Title: Florida Entomologist
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00098813/00062
 Material Information
Title: Florida Entomologist
Physical Description: Serial
Creator: Florida Entomological Society
Publisher: Florida Entomological Society
Place of Publication: Winter Haven, Fla.
Publication Date: 1992
Copyright Date: 1917
Subject: Florida Entomological Society
Entomology -- Periodicals
Insects -- Florida
Insects -- Florida -- Periodicals
Insects -- Periodicals
General Note: Eigenfactor: Florida Entomologist: http://www.bioone.org/doi/full/10.1653/024.092.0401
 Record Information
Bibliographic ID: UF00098813
Volume ID: VID00062
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: Open Access

Full Text

(ISSN 0015-4040)


(An International Journal for the Americas)

Volume 75, No. 1 March, 1992


Announcement- 75th Annual Meeting ..................................................... i


FRANK, J. H., AND E. D. McCOY-Introduction To The Behavioral Ecology of
Immigration. The Immigration of Insects to Florida, With a Tabulation of
Records Published Since 1970 ........................................................... 1
NADEL, H.-Escapees and Accomplices: The Naturalization of Exotic Ficus and
Their Associated Faunas in Florida ................................................ 29
KOPTUR, S.-Plants with Extrafloral Nectaries and Ants in Everglades Habitats 38
HALL, H. G.-DNA Studies Reveal Processes Involved in the Spread of New
World African Honeybees .......................................... .............. 51
HENGEVELD, R.-Potential and Limitations of Predicting Invasion Rates ...... 60
ALLEN, J. C., AND Y. YANG-Functional Response, Reproductive Function and
Movement Rate of a Grazing Herbivore: The Citrus Rust Mite on the Orange 72

Research Reports

HODKINSON, I. D.-New Genus ofPsyllid (Homoptera: Psylloidea: Aphalaridae)
From Florida .................................. ........................................ 84
FLOWERS, R. W., AND R. T. YAMAMOTO-Feeding on Non-Host Plants by Par-
tially Maxillectomized Tobacco Hornworms (Lepidoptera: Sphingidae) ... 89
SPINELLI, G. R., AND W. W. WIRTH-New Records and Synonymy in Patago-
nian Atrichopogon (Diptera: Ceratopogonidae) .................................... 93
IBANEZ-BERNAL, S.-Two New Species of Moth-Flies, Genus Psychoda Latreille,
From Northern Puebla, Mexico (Diptera: Psychodidae) ....................... 97
DARLINGTON, J. P. E. C.-Survey of Termites in Guadeloupe, Lesser Antilles
(Isoptera: Kalotermitidae) .............................................................. 104
ATKINSON, T. H., J. R. MANGOLD, AND P. G. KOEHLER-TwO Neotropical Cock-
roaches of the Genus Ischnoptera (Dictyoptera: Blatellidae) Established in
F lorida ........................................... ........................................ 109
SCHUSTER, D. J., AND J. F. PRICE-Seedling Feeding Damage and Preference
of Scapteriscus spp. Mole Crickets (Orthoptera: Gryllotalpidae) Associated
with Horticultural Crops in West-Central Florida ............................... 115
KRING, J. B., AND D. J. SCHUSTER-Management of Insects on Pepper and
Tomato with UV-Reflective Mulches ................................................ 119
STILING, P., A. M. Rossi, D. R. STRONG, AND D. M. JOHNSON-Life History
and Parasites ofAsphonodylia borrichiae (Diptera: Cecidomyiidae) A Gall
M aker on Borrichia frutescens ......................................................... 130

Continued on Back Cover

Published by The Florida Entomological Society


President ........................... .. ... ..... .................. J. L. Knapp
President-E lect ........................................................................ D. F. W illiams
Vice-President ............................................................................. J. E Pena
Secretary ..................... . .... ...................... D. G. Hall
Treasurer .............................................................. ................... A. C. Knapp
Other Members of the Executive Committee
J. F. Price J. E. Pefia J. R. Cassani
J. R. McLaughlin O. Liburo F. Oi

J. R. McLaughlin, USDA/ARS, Gainesville, FL ..................................... Editor
Associate Editors
Agricultural, Extension, & Regulatory Entomology
James R. Brown-Disease Vector Ecology & Control Center, NAS, Jacksonville, FL
Richard K. Jansson-Tropical Research & Education Center, Homestead, FL
Michael G. Waldvogel-North Carolina State University, Raleigh, NC
Stephen B. Bambara-North Carolina State University, Raleigh, NC
Biological Control & Pathology
Ronald M. Weseloh-Connecticut Agricultural Experiment Sta., New Haven, CT
Book Reviews
J. Howard Frank-University of Florida, Gainesville
Chemical Ecology, Physiology, Biochemistry
Louis B. Bjostad--Colorado State University, Fort Collins, CO
Ecology & Behavior
Theodore E. Burk-Creighton University, Omaha, NE
John H. Brower-Stored Product Insects Research Laboratory, Savannah, GA
Forum & Symposia
Carl S. Barfield-University of Florida, Gainesville
Genetics & Molecular Biology
Sudhir K. Narang-Bioscience Research Laboratory, Fargo, ND
Medical & Veterinary Entomology
Arshad Ali-Central Florida Research & Education Center, Sanford, FL
J. E. Pefia-Tropical Research & Education Center, Homestead, FL
Systematics, Morphology, and Evolution
Michael D. Hubbard-Florida A&M University, Tallahassee
Howard V. Weems, Jr.-Florida State Collection of Arthropods, Gainesville
Willis W. Wirth-Florida State Collection of Arthropods
Business M manager ....................................................................... A. C. Knapp
FLORIDA ENTOMOLOGIST is issued quarterly-March, June, September, and De-
cember. Subscription price to non-members is $30 per year in advance, $7.50 per copy;
institutional rate is $30 per year. Membership in the Florida Entomological Society,
including subscription to Florida Entomologist, is $25 per year for regular membership
and $10 per year for students.
Inquiries regarding membership and subscriptions should be addressed to the Busi-
ness Manager, 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 in Winter Haven, FL.
Manuscripts from all areas of the discipline of entomology are accepted for consider-
ation. At least one author must be a member of the Florida Entomological Society.
Please consult "Instructions to Authors" on the inside back cover.
This issue mailed March 31, 1992


The 75th annual meeting of the Florida Entomological Society will be held August
10-12, 1992 at the Indian River Plantation Resort and Conference Center, 555 N.E.
Ocean Boulevard, Hutchinson Island, Stuart, FL 34996 (407-225-3700) (FAX 407-225-
0003). Registration forms and information will be mailed to members and will appear
in the Newsletter.


The deadline for submission of papers and posters for the 75th annual meeting of
the Florida Entomological Society is May 15, 1992. The meeting format will be similar
to that in the past with eight minutes allotted for presentation of oral papers (with two
minutes for discussion) and separate sessions for members who elect to present a Poster
Exhibit. There will be student paper and poster sessions with awards as in previous
years. Students participating in the judged sessions must be members of the Society
and registered for the meeting. Inquiries should be directed to:

Jorge E. Pefia
Program Committee, FES
University of Florida
Tropical Research and Education Center
18905 SW 280th Street
Homestead, FL 33031
(305) 246-7048 or -6340

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Insect Behavioral Ecology '91 Frank & McCoy

Introduction To


'Entomology & Nematology Department
University of Florida
Gainesville, Florida 32611-0740

2Department of Biology and Center for Urban Ecology
University of South Florida
Tampa, Florida 33620-5150


A table is presented of the recent (published since 1970) records of presence of exotic
insects in Florida. The table includes 271 species, 209 of which were first collected in
Florida after 1970. We assumed that these insects are immigrants, and we calculated
mean rates of 7.7 and 12.0 immigrations per year in the 1970s and 1980s, respectively.
We judge that about 20 recent immigrants are, or could become, major pests in Florida.
At least 8% of the species appear to have arrived as stowaways, and many of the actual
or potential major pests are among them. Immigrant species are not equitably distributed
among orders or among families within orders. Species in the orders Lepidoptera and
Coleoptera are especially well-represented. By far the largest proportion of recent insect
immigrants to Florida comes from the Neotropical region. Our results suggest further
information that is needed to answer questions about the invasibility of Florida.


Se present una tabla con los registros recientes (publicados desde 1970) de la presen-
cia de insects ex6ticos en Florida. Esta tabla incluye 271 species, 209 de las cuales
fueron colectadas por primera vez en Florida despu6s de 1970. Asumimos que estos
insects son inmigrantes y hemos calculado las ratas promedias entire 7.7 a 12.0 inmig-
raciones por aflo en las decades de 1970 y 1980, respectivamente. Juzgamos que cerca
de 20 inmigrantes recientes, son o pueden volverse, las mayores plagas en Florida. Al
menos 8% de la species parecen haber arribado como polizontes, y muchas de las plagas
mayores, actuales y potenciales se encuentran en este porcentaje. Las species inmig-
rantes no estan distribuidas equitativamente entire ordenes o entire families en cada
orden. Las species del orden Lepidoptera estan bien representadas. Una mayor prop-
orci6n de insects inmigrantes a Florida proviene de la region del Neotropico. Nuestros
resultados sugieren que se necesita una major informaci6n para contestar preguntas
sobre esta invasion de plagas a Florida.

The recent (documented since 1970) records of immigration of insect taxa to Florida
have not been tabulated previously. Here, we provide such a tabulation. The value of
this exercise is to discover patterns that may provide insight into the processes of
immigration, colonization, and local extinction by insects of diverse behaviors (cf. Sailer
1983, Simberloff 1986). This is the behavioral ecology of invasion.

