, de aqui que no se
observe absici6n.










Syvertsen & McCoy: Citrus Weevil Symposium


387


El intercambio neto de gas fue reducido por la cantidad del Area de la
hoja consumida. Asimilaci6n de CO2, transpiraci6n, y la eficiencia del uso
del agua, fueron evaluadas usando los tejidos remanentes de las hojas
dafiadas. La proporci6n de intercambio neto de gas no cambi6 consistente-
mente con el porcentaje del Area consumida de la hoja. En hojas mas severa-
mente dafiadas por poblaciones hembras previamente sin alimentos, la
perdida de agua aument6 proporcionalmente mAs que la fotosintesis de-
clin6, resultando en un decreso de un 20% en la eficiencia del uso del
agua. La acci6n reciproca entire dafios causados por la alimentaci6n y la
tension producida por sequias, pudiera ser especialmente important.



The common species of root weevils occurring on Florida citrus are
the Fuller's rose beetle, Pantomorus cervinus (Boheman), the little leaf
notcher, Artipus floridanus Horn, the citrus root weevils, Pachneus opalus
(Oliver) and Pachneus litus (German), and the West Indian sugarcane
rootstock borer weevil, Diaprepes abbreviatus (L.) (Schroeder and Beavers
1977). All species appear to have a broad host range and are generally
localized in their distribution on citrus and other plants at locations
throughout the State.
Injury to the citrus plants results from larval feeding on roots and
adult feeding on leaves. No quantitative data are available on the annual
economic loss to citrus caused by the larvae and adults. Adult weevils are
foliage feeders and cause a characteristic notching of the leaf margins
(Bullock 1971). The notching pattern is usually characteristic of the species
and all weevil species prefer to feed on new growth. There appears to be
no preference for citrus variety and interestingly, foliar feeding has been
observed to occur mainly at night. McCoy et al. 1985, found that adult A.
floridanus consumed significantly more citrus leaf area in total darkness
compared to 12 h light and darkness or constant light. In addition, the
life expectancy of adult weevils is relatively long, about 160 days.
Other than the obvious reduction of leaf surface area by adult weevil
feeding, little is known about the effect of leaf feeding injury on citrus
leaf physiology. In apple leaves, no reduction in net photosynthesis occurs
until 10% of the leaf area is removed (Hall and Ferree 1976). In addition,
injury to large leaf veins results in lower photosynthesis than interveinal
injury and the amount of cut leaf surface exposed is more important than
the area removed (Ferree and Hall 1981). The purpose of this study was
to determine quantitatively the leaf consumption rate by different popu-
lations of adult A. floridanus and their effect on photosynthetic CO2 as-
similation, transpiration rate, and water use efficiency of citrus leaves.

MATERIALS AND METHODS
HOST PLANTS

Eleven-month-old Duncan grapefruit (Citrus paradisi Macf.) seedlings
approximately 45 cm in height were grown in the greenhouse under 50%
shade cloth and natural photoperiods. Plants were placed in a plant growth
chamber at a constant temperature of 25C, 50% relative humidity, and
a 12-h photoperiod for 5 days to precondition plants for experimentation.
All feeding experiments were conducted under these conditions.










Florida Entomologist 68 (3)


September, 1985


INSECTS

A wild population of approximately 2,000 adult A. floridanus was col-
lected randomly from navel orange (Citrus sinensis L.) and Australian
pine (Casuarina spp.) foliage in the vicinity of Wabasso, Fla. Weevils
were held in a styrofoam cooler at 20 to 250C for transport to Lake Alfred.
In the laboratory, cohorts of 300 to 350 adult weevils were placed in a
modified 10-gal aquarium fixed with a screen cover and held at 27 to 280C.
Weevils were fed newly expanded citrus foliage for approximately 2 weeks
until used for experimentation. During the first week, approximately 20%"
of the adult weevils died; thereafter, <5% of the remaining weevils died.
Weevils were prepared for feeding experiments as follows: 350 adult
male and female weevils were sexed on the basis of courtship behavior
and held separately in styrofoam containers without food for 5 days. This
starving treatment was intended to enhance uniformity of subsequent
feeding rates. Moisture was supplied to the weevils through cotton dental
wicks inserted in 1-oz plastic cups containing water. In addition, 2 mixed
adult populations of 300 weevils (starved or fed) were held in the same
manner. The 4 treatments consisted of: a) fed male and female, b) starved
male and female, c) starved female, and d) starved male.
To estimate the rate of citrus leaf consumption by a given population
of adult weevils in time, the following experiments were performed:
Randomly selected populations of 1, 5, 10, and 15 weevils from each
experimental population were placed in 80-mesh nylon bags enclosing single
attached 6-month-old citrus leaves. Prior to weevil exposure, the surface
area of each leaf was determined using a Li-Cor portable leaf area meter.
Treatments were replicated 3 times. Feeding was permitted for 24, 48, and
72-h in plant growth chambers. Thus, weevil-days (individuals x days)
varied from 1 to 45.


HOST-PLANT RESPONSES
Leaf consumption was determined by remeasuring the surface area of
the leaf and calculating the difference before and after exposure. Data
were expressed as a percentage of leaf area consumed per population
group. Leaf consumption per weevil over time, both within and between
treatments for each experiment, were tested for significance using linear re-
gression analysis and t-test.
Photosynthetic CO2 assimilation (A), transpiration rate (E), and water
use efficiency (WUE = A/E) were calculated from CO2 and H2O vapor
fluxes (Jarvis 1971) of each of the study leaves before and after the
A. floridanus feeding experiments. Net gas exchange of CO2 and H20
vapor were measured in the laboratory using an open gas exchange system
(Syvertsen 1984, Syvertsen and Smith 1983). All measurements were
made under constant environmental conditions of saturating photosynthetic
photon flux density (600-800 pmol s-'m-2), ambient air containing 340 20
pl 1-1 CO,, leaf temperature of 26 + 1C, and absolute humidity difference
from leaf to air of 6 2 pg cm-3. Preliminary measurements indicated
that these conditions were near optima for maximum rates of net gas
exchange. Net gas exchange rates after feeding injury were expressed as
a percentage of the respective rates prior to the experiments.


388










Syvertsen & McCoy: Citrus Weevil Symposium


389


RESULTS AND DISCUSSION
Typical patterns of leaf injury caused by the feeding of different
numbers of adult weevils over 72-h periods are shown in Fig. 1. The leaf
surface area removed by one weevil caged on a leaf for 72 h was ap-
proximately 4%. This feeding pattern and amount of injury per leaf is
typical of a relatively low population density of A. floridanus adults com-
mon to citrus groves in the spring and summer.
In general, the percentage of the leaf area consumed increased sig-
nificantly as the number of weevils per leaf increased (Fig. 2). This con-
dition was most pronounced when sexually mixed populations and starved
females only were tested in time. No effect of group behavior on feeding
responses were observed since the rate of leaf consumption per weevil per
day remained the same within cohorts.
In contrast to other treatments, increasing population densities of male
weevils had little effect on the percentage of leaf area consumed over
time (Fig. 2). This may be explained by the fact that the smaller adult
male A. floridanus have fewer metabolic requirements such as egg pro-
duction, and, therefore, eat less. There is no evidence to indicate any
sexual interference in feeding behavior, since the mean of the combined
rates of leaf consumption by individual starved males plus that of in-
dividual starved females, 0.57 [(0.32 + 0.82)/2 = 0.57], equals that of the
starved mixed population (0.63, Table 1).
It is unclear how the 5-day starvation period prior to leaf exposure
affected feeding behavior. This relatively long-lived insect apparently does
not require frequent feeding as subsequent leaf consumption rates of
starved and fed populations did not differ.



Weevil Feeding Injury

72 hr













0 1 5 10 15


Fig. 1. Typical feeding injury patterns on mature grapefruit leaves by
populations of 1 to 15 adult A. floridanus weevils after 72-hr (weevil-days =
0 to 45).












Florida Entomologist 68 (3)


September, 1985


Starved ?'s & 's
No. of Adults
*-1
n-5
A-10
*-15


40- z


5a a
20-
b


0- 24- 4'8 7
24 48 72


Starved "'s


a

ab A

-
-a -=s ^- - '^ ^ .^ ~~


Time (hr.)

Fig. 2. The relationship between citrus leaf consumption over time by
different cohorts of starved and fed populations of male and female A.
floridanus adult weevils. Each point is the mean of 3 leaves and are
connected for clarity. Slopes of linear regressions fitted to the raw data
were separated with unlike letters using t-tests (P<0.05).

TABLE 1. MEAN RATE (- 1 SD) OF PERCENTAGE LEAF AREA (l.a.) CON-
SUMED BY INDIVIDUAL ADULT A. floridanus WEEVILS PER DAY IN
THE EXPERIMENTS DESCRIBED IN FIG. 2.


% l.a./weevil/day


Fed male, female
Starved male, female
Starved female
Starved male


0.72 0.14
0.63 0.26
0.82 0.18
0.321 0.15


'Mean slope of the 4 linear regression lines (1, 5, 10, and 15 weevils) from each feeding
experiment.


390


Starved 9's









Syvertsen & McCoy: Citrus Weevil Symposium


fed
e 9?


1.2


1.0


0.8


0.8


starved
e 9


42


U
18


no


10

10


starved


13
43


r^n1


2 26


c 1.2
o

S1.0


S0.8
5 15 5 15 5 15
1 10 1 10 1 10
Number of Weevils
Fig. 3. Percentage change of CO, assimilation, transpiration and water
use efficiency of individual grapefruit leaves after 72 hr of feeding injury
by populations of 1 to 15 adult A. floridanus weevils. Each bar represents
mean values from 3 leaves; numbers above and below bars on transpiration
data are the percentage leaf area consumed from 72-h values in Fig. 2.


____ __ __ __


391










392 Florida Entomologist 68 (3) September, 1985

Reductions in CO2 assimilation and transpiration rates per leaf paral-
led the leaf area consumed (data not shown). Net gas exchange rates
of the remaining tissue of leaves injured by mixed populations of weevils
did not change consistently with percentage of leaf area consumption (Fig.
3). Consequently, water use efficiency was not related to numbers of weevils.
Although net gas exchange was measured 3 days after weevil removal,
water loss from injured leaf tissue possibly enhanced measured rates of
transpiration resulting in poor correlations between transpiration and leaf
consumption. In addition, enhanced CO2 diffusion into injured leaf cuticles
could also account for the 2 treatments that had higher net CO2 assimila-
tion rates after feeding injury.
Net gas exchange from leaves injured by starved female weevils ap-
pear more closely related to amount of leaf consumption (Fig. 3). Trans-
pirational water loss increased proportionally more than photosynthesis.
This resulted in up to a 20% decrease in water use efficiency for popu-
lations greater than one weevil/leaf.
Citrus leaves are thicker near the midvein than near the leaf margins
(Syvertsen and Levy 1982) where typical adult weevil feeding occurs. The
actual amount of leaf tissue removed per leaf surface area increases as
feeding injury progresses from the leaf margin towards the midvein. This
should have further compounded the impact of the higher amounts of
feeding injury-but it did not. In addition, there are relatively few veins
near the leaf margins which further minimizes the effect of weevil feed-
ing on leaf responses.
In summary, the net gas exchange data point to the importance of
measuring photosynthesis and transpiration of the remaining leaf tissue
simultaneously after leaves have been injured by adult weevils. Maximum
reduction in water use efficiency of about 20%, even after more than 40%
of the leaf had been consumed, indicates that the loss of photosynthetic
leaf surface area is relatively more important than changes in net gas
exchange of the remaining tissues. None of the leaves sustained injury
to the midvein; therefore, it is unlikely that even the leaves with the
greatest injury would abscise. Nonetheless, the decreases in water use
efficiency underscore the importance of water loss from injured leaves.
Future studies should emphasize interactions among weevil feeding injury,
host plant productivity and environmental stress, particularly drought
stress.
Florida Agricultural Experiment Station Journal Series No. 6288.

REFERENCES CITED
BULLOCK, R. C. 1971. Effectiveness of foliar sprays for control of Diaprepes
abbreviatus L. on Florida citrus. Trop. Agric. 48: 127-131.
FERREE, D. C., AND F. R. HALL. 1981. Influence of physical stress on photo-
synthesis and transpiration of apple leaves. J. Amer. Soc. Hort. Sci.
106: 348-350.
HALL, F. R., AND D. C. FERREE. 1976. Effects of insect injury simulation
on photosynthesis of apple leaves. J. Econ. Ent. 69: 245-248.
JARVIS, P. G. 1971. The estimation of resistances to carbon dioxide trans-
fer, pp. 566-631. In: Z. Sestak, J. Catsky and P. G. Jarvis (eds.).
Plant photosynthetic production: Manual of methods. Junk. The
Hague, Netherlands.
McCoY, C. W., C. SEGRETAIN, G. M. BEAVERS, AND C. TARRANT. 1985. Labora-










Syvertsen & McCoy: Citrus Weevil Symposium


393


tory rearing and biology of Artipus floridanus Horn (Coleoptera:
Curculionidae). Florida Ent. 68: 379-385.
SCHROEDER, W. J., AND J. B. BEAVERS. 1977. Citrus root weevils in Florida:
Indentification, biology and control. Proc. Int. Soc. Citriculture 2:
498-500.
SYVERTSEN, J. P. 1984. Light acclimation in citrus leaves. II. CO2 assimila-
tion and light, water and nitrogen use efficiency. J. Amer. Soc. Hort.
Sci. 109: 812-817.
SYVERTSEN, J. P., AND Y. LEVY. 1982. Diurnal changes in citrus leaf thick-
ness, leaf water potential and leaf-to-air temperature difference.
J. Exp. Bot 135: 783-789.
SYVERTSEN, J. P., AND M. L. SMITH. 1983. An inexpensive leaf chamber for
measuring net gas exchange. HortScience 17: 300-301.




SAMPLING AND DISTRIBUTION OF ARTIPUS
FLORIDANUS HORN (COLEOPTERA:
CURCULIONIDAE) ON CITRUS AND WEED HOSTS

C. A. TARRANT AND C. W. MCCOY
University of Florida, IFAS
Citrus Research and Education Center
700 Experiment Station Road
Lake Alfred, Florida 33850 USA

ABSTRACT
No correlation was found between adult populations of Artipus floridanus
Horn observed on the foliage of navel orange trees and the number of
adults emerging from the soil beneath the same trees. Only a few larvae
were found in the root zones of selected trees after one year indicating
that the low adult population collected from emergence traps during the
year was an accurate index of population density per tree. Interestingly,
teaweed and carpet grass found between the rows produced a significantly
greater number of larvae per area than citrus.
A weak negative correlation was detected between leaf consumption by
adult weevils and change in root volume after one year. Yet, there was no
correlation between adult and larval populations and root volume or trunk
diameter.

RESUME
No se encontr6 correlaci6n entire poblaciones adults de Artipus flori-
danus Horn observadas en el follaje de Arboles de naranja navel y el
nfimero de adults saliendo de la tierra debajo de los mismos Arboles. Sola-
mente se encontraron unas pocas larvas en las zonas de las raices de Arboles
seleccionados despues de un afo, indicando que bajas poblaciones de adults
colectados en trampas de emergencia durante el afio, fue un indice precise
de la densidad de la poblaci6n por Arbol. Interesantemente, las plants "tea-
weed" y "carpet grass" que se encontraban entire las hileras de Arboles,
producieron significativamente un nimero mayor de larvas por Area que los
citricos.
Despu6s de un afio se detect una d6bil correlaci6n negative entire el
consume de hojas por gorgojos adults y cambios on cl volume do raices.





Weevil Feeding Injury
72 hr


10 15










Florida Entomologist 68 (3)


Sin embargo no hubo correlaci6n entire poblaciones de adults y larvas y
de volume de raices o en el diametro de los troncos.



Each of the 5 most common root weevil species attacking citrus in
Florida, Artipus floridanus Horn, Diaprepes abbreviatus (L.), Pantomorus
cervinus (Boheman), Pachnaeus litus (Gemar), and Pachnaeus opalus
(Olivier), is associated with a wide range of host plants (Woodruff 1968,
1981, 1982; Woodruff and Bullock 1979). Field studies have been restricted
to adults on citrus (Beavers et al. 1982, Beavers and Selhime 1976). Due
to the difficulty, cost, and destructive nature of sampling in the root area
of citrus, larval populations in soil beneath trees have been estimated by
the collection of adults in emergence traps. However, few adult weevils
have been collected emerging from the root zone of citrus. A total of 7
adult D. abbreviatus were collected from 32 emergence traps beneath trees
harbouring a high population of adults (Beavers and Selhime 1976).
Similarly, so few adult Pachnaeus spp, or P. cervinus have been recovered
in emergence traps in chemical control trials that much of the data has
been unpublishable (Bullock, personal communication; Wolfenbarger,
personal communication; Brooks, personal communication).
The purpose of this paper is to examine possible reasons for a lack
of correlation between adult weevils feeding on citrus foliage and emerg-
ing from soil around citrus. Data on populations of A. floridanus collected
in a 1-year study originally designed to compare the effectiveness of soil
pesticides are reported. At the end of the study, the entire root zones of
selected trees were excavated to determine the number and distribution of
A. floridanus immatures around the trees. Plants growing between tree
rows were excavated to determine whether A. floridanus was developing on
plants other than citrus in the grove.

MATERIALS AND METHODS
A grove near Wabasso, Fla. with a history of high populations of adult
A. floridanus was selected as the study site. Sixty navel orange trees on
sour orange rootstock were planted on deep St. Lucie sand in November
1983. Prior to planting, trees were bare-rooted and trunk diameters
measured 5.0 cm above the bud union. Root volume was determined by
immersing the young trees in water and measuring displaced water. Soil
treatments (Lorsban, Ficam and Beauveria bassiana) were applied at
planting in a complete block design.
Adult populations were estimated biweekly by 2-minute visual counts on
the foliage of each tree. Adult emergence from the soil around each tree
was estimated by placing 2 plastic screened-top emergence cages each
measuring 21 cm x 30 cm x 15 cm adjacent to the trunk and counting
biweekly the number of emerging adults.
At the end of 1 year, 10 randomly selected leaves were removed from
each tree and the percent leaf consumption determined using a Licor leaf
area meter. The trunk diameter of each tree was remeasured to determine
the percent change in diameter. The percent change in root volume was
determined for 25 excavated trees.
The mean number of adult A. floridanus/tree/count on foliage and the


September, 1985


394










Tarrant & McCoy: Citrus Weevil Symposium 395

mean number of adult A. floridanus/tree emerging from soil among treat-
ments were compared by analysis of variance. Correlations between the
population estimates of A. floridanus and parameters of plant growth were
sought using the data pooled from all 60 trees.
Twenty-five randomly selected trees were excavated by removing soil
in 7.5-cm layers, beginning at the lateral root tips and working inwards in
25-cm sections. The soil was rinsed through a 0.75-cm mesh screen to re-
cover soil insects. The stage, number, and location of all curculionids were
recorded.
Plots (0.2 m2) of carpet grass and teaweed adjacent to each of 12 trees
were excavated in 7.5-cm layers and the number, stage, and depth in
soil of all curculionids recorded. The larvae were reared to adulthood on
artificial media as described by McCoy et al. (1985) so they could be identi-
fied.
The number of A. floridanus recovered from various depths and regions
of host plant root zones were compared by Chi-square analysis. The
samples of A. floridanus immatures on citrus and cover crop were com-
pared using Wilcox's signed rank test.

RESULTS

Data from soil treatments on citrus were pooled since there was no
significant difference in the number of A. floridanus adults emerging from
treated and untreated soil (Table 1).
The total number of adults collected in emergence traps ranged from
0-15 per tree (mean = 5 3). Seventy percent (212/300) of all emerging
adults were collected before mid February. Adult populations on foliage
remained low until May and then increased to approximately 8 weevils/tree
in the fall (Fig. 1).
No correlations were found between measures of plant growth and
estimates of A. floridanus populations. Feeding damage by adult weevils
consisted of notching along leaf margins and was fairly uniform among
leaves on a given tree. The mean percent leaf consumption/tree was 16 4

TABLE 1. COMPARISON OF MEAN ADULT Artipus floridanus HORN PER TREE
ON FOLIAGE AND IN EMERGENCE TRAPS ON NAVEL/SOUR ORANGE
TREES TREATED WITH Beauveria bassiana, FICAM 10G, AND
LORSBAN 15G AT WABASSO, FLA.

Mean adults/tree Mean adults/tree
on foliage emerged from soil
Treatment per sampling date1 in 1 yr1

Lorsban 15G 4.3 1.1 a 6.2 3.3 a
Bb-20 g 4.0 0.5 ab 5.1 3.7 a
Bb-200 g 3.7 1.0 abc 4.6 4.6 a
Control 1 3.3 1.3 be 6.0 3.6 a
Control 2 3.1 1.0 be 4.1 1.6 a
Ficam 3.1 0.8 c 4.0 2.7 a

IMeans marked by the same letter are not significantly different (p 0.05) using
Duncan's multiple range test.











396 Florida Entomologist 68 (3) September, 1985


o o *- *Canopy
e Emerged

S80- -08 0
o
c a


oo- l I I-<
R 3C
S600 -026
0 I ( 0

40 04


*20



Jan Feb Mar Apr May Jun Jul Aug Sep Oct

Time

Fig. 1. Seasonal abundance of A. floridanus on navel/sour orange at
Wabasso, Fla., 1984.

(Range 0-30). A weak negative correlation was detected between leaf con-
sumption and percent change in root volume (r = 0.46).
All but one larva collected in the excavation was confirmed to be A.
floridanus. The size of the smallest larvae recovered was similar to the size
of larvae reared on artificial media for 20 days at 280C (McCoy et al. 1985).
The mean number of A. floridanus immatures/tree was 3.4 + 4.5.
Nearly all the A. floridanus recovered from citrus were found within
50 cm of the trunk. Significantly greater numbers (Chi-square, p = 0.005)
of A. floridanus were recovered from depths of 7.5-15.0 cm than from either
0-7.5 cm or 15.0-22.5 cm below the soil surface on citrus (Table 2). In
grasses, greater numbers of A. floridanus were recovered from depths of
0-7.5 cm than from depths of 7.5-15.0 cm or 15.0-22.5 cm (Table 2) (Chi-
square, p = 0.005). The depth at which the majority of the larvae were
found corresponded to the depth containing the greatest mass of roots.
The frequency of samples containing large numbers of A. floridanus
immatures was significantly greater in the cover crop than in citrus (p =
0.05), despite the fact that the area excavated in each sample of cover crop
was only one-quarter of the area excavated around each tree.

DISCUSSION

The small number of adults collected in emergence traps appears to be
an accurate index of the emergence of adults from soil around young trees.
The results of the excavation indicated that the emergence traps had
covered approximately 16% of the root zone where immatures would be
located.
The number of adult A. floridanus emerging from soil around young
citrus does not account for the adult populations counted on foliage in
summer and fall. Adults must have been migrating onto the young trees
from other plants in the grove or older citrus trees. The fact that 8 times
as many weevil larvae per area were recovered from the cover crop than













Tarrant & McCoy: Citrus Weevil Symposium


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398 Florida, Entomologist 68 (3) September, 1985

from citrus suggests that plants other than citrus may play a major role in
promoting weevil populations. Life table studies may reveal the relative
contribution of various host plant species to local adult weevil populations.
The number of adults counted on citrus foliage were adequate to pro-
duce over 2,000 eggs per tree over the season (McCoy et al. 1985), yet few
larvae were found in the soil around the trees. This may be due to limited
oviposition on young citrus or high mortality of eggs and small larvae.
The weevil population observed over the year had little effect on plant
growth. Although a weak negative correlation between the percent leaf
consumption by adults and the percent change in root volume was detected,
it cannot be determined from this data whether this relationship is based
upon plant responses to foliar feeding by adults (Syvertson and McCoy
1985), feeding injury by young larvae that died before maturity, or un-
known factors linking plant growth and weevil populations.

REFERENCES CITED
BEAVERS, J. B., T. P. McGOVERN, AND V. E. ADLER. 1982. Diaprepes abbrevi-
atus: Laboratory and field behavioral and attractancy studies. En-
viron. Ent. 11: 436-9.
AND A. G. SELHIME. 1976. Population dynamics of Diaprepes
abbreviatus in an isolated citrus grove in central Florida. J. Econ.
Ent. 69: 9-10.
McCoY, C. W., C. SEGRETAIN, G. M. BEAVERS, AND C. TARRANT. 1985. Labora-
tory rearing and some aspects of the biology of Artipus floridanus
Horn (Coleoptera: Curculionidae). Florida Ent. 68: 379-385.
SYVERSTEN, J. P. AND C. W. McCoY. 1985. Feeding injury to citrus leaves
caused by adult root weevils. Florida Ent. 68: 386-393.
WOODRUFF, R. E. 1968. The present status of a West Indian weevil (Dia-
prepes abbreviatus) (Coleoptera: Curculionidae) in Florida. Florida
Dept. Agric. Cons. Serv., Div. Plant Ind., Ent. Circ. 30: 1-2.
1981. Citrus root weevils of the genus Pachnaeus in Florida
(Coleoptera: Curculionidae). Florida Dept. Agric. Cons. Serv., Div.
Plant Ind., Ent. Circ. 231: 1-4.
1982. Artipus floridanus Horn: another weevil pest of citrus.
Florida Dept. Agric. Cons. Serv., Div. Plant Ind., Ent. Circ. 237: 1-2.
AND R. C. BULLOCK. 1979. Fuller's rose weevil Pantomorus
cervinus (Boheman) in Florida (Coleoptera: Curculionidae). Florida
Dept. Agric. Cons. Serv., Div. Plant Ind., Ent. Circ. 207: 1-4.