Florida Entomologist 75(1)

What is an immigrant insect?

Whitehead & Wheeler (1990), despite the anthropocentric nature of the concept,
decided that for practical reasons they could define a native insect species as one men-
tioned (as native) in early literature. Conversely, an immigrant insect species is one
whose arrival is detectable now by lack of mention of it in early literature, but mention
of it in later literature. The earliest collection date of museum-preserved specimens of
a species might be used as the date of immigration for species thought to have immigrated.
We accept that Whitehead & Wheeler's (1990) method is reasonable for detection of
immigration of pests (such as mosquitoes, mealybugs, scale insects, and whiteflies) and
groups with popular appeal (such as butterflies). We also accept that it may be useful
generally in the northeastern part of North America, where insect faunal lists were
reasonably complete in the nineteenth century, and where immigrant insects have come
from other, distant, continents. We have no confidence, however, that its application
in Florida, especially southern Florida, will distinguish new immigrants, mainly from
the nearby Neotropics, from those that have occupied Florida for hundreds or even
thousands of years. We believe this conclusion will be especially true among species of
little economic concern or popular appeal. One major difficulty is that lists and other
knowledge of the insect fauna of Florida still are fragmentary. As is evident from our
tabulation (see below), there is a lag time between discovery of specimens of an unre-
corded species and mention of the discovery in the literature. For species of neither
economic concern nor popular appeal, this lag may exceed 100 years (see, for example,
Conoderus rufidens).
We have no easy solution to these problems. For most Neotropical insect species for
which Florida is now part of their range, we cannot tell whether the founding members
of Florida populations arrived 100 or 1,000 years ago, or indeed whether immigration
and colonization took place intermittently over the past several thousands of years.
[Although Deyrup et al. (1988) and Deyrup (in press) attempted to distinguish between
new immigrants and old-established immigrants (among ants of the Florida Keys), no
generally applicable method for the purpose has emerged, so we have not tried to
emulate their example among the immigrants that we discuss. We invite readers to use
our data to develop generally-applicable methods.] Answers to some of the questions
demand more complete knowledge of the systematics and distribution of insects, espe-
cially for the more obscure groups, in Florida and the Greater Antilles, especially Cuba.
Such studies are progressing, although slowly, and with regrettably poor contact between
entomologists in Cuba and Florida. Answers to others of the questions demand compara-
tive studies of the genetics of populations of such insects in Florida and the Greater
Antilles, as well as measurement of overseas dispersal by use of traps at sea. We have
no knowledge that such studies are in progress.

To construct our tabulation of immigrants, we searched published records (of presence
of exotic insects in Florida), and then verified the resulting list of records by consulting
authorities on the taxa included. We believe that our procedure has produced a reason-
ably-thorough tabulation but, of course, we cannot guarantee its completeness. We chose
in advance to exclude four kinds of records from our tabulation: (1) those involving
introductions (sensu Frank & McCoy 1990); (2) those published before 1971 (to make
the task manageable); (3) those of species thought to be native to North America, north
of Mexico, even if that part of their range is small (again, to make the task manageable);
and (4) those of species we dubbed taxonomicc immigrants" species whose "immigration"
to Florida was a result of improper identification. Examples of the second kind of record

-March, 1992

Insect Behavioral Ecology '91 Frank & McCoy

are two moths, Eulepidotis metamorpha Dyar and Metalectra geminicincta Schaus,
that were reported in 1991 as new to Florida (Dickel 1991), and would have been included
in our tabulation had they not, in fact, been reported prior to 1971. An example of the
third kind of record is an ant, Pseudomyrmex mexicanus Roger, found ca. 1960 (Whit-
comb et al. 1972) which would have been included in our tabulation if Texas had not
been part of its native range. Examples of the fourth kind of record follow.
A cockroach determined as Ischnoptera bergrothi (Griffini) later proved to have been
misidentified (Atkinson et al. 1990b). A coccinellid determined as Azya luteipes Mulsant
was found in 1975, but later it proved to be A. orbigera Mulsant (Woodruff & Sailer
1977, Gordon 1985). A weevil determined as Anthonomus flavus Boheman was found
in 1972 (Stegmaier & Burke 1974, Mead 1976a), but later it proved to be an undescribed
species, A. malpighiae Clark & Burke, believed to be native to Florida (Clark & Burke
1985). A weevil, Cyrtobagous salviniae Calder & Sands, was described from South
America, but part of the type series was from Florida (Calder & Sands 1985); Florida
specimens collected before 1966 had been misidentified as C. singularis Hustache, a
name which should thus be removed from Florida lists (Kissinger 1966).
A scarab thought initially to be Ataenius brevinotus Chapin was described later as
a new species, A. sciurus Cartwright, with type locality in Florida (Woodruff 1973,
Cartwright 1974). A scolytid found in 1986 and determined as being near to Araptus
accinctus Wood was identified later as A. dentifrons Wood (Deyrup & Atkinson 1987,
Atkinson et al. 1991). Mealybugs collected in the early 1960s and mentioned in Tri-Ology
as Rhizoecus cacticans Hambleton and R. leucosomus (Cockerell) were respectively R.
simplex (Hambleton) and R. cacticans (Hambleton 1973). A moth reported as Em-
pyreuma pugione L. (Adams & Goss 1978) was identified later as E. affinis Rothschild.
A butterfly reported as Anartia lytrea (Godart) (Anderson 1974) was later identified
as A. chrysopelea Hiibner. A thrips determined as Scirtothrips citri (Moulton) later was
found to be not that species but still has not been identified, although it is believed to
be of exotic origin (Flowers 1989).
Doubtless, all or almost all of the 70 species of immigrant insects reported from
northeastern North America by Hoebeke & Wheeler (1983) entered the continent as
stowaways. The list of immigrant insects reported for Florida (Table 1) does not so
readily reveal which species arrived as stowaways and which by other means, such as
flight, wind dispersal, or rafting. One way of attempting to distinguish is to assume
that all immigrant species reported for Florida whose names occur on the USDA-APHIS
list of interceptions managed to arrive in Florida as stowaways. [Insects discovered on
imported plants and plant materials at U.S. seaports and airports by USDA-APHIS
inspectors are treated as pests and are recorded and destroyed. This is done under the
Plant Quarantine and Plant Pest Acts to protect agriculture, horticulture, and other
human interests from damage by exotic insects (Sailer 1978, 1983). USDA-APHIS pub-
lishes annually an impressively long list of insects thus intercepted.] We used this
assumption with the fiscal year 1980 list of > 18,000 interceptions (PITSS 1982) and
annotated our list of immigrant insects accordingly with the letters "PS" to indicate a
potential stowaway.


Table 1 includes 271 exotic species, 209 of which were first collected in Florida after
1970. (Note that year of collection was not stated for a number of species which we
reduced to 15 by questioning authorities.) Thirteen orders of insects are represented in
our tabulation. Seven orders, Coleoptera, Diptera, Hemiptera, Homoptera, Hymenopt-
era, Lepidoptera, and Thysanoptera, together account for more than 90% of the immi-
grant species. This result is not surprising, as these seven include the most species-rich

Florida Entomologist 75(1)


Blattella asahinai Mizukubo, found in 1986, from Asia, named "Asian cockroach" (Roth
1986, Atkinson et al. 1990a).
Chorisoneura parishi Rehn, found in 1953, from South America (Atkinson et al. 1990a).
Epilampra maya Rehn, found in 1982 in and around houses, from Central America
(Nickle & Sibson 1984, Atkinson et al. 1990a).
Neoblattella detersa (Walker), found ca. 1985, from the Greater Antilles (Peck & Be-
ninger 1989).
Symploce morse Hebard, found ca. 1985, from Haiti or the Bahamas (Peck & Beninger
Myrmecoblatta wheeleri Hebard, found in 1983, from Central America (Deyrup & Fisk
Anthicus crinitus LaFerte, found in 1964, from Africa or Asia (Werner 1972).
Heterobostrychus hamatipennis (Lesne), found in 1988, from India via North Carolina
(Mead 1988).
Xylopsocus capucinus (Fabricius), found in 1978 on cassava, from Asia perhaps via
Africa or South America (Woodruff et al. 1978). PS
Acanthoscelides quadridentatus (Schaeffer), found in 1986, is a potential biocontrol
agent for Mimosa pigra L. (Leguminosae), from Central America (Center &
Kipker 1991).
Sennius latealbonotatus (Picard), year of find not stated, from Brazil, perhaps not
established (Johnson & Kingsolver 1973).
Eburia cinereopilosa Fisher, found in 1975, from Cuba (Turnbow & Hovore 1979).
Empogonius annulicornis Fisher, found in 1975, from Cuba (Hovore et al. 1978).
Heterops dimidiata (Chevrolat), found in 1975, from the Caribbean (Hovore et al. 1978).
Microtheca ochroloma StAl, found in 1972 on watercress at a nursery, from South
America (Woodruff 1974), earlier established in Alabama (Chamberlin & Tippins
Ophraella dilatipennis (Jacoby), found in 1975, from Central America (White 1979).
Azya orbigera Mulsant, found in 1975, a scale-insect predator, from the Neotropical
region (Woodruff & Sailer 1977, Gordon 1985).
Decadiomus bahamicus (Casey), found in 1991, from the Caribbean, the Bahamas, or
Bermuda (Bennett & Gordon 1991).
Diomus roseicollis Mulsant, year of find not stated, from Cuba (Gordon 1976).
Bitoma brevipes (Sharp), found in 1916, from Central America (Stephan 1989).
Cytepistomus castaneus (Roelofs), found in 1984, from Japan perhaps via northern USA
(Mead 1984).

March, 1992

Insect Behavioral Ecology '91 Frank & McCoy

Elaeidobius subvittatus (Faust), found in 1985 on flowers of African oil palm, from
Africa, important in pollination of the oil palm (O'Brien & Woodruff 1986).
Hypera postica (Gyllenhal), found in 1970, from Europe via California or Maryland,
called alfalfa weevil (Munir & Sailer 1984).
Metamasius callizona (Chevrolat), found in 1989 on Tillandsia (Bromeliaceae) in a
nursery, from southern Mexico or Central America (O'Brien & Thomas 1990,
O'Brien et al, 1990, Frank & Thomas 1991). PS
Metamasius hemipterus (L.), found in 1984 on cassava, from the Neotropical region,
an eradication attempt was ineffective (Woodruff & Baranowski 1985, O'Brien &
Thomas 1990). PS
Metamasius monilis Vaurie, found in 1972 on orchids in a greenhouse, probably eradi-
cated, from South America (Woodruff 1973a, Mead 1976a).
Microlarinus lypriformis Wollaston, found in 1971 on puncturevine, from India or the
Mediterranean region perhaps via the western USA or the Caribbean, into both
of which areas it was introduced (Stegmaier 1973b, Mead 1974).
Myctides imberbis Lea, found in 1976 on rose-apple, from Australia (Woodruff 1977).
Nicentrus saccharinus Marshall, found in 1972 on various grasses, from the Neotropical
region (Woodruff 1972, Mead 1974).
Rhopalotria mollis (Sharp), found in 1986 on Zamia (Cycadaceae) from Mexico (Wibmer
& O'Brien 1989).
Trachyphloeosoma advena Zimmerman, found in 1976, perhaps from Asia perhaps via
Hawaii (O'Brien 1984).
Conoderus bifoveatus (Palisot de Beauvois), found in 1887, from the Caribbean (Becker
Conoderus rufidens (F.), found in 1875, from the Caribbean (Becker 1975).
Laemophloeus bituberculatus Reitter, found in 1963, from Puerto Rico (Thomas 1979).
Laemophloeus permixtus Grouvelle, year of find not stated, from the Caribbean (Thomas
& Peck 1991).
Laemophloeus quinquearticulatus Grouvelle, year of find not stated, from South
America (Thomas & Peck 1991).
Laemophloeus suturalis Reitter, year of find not stated, From Central America or
South America (Thomas & Peck 1991).
Placonotus politissimus (Wollaston), found in 1960, from the Caribbean or South
America (Thomas 1984).
Minthea rugicollis (Walker), found in 1987, from the Pacific (Mead 1987b). PS
Colopterus posticus (Erichson), found in 1987 on fallen fruits of loquat, from the Neo-
tropical region (Habeck et al. 1989b).
Aphodius granarius (L.), found in 1958, from Europe probably via northern USA (Wood-
ruff 1973b).
Ataenius havanensis Balthasar, found in 1963, from the Greater Antilles (Woodruff
Onthophagus gazella (Fabricius), found in 1983, from Africa, was released in Georgia
in 1975 to assist in decomposition of cattle dung (Fincher et al. 1983, Mead 1983c).
Onthophagus taurus Schreber, found in 1971, from Europe or North Africa (Fincher &
Woodruff 1975).
Phyllophaga puberula (DuVal), found in 1960, from Cuba (Woodruff & Beck 1989).
Araptus dentifrons Wood, found in 1986, from Mexico (Deyrup & Atkinson 1987, Atkin-
son et al. 1991).

Florida Entomologist 75(1)

TABLE 1. (Continued)

Coccotrypes dactyliperda (F.), found in 1977, cosmopolitan (Atkinson et al. 1991).
Coccotrypes robustus Eichhoff, found in 1985, from the Old World perhaps via the
Greater Antilles (Atkinson et al. 1991).
Coccotrypes vulgaris (Eggers), found in 1985, from Asia or the Pacific (Atkinson et al.
Pseudothysanoes securigerus (Blackman), found in 1986, from the Greater Antilles (At-
kinson et al. 1991).
Theoborus solitariceps (Schedl), found in 1986, from the Caribbean or Central America
(Atkinson et al. 1991).
Trischidias exigua Wood, found in 1986, from Mexico (Deyrup 1987).
Xyleborus atratus Eichhoff, year of find not stated, from Asia perhaps via southeastern
USA (Atkinson et al. 1991).
Xylosandrus crassiusculus (Motschulsky), found in 1983, from Asia via South Carolina
(Chapin & Oliver 1986, Deyrup & Atkinson 1987, Atkinson et al. 1988).
Monanus concinnulus (Walker), year of find not stated, pantropical (Thomas & Peck
Nausibius sahlbergi Grouvelle, found in 1949, from South America (Thomas and Peck
Oryzaephilus acuminatus Halstead, found in 1983 at a nursery on seeds ofneem imported
from India, believed eradicated (Thomas & Woodruff 1983).
Silvanoprus scuticollis (Walker), found in 1960, pantropical (Thomas 1979).
Silvanus lewisi Reitter, year of find not stated, from the Old World tropics (Thomas
and Peck 1991).
Silvanus recticollis Reitter, found in 1975, from the Old World (Thomas 1979).
Aleochara puberula Klug, found in 1975, pantropical and subtropical (Klimaszewski
Atheta coriaria (Kraatz), found in 1980, from Europe (Frank 1981).
Cafius caribeanus Bierig, found in 1984, from the Caribbean (Frank 1985).
Cephaloxynum rambouseki Bierig, found in 1983, from Cuba (Newton 1986).
Coenonica puncticollis Kraatz, found in 1980, pantropical (Frank & Thomas 1984).
Gabronthus mgogoricus Tottenham, found in 1972, from Africa (Frank 1983).
Heterota plumbea (Waterhouse), found in 1973, from Europe (Frank & Thomas 1984).
Myrmecosaurus ferrugineus Bruch, found in 1970 in nests of Solenopsis invicta Buren
(Hymenoptera: Formicidae), itself an adventive species, from Argentina (Frank
Oligota chrysopyga Kraatz, found in 1973, pantropical (Frank 1975).
Oligota testaceorufa Bernhauer, found ca. 1875, from the Lesser Antilles (Frank 1975).
Oligota zonata Bierig, found in 1973, from the Greater Antilles (Frank 1975).
Oxytelus incisus Motschulsky, found in 1969, pantropical (Frank & Thomas 1981).
Philonthus ventralis (Gravenhorst), found in 1976, from the Old World (Frank 1983).
Platystethus spiculus Erichson, found in 1975, from the Neotropical region (Frank 1976).
Poecilocrypticus formicophilus Gebien, found in 1978, from South America (Steiner
Melanagromyza caerulea (Malloch), found in 1967 on Ipomoea spp. (Solanaceae), from
the Caribbean, Central America, or Mexico (Spencer & Stegmaier 1973).
Braula coeca Nitzsch, found in 1983 on Apis mellifera L., the only known host, which
is from the Old World perhaps via northern USA (Mead 1983a).

March, 1992

Insect Behavioral Ecology '91 Frank & McCoy

Chrysomya sp. prob. rufifacies (Macquart), found in 1991, from Europe (Mead 1991b).
Olesicoccus coccidivora (Felt), found in 1971 as parasitoid of Saissetia and Pulvinaria
scales on Barbados cherry, from South America (Mead 1974).
Culicoides jamaicensis Edwards, found in 1982, from the Caribbean (Wilkening et al.
Forcipomyia oligarthra Saunders, found in 1927, from the Pacific or South America (de
Meillon & Wirth 1979).
Monohelea multilineata (Lutz), found in 1963, from the Neotropical region (Wilkening
et al. 1985).
Goeldichironomus amazonicus (Fittkau), found in 1977, reported under name Siolimyia
amazonica Fittkau, from the Bahamas, Central America, or South America,
probably brought to Florida as eggs or larvae on aquarium plants or other aquatic
plants (Wirth 1979).
Aedes albopictus (Skuse), found in 1986, probably from Japan via Texas, named "Asian
tiger mosquito" (Peacock et al. 1988).
Aedes bahamensis Berlin, found in 1988, from the Bahamas (Pafume et al. 1988).
Neosilba perezi (Romero & Ruppel), found in 1973 on cassava, from the Caribbean
(Waddill & Weems 1978).
Oestrus ovis L., found in 1978, from the Old World (Mead 1978b).
Beckerina setifrons Borgmeier, found in 1939, from Cuba (Barnes 1991).
Coniceromyia latimana (Malloch), found in 1972, from the Caribbean (Barnes 1991).
Megaselia luteicauda (Borgmeier), found in 1971, from the Neotropical region (Barnes
Anastrepha ludens (Loew), found in 1972 in a trap, but further trapping failed to
produce more, called Mexican fruit fly (Mead 1974). PS
Ceratitis capitata (Wiedemann), found on several occasions, each time believed eradi-
cated, called Mediterranean fruit fly or "medfly" (Weems 1981, Mead 1984, 1986,
1990a). PS
Paratriphleps laeviusculus Champion, found in 1966, on Manilkara zapotilla (Jacq.)
(Sapotaceae), from the Caribbean and Central America (Bacheler & Baranowski
Leptoglossus concolor Walker, found in 1954 on Comptonia sp. (Myricaceae), from
Central America (Mead 1971, Baranowski & Slater 1986).
Sethenira ferruginea Stil, found in 1927, from the Neotropical region (Baranowski &
Slater 1986).
Antillocoris pallidus (Uhler), found in 1968, from the Neotropical region (Slater &
Baranowski 1990).