__ ___


I _










Schroeder & Beavers: Citrus Weevil Symposium


SEMIOCHEMICALS AND DIAPREPES ABBREVIATUS
(COLEOPTERA: CURCULIONIDAE) BEHAVIOR:
IMPLICATIONS FOR SURVEY

W. J. SCHROEDER AND J. B. BEAVERS
U.S. Department of Agriculture, ARS
2120 Camden Road, Orlando, FL 32803

ABSTRACT
The existence of semiochemicals that influence reproductive behavior
in the West Indian sugarcane root stalk borer weevil, Diaprepes abbrevi-
atus (L.) has been demonstrated. Semiochemicals are produced by both
male and female weevils. The aggregation of weevils is interpreted as a
pheromone-induced behavior and this specific attractant is produced by
the male weevil.

RESUME
Se ha demonstrado la existencia de "semiochemicals" que influyen el
compartamiento reproductive de Diaprepes abbreviiatus (L.). "Semio-
chemicals" son producidos por los gorgojos machos y hembras. La agrega-
ci6n de gorgojos es interpretada como un comportamiento inducido por
feromonas y que este especifico atrayente es producido por el gorgojo
macho.



Research on the reproductive behavior of Diaprepes abbreviatus has
been conducted during the last 5 years and is directed at deciphering
chemical communication between individuals of the same species. The
objective is to identify and develop naturally-occurring attractants derived
from the weevil for population survey.
Diaprepes abbreviatus L., a sugarcane rootstalk borer weevil, is an
important pest of sugarcane, citrus and other crops in the West Indies.
The adults feed on foliage of at least 76 plant species in Puerto Rico
(Martorell 1976), whereas the larvae are serious root feeders. D. abbrevi-
atus was found in Florida in 1964 (Woodruff 1964). By 1982, the weevil
was established on 4,000 ha of citrus (total citrus in Florida, 324,000 ha),
but it had not been found on sugarcane (total sugarcane in Florida, 132,000
ha). The weevil was, however, established in ornamental nurseries in south
Florida less than 10 km from the sugarcane areas (S. A. Alfieri, un-
published data). Several methods for detecting weevil spread have been
investigated. Beavers et al. (1979) examined the use of light traps and
determined that trap efficiency was not adequate for survey. Later, (1982)
Beavers et al. used sticky traps in combination with caged weevils to show
an in-flight attraction when traps were placed adjacent to plants with
adult weevils.
Adult weevils emerge from the soil in spring (April through June) and
in the fall (October through December) and often congregate in large
numbers on an individual plant of a given host species, leaving nearby host
plants undisturbed (Wolcott 1936, Woodruff 1968). Semiochemicals mediate
interactions between organisms, and when the individuals involved are the


399










Florida Entomologist 68 (3)


September, 1985


same species, the behavior-modifying chemicals are called pheromones. The
presence of a pheromone is indicated in the aggregation type of behavior
described above. Schroeder (1981), in an outdoor cage study, suggested a
possible chemical basis for this behavior by showing that D. abbreviatus
adults congregated on citrus plants on which one sex was allowed to crawl
and feed. Beavers et al. (1982) reported a similar result in a laboratory
olfactometer study. However, subsequent efforts to identify a specific be-
havioral response to frass or associated materials or extracts thereof in
the laboratory were unsuccessful. Experiments with various trap designs
in combination with weevils and weevil products as bait indicated that frass-
encrusted foliage alone was more attractive than other combinations tested.
In November 1981, we began field testing a particular trap design using
extracts of weevil frass in an effort to develop a detection method.
A trap was developed based on observations of adult D. abbreviatus be-
havior. The trap is an inverted funnel with a cage attached to the top
(Schroeder and Jones 1984) and is comparable to that of other insect traps
(Leggett and Cross 1971). A highly significant increase in the number
of captured weevils occurred when an extract of weevil frass was added
to the trap. The extract used in the initial field tests consisted of 20 g of
frass from a colony of male and female weevils (1:1) extracted in a
blender with 150 ml of chloroform/methanol/water (1:2:0.8) monophasic
solvent (Bligh and Dyer 1959). In subsequent studies, chloroform and
methanol Soxhlet extracts were used. Schroeder and Jones (1983) demon-
strated that location of the trap in a citrus tree and the wick material
significantly affected trap capture. In this study, traps in the top of the
tree captured more weevils compared to traps in the middle or lower
sections of the tree, and glass wool was the best material for release of
the attractant (compared to cotton or rubber). In another study, Jones
and Schroeder (1984) demonstrated that extracts of frass from male weevils
captured more males and females than did extracts of frass from female
weevils. With the data from these field trapping studies, we were able to
develop a laboratory bioassay.
A laboratory bioassay should reflect, as nearly as possible, the behavior
of the natural population. Based on observations of field behavior and on
field trapping studies, we determined the following: mating behavior in-
creases from 0400-1200 h; male and female weevils congregate in an area
of high pheromone concentration; and the male is the source of the be-
havior-modifying chemical that results in primary weevil aggregation. The
bioassay cage was a 25-cm circular screen (32-cm mesh) cylinder with
wood ends. Cages were oriented at a 900 angle to the prevailing breeze and
held in a screenhouse that had an opaque roof for diffuse light. A cotton
wick with the frass extract was suspended at one end of the cage and a
wick with the extract solvent at the other end. Twenty male weevils were
placed in each cage at first light in the morning, and the number of weevils
within 15 cm of the end of the cage was determined each hour. The
number of weevils congregating at the end with the frass extract was
significant and increased with time (Table 1). Changes in the bioassay
chamber, including air flow and design, are under study. The bioassay
should provide a method to follow the isolation of behavior-modifying
chemicals in the laboratory.


400










Schroeder & Beavers: Citrus Weevil Symposium


TABLE 1. MEAN NUMBER OF D. Abbreviatus MALES WITHIN THE 15-CM
AREAS AT EACH END OF THE BIOASSAY CAGE FOR 1-7 H POSTTREAT-
MENT.

1i No. weevils in
Hour 15-cm area
posttreatment Time Replications Treated Control

1 0800 23 4.1 3.2
2 0900 23 4.4 2.9
3 1000 23 5.8 3.2
4 1100 23 5.6 3.5
5 1200 18 6.3 3.1
6 1300 8 8.0 3.5
7 1400 8 7.3 3.6

'Means for 2-7 h posttreatment are significantly different (P<0.01, paired Student's
t test).

CONCLUSION

Although data from field trapping and laboratory bioassay are by no
means definitive, it is apparent that weevil excrement, or associated ma-
terials, contain active behavior-modifying chemical compounds which are
extractable in chloroform and methanol. The field trap data also suggest
that there is more than 1 active chemical in frass from male and female
weevils. Traps containing extracts of male frass captured more total insects
than other treatments. Aggregation of weevils on individual plants as de-
scribed by Wolcott (1936) is therefore interpreted as pheromone-induced
behavior. The laboratory bioassay, shown effective when applied to males,
has not shown a significant migration of mated female weevils. Unmated
female weevils have not yet been available for testing.
Additional research is needed before definitive statements can be made
about other behavior-modifying chemicals of D. abbreviatus. Preliminary
information has been accumulated and research on semiochemicals is con-
tinuing.

REFERENCES CITED
BEAVERS, J. B., T. P. MCGOVERN, AND V. E. ADLER. 1982. Diaprepes ab-
breviatus: laboratory and field behavioral and attractancy studies.
Environ. Ent. 11: 436-9.
J. M. STANLEY, H. R. AGEE, AND S. A. LOVESTRAND. 1979.
Diaprepes abbreviatus response to light traps in field and cage tests.
Florida Ent. 62: 136-9.
BLIGH, C. G., AND W. J. DYER. 1959. A rapid method of total lipid ex-
traction and purification. Can. J. Biochem. Physiol. 37: 911.
JONES, I. F., AND W. H. SCHROEDER. 1984. Capture of Diaprepes abbrevi-
atus (Coleoptera: Curculionidae) in frass extract-baited traps in
citrus. J. Econ. Entomol. 77: 334-336.
LEGGETT, J. E., AND W. H. CROSS. 1971. A new trap for capturing boll
weevils. Coop. Econ. Insect Rep. 21: 773-4.
MARTORELL, L. F. 1976. Annotated food plant catalog of the insects of
Puerto Rico. Agric. Exp. Stn., Univ. P. R. 303 pp.










402 Florida Entomologist 68 (3) September, 1985

SCHROEDER, W. J. 1981. Attraction, mating, and oviposition behavior in
field populations of Diaprepes abbreviatus on citrus. Environ.
Entomol. 10: 898-900.
AND I. F. JONES. 1984. A new trap for capturing Diaprepes
abbreviatus (Coleoptera: Curculionidae). Florida Ent. 67: 312-314.
1983. Capture of Diaprepes abbreviatus
(Coleoptera: Curculionidae) in traps: effects of location in a citrus
tree and wick materials. J. Econ. Entomol. 76: 1312-1314.
WOLCOTT, G. N. 1936. The life history of Diaprepes abbreviatus at Rio
Piedras, Puerto Rico. J. Agric. Univ. P.R. 20: 882-914.
WOODRUFF, R. E. 1964. A Puerto Rican weevil new to the United States
(Coleoptera: Curculionidae). Florida Dep. Agric., Div. Plant Ind.,
Entomol. Circ. 30: 1-2.
1968. The present status of a West Indian weevil (Diaprepes
abbreviatus (L.)) in Florida (Coleoptera: Curculionidae). Florida
Dep. Agric., Div. Plant Ind., Entomol. Circ. No. 77: 1-4.



SUSCEPTIBILITY OF ARTIPUS FLORIDANUS TO
DIFFERENT ISOLATES OF BEAUVERIA BASSIANA

C. W. McCoY, G. M. BEAVERS AND C. A. TARRANT
University of Florida, IFAS
Citrus Research and Education Center
700 Experiment Station Road
Lake Alfred, FL 33850 USA

ABSTRACT
Literature on the entomopathogens of adult and larval root weevils
is reviewed. A quantitative study to determine the pathogenicity and
sporulation on larvae of 34 isolates of Beauveria bassiana to neonatal
larvae of Artipus floridanus is reported. Six isolates were determined as
potentially superior for microbial control of citrus root weevils. Difference
in pathogenicity between fungal types was more pronounced at the lower
conidial concentration. Sporulation per cadaver increased with an increase
in virulence. No consistent differences in pathogenicity to neonatal larvae
of A. floridanus could be detected between exotic and indigenous isolates,
insect host, or location.

RESUME
Se revisa la literature de pat6genos entomol6gicos de gorgojos de
races adults y de las larvas. Se report un studio cuantitativo para de-
terminar la patogenicidad y la esporulaci6n en larvas de 34 aislados de
Beauveria bassiana hacia larvas neonatales de Artipus floridanus. Se
determine que 6 aislados eran potencialmente superiores para el control
microbial de gorgojos de races en citricos. Diferencia en patogenicidad
entire tipos de hongos fue mas pronuncida en baja concentration de conidias.
Esporulaci6n por cadAver aument6 con un aumento en virulencia. No se
pudo detectar diferencias consistentes en patogenicidad hacia larvas neo-
natales de A. floridanus entire aislados ex6ticos o indigenous, insects hos-
pederos, o localidad.











McCoy et al.: Citrus Weevil Symposium 403

Curculionid weevils in the genera Sitona, Hylobius, Diaprepes, Chalco-
dermus, and Pachnaeus that have subterranean larvae, frequently have
entomopathogens in their natural populations (Gerdin 1977, Allison 1949,
Petch 1932, Charles 1941, Mains 1958). Numerous fungi in particular have
been reported attacking either larval or adult weevils (Table 1). Bac-
teria, viruses, and protozoa appear to be less prevalent.
A number of entomopathogens have been found attacking the species
of the root weevil complex found on citrus. Jones (1915) and Wolcott
(1952) reported the fungi, Metarhizium anisopliae (Mets.), Sorokin and
Beauveria bassiana (Bals.) Vuill. from larval and adult stages of Diaprepes
abbreviatus (L.). Wolcott (1952) stated that M. anisopliae "takes a heavy
toll on larvae, pupae, and adults in captivity and might in the field."
Montes et al. (1981) found both B. bassiana and M. anisopliae infecting
adults and larvae, respectively, of Pachnaeus litus Germar as well as an
unidentified bacterium and a microsporidian (protozoan). In a Florida
survey, M. anisopliae was frequently found infecting the larvae and adults
of Pachnaeus spp., Pantomorus cervinus (Boh.), Artipus floridanus Horn,
and D. abbreviatus (Beavers et al. 1972, Beavers et al. 1983). In addition,
B. bassiana, Paecilomyces lilacinus, and Aspergillus ochraceous, in de-
scending order of occurrence, were isolated from D. abbreviatus and found
to be pathogenic to larvae of A. floridanus, Pachnaeus litus, and D. abbrevi-
atus (Beavers et al. 1983). All fungal species were most prevalent from
June through August, when seasonal rainfall was highest. Another inci-
dental microorganism isolated from D. abbreviatus larvae was a weakly
pathogenic strain of the soil-inhabiting bacterium, Serratia marcescens.
Recently, an unidentified gregarine (protozoan) was found infecting
the intestinal tract of adult A. floridanus (Tarrant, unpublished data). It
was found in 60 to 90% of the weevil populations along the east coast of
Florida in the winter. In addition, an unidentified microsporidian was found
infecting adult A. floridanus. It is unknown whether this is the same species
as the one reported by Montes et al. (1981). The fungus, Stilbella buquettii,
TABLE 1. A LIST OF ENTOMOPATHOGENIC FUNGI REPORTED ATTACKING
CURCULIONID WEEVILS.

Fungal species References

Entomophthora sp. Wilderuth, 1910
Entomophthora coleopterorum Jackson, 1934; Petch, 1944
Entomophthora phytomi Harcourt et al., 1974; Puttler et al.,
1978
Mycetosporidium jacksonae Tate, 1940
Beauveria bassiana Gerdin, 1977; Peirson, 1921;
Muller-Kogler and Stein, 1970
Metarhizium anisopliae Walstad and Anderson, 1971;
Wolcott, 1952
Fusarium oxysporum Kilpatrick, 1961
Hirsutella sp. Allison, 1949
Aspergillus sp. Tedders et al., 1973
Paecilomyces farinosus Muller-Kogler and Stein, 1970
Nomuraea rileyi Charles, 1941
Cordyceps curculionum Mains, 1958










404 Florida, Entomologist 68 (3) September, 1985

was also found infecting adult A. floridanus in south Florida in stands of
Australian pine (Tarrant, unpublished data). The potential for biological
control for any of these microbes is unknown.
Previous research has shown that entomopathogenic fungi are common
natural enemies of many insects. However, their effectiveness as regula-
tory agents appears to be limited by their inherent characteristic of being
delayed density-dependent control agents generally influenced by weather
conditions. To offset these limitations, some fungi such as B. bassiana,
Verticillium lecanii, and Hirsutella thompsonii, that are amenable to mass
production on an artificial substrate, have been developed as microbial
control agents and applied at high inoculum densities in the field under
defined conditions as biological insecticides (Ferron 1981, Hall 1981,
McCoy 1981).
B. bassiana is presently being used widely in eastern Europe and the
USSR as a biological insecticide against larvae of the Colorado potato
beetle, Leptinotarsa decimlineata (Ferron 1981). A commercial prepara-
tion of B. bassiana is also being developed by Abbott Laboratories, North
Chicago, Illinois, USA for Colorado potato beetle control. It is also highly
pathogenic to larvae of A. floridanus and persists in Florida soil, indicating
its potential as a microbial control agent for citrus root weevils (McCoy
et al. 1985, in press).
Since previous research indicates that considerable difference in patho-
genicity can occur among different biotypes of B. bassiana from different
geographical locations and hosts, a laboratory study was initiated to identify
the most virulent pathotypes of B. bassiana to the larvae of A. floridanus
as a first step in selecting the best fungal candidate for microbial control
research. A. floridanus was selected as a host for bioassay because it was
easily reared in the laboratory on artificial diet.
This paper reports the results of bioassays conducted on 34 indigenous,
exotic, and mutant isolates of B. bassiana against neonatal larvae of A.
floridanus and the selection of pathotypes for further examination.


MATERIALS AND METHODS

Only vigorous neonatal larvae of A. floridanus collected within 48 h
of hatch were used for bioassays. Eggs were obtained from a weevil colony
that had been maintained in the laboratory for approximately 4 yr.
Fungal biotypes of B. bassiana (Table 2) were obtained from different
laboratories as pure cultures or isolated directly from a given host. Each
isolate was grown on MC medium (potassium phosphate dibasic-18.0 g,
sodium phosphate heptahydrate-0.55 g, magnesium sulfate heptahydrate-
0.3 g, potassium chloride-0.5 g, glucose-5.0 g, ammonium nitrate-0.35 g,
yeast extract-2.5 g, agar-10 g, sterile distilled water (SDW, 500 ml))
for 21 days at 27 to 280C before conidial harvest. Inoculum was prepared
by placing an unknown quantity of dry conidia representative of each
isolate into a test tube containing 10 ml of SDW with 0.05% Tween 80.
To determine conidial viability, 0.5 ml of the prepared inoculum was
pipetted into flasks containing 50 ml of Sabouraud's dextrose broth. Flasks
were then agitated for 20 h on a water bath shaker at 300C. Viable conidial
counts were determined using the standard hemacytometer cell count
technique. Experimental concentrations of 1 x 105 and 1 x 107 conidia/ml










McCoy et al.: Citrus Weevil Symposium


405


were prepared by adding a known volume of the conidial suspension to
a known volume of SDW containing Tween 80 (0.05%).
One-hundred neonatal larvae, per treatment, were carefully placed in
a plastic vial (50-dram) with a nylon screen (80-mesh) base and a 1-cm
port on the side. The vial was capped and 20 ml of conidial inoculum was
added through the port. The spore suspension and larvae were gently
agitated by hand for 1 minute at which time conidia were removed by
vacuum filtration. The vial was placed in an incubator over a SDW reservoir
designed to maintain a 95 to 100% RH at 28 + 20C. After 24 h, neonatal
larvae were transferred to tissue culture units; excess larvae were dis-
carded. For each conidial concentration, 5 treated larvae were placed in a
culture well containing a moistened filter paper disc and each treatment
was replicated 12 times. An untreated control (n = 60) was always run


TABLE 2.


HOST DISTRIBUTION OF THE 34 BIOTYPES OF Beauveria bassiana
TESTED FOR PATHOGENICITY TO Artipus floridanus LARVAE IN
THE LABORATORY.


Biotype Insect host Location


RS-754
RS-783
RS-758
DA-79- (YCM)
RS-809
DA-79-3
5506
RS-757
DA-79-CM-2
A-34 mono
RS-739
5505
AF-15A
AFL
169
DA-79-2
WCBW-79
AFA
RS-252 Abbott
139
RS-736
RS-785
F-77
RS-733
DA-79-1
AF-42A
142
Jamaica
WCRW
RS-737
RS-738
RS-804
143 mono
AF-4


Coleoptera
Tenebrionidae (adult)
Diabrotica paranoense
Diaprepes abbreviatus
Diabrotica paranoense
Diaprepes abbreviatus
Scapteriscus vicinus (adult)
Tenebrionidae
Diaprepes abbreviatus
Lygus sp.
Diabrotica paranoense
Scapteriscus vicinus
Artipus floridanus
Artipus floridanus
Sitona humeralis
Diaprepes abbreviatus
Araecerus fasciculatus
Artipus floridanus (adult)
Leptinotarsa decemlineata
Sitona lineatus
Chalcodermus aeneus
Cerambycidae (adult)
Pachnaeus litus
Chalcodermus aeneus
Diaprepes abbreviatus
Artipus floridanus
Sitona dicoideus
Araecerus fasciculatus
Diabrotica virgifera
Pentatomidae
Chalcodermus aeneus
Elateridae (adult)
Sitona spp.
Artipus floridanus


Ceara, Brazil
Ceara, Brazil
Brazil
Florida, USA
Brazil
Florida, USA
Florida, USA
Ceard, Brazil
Florida, USA
Burgos, Spain
Ceard, Brazil
Florida, USA
Florida, USA
Florida, USA
Lusignan, France
Florida, USA
Florida, USA
Florida, USA
Maine, USA
South England, U.K.
Ceara, Brazil
Ceara, Brazil
Florida, USA
CearA, Brazil
Florida, USA
Florida, USA
Montpelier, France
Kingston, Jamaica
Illinois, USA
Cear6, Brazil
Ceara, Brazil
Ceara, Brazil
Australia
Florida, USA










Florida Entomologist 68 (3)


simultaneously with each series of treatments. Tissue culture wells were
then incubated at 280C. After 7 days, larvae were removed and examined
microscopically (60X) to determine larval mortality, larval mycosis, fungal
mycelial development, and conidial development on the cadavers. Biotypes
demonstrating the highest mean percent mycosis were considered most
pathogenic to A. floridanus, and the highest sporulation rate on dead larvae
were considered superior, in that, they would more readily produce a spore
residue important to fungal persistence in the soil.


RESULTS AND DISCUSSION

Pathogenicity (mean percent mycosis) and sporulation on the host
differed significantly among the 34 types at both 1 x 105 and 1 x 107
conidia/ml concentration (Table 3). Difference in pathogenicity between
fungal types was more pronounced at the lower rate. At rates of 105
conidia/ml, the mean percent mycosis caused by the 34 biotypes ranged from
0 to 93% with only 2 types causing >80% mycosis. At the higher rate
of 107 conidia/ml, the range of mean percent mycosis was 7 to 100%; 12
of 34 types caused >95% mycosis allowing little distinction between them.
Sporulation per dead cadaver increased with an increase in pathotype
virulence.
These data indicate a high degree of genetic variability among B.
bassiana biotypes for the selected properties associated with pathogenicity
and reproduction of the fungus on the cadaver. Although the rate of patho-
genicity (lethal time) for the different biotypes was not measured to keep
conidial concentrations in relation to treatments at a manageable level,
there appeared to be differences in pathogenicity expressed by some isolates.
For example, RS-758 and RS-809 changed from 0 to 80% infectivity over
the 2 rates while other pathogens such as DA-79 and RS-252 appeared to
show little change in percent mycosis.
In general, no consistent differences in pathogenicity could be detected
between exotic or indigenous biotypes, insect host, and location. For
example, 3 types isolated from D. abbreviatus (DA-79, nos. 1, 2, and 3)
at the same time and location showed significant differences in patho-
genicity. Similarly, some isolates isolated from A. floridanus in Florida
(AF-4, AF-24A) performed better or as well as exotic biotypes from other
species. Therefore, no factor could be identified as a predictor of virluence
that could be used in search for more effective isolates in future biological
control projects with fungi.
The following six biotypes were selected for further study. An in-
digenous type, AF-4 isolated from A. floridanus, and 3 exotic isolates
(143 mono from Sitona spp. in Australia, RS-804 and RS-738 from an
adult Elaterid and Chalcodermus aeneus respectively in Brazil) were su-
perior against neonatal larvae A. floridanus (Table 3). These types also
sporulated rapidly on the host and were equally effective at the higher
dosage. RS-737 isolated from a pentatomid from Brazil and WCRW from
the western corn rootworm in Illinois also showed excellent activity.
Pathogenicity is only one factor in the ultimate performance of the
fungal pathotypes in the field. A type able to persist well in the specific
environment targeted for biological control may out perform an apparently
more virulent form. For example, RS-252 which displayed excellent per-


406


September, 1985










McCoy et al.: Citrus Weevil Symposium


TABLE 3.


PATHOGENICITY AND SPORULATION ON HOST OF DIFFERENT BIO-
TYPES OF Beauveria bassiana TO NEONATE LARVAE OF Artipus
floridanus AFTER 7 DAYS IN THE LABORATORY.