Florida Entomologist 75(1)

TABLE 1. (Continued)

Cistalia signoreti Stal, found in 1969, from the Caribbean and South America (Slater
& Baranowski 1973, 1990).
Craspeduchus pulchellus (F.), found in 1961 on Corchorus siliquosus L. (Tiliaceae),
from the Neotropical region (Baranowski & Slater 1975).
Nysius scutellatus Dallas, found in 1951, from the Caribbean (Ashlock 1977, Slater &
Baranowski 1990).
Oncopeltus aulicus (Fab.), found before 1976, from the Caribbean (Slater & Baranowski
Oncopeltus cingulifer StAl, found in 1969, from the Caribbean, Central America, or
South America (Slater & Baranowski 1990).
Ozophora divaricata Barber, found in 1972, from the Caribbean (Baranowski & Slater
Paragonatas costaricensis (Distant), found in 1957, from Central America, Mexico, or
South America (Slater & Baranowski 1990).
Paragonatas divergens (Distant), found in 1960 on Baccharis halimifolia L. (Com-
positae), from the Caribbean or Central America (Palmer & Bennett 1988).
Caulotops distant Reuter, found in 1984 on yucca, from Costa Rica (Henry 1985).
Ceratocapsus nigropiceus Reuter, found in 1981 on Batis maritima L. (Bataceae), from
Jamaica (Henry & Wheeler 1982).
Hyalopsallus diaphanus (Reuter), found in 1979 on Crotalaria incana L. (Fabaceae),
from the Greater Antilles (Henry & Wheeler 1982).
Jobertus chrysolectrus Distant, found in 1980 on Ipomoea alba L. (Solanaceae), from
the Greater Antilles and Mexico (Henry & Wheeler 1982).
Paracarnus cubanus Bruner, found in 1981 on avocado, from the Greater Antilles (Henry
& Wheeler 1982).
Paramixia carmelitana (Carvalho), found in 1981 by sweeping grasses and weeds, from
Puerto Rico or South America (Henry & Wheeler 1982).
Prepops cruciferus (Berg), found in 1989, from the Neotropical region (Henry 1990).
Probus hyalina Maldonado, found in 1980 on Parthenium hysterophorus L. (Com-
positae), from Puerto Rico (Henry & Wheeler 1982).
Rhinacloa pallidipes Maldonado, found in 1983, from Puerto Rico (Henry 1984).
Euschistus acuminatus Walker, found in 1980 on jessamine, from the Caribbean
(Baranowski et al. 1983).
Oebalus grisescens (Sailer), found in 1983 on grass, from South America (Mead 1983d).
Leptodictya tabida (Herrich-Schaeffer), found in 1990 on sugarcane, from Central
America or South America, called sugarcane lace bug (Hall 1991).
Aleurocanthus woglumi Ashby, found in 1976, from Asia perhaps via the Caribbean
or Central America; an earlier establishment of this species in 1934 was eradicated
by 1937, called citrus blackfly (Hart et al. 1978). PS
Aleurotulus anthuricola Nakahara, found in 1978, from South America (Mead 1978a,
Nakahara 1989).
Bemisia berbericola (Cockerell), found in 1979 on wax myrtle, from South America via
western USA (Denmark 1982).
Dialeurodes kirkaldyi (Kotinsky), found in 1972 on Morinda citrifolia L. (Rubiaceae),
from Asia but now distributed widely (Nguyen & Hamon 1989).
Parabemisia myricae (Kuwana), found in 1984 on snowberry, from eastern Asia, also
known from Venezuela and California (Hamon 1986a, Hamon et al. 1990).
Pealius hibisci (Kotinsky), found in 1971 on cassava, from Asia (Mead 1974).

March, 1992

Insect Behavioral Ecology '91 Frank & McCoy

Melanaphis sacchari (Zehnter), found in 1977 on sugarcane, pantropical and subtropical
(Denmark 1982, 1988).
Trichosiphonaphis polygoni (van der Goot), found in 1974 on Polygonum (Polygonaceae),
from Asia (Smith & Denmark 1982).
Dikrella cedrelae (Oman), found in 1983 on Cordia sebestena L. (Ehretiaceae), from the
Greater Antilles (Mead 1983c).
Idona sexmaculata (DeLong), found in 1983 on Hibiscus tiliaceus L. (Malvaceae), from
the Caribbean (Mead 1983b).
Protalebra nexa McAtee, found in 1983 on Cordia sebestena L. (Ehretiaceae), from the
Caribbean (Mead 1983b).
Unerus colonus (Uhler), found in 1983, from the Caribbean (Mead 1983e).
Coccus capparidis (Green), found in 1974 on citrus, from the Neotropical region (Mead
1976a). PS
Philephedra tuberculosa Nakahara & Gill 1985, found in 1982 on ornamental trees,
from Central America or South America (Hamon 1986b, Pefia & McMillan 1986).
Delphacodes havanae Muir & Gifford, found in 1972, from the Greater Antilles, Central
America, or South America (Wilson 1984).
Delphacodes nigrifacies (Muir), found in 1966, from the Caribbean, Central America,
or South America (Anon. 1976).
Perkinsiella saccharicida Kirkaldy, found in 1982 on sugarcane, from Australia, called
sugarcane delphacid (Nguyen et al. 1984, Sosa 1985).
Aspidiotus tridentifer Ferris, found in 1986 on Zamia pumila L. (Cycadaceae), from
Mexico (Mead 1986).
Chortinaspis subchortina (Laing), found in 1972 on centipede grass, from Jamaica or
Panama (Mead 1976a).
Lepidosaphes laterochitinosa Green, found in 1987 on agloanema imported from the
Philippines, at a nursery, from southeastern Asia, perhaps eradicated (Mead
1987a). PS
Morganella longispina (Morgan), found in 1980 on oleander, from eastern Asia perhaps
via Haiti (Hamon 1981).
Oceanaspidiotus araucariae (Adachi & Fullaway), found in 1985 on Norfolk Island pine
at a nursery, from Hawaii, perhaps eradicated (Hamon 1985).
Opuntiaspis carinata (Cockerell), found in 1978 on Beaucarnea (Liliaceae) plants which
had been shipped 2-3 years earlier, from Mexico via Texas (Hamon 1978). PS
Parlatoria ziziphi (Lucas), found in 1985 on citrus, from eastern Asia probably via the
Caribbean, called black parlatoria scale (Mead 1985). PS
Pseudaonidia trilobitiformis (Green), found in 1972 on Ixora (Rubiaceae), pantropical
(Denmark 1982). PS
Dysmicoccus neobrevipes Beardsley, found in 1978 on Furcraea (Agavaceae), from the
Pacific (Denmark 1982). PS
Hypogeococcusfesterianus (Lizer & Trelles), found in 1984 infesting cacti imported from
Argentina at a nursery (Hamon 1984). PS
Rhizoecus americanus (Hambleton), found in 1959 on Dieffenbachia (Araceae) roots,
from the Caribbean or South America (Hambleton 1973).
Rhizoecus arabicus Hambleton, found in 1982 on a gesneriad, from Central America or
South America (Hamon 1982).
Rhizoecus cacticans Hambleton, found in 1963 on Mesembryanthemum (Mesembryan-
themaceae) and misidentified as R. leucosomus (Cockerrell), origin not stated
(Hambleton 1973).

10 Florida Entomologist 75(1) March, 1992

TABLE 1. (Continued)

Rhizoecus hibisci Kawai & Takagi, found in 1978 on a bromeliad, from Japan perhaps
via Puerto Rico (Denmark 1982).
Rhizoecus mexicanus (Hambleton), found in 1978 on Mammillaria (Cactaceae) from
Mexico (Hambleton 1979, Denmark 1982).
Rhizoecus simplex (Hambleton), found in 1961 on Neoregelia (Bromeliaceae) and misiden-
tified as R. cacticans, from South America (Hambleton 1973).
Saccharicoccus sacchari (Cockerell), found in 1944, pantropical (Mead 1980b).

Eupristina masoni Saunders, found in 1986 in fruits of banyan, from Asia (Stange &
Knight 1987, Nadel et al., this symposium).
Eupristina sp. nr. or altissima Balakrishnan & Abdurahian, found in 1987 in fruits
of lofty fig, from Asia (McKey 1989, Nadel et al., this symposium).
Parapristina verticillata (Waterston), found in 1986 in fruits of laurel fig, from Asia
perhaps via Hawaii (Stange & Knight 1987, Nadel et al., this symposium).
Eretmocerus sp., found in 1984 as parasitoid of Parabemisia myricae, apparently an
immigrant biocontrol agent (Hamon 1986a, Hamon et al. 1990).
Opius anastrephae Viereck, found in 1973 as parasitoid of Caribbean fruit fly, from the
Caribbean (Swanson 1978, 1982).
Arrhenophagus albitibiae Girault, found in 1985-1986 as parasitoid of Pseudaulacaspis
pentagon (Targioni) and P. cockerelli (Cooley) (Homoptera: Diaspididae), from
Asia (Ball & Stange 1979, Bennett & Noyes 1989).
Caenhomalopoda shikokuensis (Tachikawa), found in 1986 as parasitoid of Froggattiella
penicillata (Green) (Homoptera: Diaspididae), from Asia (Bennett & Noyes 1989).
Ooencyrtus chrysopae Crawford, found in 1976, from South America (Mead 1976c).
Aphelinus flaviventris Kurdjumov, found in 1967, captured by net, from Asia (Mead
Euderomphale vittata Dozier, found in 1985 as parasitoid of spiralling whitefly on coconut
and seagrape, from the Caribbean (Bennett & Noyes 1989).
Trichospilus diatraeae Cherian & Margabandhu, found in 1983 in a light trap and in
1985 as parasitoid of pupae of Epimecis detexta (Walker) (Lepidoptera: Geomet-
ridae), a pest of avocado, from Asia (Bennett et al. 1987).
Anochetus mayri Emery, found in 1986, origin not stated (Deyrup et al. 1989).
Epitritus hexamerus Brown, found in 1987 in leaf litter, from Asia (Deyrup 1988).
Gnamptogenys aculeaticoxae (Santschi), found in 1986, from South America (Deyrup
et al. 1989).
Leptothorax torrei (Aguayo), found in 1984, from Cuba (Deyrup et al. 1988).
Monomorium ebeninum Forel, found in 1986, from the Caribbean (Deyrup et al. 1988).
Paratrechina guatemalensis Forel, found in 1982, from Central America or South
America (Trager 1984).
Paratrechina pubens Forel, found in 1953, from the Caribbean (Trager 1984).
Quadristruma emmae (Emery), year of find not stated, pantropical (Smith 1979).
Smithistruma margaritae (Forel), found in 1986, from the Neotropical region (Deyrup
et al. 1989).
Solenopsis corticalis Forel, found in 1945, from Cuba (Deyrup et al. 1988).
Strumigenys lanuginosa Wheeler, found in 1987, from the Neotropical region (Deyrup
et al. 1989).

Insect Behavioral Ecology '91 Frank & McCoy

Strumigenys rogeri Emery, found in 1982, from Africa, perhaps via the Caribbean
(Deyrup & Trager 1984).
Strumigenys silvestrii Emery, found in 1967, from the Neotropical region (Johnson 1986).
Technomyrmex albipes (Fr. Smith), found in 1986 and perhaps eradicated, found again
in 1990, from Asia (Deyrup 1991).
Tetramorium caldarium (Roger), year of find not stated, from Africa (Bolton 1979).
Bathyplectus curculionis (Thomson), found in 1978, from Europe via California or New
Jersey, where it was released as a biocontrol agent for alfalfa weevil (Munir &
Sailer 1984, Grant & Lambdin 1990).
Carinodes havanensis (Cameron), found in 1959, from the Greater Antilles (Heinrich
Eiphosoma atrovittatum Cresson, found in 1945, from Cuba (Dasch 1979).
Eiphosoma nigrovittatum Cresson, found in 1956, from the Greater Antilles (Dasch
Neodiphyus flavivarius (Cresson), found in 1957, from Cuba (Heinrich 1987).
Chalicodoma lanata (F.), found in 1990, from the Old World (Mead 1990b).
Micranisa sp., found in 1986 in fruits of laurel fig, from Asia perhaps via Hawaii (Stange
& Knight 1987, Nadel et al., this symposium).
Odontofroggatia galili Wiebes, found in 1986 in fruits of laurel fig, from Asia perhaps
via Hawaii (Stange & Knight 1987).
Walkerella yashiroi (Ishii), found in 1986 in fruits of laurel fig, from Asia perhaps via
Hawaii (Stange & Knight 1987).
Liliacina diversipes (Kirby), found in 1987, from Mexico, Central America or South
America (Smith 1990).
Megastigmus transvaalensis (Hussey), found in 1988 in seeds of Brazilian peppertree,
from South Africa (Habeck et al. 1989a).
Philotrypesis emeryi Grandi, found in 1986 in fruits of laurel fig, from Asia perhaps via
Hawaii (Stange & Knight 1987).
Delta campaniforme (Fabricius), found in 1981, from Africa perhaps via Jamaica (Menke
& Stange 1986).
Zeta argillaceum (L.), found in 1975, from South America (Menke & Stange 1986).
Coptotermes formosanus Shiraki, found in 1980, from eastern Asia, named Formosan
subterranean termite (Mead 1980a, Thompson 1985, Koehler et al. 1991). PS
Empyreuma affinis Rothschild, found in 1978, from the Greater Antilles or the Bahamas,
larvae feed on oleander (Adams & Goss 1978).
Electrostrymon angelia (Hewitson), found in 1973, from Cuba (Anderson 1974, Miller
Strymon limenia (Hewitson), found in 1971, from the Caribbean (Anderson 1974).
Lymantria dispar (L.), found in 1971 at a trailer park, from Europe via northeastern
USA where it escaped from culture, called gypsy moth (Poucher 1974, Dixon &
Foltz 1985). PS

Florida Entomologist 75(1)

TABLE 1. (Continued)

Achaea ablunaris Walker, found in 1989, from South America (Dickel 1991).
Aglaonice hirtipalpis (Walker), found in 1984, from South America (Dickel 1991).
Anomis luridula GuenBe, found in 1989, from the Neotropical region (Dickel 1991).
Bleptina araealis (Hampson), found in 1986, from the Bahamas, probably established
earlier under the name "Nodaria" (Dickel 1991).
Callopistria jamaicensis (M6schler), found in 1987, from Jamaica (Dickel 1991).
Condica punctifera (Walker), found in 1978, from the Bahamas (Dickel 1991).
Dypterygia punctirena (Walker), found in 1985, from the Dominican Republic (Dickel
Elaphria deltoides (Mischler), found in 1983, from Jamaica or South America (Dickel
Elousa albicans Walker, found in 1984, from the Dominican Republic (Dickel 1991).
Epidromia pannosa Guenee, found in 1983, from South America (Dickel 1991).
Epidromia pyraliformis (Walker), found in 1983, from the Dominican Republic (Dickel
Eulepidotis striaepuncta (Herrich-Schaeffer), found in 1984, from Cuba (Dickel 1991).
Euscirrhopterus poeyi Grote, found in 1987, from Cuba (Dickel 1991).
Gonodontia bidens Geyer, found in 1981, from Cuba (Dickel 1991).
Hypena subidalis Guen6e, found in 1985, from South America (Dickel 1991).
Leucania dorsalis Walker, found in 1984, from the Dominican Republic (Dickel 1991).
Leucania inconspicua (Herrich-Schaeffer), found in 1984, from Cuba (Dickel 1991).
Leucania opalisans (Drandt), date of find not stated, from South America (Dickel 1991).
Leucania senescens Mbschler, date of find not stated, from Puerto Rico (Dickel 1991).
Litoprosopus haitiensis Hampson, found in 1988, from Haiti (Dickel 1991).
Macristis geminipunctalis Schaus, found in 1985, from Cuba (Dickel 1991).
Mocis cubana Hampson, found in 1989, from Cuba (Dickel 1991).
Neotuerta hemicycla (Hampson), found in 1982, from the Bahamas (Dickel 1991).
Paectes lunodes (Guen&e), found in 1989, from Central America or South America (Dickel
Physula albipunctilla Schaus, found in 1980, from Cuba (Dickel 1991).
Pseudaletia sequax Franclemont, date of find not stated, from Mexico (Dickel 1991).
Ptichodis immunis (Guen6e), found in 1989, from the Lesser Antilles (Dickel 1991).
Spodoptera androgea (Stoll), found in 1987, from South America (Dickel 1991).
Anartia chrysopelea (Hiibner), found in 1972, from Hispaniola, not established (Anderson
Hamadryas amphichloe (Boisduval), found in 1978, from the Greater Antilles (Jenkins
Ethmia submissa Busck, found in 1987, from Cuba (Dickel 1988).
Papilio androgeus Cramer, found in 1976, from the Greater Antilles, became established
for several years but is not known now (Patterson 1977).
Phoebis orbis (Poey), found in 1973, from the Greater Antilles (Bennett & Knudson 1976).
Anypsipyla univitella Dyar, found in 1983, from Cuba (Dickel 1988).
Bema neuricella (Zeller), found in 1984, from Cuba or the Bahamas (Dickel 1987).
Cactoblastis cactorum Berg, found in 1989 on Opuntia (Cactaceae), from South America
via the Caribbean (Habeck & Bennett 1990).

March, 1992

Insect Behavioral Ecology '91 Frank & McCoy 13

Epimorius testaceellus Ragonot, found in 1974, from Jamaica, reared from leaves of
Tillardsia fasciculata Swartz (Bromeliaceae) (Ferguson 1991).
Lipographis subosseella Hulst, found in 1981, from the Bahamas (Dickel 1987).
Maruca testulalis (Lever), found in 1980, from Puerto Rico (Dickel 1981).
Neoleucinoides torvus Capps, found in 1985, origin not stated (Dickel 1986).
Ozamia lucidalis (Walker), found in 1989 on Cereus (Cactaceae), from the Caribbean
(Habeck & Bennett 1990).
Parapoynx diminutalis Snellen, found in 1976 on hydrilla, from Asia (Del Fosse et al.
Sporylus cubensis Heinrich, found in 1984, from Cuba (Dickel 1987).
Stylopalpis lunigerella Hampson, found in 1985, from Cuba or the Bahamas (Dickel 1988).
Opogona purpuriella Swezey, found in 1986 on a citrus plant, from Hawaii (Mead 1987a,
Heppner et al. 1987).
Opogona sacchari (Bojer), found in 1963, from Africa and the Indian Ocean perhaps via
the Caribbean (Heppner et al. 1987, Davis & Pefia 1990). PS
Cryptaspasma lugubris Felder, found in 1981, origin not stated (Dickel 1987).
Uraniafulgens Walker, found in 1973, from Mexico (Emmel 1974).
Myrmeleon insertus Hagen, found in 1978, from the Greater Antilles (Lucas & Stange
Coryphaeschna adnexa (Hagen), found in 1980, from Cuba, called blue-faced darner
(Dunkle 1989).
Lestes spumarius Hagen in Selys, found in 1988, from Cuba or Bahamas, called Antillean
spreading (Dunkle 1990).
Crocothemis servilia, found in 1975, from Asia, called scarlet skimmer (Paulson 1978).
Erythemis plebeja (Burmeister), found in 1971, from Cuba, called black pondhawk
(Dunkle 1989).
Micrathyria aequalis (Hagen), found in 1985, from Cuba or the Bahamas, called spot-
tailed skimmer (Dunkle 1989).
Micrathyria didyma (Selys in Sagra), found in 1985, from Cuba or the Bahamas, called
three-striped skimmer (Dunkle 1989).
Neoconocephalus affinis (Palisot de Beauvois), found in 1981, from the Caribbean
(Walker & Greenfield 1983).
Neoconocephalus maxillosus (F.), found in 1969, from the Caribbean (Walker &
Whitesell 1978).
Hemipsocus chloroticus (Hagen), found in 1972, from Asia (Mockford 1973).
Embidopsocus femoralis (Badonnel), found in 1983, from Africa perhaps via Mexico
(Mockford 1987).
Trichadenotecnum circularoides Badonnel, found in 1952, from southern Africa
(Mockford 1974).