Mean percent per conidial conc.1
1 X 105 conidia/ml 1 X 107 conidia/ml
Biotype Mycosis Sporulation Mycosis Sporulation


Control
RS-758
DA-79-3
5506
RS-754
RS-783
RS-809
DA-79- (YCM)
RS-739
RS-757
A-34 mono
5505
AF-15A
DA-79-CM-2
AFL
DA-79-2
169
WCBW-79
AFA
RS-733
RS-785
RS-736
F-77
DA-79-1
139
RS-252-
Abbott
AF-42A
Jamaica
142
WCRW
RS-737
RS-738
RS-804
AF-4
143 mono


0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
1.7 ab
1.7 ab
1.7 ab
2.1 ab
2.1 ab
2.8 ab
3.3 ab
9.2 ab
9.4 ab
10.0 ab
10.4 ab
13.6 abc
15.0 abc
16.7 abc
17.8 abc
18.3 abc
19.3 abc

22.5 bcd
31.7 cd
38.2 d
38.8 d
56.7 e
64.2 e
67.3 e
69.3 e
88.9 f
92.5 f


0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
0.0 a
13.1 ab
0.0 a
0.0 a
10.4 ab
6.5 ab
13.1 ab
6.5 ab
12.3 ab
0.0 a
9.4 ab
0.0 a
19.5 ab

17.7 ab
0.9 ab
25.9 ab
0.0 a
20.0 ab
31.8 c
30.2 c
70.4 c
71.4 c
95.2 d


0.0 a
81.3 hi
18.3 abcdef
26.9 bcdefg
19.2 abcdef
16.3 abcde
86.3 hi
7.8 ab
40.4 efg
100.0 i
27.9 bcdefg
34.6 defg
13.8 abcd
33.3 cdefg
39.2 efg
98.3 i
39.2 efg
41.7 fg
34.2 defg
100.0 i
74.6 h
100.0 i
45.0 g
23.8 bcdefg
100.0 i

24.4 bcdefg
100.0 i
100.0 i
100.0 i
98.3 i
100.0 i
96.7 hi
98.3 i
90.8 hi
93.3 hi


1Means followed by the same letter are not significantly different at the 5% level of
probability using Duncan's multiple range test. Each treatment mean based on 12 replicates.


sistence in Florida soil (McCoy et al. 1985, in press), may indeed out
perform other more virulent pathotypes. Additional research is presently
being conducted with the 6 most virulent types to determine if they have
differences in a) temperature tolerances in the soil, b) growth and sporula-
tion rates and c) host specificity. Preferably, the most virulent biotype
with the widest host range, best survivorship in the soil, and growth


0.0 a
90.6 hij
55.6 def
13.0 abc
39.5 abcde
14.7 abc
79.5 fghi
25.9 abcd
7.7 ab
100.0 k
10.4 ab
63.6 ef
5.1 ab
65.5 efg
69.0 efgh
97.2 ijk
56.0 def
24.6 abcd
55.1 def
99.7 jk
88.9 ghij
99.5 jk
50.5 cdef
23.8 abcd
100.0 k

45.5 bcde
98.0 jk
99.7 jk
100.0 k
93.7 ijk
100.0 k
97.6 jk
93.7 ijk
95.6 ijk
94.3 ijk


407










Florida Entomologist 68 (3)


characteristic will be developed either as a microbial insecticide or intro-
duced into Florida soils as a biological control agent.

ACKNOWLEDGEMENT
The authors wish to express their appreciation to Mr. Charles D. Jones
for his major contributions in rearing the host material for bioassay. This
study was supported by Tropical and Subtropical Agricultural Research
Grant 83-CRSR-2-2141 under PL 89-808, Section 406.
Florida Agricultural Experiment Station Journal Series No. 6315.

REFERENCES CITED
ALLISON, J. L. 1949. Natural control of the destructive sweetclover weevil
Sitona cylindricollis Fabr. by an entomogenous fungus parasite.
Phytopathologia 39: 501.
BEAVERS, J. B., C. W. McCoY, R. F. KANAVEL, R. A. SUTTON, AND A. G.
SELHIME. 1972. Two muscardine fungi pathogenic to Diaprepes ab-
breviatus. Florida Ent. 55: 117-120.
BEAVERS, J. B., C. W. McCoY, AND D. T. KAPLAN. 1983. Natural enemies
of subterranean Diaprepes abbreviatus (Coleoptera: Curculionidae)
larvae in Florida. Environ. Ent. 12(3): 840-843.
CHARLES, V. K. 1941. A preliminary check list of the entomogenous fungi
of North America. U. S. Dept. Agric. Insect Pest Survey Bull. 21:
707-785.
FERRON, P. 1981. Pest control by the fungi Beauveria and Metarhizium,
Chapter 24, pp. 465-482. In Microbial Control of Insects and Mites,
Burges, H. D. (ed.), Academic Press, London.
GERDIN, S. 1977. Observations on pathogens and parasites of Hylobius
abietus (Coleoptera: Curculionidae) in Sweden. J. Invert. Pathol.
30: 263-264.
HALL, R. A. 1981. Fungi: Verticillium lecanii as a microbial insecticide
of aphids and scales, Chapter 25, pp. 483-498. In Microbial Control
of Insects, Vol. 2, Burges, H. D. (ed.), Academic Press, London.
HARCOURT, D. G., J. C. GUPPY, D. M. MACLEOD, AND D. TYRELL. 1974. The
fungus Entomophythora phytomi pathogenic to the alfalfa weevil,
Hypera postica. Canadian Ent. 106: 1295-1300.
JACKSON, D. J. 1934. Bionomics of weevils of the genus Sitona injurious
to leguminous crops of Britain. Ann. Appl. Biol. 7: 269-298.
JONES, T. H. 1915. The sugarcane root borer Diaprepes spengleri L. In-
sular Exp. Sta. (Rio Piedras, Puerto Rico) Bull. 14. 19 pp.
KILPATRICK, R. A. 1961. Fungi associated with larvae of Sitona spp. Phyto-
pathologia 51: 640-641.
MAINS, E. B. 1958. North American entomogenous species of Cordyceps.
Mycologia 50: 169-222.
McCoY, C. W. 1981. Pest control by the fungus Hirsutella thompsonii. In
Microbial Control of Insects and Mites, Vol. 2, Burges, H. D. (ed.),
Academic Press, London. Chapter 26, pp. 499-512.
McCoY, C. W., R. C. BULLOCK, G. G. SOARES, C. A. TARRANT, AND G. M.
BEAVERS. 1985. Pathogens of the citrus root weevil complex and the
potential use of Beauveria bassiana as a microbial control agent in
Florida. Proc. Int. Soc. Citriculture, Sao Paulo, Brazil (in press).
MONTES, M., E. ARTEAGA, AND R. BROCHE. 1981. First results of the
epizootiological study of Pachnaeus litus Germar (Coleoptera: Curcu-
lionidae). Proc. Int. Soc. Citriculture, 2: 667-669, Tokyo, Japan.
MULLER-KOGLER, E. AND W. STEIN. 1970. Gewachshausversuche mit Beau-


408


September, 1985










McCoy et al.: Citrus Weevil Symposium 409

veria bassiana (Bals.) Vuill. zur infection von Sitona lineatus (L.)
(Coleopt., Curcur.) im Boden. Zeitschrift Angew. Ent. 65: 59-76.
PEIRSON. 1921. The life history and control of the pales weevil (Hylobius
pales). Harvard Forest Bull. 3: pp. 33.
FETCH, T. 1932. A list of entomogenous fungi of Great Britain. Trans.
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PETCH, T. 1944. Notes on entomogenous fungi. Trans. Brit. Mycol. Soc.
27: 81-93.
PUTTLER, B., D. L. HOSTETTER, S. LONG, AND R. E. PINNELL. 1978. Ento-
mophthora phytomi, a mild pathogen of the alfalfa weevil in the mid
great plains. Environ. Ent. 7: 670-671.
TATE, P. 1940. On Mycetosporidium jacksonae, n. sp. parasitic in species
of Sitona weevils. Phytopathologia 32: 462-469.
TEDDERS, W. L., D. J. WEAVER, AND E. J. WEHUNT. 1973. Pecan weevil:
suppression of larvae with the fungi Metarhizium anisopliae and
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WALSTAD, J. D. AND R. F. ANDERSON. 1971. Effectiveness of Beauveria
bassiana and Metarhizium anisopliae as control agents for the pales
weevil. J. Econ. Ent. 64: 322-323.
WILDERMUTH, V. L. 1910. The clover root curculio. USDA Ent. Bull. 85.
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WOLCOTT, G. N. 1936. The life history of Diaprepes abbreviatus at Rio
Piedras. Puerto Rician J. Agric. Univ. Puerto Rico 20: 883-914.
WOLCOTT, G. N. 1952. Control of soil-inhabiting grubs of Puerto Rico. J.
Agric. Univ. Puerto Rico 34: 333-337.

- -^- -- -^- -- -^- -LI-- -

A REVIEW OF
CHEMICAL ANTAGONISTS TO MYCOPATHOGENS
OF CITRUS ROOT WEEVILS

L. S. OSBORNE AND D. G. BOUCIAS
University of Florida, IFAS,
Agricultural Research and Education Center
Apopka, FL 32703
and
Department of Entomology and Nematology
Gainesville, FL 32611, respectively.

ABSTRACT
The literature describing chemical antagonists of the mycopathogens that
attack larvae of citrus root weevils is reviewed with emphasis on com-
pounds that are either fungicidal or fungistatic and impact Beauveria
bassiana or Metarhizium anisopliae. The development of antagonist-resistant
strains is described. The nature and action of antagonists must be considered
in screening programs and strategies for the use of mycopathogens.

RESUME
Se revisa la literature donde se described quimicos agonistas del myco-
pat6geno que ataca larvas del gorgojo de races de citricos, con 6nfasis en
compuestos que sean fungicidas o fungistiticos e impactan Beauveria bassi-










410 Florida Entomologist 68 (3) September, 1985

ana o Metarhizium anisoplia. Se ilustra el desarrollo de razas agonistas
resistentes. La indole y la acci6n de agonistas debe ser considerada para
cernir programs y estrategias para el usa de mycopatogenos.


Beauveria bassiana and Metarhizium anisopliae are important natural
enemies of the soil-dwelling larval stages of citrus root weevils (Beavers
et al. 1972, 1983). Currently, these two mycopathogens are being assessed
for their potential as microbial control agents (McCoy et al. 1985). The
ecology of B. bassiana and M. anisopliae in the complex and unique micro-
environment of the rhizosphere must be understood if we are to maximize
their efficacy and achieve predictable insect control. Many biological,
physical, and chemical factors influence survival of fungi in the rhizosphere.
Of special interest are chemical antagonists, compounds that are either
fungicidal or fungistatic (i.e., inhibiting germination of fungal spores
or retarding development of mycelia while in contact with the chemical).
Chemical antagonists fall into two main categories: 1) chemicals that
enter the environment as a result of man's activities, (e.g. insecticides,
fungicides, herbicides, and fertilizers); and 2) chemicals or antibiotics pro-
duced by other organisms (bacteria and fungi). Because the longevity of
both B. bassiana and M. anisopliae in soil is important to their value as insect
pathogens, we need to understand the interaction between the pathogens,
their hosts, the chemical environment, and resident microflora. This under-
standing will allow optimal management of the agricultural system of
interest and achievement of our goals. This paper reviews literature on
chemical antagonists of insect pathogens and reports progress towards
the selection of Beauveria strains resistant to benomyl. Refinement of a
selective media which will allow recovery and evaluation of B. bassiana or
M. anisopliae under field conditions is discussed.

PESTICIDES INFLUENCING Beauveria bassiana
OR Metarhizium anisopliae

Pesticides are an inevitable part of most agricultural systems and can
be disruptive to biological control programs. Therefore, pesticides toxic
to B. bassiana or M. anisopliae must be identified and less harmful ma-
terials substituted. If no suitable substitutes are available, we should
evaluate methods of managing the system to reduce impact of chemical
antagonists on the mycopathogen being used (Gardner et al. 1984).
Both in vitro and in vivo studies have been conducted to determine the
effect of pesticides on B. bassiana or M. anisopliae (Anderson and Roberts
1983, Cadatal and Gabriel 1970, Gardner et al. 1979, Olmert and Kenneth
1974). Most frequently, the pesticide is incorporated into the fungal
culture media or introduced to the fungus via standard paper assay discs.
The zone of inhibition or quantitative measurements, such as radial growth,
are then recorded. However, these methods are not always reliable in
determining what will happen under field conditions (Chase and Osborne
1983, and Osborne and Chase 1984).
The results of selected studies are presented in Table 1. In general,
carbamate fungicides were found most toxic to both fungi. Anderson and
Roberts (1983), studying compatibility of B. bassiana with various in-
secticide formulations used to control the Colorado potato beetle, found











Osborne & Boucias: Citrus Weevil Symposium


TABLE 1. THE EFFECTS OF PESTICIDES ON Beauveria bassiana AND Metar-
hizium anisopliae.

Chemical B.B.2 M.A.2 Reference


Aldrin
Atrazine
Atrazine + 2,4-D
Azinphosmethyl 50WP
Azinphosmethyl 2F
Azinphosmethyl
Azinphosmethyl
Benomyl
Benomyl
Benomyl
BHC-20% EC
(Chlorofenrinphos)
BHC-WP
BHC
Binapacryl
Captan
Captan
Carbaryl
Carbaryl
Carbaryl
Carbaryl
Carbofuran 4F
Carbofuran
Chlorobenzilate
Chloropyrifos
Chlorothalonil
Chlorothalonil
Copper oxychloride
Daconil
DDT
DDT
DDT
pure DDT
Diazinon
Diazinon
Diazinon
Dichlorvos
Diflubenzuron 25WP
Diflubenzuron
Dinocap
Dinocap
Dieldrin
Dimecron
Dodine
Ekatin
Endosulfan 3EC
Endosulfan 50WP
Endosulfan
Endosulfan
Endrin
Endrin


NT
NT
NT


++
+- t
+++
++
++
+

+
NT

NT
+++

+ ++
++
++

+


+

-T







++
NT

+








++
+


--



+

+


NT
NT
NT
NT
NT
NT

+

+++

NT
U
NT
NT
++
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
+
NT
+NT
NT
NT
NT
NT
NT
NT



-++
U
NT
NT
+
NT
++
+++


Wang and Leu 1972
Wang and Leu 1972
Wang and Leu 1972
Anderson and Roberts 1983
Anderson and Roberts 1983
Clark et al. 1982
Olmert and Kenneth 1974
Gardner et al. 1979
Olmert and Kenneth 1974
Tedders 1981
Cadatal and Gabriel 1970

Ramaraje et al. 1967
Wang and Leu 1972
Olmert and Kenneth 1974
Machrowicz 1967
Olmert and Kenneth 1974
Anderson and Roberts 1983
Cadatal and Gabriel 1970
Gardner et al. 1979
Olmert and Kenneth 1974
Anderson and Roberts 1983
Clark et al. 1982
Olmert and Kenneth 1974
Olmert and Kenneth 1974
Clark et al. 1982
Loria et al. 1983
Olmert and Kenneth 1974
Olmert and Kenneth 1974
Cadatal and Gabriel 1970
Dirimanov and Angelova 1962
Ramaraje et al. 1967
Schaerffenberg 1964
Cadatal and Gabriel 1970
Dirimanov and Angelova 1962
Olmert and Kenneth 1974
Olmert and Kenneth 1974
Anderson and Roberts 1983
Gardner et al. 1979
Olmert and Kenneth 1974
Tedders 1981
Dirimanov and Angelova 1962
Ramaraje et al. 1967
Tedders 1981
Machrowicz 1967
Anderson and Roberts 1983
Anderson and Roberts 1983
Cadatal and Gabriel 1970
Olmert and Kenneth 1974
Cadatal and Gabriel 1970
Ramaraje et al. 1967


411










Florida Entomologist 68 (3)


September, 1985


TABLE 1. (CONT.).

Chemical' B.B.2 M.A.' Reference


Ethion
Fenvalerate 2.4EC
Fenitrothion
Ferbam
Folidiol
Granosan L
Heptachlor
HCH 5% powder
Kasumin
Lindane
Malathion
Malathion
Mancozeb
Mancozeb
Maneb
Maneb
Metalaxyl
Metiram
Metiram
Metasystox
Methomyl
Methyl parathion
Methyl parathion
Omite
Oxamyl 2EC
Panogen
Paraffin oil
Parathion
PCNB
Permethrin 2EC
Permethrin
Phelan
Piperonyl butoxide
Sodium fluorosilicate
Sulfur
Supracide
Supracide
Systox
Thiabendazole
Thiram
Toxaphene
Trichlorfon
Triphenyltin hydroxide
White summer oil
Zineb
Zineb
Zineb


+
+++
++
NT
+
+++
NT

- to +
++
+++
++
+++
-++
+++
+++

+++
+++
NT
+
++
++

++
+++



NT++

++
+
++

+++

++
++
NT


++

NT

+++


NT
NT
++
U

+++

NT


+
NT
NT
NT
NT
NT
NT
NT
NT
U
NT
NT
NT
NT
NT
+++
NT
NT

NT
NT
NT
U
NT
NT

++N
NT
NT
NT
U
NT
NT
+++
NT
U
NT
+++


Olmert and Kenneth 1974
Anderson and Roberts 1983
Cadatal and Gabriel 1970
Machrowicz 1967
Ramaraje et al. 1967
Cadatal and Gabriel 1970
Wang and Leu 1972
Schaerffenberg 1964
Cadatal and Gabriel 1970
Cadatal and Gabriel 1970
Dirimanov and Angelova 1962
Ramaraje et al. 1967
Clark et al. 1982
Loria et al. 1983
Gardner et al. 1979
Olmert and Kenneth 1974
Loria et al. 1983
Clark et al. 1982
Loria et al. 1983
Machrowicz 1967
Gardner et al. 1979
Dirimanov and Angelova 1962
Gardner et al. 1979
Olmert and Kenneth 1974
Anderson and Roberts 1983
Cadatal and Gabriel 1970
Olmert and Kenneth 1974
Dirimanov and Angelova 1962
Olmert and Kenneth 1974
Anderson and Roberts 1983
Clark et al. 1982
Machrowicz 1967
Anderson and Roberts 1983
Olmert and Kenneth 1974
Tedders 1981
Cadatal and Gabriel 1970
Olmert and Kenneth 1974
Dirimanov and Angelova 1962
Olmert and Kenneth 1974
Machrowicz 1967
Dirimanov and Angelova 1962
Olmert and Kenneth 1974
Tedders 1981
Olmert and Kenneth 1974
Machrowicz 1967
Olmert and Kenneth 1974
Tedders 1981


412


'This table is adapted from tables 9 and 10 in Roberts and Campbell (1977).
S+++ = great to complete inhibition; + + = moderate inhibition; + = slight in-
hibition; = no inhibition; U = inhibition but unquantified by author; and NT = Not
tested.










Osborne & Boucias: Citrus Weevil Symposium


413


that emulsifiable-concentrate insecticide formulations containing xylene
based, aromatic solvents were inhibitory to B. bassiana, while wettable
powders often increased colony counts. However, both technical and
formulated pyrethroids inhibited B. bassiana.
Benomyl is used regularly in many agricultural systems and is toxic
to B. bassiana at rates in excess of 0.5 ppm (Gardner et al. 1979, Olmert
and Kenneth 1974, Tedders 1981, Chase and Osborne, unpublished data).
Because benomyl is widely used on foliage plants and is not compatible
with B. bassiana, development of a resistant strain was attempted. Initially,
a few fungal colonies survived and grew on an agar plate containing
benomyl at 2 ppm. Subcultures were made at progressively greater con-
centrations of benomyl until the fungus grew and sporulated on media
containing 600 ppm benomyl. This fungicide-resistant strain has main-
tained virulence to both Artipus floridanus Horn and Galleria mellonella
(L.) and it maintained its resistance after passage through G. mellonella.
Currently, characteristics such as virulence, growth rate, and sporulation
of the resistant strain are being compared with the parental strain.
An applied aspect of laboratory pesticide screening has resulted in
a selective medium used to recover B. bassiana and M. anisopliae from soil
(Beilharz et al. 1982). The medium consists of oatmeal agar amended with
0.65 g ai dodine (Cyprex 65WP, American Cyanimid Co., Wayne, NJ 07470).
However, media containing 0.65 g ai dodine/liter results in poor recovery
of M. anisopliae and significantly slows growth of B. bassiana. Therefore,
various modifications were studied resulting in the modification of the
original medium (Chas3 and Osborne, unpublished data). This medium
contains 0.46 g ai dodine/liter of oatmeal agar and is used to isolate both
B. bassiana and M. anisopliae from potting media with minimal contamina-
tion. When the concentration of dodine is increased from 0.46 g ai to 0.55 g
ai, one can selectively inhibit M. anisopliae and isolate only B. bassiana.
When amended with 0.38 mg ai formulated benomyl/liter, recovery of B.
bassiana is inhibited without affecting recovery of M. anisopliae. The benefit
derived from making the base medium selective for one organism over the
other is that sample variance is reduced. An apparent interaction between
the organisms occasionally occurs when recovered on the same medium: We
have observed an increase in the number of recoverable CFU of both organ-
isms. This reaction is, however, inconsistent. The existence of media selective
for one species or the other will provide a means to better study the effect of
pesticides in vivo as well as the autoecology of these two insect pathogens.


CHEMICALS PRODUCED BY MICROORGANISMS THAT
INFLUENCE Beauveria bassiana or Metarhizium anisopliae
The impact of antagonistic organisms on plant pathogenic fungi has
been studied in detail (Baker and Cook 1974). In contrast the interaction
between antagonistic microorganisms and insect pathogens has received
very little attention. Huber (1958) first noted that B. bassiana spores did
not germinate in "fresh garden soil" but would germinate if the soil was
sterilized. These observations were confirmed by Wartenberg and Freund
(1961) and Walsted et al. (1970). Clerk (1969) found that soil extracts
were fungistatic and not fungicidal. Clerk also noted that the inhibiting
factor could diffuse through agar and that inhibition was lost after passing











414 Florida Entomologist 68 (3) September, 1985

extracts through membrane filters or by heat-sterilization of the extracts.
He also found that the activity noted could be overcome by adding energy
rich substances to the extracts such as glucose or extracts of certain
insects.
With continued research, specific organisms have been identified that
inhibit B. bassiana (Altahtawy 1970, Lingg and Donaldson 1981). Bacillus
subtilis was shown to inhibit both germination/growth of B. bassiana and
Bacillus thuringiensis in vitro. The two antibiotics produced by B. subtilis,
bacitracin and subtilin, were believed to contribute to the inhibition ob-
served.
Lingg and Donaldson (1981) identified Penicillium urticae as an an-
tagonist of B. bassiana. These authors demonstrated that recovery of CFU
from non-sterile soil amended with carbon sources, nitrogen sources, or
various combinations of both was negligible within 22 days after in-
oculation. However, if the same amended soils were sterilized prior to in-
oculation with B. bassiana, very large increases in recoverable CFU were
obtained over the same period of time. P. urticae was routinely isolated
from the non-sterile soil and was shown to produce a water soluble in-
hibitor of B. bassiana. The authors believed that the amendments stimu-
lated the microflora which, in turn, produced chemicals that inhibited the
growth and/or survival of B. bassiana.
Shields et al. (1981) identified the water soluble metabolite produced
by P. urticae as patulin, a substance produced by other microorganisms as
well. In their studies, 1.45 g of inhibitor per liter of media were recovered.
Other studies have shown that P. urticae can convert greater than 0.25 of
the available carbon source in a culture medium to patulin (Norstadt and
McCalla 1971a). Norstadt and McCalla (1969, 1971b) found that con-
centrations of patulin in wheat stubble mulches ranged from 40 to 75 ppm.
As stated by Shields et al. (1981), 'If patulin is a major factor in the
inhibition of B. bassiana in non-sterile soils, it presents a potentially serious
problem to use B. bassiana as a means of controlling soil-inhabiting insect
pests.'
Our understanding of chemical antagonists of mycopathogens is limited.
There are many exciting and important areas that need attention if we
are going to understand the interaction between chemicals and these bio-
logical control agents. A few of the areas that need further investigation
are: 1) We must move from the laboratory to the field in our studies of
man-made antagonists; 2) We must determine if antagonists are fungi-
cidal or fungistatic; 3) We must determine what influence fungistasis has
on epizootiology of B. bassiana and M. anisopliae. This is important because
certain authors have postulated that antagonists act as preservatives:
maintaining CFU in a dormant state until a susceptible host comes in
contact resulting in germination, growth, and infection; 4) Work has begun
towards developing resistant strains of B. bassiana to benlate and patulin
(P. urticae); and 5) We must identify chemical antagonists that can be
used to manage antagonist organisms and thus reduce their influence on
insect pathogens.

ACKNOWLEDGMENTS

The authors wish to express their appreciation to A. R. Chase, W. A.










Osborne & Boucias: Citrus Weevil Symposium


415


Gardner, C. W. McCoy, G. G. Soares, and C. A. Tarrant for reviewing an
earlier version of the manuscript. I am also grateful to E. Faircloth for
typing this manuscript.
Florida Agricultural Experiment Stations Journal Series No. 6310.