Florida Entomologist 75(1)

TABLE 1. (Continued)

Diceratothrips armatus Bagnall, found in 1987 on grapefruit stems, from Central
America or South America (Mead 1987c).
Liothrips varicornis Hood, found in 1974 on Hibiscus (Malvaceae), from Mexico (Mead
Nesothrips brevicollis (Bagnall), found in 1971 on coconut palm, from Asia (Reinert &
Nakahara 1976).
Scotothrips claripennis (Moulton), found in 1971 on coconut palm, pantropical (Reinert
& Nakahara 1976).
Caliothrips insularis (Hood), found in 1913, from the Caribbean or South America
(Nakahara 1991).
Chaetanaphothrips signipennis (Bagnall), found in 1985 on dracaena foliage plants im-
ported from Central America (Denmark & Osborne 1985).
Dichromothrips corbettii (Priesner), found in 1976 on an orchid, from southeast Asia
(Mead 1976b). PS
Dinurothrips vezenyii Bagnall, found in 1974, by sweeping weeds and grasses, from
South America (Mead 1975a).
Frankliniella schulzei (Trybom), found in 1950, from Europe, Asia or Africa (Nakahara
1974). PS
Organothrips indicus Bhatti, found in 1988 on Typha (Typhaceae) and Eichhornia (Pon-
tederiaceae), from Asia (Mead 1990b).
Rhaebothrips lativentris Karny, found in 1971 on grasses, from the Pacific but also
occurs in the Caribbean (Stegmaier 1973a, Mead 1974).
Salpingothrips armatofus Kudo, found in 1972 on kudzu vine, origin not stated (Mead
Scirtothrips sp. [not citri (Moulton)], found in 1986 on grape, origin not stated (Flowers
Taeniothrips eucharii (Whetzel), found in 1966, from Asia (Denmark 1981, O'Neill 1962).
Thrips hawaiiensis (Morgan), found in 1967 on rose, blackberry, etc., from Asia or the
Pacific (Anon. 1973, Mead 1976a). PS
Thrips palmi Karny, found in 1990 on Bidens pilosa L. (Compositae), from Asia (Mead
1. For Porthetria dispar see Lymantria dispar
2. For Siolimyia amazonica see Goeldichironomus amazonicus

orders, by far. Even if immigrants arrived in Florida at random, these orders would
be expected to account for a disproportionate number of immigrant species.
The distribution of immigrant species among orders is in many ways like the one
produced for the contiguous 48 states of the USA (Sailer 1983), but different in some
revealing ways (Fig. 1). Particularly notable is the much larger proportion of Lepidopt-
era, and much smaller proportion of Hemiptera plus Homoptera, in Florida, especially
recently. The differences may reflect variation in the composition of the respective pools
from which immigrants have been drawn, or differences in the rates of establishment -
and, thus, rates of failure for various kinds of insects in different places, or other,
similar, phenomena (Simberloff 1986). The differences also could reflect variation in the
interests of persons studying insect immigration in different places, such that the appar-
ent distribution of immigrant species among orders is, at least in part, a biased represen-
tation of the real distribution (Simberloff 1986). We suspect that the larger proportion
of Lepidoptera is at least in part the result of ability of many of these insects to fly long
distances (e.g., to Florida from the Greater Antilles).

March, 1992

Insect Behavioral Ecology '91 Frank & McCoy





* USA (1970-1980)


Fig. 1. Distribution of immigrant insect species among orders, for the contiguous
48 states of the USA (from Sailer 1983) and Florida. The upper figure compares all
known records for the USA with recent (since 1970) records for Florida; the lower figure
compares 1970-1980 records for the USA with recent records for Florida, for the five
orders for which such information was available. Note that seven orders reported by
Sailer (1983) were excluded, because they included no recent insect immigrants to

Florida Entomologist 75(1)

In many cases, immigrant species also are not very equitably distributed among
families within orders. Three families (of 17), Curculionidae, Scolytidae, and
Staphylinidae, together account for about 52% of the species of Coleoptera recorded in
Florida for the first time since 1970. Two families (of seven), Aleyrodidae and Diaspididae,
account for about 48% of the species of Homoptera first recorded in Florida within the
same time span. Single families, Noctuidae and Miridae, account for about 56% of the
recent immigrants of Lepidoptera (12 families total) and Hemiptera (six families total),
respectively. The distributions of species among families are more equitable for other
orders, but they still often are skewed noticeably.
The large number of recent immigrant insect species we have tabulated suggests
that their rate of arrival and/or discovery in Florida is high. For the 197 species collected
for the first time in Florida in 1970-1989, we calculated rates of 7.7 (s.d. = 4.6) immigra-
tions per year in the 1970s and 12.0 (s.d. = 5.7) immigrations per year in the 1980s.
These figures are greater than those proposed for the northeastern USA and eastern
Canada (Hoebeke & Wheeler 1983), a land area 25 times the size of Florida, and similar
to those proposed for the entire contiguous 48 states of the USA (Sailer 1983). Our
judgement that about 20 recent immigrants are, or could become, major pests in Florida
(see Table 1) exceeds Sailer's (1983) estimate that about seven potential major pests
immigrate to the 48 contiguous states of the USA per year. [Note that ten (50%) of the
actual or potential major pests recently reported in Florida for the first time were on
the USDA-APHIS list as having been intercepted in fiscal year 1980.] All of these
comparisons suggest either that the rate of immigration to the entire USA or the rate
of immigration to Florida has increased dramatically since the early 1980s. On the other
hand, the increase could be only apparent, being the result of improved detection or
increased effort, particularly in Florida. The tendency for certain species to immigrate
several times, noted by Sailer (1983), is evident in our tabulation.
The "PS" designation was applied to 21 species. Thus, we suggest that at least 8%
of insect immigrations to Florida result from stowing-away. The percentage of species
that have arrived as stowaways actually is much larger. First, the USDA-APHIS list
applies only to "plant pests" (which, we believe, means phytophagous insects), whereas
many of the species in Table 1 patently are not phytophagous; some even are natural
enemies of phytophagous insects. Second, we examined the USDA-APHIS list only for
fiscal year 1980, at the mid period of the two decades we considered; a cumulative list
of the USDA-APHIS interceptions for the entire two decades surely would have revealed
many more of our suspected stowaways. Third, we cannot evaluate considerable numbers
of intercepted insects because they are identified on the USDA-APHIS list only to
genus; unidentified congeners of another 38 of the species in Table 1 appear on the
USDA-APHIS list for fiscal year 1980. This last fact alone suggests that about 3 times
as many (i.e., about 24%) of all the species on our list may have arrived as stowaways,
more than that when we accept that the USDA-APHIS list does not deal with non-
phytophagous species. We note that some of the exotic species intercepted year after
year have yet failed to establish populations in mainland USA, which suggests the
effectiveness of inspection or, more likely, the difficulty that certain species have in
colonizing once they have immigrated. Some exotic species of European and Asian origin
that have been intercepted have become established, however, even in recent years,
which suggests that the best efforts of USDA-APHIS do not discover all of the insects
arriving in seaports and airports, both in private and commercial shipments and the
baggage of passengers.
The geographic origins of the recent insect immigrants to Florida are diverse. As
one might suspect, the geographic origin of immigrants to Florida is not very similar
to the origins of immigrants to the entire contiguous 48 states of the USA (Fig. 2). The
principal difference is the much larger proportion of immigrants to Florida that comes

March, 1992

Insect Behavioral Ecology '91 Frank & McCoy

E 80
E 60


0 40

S 20

C o
Fig. 2. Geographic origins of immigrant insect species. Data for the 48 contiguous
states of the USA are from Sailer (1983). Data for Florida are from records of the 236
species for which we had precise information on region of origin.

from the Neotropical region, and the much smaller proportion that comes from the
western Palearctic region (see Hoebeke & Wheeler 1983, Sailer 1983, Simberloff 1986).