REFERENCES CITED
ALTAHTAWY, M. M. 1970. Effect of Bacillus subtilis (Cohn.) on Bacillus
thuringiensis Berliner and Beauveria bassiana (Balsamo) Vuillemin.
Bull. Soc. Entomol. Egypt 54: 249-257.
ANDERSON, T. E., AND D. W. ROBERTS. 1983. Compatibility of Beauveria
bassiana isolates with insecticide formulations used in Colorado
potato beetle (Coleoptera: Chrysomelidae) control. J. Econ. Entomol.
76: 1437-1441.
BAKER, K. F., AND R. J. COOK. 1974. Biological control of plant pathogens.
W. H. Freeman Co., San Francisco.
BEAVERS, J. B., C. W. MCCOY, R. F. KANAVEL, R. A. SUTTON, AND A. G.
SELHIME. 1972. Two muscardine fungi pathogenic to Diaprepes ab-
breviatus (L.). Florida Entomol. 55: 117-120.
BEAVERS, J. B., C. W. MCCOY, AND D. T. KAPLAN. 1983. Natural enemies
of subterranean Diaprepes abbreviatus (Coleoptera: Curculionidae)
larvae in Florida. Environ. Entomol. 12: 840-843.
BEILHARZ, V. C., D. G. PARBERRY, AND H. J. SWART. 1982. Dodine: A se-
lective agent for certain soil fungi. Trans. Br. Mycol. Soc. 79: 507-
511.
CADATAL, T. D., AND B. D. GABRIEL. 1970. Effect of chemical pesticides on
the development of fungi pathogenic to some rice insects. Phillipp.
Entomol. 1: 379-395.
CHASE, A. R., AND L. S. OSBORNE. 1983. Influence of an insecticidal soap
on several foliar diseases of foliage plants. Plant Dis. 67: 1021-1023.
CLARK, R. A., R. A. CASAGRANDE, AND D. B. WALLACE. 1982. Influence of
pesticides on Beauveria bassiana, a pathogen of the Colorado potato
beetle. Environ. Entomol. 11: 67-70.
CLERK, G. C. 1969. Influence of soil extracts on the germination of conidia
of the fungi Beauveria bassiana and Paecilomyces farinosus. J. In-
vertebr. Pathol. 13: 120-124.
DIRIMANOV, M. J., AND R. ANGELOVA. 1962. Rasit Zasht. 10: 63-67. Cited
in Roberts, D. W., and A. S. Campbell. 1977. Stability of entomo-
pathogenic fungi. Misc. Publ. Entomol. Soc. Am. 10: 19-76.
GARDNER, W. A., R. M. SUTTON, AND R. NOBLET. 1979. Evaluation of the
effects of six selected pesticides on the growth of Nomuraea rileyi
and Beauveria bassiana in broth cultures. J. Georgia Entomol. Soc.
14: 106-113.
GARDNER, W. A., R. D. GETTING, AND G. K. STOREY. 1984. Scheduling of
Verticillium lecanii and benomyl applications to maintain aphid
(Homoptera: Aphidae) control on chrysanthemums in greenhouses.
J. Econ. Entomol. 77: 514-518.
HUBER, J. 1958. Untersuchungen zur Physiologie Insektentotender Pilze.
Arch. Mikrobiol. 29: 257-276.
LINGG, A. J., AND M. D. DONALDSON. 1981. Biotic and abiotic factors affect-
ing stability of Beauveria bassiana conidia in soil. J. Invertebr.
Pathol. 38: 191-200.
LORIA, R., S. GALAINI, AND D. W. ROBERTS. 1983. Survival of inoculum of
the entomopathogenic fungus Beauveria bassiana as influenced by
fungicides. Environ. Entomol. 12: 1724-1726.
MACHROWICZ, I. 1967. Wplyw niektorych srodkow chemicznych ochrony
roslin na rozwoj kilku grzybow w czystych kulturach. [Effect of some










Florida Entomologist 68 (3)


plant protection chemicals on the development of some fungi in pure
culture.] Zesz. nauk. wyzsz. Szk. roln. Szczec. Ser. 3, 24: 179-184.
McCoY, C. W., G. M. BEAVERS, AND C. A. TARRANT. 1985. Susceptibility of
Artipus floridanus to different isolates of Beauvaria bassiana. Florida
Entomol. 68: 402-409.
NORSTADT, F. A., AND T. M. MCCALLA. 1969. Microbial populations in
stubble-mulched soil. Soil Sci. 107: 188-193.
NORSTADT, F. A., AND T. M. MCCALLA. 1971a. Effects of patulin on wheat
grown to maturity. Soil Sci. 111: 236-243.
NORSTADT, F. A., AND T. M. MCCALLA. 1971b. Growth and patulin forma-
tion by Penicillium urticae Bainer in pure and mixed cultures. Plant
Soil. 34: 97-108.
OLMERT, I., AND R. G. KENNETH. 1974. Sensitivity of the Entomopathogenic
Fungi, Beauveria bassiana, Verticillium lecanii, and Verticillium
sp. to fungicides and insecticides. Environ. Entomol. 3: 33-38.
OSBORNE, L. S., AND A. R. CHASE. 1984. Influence of acephate and oxamyl
on Alternaria panax and on Alternaria leaf spot of schefflera. Plant
Dis. 68: 870-872.
RAMARAJE URS, N. V., H. C. GOVINDU, AND K. S. S. SHASTRY. 1967. The
effect of certain insecticides on the entomogenous fungi Beauveria
bassiana and Metarrhizium anisopliae. J. Invertebr. Pathol. 9: 398-
403.
ROBERTS, D. W., AND A. S. CAMPBELL. 1977. Stability of entomopathogenic
fungi. Misc. Publ. Entomol. Soc. Am. 10: 19-76.
SCHAERFFENBERG, B. 1964. Biological and environmental conditions for the
development of mycoses caused by Beauveria and Metarrhizium. J.
Invertebr. Pathol. 6: 8-20.
SHIELDS, M. S., A. J. LINGG, AND R. C. HEIMSCH. 1981. Identification of a
Penicillium urticae metabolite which inhibits Beauveria bassiana.
J. Invertebr. Pathol. 38: 374-377.
TEDDERS, W. L. 1981. In vitro inhibition of the entomopathogenic fungi
Beauveria bassiana and Metarhizium anisopliae by six fungicides
used in pecan culture. Environ. Entomol. 10: 346-349.
WALSTED, J. D., R. F. ANDERSON, AND W. J. STAMBAUGH. 1970. Effects of
environmental conditions on two species of muscardine fungi (Beau-
veria bassiana and Metarrhizium anisopliae). J. Invertebr. Pathol,
16: 221-226.
WANG, P., AND L. LEU. 1972. Effects of insecticides and herbicides to the
fungi parasitic on nymph of grass cicada, Mogannia hebes Walker.
Rept. Taiwan Sugar Exp. Stn. No. 55: 103-109.
WARTENBERG, H., AND K. FREUND. 1961. Der Konservierungseffekt Anti-
biotischer Mikroorganismen an Konidien von Beauveria bassiana
(Bals.) Vuill. Zentrabl. Bakteriol. Parasitenk. Infekt. Abt. 2. 114:
718-724.


416


September, 1985











Bullock: Citrus Weevil Symposium


POTENTIAL FOR CONTROLLING CITRUS ROOT
WEEVIL LARVAE AND ADULTS WITH CHEMICALS

R. C. BULLOCK
University of Florida, IFAS
Agricultural Research & Education Center
P. O. Box 248, Fort Pierce, Florida 33454

ABSTRACT
Larvae of 5 weevil species attack the roots of citrus trees in Florida.
Since 1932, insecticides have been evaluated and recommended for control
of the soil-inhabiting larvae as well as foliage-feeding adults of this weevil
complex whose members include Diaprepes abbreviatus L., Pachnaeus litus
(Germar), P. opalus (Olivier), Pantomorus cervinus (Boheman), and
Artipus floridanus Horn. At the present time, no chemical compound is
available that has sufficient persistence as a foliar spray or soil treatment
to provide a Florida citrus grower with season-long control.

RESUME
Larvas de 5 species de gorgojos atacan las races de arboles citricos en
la Florida. Desde 1932 se han evaluado y recomendado insecticides para
controlar larvas que habitan en la tierra, lo mismo que adults que se
alimentan del follaje, el grupo de gorgojos cuyos miembros incluyen a
Diaprepes abbreviatus L., Pachneous litus (Germar), P. opalus (Olivier),
Pantomorus cervinus (Boehman), Artipus floridanus Horn. Actualmente
no hay ningin compuesto quimico que sea suficientemente persistent como
rociador de follaje o para tratar los suelos, y proveer control durante toda
la temporada al agricultor.



Watson and Berger (1932) published the first recommendation for
control of a citrus root weevil in Florida. They suggested poisoning adult
Pachnaeus litus (Germar) by spraying trees with a fluosilicate. Cryolite
and parathion were evaluated by Wolfenbarger (1952).
Foliar sprays have continued to be part of the control program for
these insects as well as the Fuller rose beetle (FRB) Pantomorus cervinus
(Boheman) (Bullock 1965, Dickson 1950, Elmer 1960, King 1958) that
King (1958) reported as a pest of Florida citrus and Diaprepes abbreviatus
L. (Bullock 1971, Herbaugh 1978, Schroeder & Lyons 1976, Wong et al.
1975a), detected in 1964 at Apopka, Florida.
Some of the early problems in pesticide screening arose from the
investigators' attempts to evaluate adult populations quantitatively in
field tests by shaking limbs or dislodging the adults onto ground cloths
(Elmer 1960, King 1958, Wolfenbarger 1952) or by searching trees for
specified lengths of time (Elmer 1960). It was difficult for these research-
ers to determine whether live weevils had survived exposure to spray resi-
dues or had just arrived in the tree. Measurements of efficacy became more
exact when adults were caged on treated foliage (Bullock 1971, Elmer
1960).
During the past 25 years, the insecticides and acaricides appearing in
the "Spray & Dust Schedule" and "Citrus Spray Guide" have been screened


417










418 Florida Entomologist 68 (3) September, 1985

against one or more of the members of the weevil complex. Other com-
pounds, registered for use on citrus but not necessarily recommended in
these publications, were also tested as well as promising compounds as
yet unregistered (Bullock 1965, 1971a, 1971b, Collins et al. 1976, Har-
baugh 1978, Lovestrand & Beavers 1980, Schroeder et al. 1976, Schroeder
& Lyons 1976, Wong et al. 1975a). This screening program revealed that
compounds tested as dilute foliar sprays differed in efficacy against FRB
and Diaprepes. Duration of effectiveness seldom exceeded 7 days for any
compound tested at manufacturer's rates. Increasing the dosage or ap-
plication in concentrate sprays extended the period of effectiveness to at
least 4 weeks (Schroeder et al. 1976, Wong et al. 1975b).
No material had sufficient persistence to permit a Florida grower, wish-
ing to employ foliar spraying as his sole method of adult weevil control,
to realize success with a single application. Protection of attractive, young,
expanding flush was not feasible since continued leaf expansion, as well
as emergence of subsequent flushes, generated new leaf area lacking toxic
residues. To control adults, multiple applications were deemed necessary.
This procedure failed to provide adequate control of Diaprepes in one
Apopka grove and resulted in destruction of many beneficial insects that
had flourished in the infested grove prior to the eradication attempt
(Collins et al. 1976).
Treatment of soil for control with insecticides effective against larval
stages offers a different approach that spares certain beneficial and
eliminates the spectre of environmental contamination from spray drift.
Control of soil-inhabiting grubs was initiated by Barrow in 1921 vs.
Diaprepes sp. with paradichlorobenzene and was continued against that
genus by Wolcott (1951) in Puerto Rico and by King (1958) in Florida vs.
FRB with chlorinated hydrocarbons. Even though dieldrin and aldrin
were the recommended insecticides used in the Florida program from
1958 until 1975, 59 candidate insecticides have been screened in field tests
since 1963 to find suitable substitutes for use in a soil treatment pro-
gram (Table 1). No material will provide control with a single applica-
tion. None are sufficiently persistent to last a growing season or even
the 3-month span of the weevil with the shortest life cycle: the little leaf
notcher (LLN), A. floridanus.
Two of the pesticides listed in the "Florida Citrus Spray Guide 1984"
will provide complete kill: the soil fumigants Soilbrom (EDB) and Telon
II (1, 3-dichloropropene). Both are effective eradicants that have been
used in land preparation and nematode barriers. Both materials, when
chiselled-in commercially or injected experimentally were lethal to buried
FRB and LLN larvae.
Using Wylie's (1956) Drosophila technique, bioassay of dieldrin- and
aldrin-treated grove soils during the 1960's at Ft. Pierce revealed that
those compounds were acting as weevil adulticides. Being nearly insoluble
in water, they remained where they were placed, i.e., within the top inch
when broadcast applied or at whatever depth a disk or mechanical hoe was
set when 'incorporating' the material. The efficacy of both compounds,
measured by failure of weevil emergence, was mistakenly attributed to
larval mortality although, under Indian River area conditions, it was
actually death of adults when they commenced passage through the toxic













TABLE 1. LIST


Bullock: Citrus Weevil Symposium

OF CHEMICALS TESTED AS SOIL INSECTICIDES.


Year(s)
Tested


Abate 2 SG
Agnape GF-35
Akton 10G
Altosid SR-10
Amaze 15G
Baygon 5G
Bay 25141 (see
Dasanit)
Bay 37289 10G
Bay 77488 5G
Bay 78182 1G, 5G
Bay 88941 10G
Bux 10G
Carbaryl 20G
CGA 12223 10G

Chevron 5305 10G
Chlordane 10G
Counter 15G
Dasanit 5G
Diazinon 5G
*Dimefex 10%G
DS-15647 10G
duPont 1179 5G,
95WS
Dursban 10G
*Dyfonate 10G
EDB (Soilbrom)
FBC-34570
Ficam 10G, 76W
FMC-35110 15G
Furadan 10G
GC-4072 10G
Geigy GS-13005 5G
Guthion 10G
HCS-3260 10G
Heptachlor


1976
1966
1965,71
1984
1979-81
1967-8


1965
1967
1967-8
1970
1966, 70-1
1970
1976-7, 79,
82-3
1968, 70
1970-1
1976
1964-5
1963-4
1980
1975
1966, 68

1971
1979
1982
1984
1982-4
1979-80
1966,70-1
1964-5
1971
1963-4
1971-2, 75-6
1957


*HLR-RO-13-42175G

ICI-PP211 10G
Kepone 5G
Landrin 15G
Lorsban 15G
(see Dursban)
*MAAG RO-15-
6510 500EC
MAT-4016 10G
Methyl-ethyl
Guthion 10G
NAK-1420 1G
Nemacur 15G
Nemagon 8.6EC
NIA-10242 (see
Furadan)
Morton EP-316 2G
Oncol 5G, 20E
Ortho-5353 (see
Bux)
Ortho-11775 10G
Padan 10G
Phosvel 5G
Shell SD-9098
(see Akton)
SD-41706 10G
Sta-thion 10G
Stauffer N-2790 5G
Supracide 2E
TDE 5G
Thiodan 5G
Temik 15G
UC-54229 100S
UC-57193 4E
UC-67546 75W
Vydate 10G, 2L


*Evaluated only at CREC.

barrier at the soil surface during exodus. Nigg et al. (1979) reported a
similar placement for chlordane applied to an Indian River area soil.
We realize now that aldrin, chlordane, and many other soil-applied
insecticides are toxic to neonate larvae dropping to the soil to enter the
ground. The survival of neonate larvae in treated soils was first investi-
gated in Florida by Norman et al. (1974) at the USDA laboratory in
Orlando. With a different technique, Jones and Schroeder (1984) and
Schroeder and Sutton (1978) revealed that the maximum period of accept-
able control (80% mortality) does not exceed 8 weeks in the sandy soils


419


Year(s)
Tested


1979

1972
1966
1980-4
1979-83

1984

1979

1963
1979, 80
1975-6
1968


1967
1983


1970
1971
1976


1976
1967
1966
1972
1966
1958
1976
1980
1980
1980
1972,77-8,
80-3










420 Florida Entomologist 68 (3) September, 1985

used in their assay vs. D. abbreviatus. Assays of 4 weeks duration con-
ducted by Brooks at CREC Lake Alfred with soils prepared in the labora-
tory confirmed the activity of the same insecticides against P. opalus, P.
litus, and P. cervinus. Bioassay of field soils one year after treatment re-
vealed that effectiveness was reduced by over one half.
The key factor influencing the effectiveness of an insecticide in soil is
the length of time it will remain biologically active. Harris (1972) lists
a number of factors that influence this biological activity: soil type, organic
content, soil moisture, and temperature. The Manatee, Oldsmar, Parkwood,
Pompano, and Sunniland soils of the east coast of Florida are all sandy
with organic content of less than 2% and little clay. The activity of
carbamates, organophosphates, and organo-chlorines are inversely pro-
portional to the organic matter content in moist soil, so our Florida sands
should provide an excellent environment in which to evaluate activity.
Perhaps the most important thing we do in our testing program is to
apply our materials to moist soils. We apply at least a 1/2-acre inch of
water to the plots during treatment application. This creates the best
opportunity for a candidate to perform well. Moisture 'dissolves' the toxicant
off the granular carrier. Volatilization requires soil moisture and if
volatilization diminishes the effectiveness of a toxicant through loss of con-
centration in the soil, but the gas phase is toxic to the pest, then a moist
soil will enhance the efficacy of the compound.
Those compounds that are water soluble and possess low partition co-
efficients require moist soil to move to the arena where they will be most
effective. For example, if larvae are distributed to a 12-inch depth, the
toxicant should be distributed evenly throughout the profile to come in
contact with the larvae.
Heat is absorbed or surrendered more rapidly in wet soil. Annual
fluctuations in temperature at the 6-inch depth in Parkwood soil in the
Indian River area swing from 59 to 750F and 63 to 820F with a mean
of 68.60F in shade and 740F in unshaded soil, respectively (DuCharme
1971). Thermolabile compounds would have to be incorporated to depths
that would prevent destruction by high temperatures.
Chemical and microbial degradation and volatilization are all tempera-
ture-dependent activities contributing to dissipation of residues. Although
ground cover moderates soil temperature (soil temperatures are higher
in bare soils), ground cover also increases soil moisture loss through
transpiration. Presence of dew on ground cover interferes with application
since granules will adhere to the wet plants and fail to reach the soil. The
problem with ground cover is much less important in mature groves where
the tree canopy has shaded out the area from trunk to drip line.
Ground litter is a problem. In two experiments at Indian Summer
Grove in St. Lucie County during 1979 and 1981 comparing the application
of larvicides to clean and 'littered' soil surfaces with a tractor-mounted
herbicide boom, significantly more FRB adults survived emergence through
litter-covered soil treated with chlorpyrifos at 2.75 lb AI/A in 69 GPA
spray and oxamyl at 10 lbs AI/A in 50 GPA than survived treatments on
litter-free soil.
Soil treatment may interfere with predation of neonate larvae on the
soil surface. Arboreal predators would be unaffected, but some of the
predators on the grove floor identified by Buren & Whitcomb (1978),










Bullock: Citrus Weevil Symposium 421

Richman et al. (1982) and Whitcomb et al. (1982) could be eliminated
from the 'drop' zone. These might be temporary disruptions because re-
colonization by foragers could occur from neighboring untreated areas of
soil as soon as toxic residues fell below lethal levels.
On two occasions, the ant-lion Myrmeleon crudelis Walker was success-
fully constructing craters in the soil of each treatment except chlorpyrifos
by July, one month after treatment. In that 1979 test, at Rangeline Grove
#6 in Vero Beach, active craters were never found in chlorpyrifos-treated
soil but occurred in aldrin, carbosulfan, isofenphos, isozophos, NAK-1420,
and MAT-4016 soils. In 1980, adult ant-lions emerged during September
from all treated soils except aldrin and NAK-1420 appearing in traps over
soils treated with oxamyl, chlorpyrifos, isofenphos, and trimethacarb. Ant
colonies became established during June, 1979 in all treatments except
isozophos and chlorpyrifos. Colonies were encountered during July in the
isozophos treated soil but not until November in chlorpyrifos soil.
With a choice of compounds limited to the non-persistent pesticides now
favored by government regulators, there may be little danger that non-
target grove fauna will be permanently eliminated. Yet, to fully under-
stand the influence an applied chemical has on the environment, the effect
on non-target species should be investigated.
We have applied chemicals to foliage for control of weevil stages oc-
curring in the tree canopy and treated the surface of grove soil for control
of stages inhabiting that medium. Another approach is to incorporate pro-
tectants in the planting hole at the time of planting. This is being current-
ly investigated and may be a technique to prevent destruction of young
plantings being established in infested soils.

CONCLUSION
The potential for controlling adults and larvae of the citrus root weevil
complex with the available non-persistant chemicals is not promising.
The research program has identified compounds that are effective as foliar
sprays against other citrus pests as well as weevils When these compounds
are used for their primary purpose, they kill weevils as well and are an
added benefit to the grower if applications coincide with periods of peak
weevil emergence.
The research program has also identified several compounds that have
shown efficacy vs. soil inhabiting stages of the weevils. Two of these, oxamyl
and chlorpyrifos, have been available recently but only chlorpyrifos has
been extensively used.
An annual program that combined a single foliar spray and a soil treat-
ment timed to disrupt the adult life cycle as well as larval reentry during
the species peak emergence period would contribute to population reduction
and grower relief but fail to provide year-long control.
Florida Agric. Expt. Sta. Journal Ser. No. 6324.

LITERATURE CITED
BARROW, E. H. 1924. White grubs, Lachnosterna sp., and larvae of the
weevil root borer, Diaprepes spengleri L., attacking sugar cane in
the quanica District of Puerto Rico, and methods practiced for
controlling them. J. Dept. Agric. Puerto Rico 8: 22-6.










Florida Entomologist 68(3)


September, 1985


BULLOCK, R. C. 1965. Effectiveness of foliar sprays for control of Fuller
rose beetle on Florida citrus. Florida Entomol. 48: 159-61.
BULLOCK, R. C. 1971a. Effectiveness of foliar sprays for control of
Diaprepes abbreviatus L. on Florida citrus. Trop. Agric. (Trin.)
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BULLOCK, R. C. 1971b. Foliar sprays for control of the Fuller rose beetle,
Pantomorus cervinus (Boh.). 1971 Ann. Res. Rpt., IFAS, Univ. of
Florida, Gainesville: 218.
BUREN, W. F. AND W. H. WHITCOMB. 1978. Ants of citrus: some con-
siderations. Proc. Int. Soc. Citriculture 2: 406-7.
COLLINS, H. L., C. L. MANGUM AND D. E. HENDRICKS. 1976. Evaluation
of foliar sprays for control of adult Diaprepes abbreviatus L. on
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DUCHARME, E. P. 1971. Soil temperatures in Florida citrus groves.
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ELMER, H. S. 1960. Evaluation of insecticides for control of the Fuller
rose beetle on citrus in California. J. Econ. Entomol. 53: 164-5.
HARRIS, C. R. 1972. Factors influencing the effectiveness of soil insecti-
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secticide & Acaricide Tests 4: 37.
JONES, I. F. AND W. J. SCHROEDER. 1984. Citrus, D. abbreviatus control,
Plymouth, Florida, 1982. Insecticide & Acaricide Tests 9: 67.
KING, J. R. 1958. Occurrence, distribution and control of Fuller's rose
beetle in Florida citrus groves. Florida State Hort. Soc. Proc. 71:
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LOVESTRAND, S. A. AND J. B. BEAVERS. 1980. Effect of Diflubenzuron on
four species of weevils attacking citrus in Florida. Florida Entomol.
65: 112-15.
NIGG, H. W., R. F. BROOKS AND R. C. BULLOCK. 1979. Chlordane residues
in Florida citrus soils. Florida Entomol. 62(1): 54-8.
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RICHMAN, D. B., W. H. WHITCOMB AND W. F. BUREN. 1982. Predators of
Diaprepes abbreviatus (Coleoptera: Curculionidae) in Florida and
Puerto Rico citrus groves. Florida Entomol. 66: 215-21.
SCHROEDER, W. J., J. B. BEAVERS, R. A. SUTTON AND A. G. SELHIME. 1976.
Ovicidal effect of Thompson-Hayward TH 6040 in Diaprepes abbrevi-
atus on citrus in Florida. J. Econ. Entomol. 69(6): 780-2.
SCHROEDER, W. J. AND D. J. LYONS. 1976. Citrus, D. abbreviatus control,
Plymouth, Fla. Insecticide & Acaricide Tests 2:41.
SCHROEDER, W. J. AND R. A. SUTTON. 1978. Citrus, D. abbreviatus control,
Plymouth, Florida, 1975. Insect & Acaricide Tests 3: 54.
WATSON, J. R. AND E. W. BERGER. 1932. Citrus insects and their control.
Fla. Agric. Ext. Bull. 67. Univ. of Fla., Gainesville, Florida.
WHITCOMB, W. H., T. R. GOWAN AND W. F. BUREN. 1982. Predators of
Diaprepes abbreviatus (Coleoptera: Curculionidae) larvae. Florida
Entomol. 65: 150-8.
WOLCOTT, G. N. 1951. Control inhabiting grubs of Puerto Rico. J. Econ.
Entomol. 44: 58-60.
WOLFENBARGER, D. 0. 1952. Some notes on the citrus root weevil. Florida
Entomol. 35: 139-40.
WONG, T. T. Y., J. B. BEAVERS, R. A. SUTTON AND P. A. NORMAN. 1975a.
Field tests of insecticides for control of adult Diaprepes abbreviatus


422










Bullock: Citrus Weevil Symposium 423

on citrus. J. Econ. Entomol. 68: 119-21.
WONG, T. T. Y., R. A. SUTTON, J. B. BEAVERS AND P. A. NORMAN. 1976b.
Diaprepes abbreviatus control on citrus foliage with carbaryl. J.
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WYLIE, W. D. 1956. Determination of insecticide residues in soil by using
Drosophila. J. Econ. Entomol. 49: 38-40.










Florida Entomologist 68 (3)


A NEW SPECIES OF THRAULUS (EPHEMEROPTERA:
LEPTOPHLEBIIDAE: ATALOPHLEBIINAE) FROM
SOUTHERN INDIA

PETER M. GRANT
Department of Entomology, Florida A&M University, Tallahassee,
FL 32307, and Department of Biological Sciences, Florida
State University, Tallahassee, 32306, USA
AND
K. G. SIVARAMAKRISHNAN
Department of Zoology, Madura College, Madurai 625011, Tamil
Nadu, India

ABSTRACT
Thraulus gopalani, n. sp., is described from specimens collected in
southern India. Descriptions are provided for the male imago, female
subimago, and nymph.

RESUME
Se describe Thraulus gopalini, n. sp., de especimenes colectados en el sur
de la India. Se proven descripciones del imago macho, del subimago hembra,
y de la ninfa.


The genus Thraulus (Ephemeroptera: Leptophlebiidae) is widespread
throughout the Eastern Hemisphere, being found in Europe, Africa,
India, southeastern Asia, northern Australia and the Indo-West Pacific. Of
its 11 described species only one, T. semicastaneus (Gillies), was previously
known from India and was collected by Gillies (1951) near Pune, Maharash-
tra State.
One of us (KGS) recently collected specimens from southern India
that represent a new species of Thraulus. The following is a description
of the male imago, female subimago, and nymph of Thraulus gopalani,
n. sp.
A number in parentheses after a measurement or count indicates the
number of specimens examined. All measurements are in millimeters. For
the holotype, we have given the information on all labels; we have separated
the information given on different labels by a semicolon.

Thraulus gopalani Grant and Sivaramakrishnan, NEW SPECIES
Figs. 1-19

MALE IMAGO (in ethanol).-Length: body, 7.8 (1); fore wings, 6.8 (1).
HEAD (Figs. 1-3); Brownish yellow, posterior half of dorsal surface
washed evenly with dark brown, narrow dark brown bands outline antennal
sockets; 2 narrow dark brown bands extend from dorsomedial margin of
antennal socket: one extends to frontal longitudinal carina and the other
to anteromesal base of lateral ocelli; frontal margin dark brown; dorsal
longitudinal carina extends posteriorly from posteromesal corner of lateral
ocelli to 2/3 distance to posterior margin of head (Fig. 1), anterior half


424


September, 1985










Grant & Sivaramakrishnan: New Thraulus from India 425

of carina dark brown; posterior margin of head concave; mouthparts
washed heavily with black. Eyes (Fig. 1-3); Upper portion light orange;
suboval in dorsal view (Fig. 1), dorsal surface rounded (Figs. 2-3);
separated dorsally by ca. 1/5 width of upper portion of an eye (Figs.
1-2). Lower portion black. Ocelli (Figs. 1-2) with lens clear to opaque
white, wide dark brown band outlines base of lens; lateral ocelli with
dorsal surface basal to dark brown band brownish yellow; contiguous with
upper portion of eyes laterally (Fig. 1); carina defines mesal edge of
each ocellus, anterior end of carinae thickened slightly forming a small
mesally projecting process; carinae intersect dorsal longitudinal carina at
most anterior point (Fig. 1). Antennae yellow, scape with dark brown
macula on anterior surface, basal 2/3 of pedicel dark brown.
THORAX: Pronotum brownish yellow, brown macula in center of each
lateral half, margins dark brown. Mesonotum light brown, carinae brown,
posterior half of scutellum brown. Metanotum brownish yellow. Pleura and
stern light brown, washed unevenly with dark brown, carinae dark brown.
Fore wings (Fig. 4) hyaline, narrow dark brown band between costal brace
and apex of vein A2, membrane basal to band washed evenly with brown;
small brown macula on bullae of veins Sc and R,; oblique cross vein be-
tween veins R4,5 and MA, adjacent to vein MA fork; length 3.2 width (1).
Hind wings (Figs. 5-6) with basal 1/2 brown, apical 1/2 hyaline, axillary
area brownish yellow; apex of costal projection pointed, sides of projection
almost orthogonal; apex of projection located 0.6-0.7 distance from base
to apex of wings (1); apex of wings bluntly rounded; length 1.6 width
(1). Fore legs: Coxae dark brown, carinae darker. Trochanters brownish
yellow, mesal surface and apex dark brown. Femora brown. Tibiae with
offset basal end light brown, apical 1/4 dark brown, intervening portion
white. Tarsi white. Claws white, dissimilar: one blunt, pad-like; one
apically hooked. Middle legs: [broken off and missing]. Hind legs as in fore
legs except for: Trochanters with lateral half dark brown, mesal half
yellow. Femora dark brown, basal 3/10 and apex yellow. Tibiae with
apical 1/7 dark brown, outer margin narrowly lined with dark brown,
remaining portion and extreme apex white. Claws as in Fig. 7.
ABDOMEN: Terga washed uniformly with brown, posterior margin of all
terga dark brown; anterior margin of tergum 1 dark brown, undulating;
terga 2-7 with a narrow light yellow median longitudinal streak extending
posteriorly from anterior margin to 2/3 segment length; terga 2-9 with
shorter and wider submedian streaks; lateral folds dark brown; spiracular
areas and anterolateral corners of each tergum immediately above lateral
folds light brownish yellow. Sternum 1 brown; anterior, anterolateral, and
posterior margins light brownish yellow; sterna 2-7 light brownish yellow,
with large median and lateral maculae; maculae widen on posterior sterna
and unite on sternum 7; sternum 8 brown, anterior margin light yellow;
sternum 9 brown; posterolateral corners of sterna 1-8 dark brown. Caudal
filaments white, articulations dark brown.
GENITALIA (Figs. 8-9): Styliger plate (Fig. 8) brown; rounded mesal
emargination on posterior margin. Forceps (Fig. 8) with wide basal 1/2 of
segment 1 brown, apical 1/2 and segments 2 and 3 washed evenly with
dark brown; segment 1 apical width 0.3 basal width (1); mesal margin
of basal 1/2 of segment 1 without spine-like setae; mesal margin of apical
half of segment 1 and segments 2 and 3 densely lined with small spine-like










Florida, Entomologist 68 (3)


5


k
ct:

E p
i
j 4
a i


1, i

i'


10


Figs. 1-11, Thraulus gopalani, n. sp. Figs. 1-9, male imago. 1. Dorsal view
of head. 2. Frontal view of head. 3. Lateral view of head. 4. Fore wing. 5.
Hind wing drawn to scale of fore wing. 6. Hind wing, enlarged. 7. Hind
claw. 8. Ventral view of genitalia. 9. Dorsal surface of left penis. Figs. 10-11,
female subimago. 10. Teratological ninth sternum. 11. Probable normal
shape of ninth sternum.

setae. Penes (Figs. 8-9) light brown; long, narrow, tapering to a mesally
projecting beak-like apex (Fig. 9); mesal margin slightly concave in
middle 1/3; basal 1/2 of lateral margins straight, apical 1/2 gradually
converges mesally; contiguous along most of mesal length but not fused;


September, 1985


426










Grant & Sivaramakrishnan: New Thraulus from India 427

each penis with 6 spine-like dorsal setae (Fig. 9), setae arranged in a
longitudinal row and project laterally.
MALE SUBIMAGO.-Unknown.
FEMALE IMAGO.-Unknown.
FEMALE SUBIMAGO (in ethanol).-Length: body, 8.3 (1); fore wings, 8.9-
9.0 (1). Characters as in male imago except for the following.
HEAD: Light brownish yellow, washed unevenly with dark brown,
carinae dark brown; a large dark brown macula on posterior margin mesal
to each eye; dorsal longitudinal carina extends from center of head to
posterior margin; posterior margin undulate, convexly rounded mesally.
Eyes separated by ca. 5.5 width of an eye. Lateral ocelli with apical 1/2 clear
to opaque white, basal 1/2 dark brown; 2 submedian parallel longitudinal
carinae between ocelli, anterior ends of carinae bifurcate; 1 branch inter-
sects edge of antennal socket and the other intersects base of median ocellus,
posterior ends of carinae converge and intersect dorsal longitudinal carina
at its most anterior point.
THORAX: Mesonotum light brownish yellow; anterior bulbous portion
and scutal humps brown; long oval light brown area encompasses each
inner parapsidal suture; notal furrow dark brown anterior to wing bases;
outer parapsidal suture posterior to wing bases brown; posterior 1/2 of
scutellum dark brown. Fore wings with membrane cloudy white; small
dark brown macula on bulla of vein Sc, smaller macula on bulla of veins
R, and R.J5. Fore legs: Trochanters dark brown, anterior surface light
brown; [remaining leg segments broken off and missing]. Middle and hind
legs: Trochanters light brown, anterior and posterior surfaces dark brown;
[remaining leg segments broken off and missing].
ABDOMEN (Figs. 10-11) : Tergal coloration as in male imago but lighter
brown; apex of spine on posterolateral corners of tergum 9 extends more
posteriorly than posterior margin of tergum 9. Sternum 7 with straight
posterior margin; posterolateral corners of sternum 8 converge posteriorly
(Fig. 10); apex of sternum 9 rounded but asymmetrical (Fig. 10).

NYMPH (in alcohol).--Size range of specimens examined: head width, ca.
1.0-1.5 (4); body length, ca. 5.6-8.5 (4).
HEAD: Brownish yellow; washed evenly with brown between eyes and
ocelli, around antennal sockets, and anterior margin of clypeus; posterior
margin convexly rounded. Eyes: Upper portion (males) reddish brown,
oval. Lower portion black; eyes of female separated by ca. 6 times width
of an eye (1). Antennae with scape, pedicel, and base of flagellum light
yellow, middle 1/3 of pedicel washed lightly with brown. Mouthparts (Figs.
12-16) brownish yellow, washed evenly with brown especially on lateral
margins: Labrum (Figs. 12-13) with a rectangular mesal emargination
anteriorly (Fig. 13); width 2.6 length (1); 2 rows of dorsal setae not
parallel (Fig. 12); inner row almost straight, situated just anterior to
center of labrum, ca. 0.5 width of labrum (2) ; outer row curved, 0.4
width of labrum (2) ; lateral margins with few setae. Mandibles (Fig. 14)
with lateral margin smoothly rounded; lateral setae sparse, thin clump
near middle of lateral margin, thinning posteriorly (Fig. 14). Maxillae with
width of apical setal row 0.8-0.9 width of galealacinia (2); width of sub-
apical setal row 0.4 width of galealacinia (2); 18-23 pectinate setae (2);











428 Florida Entomologist 68 (3) September, 1985

beak-like protuberance on mesal margin at end of subapical row. Labial
palpi (Figs. 15-16) with inner and outer margins of segment 1 washed
evenly with brown, a brown macula midway between base of palpi on
ventral surface; ventrally paraglossae with long setae on mesal margin,
row of setae extends laterally from mesal setal patch (Fig. 15); segment
3 with row of long thin lateral setae and 6-7 large dorsal setae (Fig. 16).
THORAX: Pronotum brownish yellow, margins dark brown, 2 dark
brown submedian maculae in center and 1 dark brown median macula on
posterior margin. Mesonotum brownish yellow, lateral and posterior margins
washed unevenly with dark brown; fore wing pads with basal transverse
dark brown band. Metanotum brownish yellow, washed unevenly with dark
brown; basal half of hind wing pads dark brown. Pleura and stern
brownish yellow, washed unevenly with brown. Fore legs: Coxae brownish
yellow, washed evenly with dark brown; lateral margin lined with setae.
Trochanters with anterior and posterior surfaces dark brown, lateral and
mesal surfaces brownish yellow; with an apical row and a shorter sub-
apical row of setae. Femora with basal 1/2 white, apical 1/2 washed
evenly with dark brown. Tibiae light brownish yellow, apex washed
evenly with dark brown; inner margin flattened, densely covered with
short setae. Tarsi light brownish yellow. Claws (Fig. 17) with 10-13
denticles; denticles decrease in size apically. Middle legs as in fore legs ex-
cept: Trochanters with apical row of setae only. Tibiae with inner margin
covered sparsely with very short, tiny setae. Hind legs as in middle legs
except: Tibiae densely covered with short setae, base and lateral margin
with few setae.
ABDOMEN: Terga brownish yellow, washed evenly with dark brown,
washings heavier laterally and on posterior margins; terga 2-9 with a
brownish yellow longitudinal mesal stripe; terga 2-8 with 2 submedian
brownish yellow spots on anterior margins; spiracular areas white. Sterna
light yellow; sterna 1-8 with paired sublateral maculae; posterior margin
of sternum 8 and all of sternum 9 washed evenly with dark brown; mesal
margin of posterolateral spines on segments 8 and 9 dark brown; lateral
portions of posterior margins narrowly dark brown. Gills (Figs. 18-19)
washed evenly with dark brown: gills on abdominal segment 1 with a long
lanceolate dorsal lamella and an oval ventral lamella (Fig. 18); margin
of apical 2/3 of lamella lined with fimbriae; lamellar length ca. 3 times
width; lengths of fimbriae increase apically. Gills on abdominal segments
2-7 with oval dorsal and ventral lamellae; lamellae as in gills on abdominal
segment 1 except fimbriae cover all margins except extreme basal portion
(Fig. 19). Caudal filaments brown basally, fading to light brown towards
apex.
REMARKS.-Imagos of T. gopalani can be distinguished from all other de-
scribed species of Thraulus by the following combination of characters: (1)
the upper portion of the male eyes are separated (Figs. 1-2); (2) fore
wings have a narrow dark brown band between the costal brace and vein
A., (Fig. 4); (3) the bullae of veins Sc and R, have a small dark brown
macula (Fig. 4); (4) the basal 1/2 of the hind wings is brown and the
apex is bluntly rounded (Fig. 6); and (5) each penis has a single longi-
tudinal row of spine-like setae on its dorsal surface (Fig. 9).
Nymphs of T. gopalani can be distinguished from all other described
species of Thraulus (with known nymphal stage) by the following com-









Grant & Sivaramakrishnan: New Thraulus from India 429





12










14 15

















13. Anterior emargination of labrum, enlarged. 14. Mandible, lateral setal
pattern. 15. Left paraglossal setal pattern, ventral view. 16. Third segment
of labial palp, dorsal surface. 17. Fore claw. 18. First abdominal gill. 19.
Fourth abdominal gill.
bination of characters: (1) the labrum has a rectangular mesal emargina-
tion anteriorly (Fig. 13) ; (2) the inner row of the dorsal setae is located
just anterior to the middle of the labrum (Fig. 12); (3) the outer margin
of the mandibles lacks a tuft of setae at the base of the incisors (Fig. 14);m
(4) the denticles on the claws decrease in size apically (Fig. 17); and (5)
the abdominal gills on segment 1 have a dorsal lanceolate portion and a
ventral fimbriate lamellar portion (Fig. 18), and the abdominal gills on
segments 2-7 have dorsal and ventral fimbriate lamellar portions (Fig. 19).
Thraulus gopalani does not appear to be closely allied with any one
of the other described species of Thraulus. In the images it shares the
character of separated male eyes with T. bells Eaton and T. turbinatus










Florida, Entomologist 68 (3)


September, 1985


(Ulmer), claw shape with T. fasciatus (Kimmins), dorsal spine-like penile
setae with T. turbinatus and T. semicastaneus, and hind wing shape and
coloration with T. duliti (Demoulin). In the nymphs it shares the character
of mandibular setal pattern with T. bellus, claw shape with T. torrentis
(Gillies), and shape of the first pair of abdominal gills with T. torrentis
and T. fasciatus. Phylogenetic relationships among the species of Thraulus
are presently being studied as part of a systematic revision of the Thraulus-
group genera by the senior author.
Imagos of T. gopalani key to couplet 3 (T. torrentis and T. duliti) in
Peters and Tsui (1972) but can be distinguished from those 2 species by:
(1) the metathoracic tibiae being dark brown on the apical 1/7 with the
remaining portion and extreme apex white and (2) the upper portion of
the eyes are not contiguous dorsally (Figs. 1-2). Nymphs of T. gopalani
key to T. torrentis in Peters and Tsui (1972) but can be separated from
T. torrentis by: (1) the labrum having a rectangular emargination an-
teriorly (Fig. 13) and (2) the outer margin of the mandibles lacks a tuft
of setae at the base of the incisors (Fig. 14).
The only male imaginal fore claw available for examination is damaged.
Comparison of the fore and hind claws indicates that at least the shape
of the outer margin of the hooked claw and the hook itself are similar.
On the genitalia slide of the male imago the forceps and styliger plate
are mounted with the dorsal surface up. The penes are not attached to the
rest of the genitalia but are mounted superimposed over the styliger plate.
As the genitalia are oriented on the slide, the spine-like setae of the penes
appear to be on the ventral surface. Examination of the penes of T. semi-
castaneus from India, T. bishop Peters and Tsui from Malaysia, and T.
demoulini Peters and Tsui from Thailand indicates that all 3 species
have a row of spine-like setae only on the dorsal surface. We believe that
the penes of T. gopalani were inadvertently rotated during mounting and
that the spine-like setae do indeed occur on the dorsal surface.
The penes are divergent from one another on the slide, but a photo-
graph taken before the genitalia were permanently mounted shows that
the penes are naturally contiguous along most of their mesal length.
The station of the middle and hind nymphal tibiae are unique to this
species. The setae lining the inner margin of the middle tibiae are ex-
tremely reduced in length. The hind tibiae are densely covered with setae
except for the extreme base and the outer margin.
The ninth sternal apex of the female subimago and its final nymphal
instar exuviae is asymmetrical (Fig. 10). Two female nymphs from the
same locality were examined, and both had symmetrical ninth sterna. This
asymmetry is most likely a teratology; the typical shape is probably sym-
metrical, resembling Fig. 11.
The number of pectinate setae forming the subapical row on the maxil-
lae vary with a large female nymph having more (23) than a smaller
male (18-19). Larger nymphs of both sexes also have more denticles on
the claws.
There was only a slight indication that denticles were present on the
labrum.
Thraulus gopalani differs from the generic description given for Thraulus
by Peters and Edmunds (1970) in 3 respects: (1) the male imaginal eyes
are not contiguous, (2) the setal tuft on the outer mandibular margin


430










Grant & Sivaramakrishnan: New Thraulus from India 431

just basal to the incisors is lacking (cf. Peters and Edmunds 1970, their
Fig. 232), and (3) the denticles on the claws become progressively smaller
apically. This is the first time that spine-like setae on the dorsal surface
of the penes have been described for any species of Thraulus.
GEOGRAPHIC DISTRIBUTION.-Thraulus gopalani is known only from south-
ern Tamil Nadu State, India.
BIOLOGY.-Nymphs have been collected in March and December; adults
were reared from final instar nymphs collected in March. Nymphs inhabit
the underside of rocks in heavily silted side pools with a slow current.
ETYMOLOGY.-This species is named in honor of Prof. G. Gopalan, Madura
College, Madurai, for having been of great assistance to the junior author
on his field trips.
TYPE DATA.-Holotype male imago (in ethanol) with the following labels:
INDIA: Tamil Nadu State, Kottum Thalam, nr. Papanasam, Tamraparany
River, 54 km S Tenkasi, 250m, 20 III 1978, K. G. Sivaramakrishnan;
Thraulus gopalani, Grant and Sivaramakrishnan; holotype, Grant and
Sivaramakrishnan; wings on slide, KGS: 82#11:82-18; claw on slide (fore),
KGS:82#11:82-19; male genitalia on slide, KGS:82#11:82-20. This speci-
men is in fair condition: the upper portion of the eyes are collapsed; the
head, 2 caudal filaments, and a portion of the left mesopleuron are loose
in the microvial with the imago; and only 3 legs are present (1 fore leg).
Three microvials are in the holotype vial: one contains the imago, one
the left hind claw, and one the final nymphal instar and subimaginal
exuviae.
Paratypes (in ethanol): Female subimago (with its associated final
nymphal instar exuviae), same data as holotype. Three nymphs, same data
as holotype; mouthparts on slide: PMG-1984-THR33. One nymph, same
data as holotype but collected 10 XII 1982; mouthparts on slide: PMG-
1984-THR32, fore claw on slide: PMG-1984-THR31.
The holotype (with wings, fore claw, and male genitalia slides) and 3
nymphal paratypes (with mouthparts slides) are deposited in the collection
of the Entomology Institute, Loyola College, Madras, India. The female
subimaginal and 1 nymphal paratypes (with mouthparts and fore claw
slides of nymph) are deposited in the collection of Florida A&M University.
Adult and nymphal stages are associated by rearing.

ACKNOWLEDGMENTS

We would like to thank M. D. Hubbard, M. L. Pescador, W. L. Peters,
A. R. Soponis, and the two reviewers for their editorial comments; G. J.
Wibmer for translating the abstract into Spanish; J. G. Peters for assist-
ance with the illustrations; D. R. Strong for access to the word pro-
cessor; and G. C. Floersch for photographic services. This study was
supported by a research program (FLAX 79009) of CSRS/USDA to
Florida A&M University and a Sigma Xi Grant-in-Aid of Research to PMG.

REFERENCES CITED
GILLIES, M. T. 1951. Further notes on Ephemeroptera from India and
South East Asia. Proc. R. Ent. Soc. London, (B) 20: 121-130.









432 Florida Entomologist 68 (3) September, 1985

PETERS, W. L. AND G. F. EDMUNDS, JR. 1970. Revision of the generic
classification of the Eastern Hemisphere Leptophlebiidae (Epheme-
roptera). Pac. Ins. 12: 157-240.
PETERS, W. L. AND P. T. P. TSUI. 1972. New species of Thraulus from Asia
(Leptophlebiidae: Ephemeroptera). Orient. Ins. 6: 1-17.



SYSTEMATICS OF THE NEARCTIC GENUS PSEUDIRON
(EPHEMEROPTERA: HEPTAGENIIDAE:
PSEUDIRONINAE)

MANUEL L. PESCADOR
Dept. of Entomology and Structural Pest Control
Florida A&M University, Tallahassee, FL 32307

ABSTRACT
The genus Pseudiron is redescribed and the subimagos are described for
the first time. Pseudiron meridionalis Traver is synonymized with P.
centralis McDunnough leaving Pseudiron a monotypic genus. Pseudiron
centralis is redefined, and its biology, ecology, distribution, and geographic
variation in the Central United States and Canada is discussed.

RESUME
Se redescribe el g6nero Pseudiron meridionalis Traver y los subimagos
son descritos por primera vez. Se sinonimiza Pseudiron meridionalis Traver
con P. centralis McDunnough, lo que deja a Pseudiron como genero mono-
tipico. Se redefine Pseudiron centralis y se discute su biologia, eco-
logia, distribuci6n, y variaci6n geogrAfica en las parties centrales de Estados
Unidos, y en Canada.


McDunnough (1931) established the genus Pseudiron for P. centralis
based on female images. The nymph was first described and tentatively
referred to Pseudiron by Spieth (1938), and with additional specimens
available, Burks (1953) subsequently complemented the nymphal descrip-
tion and accepted Spieth's generic assignment of the nymph. The genus
has been assigned to various subfamilies and/or families. McDunnough
(1931) originally noted that the genus had typical heptageniid venation
and was close to Siphloplecton. Traver (in Needham, Traver and Hsu,
1935) assigned Pseudiron, along with Metretopus and Siphloplecton, to the
subfamily Metretopinae, while Lestage (1938) included Pseudiron and
Siphloplecton in Siphloplectonidae. Burks (1953) assigned Pseudiron to the
family Ametropidae (sic), in which he also included Metretopus and Siphlop-
lecton. Edmunds and Traver (1954) established the subfamily Pseudironinae
in Heptageniidae for Pseudiron. This arrangement has been uniformly fol-
lowed in subsequent classifications (Demoulin, 1958; Edmunds, et al., 1963;
Koss and Edmunds, 1974; Edmunds et al., 1976; Berner, 1978; and
McCafferty and Edmunds, 1979) and is based upon internal and external
morphology, and studies on the eggs.
Except for generic descriptions of the adult and nymph of Pseudiron










Pescador: Systematics of Pseudiron 433

by Edmunds et al. (1976), taxonomic accounts of the genus have been
limited. Collections of more specimens in recent years, including reared
adults, allows a more definitive description of the genus. Included herein
is a redescription of the genus based on the holotype, paratypes and series
of recently collected specimens from various localities throughout its geo-
graphic range.