Florida's Neotropical Insect Fauna
Six species of butterflies are listed among the Rare and Endangered Biota of
Florida (Baggett 1982). They are Chlorostrymon maesites Herrich-Schaeffer, Eunica
tatila Herrich-Schaeffer, Strymon acis Drury, Eumaeus atala Poey, Heraclides aris-
todemus (Esper), and Anaea troglodyta F. These are Neotropical species, and all occur
in Cuba and other islands. Butterflies have more popular appeal than do most insects,
and have received more attention in two ways. First, their presence in Florida was
discovered relatively quickly. Second, the color patterns of the Florida populations of
S. acis, H. aristodemus, and A. troglodyta differ slightly from those of populations in
the West Indies, leading to description of Florida subspecies S. a. bartrami Comstock
& Huntington (Bartram's hairstreak), H. a. ponceanus Schaus (Schaus' swallowtail),
and A. t. floridalis Johnson & Comstock (Florida leafwing) (Gerberg & Arnett 1989).
It is unclear whether Florida populations of E. atala, which have been described as a
distinct subspecies (E. a. florida Roeber, the Florida atala), differ in any substantial
way from populations in the Bahamas (Baggett 1982, Riley 1975).

Florida Entomologist 75(1)

Florida's Rare and Endangered butterflies are Neotropical immigrants that would
have been placed in our tabulation of immigrants (Table 1) had their first mention in
the literature been after 1970. They would presumably have been placed on the USDA-
APHIS list of plant pests had they been intercepted by inspectors. Indeed, the 1980
list of interceptions gives a Eumaeus species (unidentified) as having been found on a
cycad imported from Mexico (PITSS 1982). Isolation of populations of three (perhaps
four) of them in Florida, from populations in Cuba and other islands, has been sufficient
to lead to slight characteristic differences in color pattern. These differences, in turn,
have led to the description of the Florida populations as distinct subspecies. Perhaps
these differences in color patterns have a genetic basis. If they do, then we suggest the
same is likely true for many other immigrants, but that the phenotypic expression is
less apparent. These butterflies may perhaps represent thousands of species of largely
Antillean insects that depend in some way on cold-sensitive Neotropical plants, and
have immigrated to southern Florida only since the last (Wisconsian) glaciation. The
successful colonists among them subsequently may have diverged genetically from their
parental populations.
Neotropical species that do not depend in some way on cold-sensitive Neotropical
plants, and that can tolerate freezing temperatures, may have immigrated to, and some-
times colonized, Florida even before the last glaciation. As most of Florida from Tampa
Bay southward appears to have been submerged as late as the early Miocene (Alt 1967,
Winker & Howard 1977), these colonists likely arrived since then. Such colonists may
have diverged more from their parental populations than did the six butterflies. Such
wide divergence must depend not only on the earliest date of immigration, but also on
maintenance of contact with the parental gene pool (i.e., frequency of arrival of sub-
sequent immigrants).

Invasibility of Florida

All of the information we have presented might lead one to conclude that, for some
reason, Florida is particularly prone to invasion (i.e., immigration plus colonization) by
insects. We do not know with certainty the total number of insect species in Florida,
nor the number of exotic origin, so we cannot ascertain the percentage of the fauna
made up of exotics. For a wide range of organisms other than insects, however, the
percentage appears to be substantial (data in Ewel 1986). Naturalized exotics constitute
about 15% of Florida's plant species, 16% of its fish species, 22% of its amphibian species,
42% of its reptile species, 5% of its bird species, and 23% of its mammal species. Most
of these percentages are near those reported for the insect faunas of supposedly "invasion-
prone" regions, such as Hawaii (29%, Simberloff 1986) and Tristan da Cunha (28%,
Holdgate 1960), but contrast with those reported for the insect faunas in regions thought
to be less "invasion-prone," such as the contiguous 48 states of the USA (1.7%, Sailer
While these differences in percentages would seem to provide evidence of a convincing
difference between regions that are "invasion-prone" and those that are not, they are
deceptive in at least two ways. First, percentages, by their nature, can be misleading
in cases such as these (Simberloff 1986). If exactly the same number of exotic insect
species colonized, say, Hawaii and North America north of Mexico, then Hawaii's insect
fauna would de facto contain a much higher percentage of exotics than North America's.
This result occurs because North America's insect fauna is much larger than Hawaii's
(data in Simberloff 1986). Spatial scale also comes into play here, as certain parts of
North America, such as Florida, clearly are different from most of the rest of it in terms
of their complements of exotic species. Second, one cannot truly assess the relative
invasibility of a geographic region without rather detailed information on the sizes and

March, 1992

Insect Behavioral Ecology '91 Frank & McCoy

compositions of the pools from which immigrants are being drawn, the rates of immigra-
tion from those pools to the targets, and the rates of success that immigrants have in
colonizing the targets (McCoy & Heck 1987, Simberloff 1986).
Because we lack good information on the size and composition of Florida's insect
fauna, as well as other necessary information, we cannot assess its relative invasibility
with any degree of assurance. Whether its native species provide less "biotic resistance"
to invasion than other regions (see Ewel 1986, Sailer 1983); whether its location predis-
poses it to ready immigration of flying, wind-blown, and rafting exotics from the
Bahamas, the Yucatan peninsula of Mexico, Cuba and other islands of the Greater
Antilles; and whether habitat changes induced by man enhance its colonization by immi-
grants (see Ewel 1986, Simberloff 1986) are important, interesting, but currently un-
answerable questions. Once we possess the requisite information, then we can begin to
address such questions rigorously.


The process of invasion by insects is complex. It requires the ability to move to a
new location ("immigration"), the ability to establish populations at the new location
("colonization"), and the ability to resist local extinction there. The symposium contribu-
tions address all of these components of invasion in relation to Florida.
Two of the contributions focus on the invasion of Florida by African honeybees.
African bees will soon become well-established across the southern tier of the United
States; the highest concentration of feral African bees will be in Florida. H.G. Hall
discusses the process of New World African and European honeybee hybridization. He
concludes that it is multifaceted, and that generalizations cannot be made about the
entire process if only limited aspects are studied; the different components must be
defined and evaluated. Among these components are climate (tropical or temperate),
kind of colony (feral or managed), matriline (African or European), and kind of population
(established or transient).
R. Hengeveld analyzes invasion of the New World by the African bee, as well as
invasion of Europe by the collared dove. He constructs models of invasion, based on
population growth and dispersal. His models appear to offer a more parsimonious expla-
nation of invasions than do models based on invasion-proneness of species and biotopes.
J.C. Allen, Y. Yang, J.L. Knapp, and P.A. Stansly provide a model of the attack
rate for a grazing herbivore, the citrus rust mite. They obtain the model as a Type 2
functional response analogous to Holling's disc equation, and suggest that it can help to
indicate what further data are needed to make reliable models for use in population
dynamic studies and economic predictions. They suggest further that the model could,
with only slight modification, be applied to most grazing herbivores. It might, therefore,
be used profitably to make predictions about the potential effects of immigrant herbivores
on native vegetation.
H. Nadel and her coauthors, J.H. Frank and R.J. Knight, discuss the weedy figs of
southern Florida and the immigrant agaonid wasps that routinely pollinate them. They
note that other immigrant wasps occupy the fruits of one of these fig species and may
interact with the pollinators, and that more complex interactions likely occur among the
diverse inhabitants of the fruits of native figs. They suggest that non-pollinating fig
faunas, because of their potentially negative effect on agaonid populations, may play a
role in control of weedy figs.
S. Koptur examines nectar-drinking ant abundance, recruitment of these ants to
baits, and proportion of plants with extrafloral nectaries in three habitats in the
Everglades. She finds that the habitat with the highest ant abundance and recruitment
also has the most plants with extrafloral nectaries. As these ants are potential protectors

Florida Entomologist 75(1)

of plants against herbivores, they may reduce the abundance of native herbivores and
reduce the amount of colonization and the persistence of immigrant herbivores in the
habitats in which they are common.


The list of immigrant species that we compiled was criticized, annotated, corrected,
and expanded by David Baggett, Richard Baranowski, Fred Bennett, Jerry Butler,
Paul Choate, Harvey Cromroy, Harold Denmark, Mark Deyrup, Terry Dickel, Sidney
Dunkle, Thomas Emmel, John Epler, John Foltz, Alan Gettman, Virendra Gupta, Dale
Habeck, Avas Hamon, John Heppner, James Lloyd, Frank Mead, Charles O'Brien, Lois
O'Brien, Richard Patterson, William Peters, Richard Roberts, Lionel Stange, Gary
Steck, Michael Thomas, Thomas Walker, and Willis Wirth. Mark Deyrup and Peter
Stiling kindly reviewed the manuscript for us. We thank Jorge Pefia for supplying
resumenes for all of the contributions to the symposium. This is University of Florida,
Institute of Food & Agricultural Sciences, journal series no. R-02163.


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24 Florida Entomologist 75(1) March, 1992

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(ed.) 1975a. Insect detection. Tri-Ology 14(1): 5.
--. (ed.) 1975b. Insect detection. Tri-Ology 14(2): 6.
-- 1976a. First Florida or United States records of invertebrates reported through
the cooperative survey program. Florida Dept. Agr. Consum. Serv., Divn. Pl.
Industry, Biennial Rept. 30: 45-46.
(ed.) 1976b. Insect detection. Tri-Ology 15(6): 10.
ed.) 1976c. Insect detection. Tri-Ology 15(11): 6.
ed.) 1978a. Insect detection. Tri-Ology 17(9): 11.
ed.) 1978b. Insect detection. Tri-Ology 17(10): 8.
ed.) 1980a. Insect detection. Tri-Ology 19(8): 11-12.
(ed.) 1980b. Bureau of Entomology. Tri-Ology 19(9): 3-9.
-- (ed.) 1983a. Insect detection. Tri-Ology 22(3): 9.
(ed.) 1983b. Insect detection. Tri-Ology 22(6): 5-6.
S(ed.) 1983c. Insect detection. Tri-Ology 22(7): 3-5.
(ed.) 1983d. Insect detection. Tri-Ology 22(11): 4-6.
-- (ed.) 1983e. Insect detection. Tri-Ology 22(12): 4-5.
-- (ed.) 1984. Bureau of Entomology. Tri-Ology 23(7): 1-3.
---. (ed.) 1985. Insect detection. Tri-Ology 24(10): 2.
-- (ed.) 1986. Insect detection. Tri-Ology 25(5): 7.
-- (ed.) 1987a. Bureau of Entomology. Tri-Ology 26(2): 3-6.
-- (ed.) 1987b. Household and structures. Tri-Ology 26(5): 6.
(ed.) 1987c. Insect detection. Tri-Ology 26(8): 3.