MATERIALS AND METHODS

All measurements were made using a calibrated ocular micrometer
and are given to the nearest 0.5 mm. Leg measurements of male images
were as follows: the femora were measured from the apex of the trochanter
to the apex of the femur along the dorsal surface; the tibiae and tarsi
were measured from base to apex along the dorsal surface. Each of the
five tarsal segments were measured and numbered from one (basal) to
five (apical) and then arranged according to descending length as shown
in the generic description.
To determine fecundity, female images were dissected, and all eggs
were removed and counted under a dissecting microscope.
Localities, stages (N for nymph; A for adult which includes both
imago and subimago), and deposition of examined specimens are given in
the treatment to facilitate access to specimens for future reference. Ab-
breviations for depositories are as follows: University of Alberta (UA),
Canadian National Collection (CNC), Florida State Collection of Arthro-
pods (FSCA) [including Florida A&M University (FAMU)], Illinois
Natural History Survey (INHS), Purdue University (PU), and University
of Utah (UU).

Genus Pseudiron McDunnough

Pseudiron McDunnough, 1931:91; Traver, 1933:123; Traver, 1935:436;
Spieth, 1938:3; Burks, 1953:148; Berner, 1959:46; Edmunds, Allen and
Peters, 1963:13; Edmunds, Jensen, and Berner, 1976:208.
Species included: Pseudiron centralis McDunnough (=Pseudiron meri-
dionalis Traver).
Imago.-Length: 8 body 11-14 mm; 3 fore wings 12-14 mm; 2
body 11-15 mm; 9 fore wings 12-14 mm. Head: eyes separated dorsally by
width approximately 1.3x that of median ocellus, extend ventrally to frontal
margin; frontal margin not produced ventrally. Thorax: pronotum with
broad U-shaped posteromedian emargination; fore wing (Fig. 1) with
basal costal cross veins well developed, stigmatic cross veins anastomosed.
Hind wings (Fig. 2) with obtuse costal projection; 3-4 cubital intercalaries;
length 0.30-0.35x length of fore wings. Male fore leg; tibiae (3.2-3.5 mm)
0.75-0.85x length of femora; tarsi 1.5-1.7x length of femora, 2.0-2.4x length
of tibiae; tarsal segments in order of descending length: 2=3, 4, 1, 5; basal
tarsal segment 0.7-0.8 as long as segment 2. Hind legs: tibiae (2.0-2.3 mm)
0.45-0.55x length of femora; tarsi 0.6-0.7x length of femora, 1.25-1.3x
length of tibiae; tarsal segments in order of descending length: 1=2, 3=5,
4; basal tarsal segment fused or partially fused to tibiae. Claws (Fig. 4) on
all legs dissimilar, 1 blunt and pad-like, and 1 hooked with small opposing
hook. Male genitalia (Fig. 5): posterior margin of genital plate deeply
concave, distinctly produced at bases of forceps. Genital forceps four seg-









Florida Entomologist 68 (3)


September, 1985


mented; combined length of segments 3 and 4 approximately 0.66x length of
segment 2; segment 1 approximately 0.20-0.25x length of segment 2. Basal
half of penes fused, apical half widely divergent and rod-shaped (Fig. 5);
titillators absent. Cerci 2.0-2.4x length of body. Female ninth sternum with
shallow cleft at apex (Fig. 3).
Mature nymph.-Body length 11-16 mm. Head capsule subtriangular,
1.2-1.3x as wide as long; anterior and lateral margins convex, glabrous;
posterior margin straight; eyes not extending to posterolateral angle.
Mouthparts adapted for predation (Fig. 7-12). Labrum (Fig. 6) 0.5-0.6 as


*:j



N '


S .. 5 . :
Fig. 1-5. Pseudiron centralis. Fig. 1-2, 4-5. & imago: 1, fore wing; 2,
hind wing; 4, fore claw; 5, genitalia, ventral view. Fig. 3, 9th sternum of
imago.


434









Pescador: Systematics of Pseudiron


wide as head capsule, anterior margin with broad shallow U-shaped
median emargination, densely pilose. Mandible (Fig. 7, 8): outer incisor
stout, forked and serrate (Fig. 8); inner incisor smaller, basal half broad,
flared and with lateral serrations (Fig. 8); molar region reduced with
long pectinate spines (Fig. 8). Maxillae (Fig. 10, 11): galea-lacinia with
stout crown spines, one broadly serrate; long subapical and lateral spines;
palpi four-segmented; segments 1 and 2 subequal length; segment 3 ap-
proximately 0.20x length of segment 2, 0.45x length of segment 4; palpi
sparsely pilose; segment 3 flexible, somewhat membranous, not as sclero-
tized as other segments. Lingua of hypopharynx truncate (Fig. 9); greatly
reduced; superlinguae lobe-like with minute apical hairs (Fig. 9). Labium
(Fig. 12) with narrow deep V-shaped separation between glossae; glossae
distinctly broader than paraglossae; palpi two-segmented, segments sub-
equal in length; apical segment 0.20-0.25x as broad as basal segment.
Pronotum (Fig. 18) widest posterolaterally, greatly flared laterally with
prominent posterolateral projection extended beyond base of developing


K'


I'





-t' /rt^
Q ........___ 6-*_


,F


Fig. 6-12. Pseudiron centralis, mature nymph: 6, labrum; 7, left
mandible; 8, enlarged incisor and molar area of left mandible; 9, hypo-
pharynx; 10, left maxilla; 11, enlarged apex of galea-lacinia; 12, labium.
In Fig. 6, 9, 12, dorsum on left, venter on right.


435









Florida Entomologist 68 (3)


fore wing; deep rectangular median incision with thick hairs (Fig. 18);
anterior margin broad, U-shaped. Fore legs: femora with sparse minute
hairs on anterior (leading) margin, glabrous dorsally, posterior margin
fringed with long setae; tibiae, tarsi, and claws distinctly bowed; tibiae
with moderately long, sharp, pointed subapical spine, tibiae 0.6-0.65x length
of femora, 0.75-0.8x length of tibiae. Middle and hind legs: similar to fore
legs in armature; tibiae of hind leg 0.5-0.55x length of femora, tarsi 0.4-0.5x
length of femora, 0.7-0.8x length of tibiae. Claws (Fig. 13-16) long, slender
with prominent constriction at approximately 2/3 distance from base (Fig.
13, 15). Gills on abdominal segment 1 with lamella reduced to short slender
filament, fibrilliform portion well developed, longer than lamella; gills on
segments 2-7 (Fig. 17) with broad lamellae, lamellae tapered apically;
lamellae with slender filament arising from ventral surface approximately
1/3 distance from base (Fig. 17), fibrilliform portion well developed.
Abdomen: terga with short, thick posterior spines; segments 8-9 with
small acute posterolateral projection. Lateral margins of terminal filaments
and mesal margins of cerci densely setaceous; minute spines at articulation
of each segment.
Discussion.-The illustrations of three-segmented maxillary palpi of
Pseudiron by Spieth (1938) and Jensen (1972) are incorrect. The nymphs
have four segments of the maxillary palpi.
Pseudiron can be distinguished from all other genera of Heptageniidae


/
*

/


13


F


; ;


16


15


Fig. 13-16. Pseudiron centralis, nymphal claw. 13-14, Scanning electron
micrographs: 13, whole claw (35x); 14, enlarged constriction of claw
(190x). Photomicrographs: 15, whole claw (31x); 16, enlarged constriction
of claw (200x).


436


September, 1985









Pescador: Systematics of Pseudiron


Fig. 17-18. Pseudiron centralis, mature nymph. 17, abdominal gill 4; 18,
head and pronotum. Fig. 19, geographic distribution of P. centralis.

by the following combinations of characters. In the images: (1) male
eyes are separated dorsally by approximately 1.3x the width of the median
ocellus; (2) male fore tarsi are at least twice the length of fore tibiae; (3)
basal segment of hind tarsi are fused or partially fused to tibiae; (4)
frontal margin of head is not produced ventrally; and (5) apical halves
of penes are widely divergent and lack median titillators (Fig. 5). In the
nymph: (1) maxillary palpi are four-segmented (Fig. 10); (2) linguae
of hypopharynx are truncate and superlinguae are greatly reduced and
lobe-like (Fig. 9); (3) glossae are broader than paraglossae (Fig. 12);
(4) basal segment of labial palpi is at least four times as broad as the
apical segment (Fig. 12); (5) long, slender tarsal claws are equal to


437










438 Florida Entomologist 68 (3) September, 1985

or slightly longer than tarsi and are prominently constricted at approxi-
mately 2/3 distance from base (Fig. 14-16); and (6) lamellae of abdominal
gills 2-7 have a slender filament arising from the ventral surface at ap-
proximately 1/3 distance from the base (Fig. 17).


Pseudiron centralis McDunnough

Pseudiron centralis McDunnough 1931:91; Traver 1933:123; 1935:437;
Burks 1953:148; Berner 1959:46; 1977:23; Edmunds, Jensen and
Berner, 1976:210.
Pseudiron meridionalis Traver 1935:437; Berner, 1959:46; 1977:23; Peters
and Jones, 1973:246; Edmunds, Jensen, and Berner, 1976:210;
NEW SYNONYMY
Male imago (in alcohol). Length: body 11-14 mm; forewings 12-14 mm.
Eyes bluish black, greyish orange on live specimens. Head pale yellow.
Basal half of ocelli black, apical half white. Antennae pale yellow, scape
darker washed with brown. Thorax: pronotum yellow to light brown. Meso-
and metanota orange yellow to brown; margins, parapsidal furrows and
median of scutellum reddish brown to dark brown. Pleura pale yellow
with scattered amber-yellow or brown linings near base of wings and legs.
Pro- and metasterna pale to brownish yellow, apophyseal pits amber-yellow
to dark drown. Mesosternum yellow to dark brown, apophyseal pits amber-
yellow to dark brown. Legs: coxae pale yellow with black-brown mid-apical
marking. Femora yellow with median and apical dark brown bands. Tibiae
yellow, apex of fore tibiae reddish yellow. Tarsi pale yellow, dorsum of
tarsal joints including claws dark brown. Wings: membrane of fore wings
hyaline, translucent white between Rs and C; longitudinal and cross veins
dark brown, basal 1/2 of vein Sc brownish yellow. Membrane of hind
wings hyaline; longitudinal and cross veins light brown, basal 1/2 of vein
Rs darker. Abdomen: terga yellow to light brown, darker on terga 1 and
8-10, pale yellow to hyaline along lateral margins. Genitalia: forceps yellow
to light brown, dorsum of segmental joints dark brown. Caudal filaments
with base faintly tinged with yellow.
Female imago (dried and in alcohol). Length 11-15 mm; fore wings
12-14 mm. Head yellow with or without shades of amber-yellow or dark
brown. Color of antennae, ocelli and eyes as in male imago. Thorax: pro-
notum yellow to ruddy brown. Meso- and metanota yellow to light brown,
slightly darker along posterolateral areas; ridges on parapsidal furrows
and apex of metascutellum lined with brown. Pleura pale yellow, pleurites
thinly margined with dark yellow or brown. Sterna pale yellow, apophyseal
pits amber-yellow to light brown. Color and markings of legs as in male
imago except brown markings on coxae not as extensive. Wings: fore wings
as in male imago except longitudinal veins pale yellow, progressively darker
toward apex, and cross veins between veins C and R thickened and dark
shiny brown. Membrane of hind wings hyaline, longitudinal and cross
veins pale yellow except those between veins MA and C brown. Abdomen:
terga pale yellow, anterior margins of terga 2-7 dark brown. Sterna pale
yellow. Caudal filaments as in male imago.
Male and female subimago (in alcohol). Head color and markings,
eyes, ocelli and antennae as in imago. Thorax: nota color and markings as
in imago except lateral areas of scutellum dark smoky brown. Pleura and











Pescador: Systematics of Pseudiron 439

sterna as in imago except mesofurcasternite slightly more extensive. Color
and markings as in imago except femoral banding when present not as
pronounced; tarsi smoky yellow to light brown. Wings: membrane of fore
and hind wings translucent greyish white, apical third faintly shaded with
brown; apical margins with short hairs; longitudinal and cross veins pale
yellow except cross veins in apical third of fore wings brown. Abdomen:
color and markings as in imago. Male genitalia: genital forceps amber-
yellow to light brown, darker distally. Caudal filament yellow, amber yellow
to brown at base. Segments densely covered with short hairs.
Mature nymph (in alcohol). Body length, 11-16 mm. Head pale yellow,
vertex and areas between ocelli pale yellow to brown. Eyes black. Outer
half of lateral ocelli greyish white, inner half black; median ocellus black.
Antennae pale yellow. Mouthparts: inner incisor of mandibles with 5-6
teeth-like lateral serrations; molar region with 12-16 long pectinate setae
(Fig. 8). Galea-lacinia of maxillae with 7-12 long pectinate subapical
setae. Thorax: pronotum pale yellow, slightly darker medially, flared lateral
margins translucent pale yellow. Mesonotum yellow, anterior margin and
sclerites near anterior base of fore wing pads dark yellow to greyish brown.
Metanotum pale yellow. Sterna yellow, prosternum paler. Legs pale yellow,
apical 2/3 of claws amber yellow to greyish brown; ventral articular points
of trochanter and femora dark shiny brown; femora with brown post-
median band; tibio-tarsal joints brown dorsally. Abdomen: terga pale
yellow, terga 8 chocolate brown; terga 2-7 either with or with out an-
terior and sublateral brown markings, most pronounced on terga 2-3
and becoming progressively less intense on terga 4-7; terga 2-9 with a
small amber-yellow to dark brown sclerotized area near posterolateral
corners. Sterna pale yellow, sterna 8 brown, pale yellow medially. Gills
pale yellow, darker along base of trailing edge of lamellae ranging from
yellow to brown. Caudal filaments pale yellow.
Discussion.-The genus Pseudiron has previously included two species,
P. centralis and P meridionalis. McDunnough (1931) first described P.
centralis from 3 female images collected from Kansas (USA), and Mani-
toba (Canada). Traver (1935) (in Needham, Traver and Hsu) subse-
quently redescribed the species based on the paratypes and additional col-
lection of female images from Kansas. The male images of the species were
first reported by Burks (1953).
Pseudiron meridionalis was described by Traver (1935) from a single
male imago collected from the Chattahoochee River, Atlanta, Georgia.
While examining the collection of Pseudiron from various localities in
Canada and United States, in preparation for the revision of the mayflies
of Florida, it became apparent that P. centralis and P. meridionalis are the
same species. The reddish brown color that Traver (1935) used to dis-
tinguish P. meridionalis from P. centralis results from sexual dimorphism.
Traver was understandably handicapped by having only a male specimen
on which to base the description of P. meridionalis, and P. centralis was
known at the time only from female images. The two species are herein
synonymized, with P. centralis as senior synonym.
The redescription of P. centralis is based on the paratypes, and recently
collected specimens including reared adults.
Pseudiron centralis exhibits an interesting geographic gradation of
color and pigmentation. In the following discussions, specimens of P.










440 Florida Entomologist 68(3) September, 1985

centralis collected from a given geographic area (geographic subdivisions
adapted from Edmunds et al., 1976) are referred to as follows: northern
forms for Alberta and Saskatchewan Provinces (Canada), and Colorado,
Utah and Wyoming (United States); southwestern forms for Southwest
U.S.; central forms from Central U.S.; and southeastern forms for South-
east U.S. The northern forms are generally darker and more heavily pig-
mented than the central and southeastern forms. Only one specimen (a
female imago collected from Green River, Utah) from the southwest was
available, and was uniformly pale yellow, similar to most of the south-
eastern forms. Apparently the pigments of this particular specimen faded.
The northern nymphs have a darker brown frons and vertex compared
to the uniformly pale brown to amber-yellow of the central forms, and
yellow in the southeastern forms. The anterolateral corners of the mesono-
tum of the northern nymphs are washed with dark brown, amber-yellow
to light brown in the central forms, and pale yellow in the southeastern
forms with the exception of two immature nymphs from Florida which
have the mesonotal corners brown. The northern nymphs have a darker
femoral band than the central nymphs while this brown median band is
rarely present among the southeastern nymphs; if present, it is a light
brown femoral band. Abdominal pigmentation shows a similar geographic
dine as the median femoral band. The abdominal terga of the northern
nymphs have extensive brown markings which gradually becomes less ex-
tensive among the central forms to almost absent in the southeastern
forms, except for a few individuals which have the anterior markins
washed with reddish brown. Abdominal tergum 8 of the nymph ranges
from uniformly chocolate brown among the northern forms to brown in
the central forms and light brown or yellow in the southeastern forms. A
few nymphs from Kansas however, have the color of abdominal tergum 8
similar to the northern forms, and a few of the southeastern nymphs have
the same uniformly light brown terga as the central forms.
Although the adults are not as well represented as the nymphs, either
numerically or geographically in the collections, there exists a similar geo-
graphic pattern of variations in color and pigmentation. Like the nymphs,
the northern adults are generally darker and more extensively pigmented
than the central and southeastern forms. The female images of the north-
ern forms have areas between the eyes, ocelli and antennae washed with
brown, and the posterior margin and frontal carina black while the central
and southeastern females have uniformly amber-yellow to pale yellow head.
The thorax of the northern female images invariably has the pronotum
tinged with brown, and the sternal apophyseal pits dark brown. The pro-
notum of the central forms are mostly tinged with amber-yellow, rarely
with pale brown, and the sternal apophyseal pits are amber-yellow, while
the southeastern forms have the pronotum uniformly pale yellow except
for two female images from Tennessee which are tinged with amber-yellow,
and the sternal apophyseal pits are pale yellow. The northern adults, and
a few southeastern ones as well, have a prominent brown median band
on the femora, while the central forms and most of the southeastern
forms, lack the femoral band. Markings of the adbominal terga of adults
do not show as distinct a geographic clinal variation as in the nymphs but
the northern forms generally have more extensive brown marks than the
central and southeastern forms, both of which either have terga which are


__










Pescador: Systematics of Pseudiron


uniformly pale yellow or thinly washed with brown on the anterior margins.
The northern male images particularly the specimens from Canada, have
the entire abdominal terga thinly washed with brown; the anterior margins
and the entire surface of terga 8-10 are much darker. The abdominal
terga of the females are not as extensively washed with brown as the
males, especially on terga 1-2. Terga 3-10 have brown narrow markings
confined to the anterior margin.
Other variations-such as the whitish granulations on the head, thorax
and abdomen of the adults, and brown or amber yellow submedian streaks
on the abdominal terga-randomly occur throughout the geographic dis-
tribution of the species. For most nymphs the dark brown marking on the
base of the trailing edge of the gill lamellae occurs on gill 7, but several
nymphs from Canada have this brown mark on gills 5-7. Nymphs from
Florida do not have marking on the gills.
Biology and Ecology.-In a detailed study of the life history and
abundance of P. centralis in the Sand River in east-central Alberta, Canada,
Soluk and Clifford (1984) observed that the species has a univoltine summer
life cycle and the eggs remain dormant for approximately nine months.
The first instar larvae appeared in late April and matured in less than
eight weeks. Adult emergence occurred from late June to late July. Col-
lection records indicate that the species appears to have the same emergence
period throughout its geographic range except in Florida where emergence
appears to occur earlier from mid-March to early May, based on FAMU
collection records representing about a ten year record of collecting in the
northwestern section of the state.
In the Blackwater River, Northwest Florida, the adults of P. centralis
emerge about mid-day (J. G. Peters, pers. comm.).
Egg fecundity of P. centralis is quite variable. Soluk and Clifford (1984)
counted 467 and 626 eggs from two female images collected from Canada.
I recorded a total of 692 eggs from a single female imago from Tennessee.
Female images from Florida apparently have higher number of eggs as I
counted 1553, 1670 and 1724 eggs from three dissected specimens.
The nymphs of Pseudiron are mostly associated with sandy river beds
in medium to large rivers over much of North America (Edmunds et al.,
1976). In the Sand River, Alberta, the nymphs were associated with three
types of substrates (shifting sand, marginal sand, and gravelly sand) in
the river bed, and exhibited a shift in the their association with the types
of sandy substrate during development (Soluk and Clifford, 1984). Ac-
cordingly, Stage I nymphs (lacking wing pads) were associated with sand
areas, and stage III (wing pads longer than the distance between them) and
stage IV (darkened wing pads) nymphs with shifting sand areas. The
shift of the older nymphs to shifting sand substrates appears to be a
mechanism that allows the nymphs to exploit either the greater prey avail-
ability or the lower number of potential predators and competitors in
these areas (Soluk, 1983). In the Blackwater River, Northwest Florida,
P. centralis has mostly been collected in shifting sand, strong current, and
in deeper areas of the river.
The nymphs of P. centralis feed primarily on chironomid larvae. In the
Sand River, Alberta, the nymphs were the only epibenthic predators that
occupied areas of actively shifting sand (Soluk and Clifford, 1984). In
the Blackwater River, Northwest Florida, two predaceous, sand dwelling-









Florida Entomologist 68 (3)


September, 1985


species, a mayfly, Dolania americana Edmunds and Traver, and a dragon-
fly, Progomphus obscurus (Rambur) coexist with P. centralis nymphs.
There is a dietary overlap among these three carnivores but partitioning
of resources and lessening of potential competition is achieved through
differential microhabitat utilization (Tsui and Hubbard, 1979). Nymphs of
P. centralis inhabit the sand surface while D. americana and P. obscures
actively burrow into the substrates.
A discussion of the nymphal habits of Pseudiron by Edmunds et al.,
(1976) indicated that the nymphs lie on top of the sand, facing the current,
with all three pairs of legs directed posteriorly and anchored in the sand.
My observations however, showed the legs to be more laterally directed,
spread in a spider-like fashion with claws anchored in the sand (see Plate
III, Peters and Jones, 1973). The claws have a prominent constriction near
the apex (Fig. 13-16) and inside it is a mass of nerve cells. Additionally,
distal to the constriction is a flexible portion of the claws. The functional
significance of these nerve cells and flexible distal portion of the claws is
unknown.
Geographic Distribution (Fig. 19). The genus Pseudiron has a wide
geographic distribution occurring in Central and Southeast United States
west to Utah and Wyoming, and across Western and Central Canada.
Pseudiron, a boreal endemic, probably had undergone the same dispersal
mechanisms as the Nearctic mayfly genera Siphloplecton and Baetisca,
which have similar distributional patterns (see Berner, 1978; Pescador and
Berner, 1981). The Pleistocene glaciations probably pushed Pseudiron
southward to its present geographic extension, and populations eventually
moved back northward perhaps via the Mississippi drainage after the
Pleistocene ice sheet retreated. A similar dispersal process has been at-
tributed to Siphloplecton by Berner (1978) and for Baetisca by Pescador
and Berner (1981).
Specimens Examined.-CANADA: ALBERTA: Sand R nr mouth 54022'N,
1110 2'W, 25 VII 1977 (A, reared) (FSCA), 15 & 23 VI 82 (N,A, reared)
(UA); Milk R at Writing, Stone Prov. Pk, 21 VII 82 (N,A, reared) (UA).
SASKATCHEWAN: Saskatchewan R at Saskatoon, 8 XII 70 (N) (FSCA).
UNITED STATES: FLORIDA: Okaloosa Co., Blackwater R, FAMU Biol.
Sta. 4 1/4 mi NW Holt, 31 I 71 (N), 22 II 71 (N), 13 III 71 (A, reared),
23 IV 71 (A, reared), 8 IV 72 (N), 1 V 74 (A, reared), 1 V 74 (A, reared),
1 V 75 (A, reared), 15 IV 76 (N,A), 16 IV 77 (N), 3 V 77 (A), 9 V 77
(N,A, reared), 22 IV 78 (N), 3 IV 79 (A, reared); Blackwater R at
Bryant bridge 3 mi NW Holt, 20 II 71 (N); Blackwater R, Kennedy bridge
6 mi W Blackman 23 IV 74 (N,A); Blackwater R, Peaden bridge 4 1/2 mi
NW Cannon Town, 28 IV 76 (A,N), 11 V 84 (A, reared); Santa Rosa Co.,
Blackwater R, Riley Landing, 3 mi NW Holt, 24 IV 71 (N), 7 IV 84 (A)
(all specimens, FAMU); Walton Co., at light 1/2 mi W Defuniak Springs
Hwy 90, 20 IV 60 (A) (FSCA). ILLINOIS: Clinton Co., Centralia, at
light, 17 VI 47 (A) (INHS); Lee Co., Prophetstown dredging sandy bottom
of Rock R 15 yds from bank, 21 V 25 (N) (INHS) ; Dixon, at light, 26 VI
47 (A) (INHS); Rock Falls, Rock R. at light, 26 VI 67 (A) (INHS);
Wabash Co., Mt Carmel, at light, 18 VI 47 (A) (INHS); Whiteside Co.,
Prophetstown, Rock R 26 VI 67 (A) (INHS); Winnebago Co., Rockford,
2 VI 49 (A) (INHS). INDIANA: Pike Co., White R nr Petersburg Plant,
2 V 75 (N) (PU). IOWA: County 77, 3 VII 39 (A) (INHS). KANSAS:


442










Pescador: Systematics of Pseudiron


Douglas Co., Lawrence, 26 VI 30 (A) (CNC); Sedgewick Co., Arkansas R,
2.8 mi S Bentley, 6 VI 75 (N) (SBSK); Saline Co., Saline R, New Cambria,
10 VI 76 (N) (SBSK). MISSISSIPPI: Leflore Co., Tallahatchie R at Green-
wood, 6 VI 56 (A) (FSCA). NEBRASKA: Lincoln Co., South Platte R at
North Platte, 6 VII 81 (A) (UU) ; Keith Co., Ogallala at light nr Plate R,
22 VI 81 (A) (UU). TENNESSEE: Shelby Co., Business District at store
windows, 7 VI 56 (N) (FSCA). TEXAS: Jasper Co., small stream at
bridge on Farm Rd. 256, 10 mi SE Colmesneil, 4 V 77 (N) (PU). UTAH:
Green R Hideout Canyon, 3 X 47 (A) (UU). WYOMING: Sweetwater
Co., Blacks Fort R at Hwy I 80 W Green R, 17 VII 68 (N) (UU).

ACKNOWLEDGMENTS

This research was supported by a research grant (FLAX 79009) of
SEA/CR, USDA, to Florida A&M University.
I thank L. Berner, University of Florida, G. F. Edmunds, Jr., University
of Utah, P. Leichti, State Biological Survey of Kansas, W. P. McCafferty and
W. D. Waltz, Purdue University, J. E. H. Martin, Canadian National Col-
lections, D. Soluk, University of Toronto, and J. D. Unzicker, Illinois
Natural History Survey, for the loan of specimens.
My sincere thanks to J. G. Peters for many of the illustrations. Gratitude
is expressed to W. Miller, Florida State University, for his assistance in
using the Scanning Electron Microscopy, and L. Berner for the photo-
microscopy of the nymphal claw. M. D. Hubbard, R. W. Flowers, and
J. G. Peters, Florida A & M University, and S. L. Jensen, Southwest
Missouri State University read and offered valuable comments on the
manuscript.

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.1977. Distributional patterns of southeastern mayflies
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Bull. Soc. Entomol. Belg. 78: 155-182.
MCDUNNOUGH, J. 1931. New Species of North American Ephemeroptera.
Can. Ent. 63: 82-93.
NEEDHAM, J. G., J. R. TRAVER, AND Y. C. Hsu. 1935. The biology of mayflies
with a systematic account of North American species. Comstock
Publ. Co., Ithaca, N. Y. xvi + 759.
PESCADOR, M. L. AND L. BERNER. 1981. The family Baetiscidae (Ephemerop-
tera). Part II Biosystematics of the genus Baetisca. Trans. Amer.
Ent. Soc. 107: 163-228.
PETERS, W. L. AND J. JONES. 1973. Historical and biological aspects of the
Blackwater River in northwestern Florida. In Proceedings of the
First International Conference on Ephemeroptera, W. L. Peters and
J. G. Peters eds., p. 242-253. E. J. Brill, Leiden.
SOLUK, D. A. 1983. Ecology of shifting sand areas in rivers. M. Sc.
Thesis, University of Alberta. 120p.
AND H. F. CLIFFORD. 1984. Life history and abundance of the
predaceous psammophilous mayfly Pseudiron centralis McDunnough
(Ephemeroptera:Heptageniidae). Can. J. Zool. 62: 1534-1539.
SPIETH, H. T. 1938. Two interesting mayfly nymphs with a description
of a new species. Amer. Mus. Novitates. 970: 1-7.
TRAVER, J. R. 1933. Heptagenine mayflies of North America. J. New
York Ent. Soc., 41: 105-25.
TsUI, P. T. P. AND M. D. HUBBARD. 1979. Feeding habits of the predaceous
nymphs of Dolania americana in northwestern Florida (Ephemerop-
tera: Behninigiidae). Hydrobiologia 67(2): 119-23.



THE IMPACT OF PHOSPHATE MINING ON
CULEX NIGRIPALPUS AND CULEX SALINARIUS
(DIPTERA: CULICIDAE) POPULATIONS IN
CENTRAL FLORIDA

MARC SLAFF AND JOHN D. HAEFNER
Polk County Environmental Services
P. O. Box 39
Bartow, Florida 33830, USA

ABSTRACT
The seasonal distribution and abundance of Culex nigripalpus Theobald
and Cx. salinarius Coquillett were compared in mined and unmined areas
of the central Florida phosphate region. Total Culex spp. populations were
significantly higher in mined than in unmined areas, but seasonal trends
were similar in both locations. The 2 species demonstrated very little
seasonal overlap, with Cx. salinarius being most numerous from March
through June and Cx. nigripalpus dominating from June through No-
vember. Within the mined region, no difference was seen in adult Culex
spp. population levels between waste clay and waste sand areas.

RESUME
Se compare la distribuci6n y abundancia estacional de Culex nigripal-
pus Theofald y de C. salinarius Coquillet en areas minadas y no minadas de
la region fosfatera del centro de la Florida. El total de poblaciones de










Slaff & Haefner: Phosphate Mining & Culex


445


Culex spp. fue significativamente mAs alto en Areas minadas que en las no
minadas, pero la tendencies estacionales fueron similares en los dos lugares.
Las 2 species demostraron my poco solape estacional, siendo Cx. salinarius
mAs numeroso de Mayo a Juno, y Cx. nigripalpus dominando de Junio a
Noviembre. Dentro de la region minada, no se observ6 diferencias en niveles
de poblacion adulta de Culex spp. entire Areas arcillosas y arenosas.


Culex nigripalpus Theobald and Cx. salinarius Coquillett are important
pest mosquitoes throughout Florida (Provost 1963). Within the state, Cx.
nigripalpus is the demonstrated vector of St. Louis encephalitis (SLE)
to humans (Dow et al. 1964). Culex salinarius may also transmit SLE
(Clarke et al. 1977) and is a documented nuisance to man (Provost 1963,
Steelman 1975).
Processing phosphate ore creates large impoundments where suspensions
of waste clay and waste sand settle, allowing water to be re-used (Hoppe
1976). Many hectares of emergent vegetation often cover these sites, pro-
viding conditions similar to those that have produced large Culex spp. popu-
lations in other areas (Chapman & Ferrigno 1956, Clements & Rogers 1964).
In the chemical process of separating sand from phosphate ore, ammonia
is often used to maintain slightly basic pH levels (Smith 1976). There is
evidence that under some conditions increased numbers of Culex spp. are
found in association with higher levels of nitrogenous materials such as
ammonia (Hagstrum & Gunstream 1971, O'Meara & Evans 1983). The
possible impact of ammonia on Culex spp. populations in the phosphate
district was examined.

MATERIALS AND METHODS
Study sites were chosen in both mined and unmined areas. Those in the
non-phosphate area were located adjacent to lakes and fresh water marshes.
The most abundant plant species included maidencane (Panicum hemitomon
Shult.), pickerelweed (Pontederia lanceolata Nutt.), arrow arum (Pel-
tandra virginica (L.) Kunth), water primrose (Ludwigia octovalis (Jacq.)
Raven), sedge (Carex spp.) and cattail (Typha spp.). These habitats
were chosen to provide a "worst case" unmined situation, since Culex spp.
require permanent water habitats for completion of their life cycle (Car-
penter & LaCasse 1955). Two sites were each sampled with 2 CDC
portable light traps every other week from May 1982 through December
1983. Each trap had a 2.8-3.5kg dry ice supplement and was operated from
ca. 30 min before sunset to ca. 30 min after sunrise.
The phosphate sites were all located at least 15 km from the unmined
areas. Within the phosphate region, 2 waste clay and 2 tailing sites were
sampled. In mining phosphate ore, clay is separated by a centrifugation
process and pumped in suspension to diked holding ponds. Because the
clay swells 6-10-fold when wet and settles slowly, the sites for this ma-
terial are very large, ca. 250 ha. Most of a site is wet, and from 25-100%
may be covered with emergent and floating cattails, water primrose and
water hyacinth (Eichhornia crassipes (Mart.) Solms). The settling cells
are over 10 m deep and require at least 5 yrs to fill.
Waste sand is removed from phosphate ore with a chemical flotation
process. The sand is coated with a reagent, frothed so that it floats, and









446 Florida Entomologist 68 (3) September, 1985

then removed. The phosphate is then treated in the same manner. A basic
pH is required for this operation, and ammonia is frequently used to
produce the proper environment (Smith 1976). The sand, which does not
expand, is pumped to settling sites that are generally smaller than 15 ha.
Cattails and water primrose are the dominant plants in the sand sites. To
determine if ammonia levels were higher in the tailing than in the waste
clay ponds, a posteriori water samples were taken in each location on 7
dates from August through November 1984.
Although finding totally isolated sites was not possible within the
phosphate district, the 2 waste clay settling areas were over 5 km from the
2 tailing sites. Each area was sampled in the same manner described for
the non-phosphate region. In addition to CDC trapping, seasonal patterns
were confirmed with 10 emergence traps (Slaff et al. 1984) operated con-
tinuously at a tailing site from December 1983 through December 1984.
The traps were checked every 2 weeks for mosquitoes. Due to the in-
accessibility of the habitats, no larval samples were taken. Data from all
CDC trap collections were analyzed using Mann-Whitney and t-tests, where
appropriate (Zar 1974).
RESULTS AND DISCUSSION
CDC light traps showed that seasonal trends of host-seeking female mos-
quitoes were similar at all sites. These data were therefore combined and
are illustrated in Fig. 1. Adult emergence patterns at the tailing site are
20- om--.o Cx. nigripalpus
*-- Cx. salinarius 1

I I
I c I! ll
15 I 1 I1
o I I l


o1 *I
x 1 i S !
z10- 1 0 0 1


S0 0

5- a


VV
O*
v e\ 4 .j 00\

MJ J A SO N DJ F MAMJ J A SON D
a e
y c
MONTH
Fig. 1. Dry-ice-baited CDC trap collections of adult female Cx. nigripal-
pus and Cx. salinarius in central Florida during 1982-83.










Slaff & Haefner: Phosphate Mining & Culex


447


shown in Fig. 2. The results of both sampling methods demonstrate an
abrupt and distinct seasonal exclusivity for the 2 species. Populations of
Cx. salinarius dominated from January through June, then plummeted as
Cx. nigripalpus levels rose gradually. Culex nigripalpus were over 90% of
all Culex spp. collected from August through October. Other researchers
(Knight 1954, Provost 1963, O'Meara & Evans 1983) have reported similar
observations for these 2 mosquitoes in Florida.
The reasons for the temporal differences between these 2 species in
this study are unclear. Throughout most of its range, Cx. salinarius
reaches greatest abundance during the summer, when temperatures peak
(Eldridge et al. 1972, Slaff & Crans 1981). Our information suggests that
the population decline of Cx. salinarius in Florida is not due to increases
in mean temperature, and may instead be due to a competitive interaction
with Cx. nigripalpus.
Table 1 shows that CDC trap collections of Culex spp. were significant-
ly higher in mined than in unmined sites. This clearly demonstrates the
effect of impoundment formation on Culex spp. population levels. Other
researchers have reported increases in Culex spp. populations in both low
dike, salt marsh impoundments (Clements & Rogers 1964, Fleetwood et al.
1978) and high dike, fresh water impoundments (Slaff & Crans 1982).
Apparently, either fresh or brackish, standing water containing abundant
emergent vegetation can lead to an increase in Culex spp. numbers.
CDC trap collections of Cx. nigripalpus in tailing and waste clay sites


180- 0o-m- o Cx. nigripalpus
*-*- Cx. salinarius

I'\



*0
a 120-
S0o







es I
Y V
I 1 o
















Fig. 2. Emergence trap collections of Cx. nigripalpus and Cx. salinarius
in a tailing site during 1983-84.

in a tailing site during 1983-84.










Florida Entomologist 68 (3)

MEAN NUMBER OF ADULT Culex SPP. PER
VS. MINED SITES DURING 1982-83.


September, 1985

CDC TRAP IN UNMINED


Unmined Mined
Month Monthly mean Monthly mean

March 67.2 674.5
April 265.7 4934.8
May 363.1 3850.5
June 469.1 4306.9
July 566.1 3881.1
August 242.8 716.8
September 208.4 2876.3
October 338.1 2849.6
November 65.3 1734.9
December 60.8 700.5
Grand Mean S.E. 264.7 54.9a 2652.6 508.7b


Means followed by different letters are significantly different
p<0.01).


(Mann-Whitney U-test,


are shown in Table 2. The data are from the time period when the species
was most abundant. The overall 2-yr means for adult Cx. nigripalpus were
not significantly different in waste clay and tailing habitats. Similar results
were noted for Cx. salinarius during March through July 1982-83 (Table
3). This is despite higher mean levels of ammonia in the 2 tailing sites
(16.4 & 14.5 mg/liter) vs. the 2 waste clay sites (1.3 & 0.6 mg/liter). The
impact of nitrogenous materials on Culex spp. is unclear, however, with
some studies noting a positive correlation (Smith & Enns 1967, Rutz et al.
1980, O'Meara & Evans 1983) and others citing the apparent absence
of such an interaction (Carlson 1983a,b).
Although further work is needed to determine the precise responses
of Cx. nigripalpus and Cx. salinarius to chemical differences in the water
within the phosphate district, population levels of these 2 species were
much higher in the mined than in the unmined areas of this study. Given


TABLE 2.


MEAN NUMBERS OF ADULT Cx. nigripalpus PER CDC TRAP IN
WASTE CLAY AND TAILING SITES DURING 1982-83. (N = NUMBER
OF SAMPLES).


Tailing Waste clay
Month n Mean S.E. n Mean S.E.

July 18 1489.7 300.9 18 1713.5 307.2
August 18 1949.6 620.9 21 1624.1 253.6
September 22 2294.3 276.8 21 1837.7 343.6
October 24 2183.6 378.1 22 2253.0 335.7
November 22 795.4 160.9 23 957.4 268.4

Entire Period 104 1752.8 168.7a 105 1668.3 137.9a

Means followed by the same letter are not significantly different (t-test, p>0.05).


448


TABLE 1.










Slaff & Haefner: Phosphate Mining & Culex 449

TABLE 3. MEAN NUMBER OF ADULT Cx. salinarius PER TRAP IN WASTE CLAY
AND TAILING SITES DURING 1982-83. (N=NUMBER OF SAMPLES).

Tailing Waste clay
Month n Mean S.E. n Mean S.E.

March 9 852.7 176.4 8 714.6 225.8
April 9 5652.9 + 1277.3 12 2721.0 1038.2
May 23 2656.1 408.3 21 2646.3 690.4
June 20 1061.1 294.3 22 1876.4 753.1
July 18 375.8 136.2 18 818.9 279.5

Entire Period 79 1868.7 269.7a 1852.2 324.5a

Means followed by the same letter are not significantly different (t-test, p>0.05).
the need of the phosphate industry to maintain large bodies of standing
water for mineral processing, the challenge to develop cost-effective control
methods in the region is substantial.

ACKNOWLEDGEMENTS

The authors thank J. Nemjo and M. Gurien for their assistance during
this study. The firms of International Minerals & Chemicals, and W. R.
Grace are thanked for providing access to their phosphate mining opera-
tions. The comments and suggestions of Dr. C. D. Morris are also gratefully
acknowledged. This work was supported in part by grant no. 81-03-015 of
the Florida Institute of Phosphate Research.

REFERENCES CITED
CARLSON, D. B. 1983a. The use of salt-marsh mosquito control impound-
ments as waste water retention areas. Mosq. News 43: 1-6.
1983b. Ovipositional response of Culex quinquefasciatus to
southeast Florida waste water. Mosq. News 43: 284-87.
CARPENTER, S. J. AND W. J. LACASSE. 1955. Mosquitoes of North America.
Univ. Calif. Press, Los Angeles, California, VI + 360p.
CHAPMAN, H. C. AND F. FERRIGNO. 1956. A three year study of mosquito
breeding in natural and impounded salt marsh areas of New Jersey.
Proc. N. J. Mosq. Exterm. Assoc. 65: 59-66.
CLARK, G. G., H. L. PRETULA, T. JAKUBOWSKI AND M. A. HURD. 1977. Arbo-
virus surveillance in Illinois in 1976. Mosq. News 37: 389-95.
CLEMENTS, B. W. AND A. J. ROGERS. 1964. Studies of impounding for the
control of salt marsh mosquitoes in Florida, 1958-1963. Mosq. News
24: 265-76.
Dow, R. P., P. H. COLEMAN, K. E. MEADOWS AND T. H. WORK. 1964. Isola-
tion of St. Louis encephalitis viruses from mosquitoes in the Tampa
Bay area of Florida during the epidemic of 1962. Am. J. Trop. Med.
Hyg. 13: 462-68.
ELDRIDGE, B. F., C. L. BAILEY AND M. D. JOHNSON. 1972. A preliminary
study of the seasonal geographic distribution and overwintering of
Culex restuans Theobald and Culex salinarius Coquillett (Diptera:
Culicidae). J. Med. Entomol. 9: 233-38.
FLEETWOOD, S. C., C. D. STEELMAN AND P. E. SCHILLING. 1978. The effects










Florida Entomologist 68 (3)


of waterfowl management practices on mosquito abundance and
distribution in Louisiana coastal marshes. Mosq. News 38: 105-12.
HAGSTRUM, D. W. AND S. E. GUNSTREAM. 1971. Salinity, pH and organic
nitrogen of water in relation to presence of mosquito larvae. Ann.
Entomol. Soc. Amer. 64: 465-67.
HOPPE, R. 1976. From matrix to fertilizers, Florida's phosphate industry
girds to produce over 50 million tpy. Eng. Min. J. 177(9) : 81-93.
KNIGHT, K. L. 1954. Mosquito light trap collections at Yukon, Florida,
for the six year period, 1948-1953. Proc. New Jersey Mosq. Exterm.
Assoc. 41: 251-57.
O'MEARA, G. F. AND F. D. S. EVANS. 1983. Seasonal patterns of abundance
among three species of Culex mosquitoes in a south Florida waste
water lagoon. Ann. Entomol. Soc. Amer. 76: 130-33.
PROVOST, M. W. 1963. Biology of Culex nigripalpus. Proc. Florida Anti-
Mosq. Assoc. 34: 25-30.
RUTZ, D. A., R. C. AXTELL AND T. D. EDWARDS. 1980. Effect of organic
pollution levels on aquatic insect abundance in field pilot-scale an-
aerobic animal waste lagoons. Mosq. News 40: 403-09.
SLAFF, M. AND W. J. CRANS. 1981. The activity and physiological status
of pre- and posthibernating Culex salinarius (Diptera: Culicidae)
populations. J. Med. Entomol. 18: 65-68.
1982. Impounded water as major producer of Culex sali-
narius (Diptera: Culicidae) in coastal areas of New Jersey, USA.
J. Med. Entomol. 19: 185-190.
J. D. HAEFNER, R. E. PARSONS AND F. WILSON. 1984. A
modified pyramidal emergence trap for collecting mosquitoes. Mosq.
News 44: 197-99.
SMITH, P. R., JR. 1976. Phosphate flotation. Pages 1265-84 In: Flotation,
Vol. 2, M. C. Fuerstenan (ed.). Amer. Inst. Mining, Met. and Pet.
Eng., Inc. New York, New York.
SMITH, W. L., JR. AND W. R. ENNS. 1967. Laboratory and field investiga-
tions of mosquito populations associated with oxidation lagoons in
Missouri. Mosq. News 27: 462-66.
STEELMAN, C. D. 1975. Correspondence in the AMCA Newsletter. Amer.
Mosq. Control Assoc. Newsl. 1: 9.
ZAR, J. H. 1974. Biostatistical analysis. Prentice-Hall, Inc. Englewood
Cliffs, N. J., XIV + 620p.



EFFECTS OF SYNTHETIC PYRETHROIDS ON
GROWTH AND DEVELOPMENT OF THE FALL
ARMYWORM, SPODOPTERA FRUGIPERDA

GINGER L. GIST1 AND CHARLES D. PLESS
Department of Entomology and Plant Pathology
University of Tennessee
Knoxville, TN 37901-1071

ABSTRACT
Nine synthetic pyrethroids were evaluated at 1 ppm in an artificial diet
fed to larvae of the fall armyworm, Spodoptera frugiperda (J. E. Smith)

'Current Address: Department of Environmental Health, Box 22960 A, East Tennessee
State University, Johnson City, TN 37614-0002.


450


September, 1985










Gist & Pless: Developmental Effects of Pyrethroids 451

(Lepidoptera: Noctuidae). All compounds were effective insecticides for
FAW control at this sublethal concentration because they inhibited growth
of larvae, reduced the amount of feeding by larvae, reduced mobility of
adults, and in 8 instances reduced fecundity.

RESUME
Se evaluaron 9 pyrethroids sint6ticos a 1 ppm en una dieta artificial
usada para alimentar larvas del cogollero, Spodoptera frugiperda (J. E.
Smith) (Lepidoptera: Noctuidae). Todos los compuestos fueron insecticides
efectivos en controlar al cogollero a esta concentraci6n subletal, porque ellos
inhibieron el crecimiento de las larvas, reducieron la cantidad comida por
las larvas, la mobilidad de los adults, y en 8 ocasiones la fecundidad.



The photostable synthetic pyrethroids have high acute toxicities as well as
chronic effects on the fall armyworm (FAW), Spodoptera frugiperda (J. E.
Smith) (Gist and Pless 1985 a,b,c). Chronic effects are evident at con-
centrations of pyrethroids lower than those causing mortality. Such effects
may prevent damage to plants. Use of lower concentrations might reduce
the development of resistance in pest populations and minimize detri-
mental effects to beneficial arthropods (Ross and Brown 1982). Reese and
Beck (1976) hypothesized that chronic effects, such as slowing develop-
mental rate, could increase mortality through longer exposure of target
species to parasites, predators, pathogens, and adverse physical factors.
Effects of sublethal dietary concentrations of pyrethroids on insects
have been investigated only recently. Tan (1981) found that cypermethrin
and permethrin induced a significant extension of the larval period of
Pieris brassicae, with a reduction in the maximal larval and pupal weights.
Fecundity of adults in those experiments was also reduced, possibly due
to the reduction of pupal weights. Ross and Brown (1982) found that
sublethal concentrations of fenvalerate and permethrin inhibited larval
growth (decreased overall larval weight) of FAW. NRDC-161 in the diet
of Anthonomus grandis grandis reduced the fecundity of the females
(Moore 1980).
The quantitative nutritional approach to studying insect growth and
development consists of measuring the amount of food consumed, digested
and assimilated, excreted, metabolized, and converted into biomass (Wald-
bauer 1968). Analysis of these measurements reveals how organisms re-
spond to different foods and which food components (or additives) exert
the greatest effects on growth (Schribner and Slansky 1981). Information
on the effects of sublethal dietary concentrations of pyrethroids on feeding
indices has not been published.
The purpose of this study was to evaluate the effects of sublethal dietary
concentrations of nine synthetic pyrethroids on the growth, development,
and subsequent fecundity of a laboratory strain of FAW.

MATERIALS AND METHODS

Insecticide-acetone (wt/vol) solutions were mixed with dry diet com-
ponents (Bio-Serv Corn Earworm Rearing Media, Bio-Mix #9394, packet
A) in a blender for 10 min.










452 Florida Entomologist 68 (3) September, 1985

The acetone was allowed to evaporate overnight. The diet was then pre-
pared according to directions and stored in a refrigerator (120C) until
needed. The final concentration of pyrethroid in the diet was 1 ppm.
Control diet was treated with acetone only. The synthetic pyrethroids were
technical formulations of permethrin and cypermethrin (ICI Americas,
Inc.); permethrin, cypermethrin, Pounce, and Ammo@ (FMC Agricultural
Chemical Group); Pydrin (Shell Development Co.); Mavrik (Zoecon
Corp.); and Pay-Off (American Cyanamide Co.).
Thirty larvae in the 3rd instar from a laboratory culture (Gist and
Pless 1985a) were weighed and placed individually onto weighed squares
of treated or control diet in 60-mm-dia. petri dishes. All measurements
were made during 4th-6th instars because younger FAW (lst-3rd instars)
consume < 2% of the total dietary intake (Luginbill 1928). Thus, by
allowing the 3rd instar to acclimate, "loss of appetite" upon initial ex-
posure to a new food, as discussed by Wiklund (1973) and Jermy, et al.
(1968), was avoided. Fresh diet was provided as needed to allow the larvae
to feed freely. All larvae were kept within environmental chambers at
27 + 20C, L14:D10 photoperiod, and 60-70% RH. Frass was separated
from uneaten diet, and separately they were dried and weighed. The weight
and instar of each larva was recorded daily. Thirty aliquots of each experi-
mental diet and the control diet were weighed, dried, and reweighed to de-
termine the initial percentage of dry matter.
Newly emerged adults were placed in 4-liter cylindrical wire cages
lined with paper toweling for an ovipositional substrate. Cotton saturated
with an ascorbic acid-beer (1.5 g/828 ml) solution was placed into each
cage for adult diet. The number of egg masses and eggs for each treat-
ment was recorded. Egg masses were clipped from the paper toweling,
surface sterilized with sodium hypochlorite, and placed on control diet
within the environmental chambers. The number of eggs that had not
hatched after 7 days was recorded.
The nutritional indices (Scribner and Slansky 1981, Waldbauer 1968)
calculated were relative growth rate (RGR); relative consumption rate
(RCR) ; approximate digestibility (AD); efficiency of conversion of digested
food (ECD); and efficiency of conversion of ingested food (ECI). Statisti-
cal analyses were performed where needed and significant differences be-
tween means were detected by Dunnett's test (Zar 1974).


RESULTS AND DISCUSSION

Larvae fed synthetic pyrethroids required significantly longer to reach
their maximum weight than larvae fed the control diet (Table 1). Increases
ranged from 2X [permethrin (ICI)] to 3X [cypermethrin (FMC)]. Although
the duration of stadia 4-6 was increased, the duration of the prepupal
stadia remained approximately the same as for the control. This suggests
that pyrethroids at 1 ppm exert a detrimental effect on actively feeding
stages.
Larvae fed pyrethroid-treated diet had significantly lower maximum
weights than the control group (Table 1). Scriber (1977) stated that
larval growth can be reduced by lack of water. Although all diets con-
tained sufficient water (ca. 81%) for normal growth, larvae that fed on
treated diet were more flaccid than control larvae, indicating a lack of body












Gist & Pless: Developmental Effects of Pyrethroids 453



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Florida. Entomologist 68 (3)


water. Abnormally low weights of treated larvae were not apparent until
the 6th instar. Pupal weights were reduced significantly by 5 of the
pyrethroids. The most dramatic reductions of weight were caused by
permethrin (FMC) (38% less than the control) and cypermethrin (FMC)
(44% less than the control).
All of the pyrethroids tested significantly reduced the RGRs (Table
2). In no case was AD, ECD, or ECI reduced by the pyrethroids, indicating
that although these compounds do effect mortality when incorporated into
the diet at 1 ppm, there is no metabolic "cost" incurred to detoxify them
(Scriber and Slansky 1981). Additives in the food that reduce feeding
usually impose a reduced RCR (Scriber and Slansky 1981). A reduction
in RCR occurred with all the pyrethroids tested indicating that these
compounds deter feeding. This has been further substantiated by Gist and
Pless (1985b) who found that these pyrethroids deterred feeding by
3rd instar FAW at 50 ppm and 5 ppm, both in 2-choice and no-choice tests.
An imposed reduction in RCR should result in lengthy extension of the
larval stadium with final body weight reduced below normal (Mathavan
and Muthukrishnan 1976, McGinnis and Kasting 1959, Mukerji and Guppy
1970, Rojas-Rousse and Kalmes 1978). We concluded that reduction in RCR
was induced by the pyrethroids because they deter feeding, increase time
in the larval stage, and decrease final body weights.
Larvae reared on the treated diets pupated normally, and emergence
of the adults was comparable to control adults (Table 3); however, many
of the subsequent adults were unable to inflate their wings upon emergence.
This might add to population control since adults would be unable to fly
when disturbed, thus making them more susceptible to natural mortality
factors. Mating and feeding would also be inhibited by their inability to
fly.

TABLE 2. EFFECTS OF NINE SYNTHETIC PYRETHROIDS IN ARTIFICIAL DIETS
FED TO LARVAE OF Spodoptera frugiperda ON NUTRITIONAL
INDICES1 (4TH-6TH INSTARS) OF 1 PPM.

Compound AD2 ECD2 ECI2 RCR2 RGR2

Control 67.5 15.8 10.5 3.38 0.35
permethrin (FMC) 55.3 NS 8.9 NS 4.8 NS 2.08 0.10 *
Ammo@ 48.8 NS 14.1 NS 6.0 NS 2.87 0.16 *
Mavrik@ 47.0 NS 15.5 NS 7.3 NS 2.03 0.15 *
Pounce@ 46.4 NS 14.4 NS 6.6 NS 1.83 0.12 *
cypermethrin (ICI) 46.0 NS 14.1 NS 5.9 NS 2.08 0.13 *
cypermethrin (FMC) 42.3 NS 9.3 NS 3.9 NS 2.94 0.12 *
permethrin (ICI) 42.2 NS 16.3 NS 6.8 NS 2.43 0.17 *
Pydrin@ 42.2 NS 17.6 NS 7.0 NS 1.88 0.13 *
Pay-Off 36.0 NS 16.9 NS 6.0 NS 2.11 0.13 *

'AD (Approximate digestibility) = (I-F)/I; ECD (Efficiency of conversion of digested
food) = B/(I-F); ECI (Efficiency of conversion of ingested food) = AD x ECD; RCR
(Relative consumption rate) = I/T/B; RGR (Relative growth rate( = RCR x ECI;
where B = biomass gained, I = ingested food, F = feces egested (undigested food -
excretory products), I-F = assimilated food, B = mean weight during time period T,
and T = time in days to maximum weight.
2*= Significantly different from control (p<0.05), NS = not significantly different
from control (Dunnett's procedure).


454


September, 1985











Gist & Pless: Developmental Effects of Pyrethroids 455

TABLE 3. EFFECTS ON FECUNDITY AND PUPAL ECLOSION OF 1 PPM OF NINE
SYNTHETIC PYRETHROIDS IN ARTIFICIAL DIETS FED TO LARVAE OF
Spodoptera frugiperda.

Adults %
failing uninflated eggs % eggs not
Compound to emerge wings masses/ ? eggs/ 9 hatching

Control 10.0 0.0 9.8 1011.4 0.7
Pydrin 14.8 13.0 19.8 1982.0 10.7
Pounce 10.3 0.0 8.2 575.6 10.2
cypermethrin
(FMC) 8.3 9.1 8.5 353.6 11.3
permethrin (ICI) 8.0 17.4 5.7 465.7 6.7
permethrin
(FMC) 7.1 15.4 4.9 355.7 14.3
cypermethrin
(ICI) 3.9 8.0 7.5 454.5 10.0
Ammo 3.5 21.4 6.2 497.9 4.2
Pay-Off@ 3.3 10.3 7.0 571.9 4.5
Mavrik 0.0 43.3 6.3 407.0 7.4

Treatment reduced the number of eggs/female by ca. 50%; however,
there was a 2-fold increase with Pydrin-treated insects (Table 3).
Hormologosis, a phenomenon in which subharmful quantities of stress agents
are stimulating (Luckey 1968), is a possible explanation for the increase
seen with Pydrin. Eggs laid by treated females had 6X (Ammo@) to 20X
[permethrin (FMC)] greater mortality than eggs laid by control females.
In conclusion, the synthetic pyrethroids can be effective insecticides for
FAW control at sublethal concentrations because they inhibit growth of
the larvae, reduce the amount of feeding by larvae, reduce mobility of
adults and reduce fecundity. These characteristics might help prevent the
formation of large FAW populations in the field thus reducing overall
economic damage.

LITERATURE CITED
GIST, G. L. AND C. D. PLESS. 1985a. Comparative toxicities of synthetic
pyrethroids on the fall armyworm, Spodoptera frugiperda. Florida
Entomol. 68: 312-315.
AND 1985b. Feeding deterrent effects of syn-
thetic pyrethroids on the fall armyworm, Spodoptera frugiperda.
Ibid. 68: 456-461.
AND 1985c. Ovicidal activity and ovipositional
repellent properties of synthetic pyrethroids on the fall armyworm,
Spodoptera frugiperda. Ibid. 68: 462-466.
JERMY, T., F. E. HANSON, AND V. G. DEITHER. 1968. Induction of specific
food preference in lepidopterous larvae. Entomol. Exp. Appl. 11:
211-230.
LUCKEY, T. D. 1968. Insecticide hormologosis. J. Econ. Entomol. 61: 7-12.
LUGINBILL, P. 1928. The fall armyworm. USDA Tech. Bull. #34. P. 92.
MATHAVAN, S. AND J. MUTHUKRISHNAN. 1976. Effect of ration levels and
restriction of feeding durations of food utilization in Danas chrysip-
pus. Entomol. Exp. Appl. 19: 155-162.










Florida Entomologist 68 (3)


McGINNIS, A. J. AND R. KASTING. 1959. Nutrition of the pale western
cutworm, Agrotis orthogonia Morr. I. Effects of underfeeding and
artificial diets on growth and development, and a comparison of
wheat sprouts of thatcher, Triticum aestivum L., and Golden Ball.,
T. durum Desf., as food. Can. J. Zool. 37: 259-267.
MOORE, R. F. 1980. Behavioral and biological effects of NRDC-161 as
factors in control of the boll weevil. J. Econ. Entomol. 73: 265-267.
MUKERJI, M. K. AND J. C. GUPPY. 1970. A quantitative study of food con-
sumption and growth in Pseudaletia unipuncta. Can. Entomol. 102:
1179-1188.
REESE, J. C. AND S. D. BECK. 1976. Effects of allelochemics on the black
cutworm, Agrotis ipsilon; effects of p-benzoquinone, hydroquinone,
and duroquinone on larval growth, development, and utilization of
food. Ann. Entomol. Soc. Amer. 69: 59-67.
ROJAS-ROUSSE, D. AND R. KALMES. 1978. The development of male Dio-
dromus pulchellus in the pupae of Acrolepiopsis assectella: Com-
parison of assimilation and energy losses under two temperature
regimes. Environ. Entomol. 7: 469-481.
RoSS, D. C. AND T. M. BROWN. 1982. Inhibition of larval growth in Spodop-
tera frugiperda by sublethal dietary concentrations of insecticides.
J. Agric. Food Chem. 30: 193-196.
SCRIBER, J. M. 1977. Limiting effects of low leaf-water content on the
nitrogen utilization, energy budget, and larval growth of Hylaphora
cecropia (Lepidoptera: Saturniidae). Oecologia (Berlin). 28: 269-
287.
AND F. SLANSKY, JR. 1981. The nutritional ecology of im-
mature insects. Annu. Rev. Entomol. 26: 183-211.
TAN, K. H. 1981. Antifeeding effect of cypermethrin and permethrin at
sublethal levels against Pieris brassicae larvae. Pestic. Sci. 12: 619-
626.
WALDBAUER, G. P. 1968. The consumption and utilization of food by insects.
Adv. Insect Physiol. 5: 229-288.
WIKLUND, C. 1973. Host plant suitability and the mechanism of host se-
lection in larvae of Papilio machaon. Entomol. Exp. Appl. 16: 232-
242.
ZAR, J. H. 1974. Biostatistical analysis. Prentice-Hall, Inc., Englewood
Cliffs, N.J. P. 620.

*-- -- --^- *- -**-- *--- i L *-L -* -

FEEDING DETERRENT EFFECTS OF SYNTHETIC
PYRETHROIDS ON THE FALL ARMYWORM,
SPODOPTERA FRUGIPERDA

GINGER L. GISTt AND CHARLES D. PLESS
Department of Entomology and Plant Pathology
University of Tennessee
Knoxville, TN 37901-1071 USA

ABSTRACT
Nine synthetic pyrethroids were tested in the laboratory for feeding
deterrency to 3rd instar fall armyworm, Spodoptera frugiperda (J. E. Smith)

1Current Address: Department of Environmental Health, Box 22960 A, East Tennessee
State University, Johnson City. Tennessee 37614-0002.


September, 1985


456











Gist & Pless: Pyrethroids Deter Feeding 457

(Lepidoptera: Noctuidae). In no-choice tests all pyrethroids were effective
feeding deterrents at 50 ppm. At 5 ppm all but Pounce were significant
deterrents.

RESUME
Se probaron el el laboratorio 9 pyrethroids sinteticos para disuadir la
alimentaci6n del tercer estadio del cogollero, Spodoptera frugiperda (J. E.
Smith) (Lepidoptera: Noctuidae). En pruebas sin selecci6n, a 50 ppm todos
los pyrethroids fueron efectivos en disuadir alimentaci6n. A 5 ppm todos
menos Pounce disuadieron significativamente.


An insect feeding deterrent is a chemical which, after initial gustatory
contact, prevents further biting by the insect (Chapman 1974). Chemical
feeding deterrents which reduce feeding damage to individual plants with-
out necessarily reducing absolute pest numbers, may have potential as an
unconventional approach to pest control (Munakata 1970, Pedigo 1975).
The synthetic pyrethroids have shown distinctive insect repellent effects.
Tan (1981) reported that permethrin and cypermethrin were feeding
deterrents for Pieris brassicae larvae, and they exhibited an irritant re-
sponse with repeated regurgitation. Ruscoe (1977) found permethrin to
be a feeding deterrent for Plutella xylostella (Linnaeus) larvae; at sub-
lethal doses they avoided treated surfaces. Hall (1979) observed behavioral
changes, most notably reduced feeding and avoidance reactions, in Cono-
trachelus nenuphar (Herbst) and Tetranychus uriticae Koch in response
to pyrethroid treatment. Ruscoe (1977) noted that crop damage attributed
to Trichoplusia ni (Hubner) and Anthonomus grandis grandis Boheman
in pyrethroid-treated fields was lower than could be accounted for by the
LD,5 value. He hypothesized the reduction to be due to the feeding re-
pellent properties of the pyrethroids.
The purpose of this study was to evaluate in the laboratory the effects
of nine synthetic pyrethroids on the feeding behavior of larvae of the
fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith).

MATERIALS AND METHODS
NO-CHOICE TESTS

These feeding behavior tests were modified from Wada and Munakata
(1968). One cm2 pieces were clipped from corn leaves 8-10 weeks old. A
0.1 ml acetone solution of each insecticide was applied to each leaf bit
and allowed to air dry. Acetone was used as a control.
Five treated pieces were placed at random in 15-cm-diam petri dishes
with 5 laboratory-reared 3rd-instar larvae that had been deprived of food
(corn leaves) for the 2 previous hours. The dishes were placed in dark
environmental chambers at 27 20C and 60-70% RH. After 2 h the leaf
area consumed was measured according to Dethier's (1947) method. The
concentrations tested were 50 ppm and 5 ppm, with 5 replications of each
concentration.

TWO-CHOICE TESTS

These differential feeding behavior tests were modified from Young and










458 Florida, Entomologist 68 (3) September, 1985

McMillan (1979). Petri dishes, 15-cm-diam, were divided into quadrants
that were labeled alphabetically clockwise. Two pyrethroid-treated leaf
pieces each were placed in quadrants A and C and two acetone-treated
leaf bits each were placed in quadrants B and D. One laboratory-reared
3rd-instar larva was placed in the center of each dish and the dishes were
placed in the dark environmental chambers under the conditions described
above. After 24 h, the leaf area consumed was measured according to
Dethier's (1947) method. The concentrations tested were 50 ppm and 5
ppm with five replications at each concentration.
Insecticides used in both experiments were permethrin and cypermethrin
(ICI Americas, Inc.); permethrin, cypermethrin, Pounce@, and Ammo@
(FMC Agricultural Chemical Group); Mavrik (Zoecon Corp.); Pydrin@
(Shell Development Co); and Pay-Off@ (American Cyanamid).

RESULTS

NO-CHOICE TESTS
At 50 ppm all pyrethroids were effective feeding deterrents (Table 1).
Reduction of leaf area consumed ranged from 92.5% (Pydrin@) to 55%
(Pounce).
At 5 ppm (Table 2) the feeding ratios increased 2 to 6 fold over
those at 50 ppm, indicating a reduction in the protection by the pyrethroids
when used at lower concentrations. Reduction of leaf area consumed ranged
from 82.5% (permethrin [FMC]) to 7.2% (Pounce@). Pounce was not
an effective feeding deterrent at this concentration.

TWO-CHOICE TESTS
At 50 ppm all of the pyrethroids were effective feeding deterrents
(Table 3). Reduction of leaf area consumed ranged from 97.7% (cyper-
methrin [ICI]) to 83.9% (Ammo@).

TABLE 1. FEEDING DETERRENCE OF NINE SYNTHETIC PYRETHROIDS AT 50
PPM IN NO-CHOICE TESTS ON 3RD INSTAR FALL ARMYWORM.

Area (mm2)
Compound consumed ( SE) Feeding Ratiol

Pydrin@ 4.0 ( 1.6) 0.075a
cypermethrin (ICI) 4.3(0.5) 0.081a
Mavrik 4.5 ( 1.1) 0.084a
permethrin (FMC) 8.2 ( 1.7) 0.153a
cypermethrin (FMC) 8.8 ( 1.9) 0.166a
permethrin (ICI) 10.0 ( 0.7) 0.188a
Pay-Off@ 11.3 ( 1.6) 0.213a
Ammo 14.7 (1.9) 0.275a
Pounce 24.0 ( 7.6) 0.450b
control 53.3 (2.5) 1.000c

1Treated area consumed (mm2)/control area consumed (mm2). Numbers followed by a
common letter are not significantly different according to the SNK test (P=0.05).











Gist & Pless: Pyrethroids Deter Feeding


459


TABLE 2. FEEDING DETERRENCE OF NINE SYNTHETIC PYRETHROIDS AT 5 PPM
IN NO-CHOICE TESTS ON 3RD INSTAR FALL ARMYWORM.


Compound


Area (mm2)
consumed (-+ SE)


permethrin (FMC)
cypermethrin (ICI)
Pay-Off@
Pydrin
Ammo
permethrin (ICI)
cypermethrin (FMC)
Mavrik
Pounce
control


9.3 (-2.5)
10.5 ( 0.4)
13.0 ( 1.5)
14.3( 2.4)
16.3 ( 2.5)
20.8 ( +1.0)
21.8 ( 1.4)
27.7 ( 2.2)
49.5 ( 8.6)
53.3 ( 2.5)


Feeding Ratio1


0.175a
0.197a
0.244ab
0.269ab
0.306ab
0.391bc
0.410c
0.519c
0.928d
1.000d


'Treated area consumed (mm2)/control area consumed (mm2). Numbers followed by
a common letter are not significantly different according to the SNK test (P=0.05).
At 5 ppm (Table 4) the feeding ratios again were higher than at
50 ppm although the difference (averaging ca 2-fold) were not as great
as those in the no-choice tests. Reduction of leaf area consumed ranged
from 93.9% (cypermethrin [FMC1) to 55.0% (Pounce).

DISCUSSION

Chapman (1974) stated that effective feeding deterrents should have
3 main properties: (1) they should be persistent, (2) they should have no
harmful effects on non-target organisms, and (3) they should be trans-
located to untreated parts of the plant. The greater photostability of the
synthetic pyrethroids relative to the more commonly used classes of insecti-
cides is well documented (Breese 1977, Burt et al. 1977, Elliot et al. 1978).

TABLE 3. FEEDING DETERRENCE OF NINE SYNTHETIC PYRETHROIDS AT 50 PPM
IN 2-CHOICE TESTS ON 3RD INSTAR FALL ARMYWORM.

Area (mm2)
consumed1 ( SE)
Compound treated control Feeding ratio'

cypermethrin (ICI) 1.0(-0.5) 42.9(-+ 5.9) 0.023a
Pydrin 0.6 ( 0.3) 25.5 (- 6.4) 0.024a
cypermethrin (FMC) 1.0(0.4) 38.2(- 3.0) 0.026a
permethrin (FMC) 0.7(-0.2) 19.7(- 6.3) 0.035a
Pay-Off 4.7 (2.8) 77.8 (-21.7) 0.060a
Mavrik 1.7 ( 7.3) 22.2 ( 7.3) 0.077a
Pounce 4.6 ( 2.1) 58.6 ( 20.2) 0.078a
permethrin (ICI) 1.1(0.2) 9.3( 4.1) 0.118a
Ammo 5.6 (3.2) 34.8 (-10.5) 0.161a
control 74.5 ( 17.5) 1.000b

1Treated area consumed (mm2)/control area consumed (mm2). Numbers followed by
a common letter are not significantly different according to the SNK test (P=0.05).











460 Florida Entomologist 68 (3) September, 1985

TABLE 4. FEEDING DETERRENCE OF NINE SYNTHETIC PYRETHROIDS AT 5 PPM
IN 2-CHOICE TESTS ON 3RD INSTAR FALL ARMYWORM.

Area (mm2)
consumed1 ( SE)
Compound treated Control Feeding ratio'

cypermethrin (FMC) 1.7( 1.3) 27.7( 10.9) 0.061a
cypermethrin (ICI) 1.9 ( 1.4) 25.1 ( 3.4) 0.076a
Ammo 12.2 ( 7.8) 142.0 (-16.5) 0.086a
Pay-Off@ 8.5 (- 3.2) 93.6 (-15.2) 0.091a
Mavrik@ 10.6 ( 5.3) 75.3 ( 30.0) 0.141a
permethrin (ICI) 6.6 (- 1.8) 46.3 ( 29.6) 0.143a
permethrin (FMC) 22.1 (- 3.7) 130.4 (29.6) 0.169a
Pydrin 4.3 ( 1.4) 21.9 ( + 1.3) 0.196a
Pounce 44.4( 29.0) 96.8( 29.0) 0.450b
control -74.5 ( 17.5) 1.000c

'Treated area consumed (mm2)/control area consumed (mm2). Numbers followed by a
common letter are not significantly different according to the SNK test (P=0.05).

The pyrethroids have also been shown to have low toxicity to many
parasites and predators (Coats et al. 1979, Rajakulendran and Plapp 1982,
Wilkinson et al. 1979). Due to their low polarity, the pyrethroids are not
plant systemics; however, because the pyrethroids are toxicants as well
as feeding deterrents, the need for systemic activity of the deterrent is
reduced.
Feeding deterrents may provide indirect benefits. Irritant responses to
pyrethroid exposure, probably due to the excitorepellent effect of the chemi-
cal on insect tarsi (Metcalf and Metcalf 1975), often caused the insect
to drop from the plant, wander off the plant in a search for food, or starve
(Lange 1962, Wright 1967). This may explain the variation in amount of
control leaf area consumed in the 2-choice tests since a strong irritant re-
sponse to crawling over the pyrethroids would result in a disturbance of
feeding. In addition, differences in isomeric ratios of the permethrins and
cypermethrins may give varied results.
In this study the synthetic pyrethroids were effective feeding deterrents
for FAW at rates comparable to their LD,, values (Gist and Pless 1985a).
Feeding deterrent concentrations were also ovicidal as well as effective
ovipositional repellents (Gist and Pless 1985b). This combination of toxic
and repellent effects, along with greater field stability, reduced toxicities
to predators and parasites, and lower environmental health hazards makes
the pyrethroids possible insecticide choices for many pest management pro-
grams.

LITERATURE CITED
BREESE, M. H. The potential for pyrethroids as agricultural, veterinary,
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BURT, P. E., M. ELLIOTT, A. W. FARNHAM, N. F. JANES, P. H. NEEDHAM,
AND J. H. STEPHENSON. 1977. Evaluation of pyrethroids for insect
control. In Crop Protection Agents-Their Biological Evaluation.
N. R. McFarlane (ed.). Academic Press, London. P. 638.











Gist & Pless: Pyrethroids Deter Feeding


461


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three synthetic pyrethroids to eight coccinellids, an eulophid parasi-
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DETHIER, V. G. 1947. Chemical Insect Attractants and Repellents. Blackis-
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ELLIOT, M., N. F. JANES, AND C. POTTER. 1978. The future of pyrethroids
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GIST, G. L. AND C. D. PLESS. 1985a. Comparative toxicities of synthetic
pyrethroids on the fall armyworm, Spodoptera furgiperda. Fla. En-
tomol. 68: 312-315.
AND 1985b. Ovicidal activity and ovipositional
repellent properties of synthetic pyrethroids on the fall armyworm,
Spodoptera frugiperda. Ibid. 68: 462-466.
HALL, R. R. 1979. Effects of synthetic pyrethroids on major insect and
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LANG, W. H. 1962. Antifeeding compounds: Insect control by starvation.
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METCALF, R. L. AND R. A. METCALF. 1975. Attractants, repellents, and
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MUNAKATA, K. 1970. Insect antifeedants in plants. In Control of Insect Be-
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PEDIGO, L. P. 1975. Insect threats and challenges to Iowa's agroecosystems.
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RAJAKULENDRAN, S. V. AND F. W. PLAPP, JR. 1982. Comparative toxicities
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predator, Chrysopa carnea. J. Econ. Entomol. 75: 769-772.
RUSCOE, C. N. E. 1977. The new NRDC pyrethroids as agricultural insecti-
cides. Pestic. Sci. 8: 236-242.
TAN, K. H. 1981. Antifeeding effect of cypermethrin and permethrin at
sub-lethal levels against Pieris brassicae larvae. Ibid. 12: 619-626.
WADA, K. AND K. MUNAKATA. 1968. Naturally occurring insect control
chemicals. J. Agric. Food Chem. 16: 471-474.
WILKINSON, J. D., K. D. BIEVER, AND C. N. IGNOFFO. 1979. Synthetic pyre-
throids and organophosphate insecticides against the parasitoid
Apantheles marginiventris and the predators Geocoris punctipes,
Hippodamia covergens, and Podisus maculiventris. J. Econ. Entomol.
72: 473-475.
WRIGHT, D. P., JR. 1967. Antifeedants In Pest Control. W. D. Kilgore and
R. L. Doutt (eds.). Academic Press, New York. P. 206.
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strains of fall armyworm larvae on carbaryl treated surfaces. J. Econ.
Entomol. 72: 202-203.




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