Insect Behavioral Ecology '91 Frank & McCoy

-- (ed.) 1988. Insect detection. Tri-Ology 27(9): 6.
--. (ed.) 1990a. Federal-State plant protection programs. Tri-Ology 29(5): 4.
--. (ed.) 1990b. Bureau of Entomology. Tri-Ology 29(8): 6.
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--. (ed.) 1991b. Insect detection. Tri-Ology 30(8): 5-6.
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26 Florida Entomologist 75(1) March, 1992

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Insect Behavioral Ecology '91 Frank & McCoy

STANGE, L. A., AND R. J. KNIGHT. 1987. Fig pollinating wasps of Florida (Hymenopt-
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AND H. R. BURKE. 1974. Anthonomus flavus (Coleoptera: Curculionidae) a
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AND R. E. WOODRUFF. 1983. First records of a stored products pest,
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THOMPSON, C. R. 1985. Detection and distribution of Formosan termites (Isoptera:
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WERNER, F. G. 1972. Additions to the Nearctic Anthicus (Coleoptera: Anthicidae).
Proc. Ent. Soc. Washington 77: 472-477.
Habits and present distribution in Florida of the exotic ant Pseudomyrmex
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WHITE, R. E. 1979. A neotropical leaf beetle established in the United States
(Chrysomelidae). Ann. Ent. Soc. America 72: 269-270.
WHITEHEAD, D. R., AND A. G. WHEELER. 1990. What is an immigrant arthropod?
Ann. Ent. Soc. America 83: 9-14.
WIBMER, G. J., AND C. W. O'BRIEN. 1989. Additions and corrections to annotated
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and of South America. Southwestern Ent. suppl. 13: 1-49.

Florida Entomologist 75(1)

WILKENING, A. J., D. L. KLINE, AND W. W. WIRTH. 1985. An annotated checklist
of the Ceratopogonidae (Diptera) of Florida with a new synonymy. Florida Ent.
68: 511-637.
WILSON, S. W. 1984. The first record of Delphacodes havanae Muir & Gifford in the
United States (Homoptera: Fulgoroidea: Delphacidae). Great Lakes Ent. 16: 188.
WINKER, C. C., AND J. D. HOWARD. 1977. Correlation of tectonically deformed
shorelines on the southern Atlantic coastal plain. Geology 5: 124-127.
WIRTH, W. W. 1979. Siolimyia amazonica Fittkau, an aquatic midge new to Florida
with nuisance potential. Florida Ent. 62: 134-135.
WOODRUFF, R. E. 1972. Nicentrus saccharinus Marshall, a potential sugarcane pest
accidentally introduced into Florida (Coleoptera: Curculionidae). Florida Dept.
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- 1973a. An orchid weevil new to the United States (Coleoptera: Curculionidae).
Florida Dept. Agr. Cons. Serv., Divn. P1. Ind., Ent. Circ. 129: 1-2.
- 1973b. The scarab beetles of Florida (Coleoptera: Scarabaeidae), Part I. Ar-
thropods Florida Neighboring Land Areas 6: i-xi, 1-220.
1974. A South American leaf beetle pest of crucifers in Florida (Coleoptera:
Chrysomelidae). Florida Dept. Agr. Cons. Serv., Divn. P1 Ind., Ent. Circ. 148: 1-
1977. A weevil pest of rose-apple (Syzygium jambos), apparently new to the
United States (Coleoptera: Curculionidae). Florida Dept. Agr. Cons. Serv., Divn.
P1. Ind., Ent. Circ. 183: 1-2.
- AND R. M. BARANOWSKI. 1985. Metamasius hemipterus (Linnaeus) recently
established in Florida. Florida Dept. Agr. Cons. Serv., Divn. P1. Ind., Ent. Circ.
272: 1-4.
AND B. M. BECK. 1989. The scarab beetles of Florida (Coleoptera:
Scarabaeidae), Part II. Arthropods Florida Neighboring Land Areas 13: i-vi,
--, AND R. I. SAILER. 1977. Establishment of the genus Azya in the United States
(Coleoptera: Coccinellidae). Florida Dept. Agr. Cons. Serv., Divn. P1. Ind., Ent.
Circ. 176: 1-2.
---, E. J. GERBERG, AND T. J. SPILMAN. 1978. A false powder-post beetle new
to the United States (Coleoptera: Bostrichidae). Florida Dept. Agr. Cons. Serv.,
Divn. P1. Ind., Ent. Circ. 230: 1-2.

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Insect Behavioral Ecology '91 Nadel et al.


'Royal British Columbia Museum, 675 Bellville Street,
Victoria, B.C., CANADA V8V 1X4

2Entomology and Nematology Department, University of Florida,
Gainesville, Florida 32611-0740

"USDA-ARS, 13601 Old Cutler Rd., Miami, Florida 33158


Over 60 exotic Ficus (fig) species have been introduced into southern Florida as
ornamentals. Three of these, F. altissima Blume, F. benghalensis L., and F. microcarpa
L. are now weedy because they are pollinated routinely by immigrant agaonid wasps
[Eupristina sp., Eupristina masoni Saunders, and Parapristina verticillata (Waterston)
respectively]. Conditions for colonization by these wasps appear to have been met, and
are potentially suitable for pollination of two other fig species. Four other immigrant
wasp species (three pteromalids and a torymid) occupy the fruits of F. microcarpa and
may interact with the pollinating wasps. Such interactions are more complex, but scarcely
understood, in the native F. area Nuttall and F. citrifolia P. Miller, in which at least
10 and 14 species respectively of other animals occur routinely. These other animals
include Hymenoptera (Torymidae, Eurytomidae, and Pteromalidae), Diptera
(Cecidomyiidae), Coleoptera (Staphylinidae), Acarina (Tarsonemidae), and Nematoda
(Diplogasteridae and Aphelenchoididae). Because of their potentially negative effect on
agaonid populations, non-pollinating fig faunas should be examined to determine whether
they may play a role in control of weedy figs.


Mas de 60 species de Ficus se han introducido en Florida como ornamentales. Tres
de estos, F. altisima Blume, F.benghalensis L., y F. microcarpa L., se consideran
como malezas porque son polinizadas rutinariamente por avispas migratorias, per-
tenecientes a la familiar Agaonidae [Eupristina sp., Eupristina masoni Saunders, y
Parapristina verticillata (Waterson) respectivamante]. Las condiciones para la coloniza-
ci6n de estas avispas es adecuada para la polinizaci6n de otras 2 species de caucho.
Otras cuatro species de avispas (tres pteromalidos y un torymido) ocupan las frutas de
F. microcarpa y podrian entrecruzarse con las avispas polinizadoras. Estas interacciones
son mas complejas y poco conocidas en las plants nativas F. aurea Nuttall y F. citrifolia
P. Miller, en las cuales ocurren frequentemente por lo menos 10 y 14 species de otros
animals. Estos otros animals incluyen Hymenoptera (Torymidae, Eurytomida y
Pteromalida), Diptera (Cecidomyiidae), Coleoptera (Staphylinidae), Acarina (Tar-
sonemida) y Nematoda (Diplogasteridae y Aphelenchoididae). Por su efecto negative en
las poblaciones de Agaonidos, la fauna no polinizadora de los cauchos debe ser examinada
para determinar si ellos juegan un papel en el control de estas malezas.

In addition to two native figs, Florida hosts over 60 exotic Ficus species. Of these,
only a few are encountered commonly. For decades figs have been highly touted as

Florida Entomologist 75(1)

shade and ornamental trees with the additional attraction of being sterile when not
accompanied by their pollinators. They are easily propagated by cuttings (Condit 1969)
and placed precisely in desired spots; a great advantage considering the enormous size
attained by some species. The roots have a capacity to invade and damage streets,
sewers, pools, and other manmade structures. Because of their sterility, exotic figs also
posed no apparent threat of invasion into the already disturbed Everglades and other
natural communities. Since the early 1970s, however, the picture has changed with the
inadvertent introduction of fig pollinators.
We present only a brief discussion of the weedy fig problem and the factors leading
to it because these subjects were considered by McKey & Kaufmann (in press). We
suggest that a solution should be sought within the untapped potential of the diverse
non-pollinating faunas in figs, and we stress the lack of knowledge about this group of
organisms, using the native fauna as an example.


The genus Ficus (Moraceae) has about 750 species, and is distributed in the tropics
and subtropics worldwide. About one-half of the species are monoecious, the rest being
gynodioecious but functionally dioecious. Most grow as trees, while others are shrubs
or climbers. Germination in many species occurs on other trees, with the seedlings
growing epiphytically while sending a network of roots down to the soil, eventually
"strangling" their nurse trees. Others, however, begin their lives on rocks or directly
in soil. Pantropical in distribution, only a few fig species extend into warm temperate
regions. Two species are native to North America, Ficus citrifolia P. Miller, the shortleaf
fig, and F. aurea Nuttall, the strangler fig, both of which are restricted to the subtropics
of Florida, although their ranges extend to the Caribbean and Central America, and F.
citrifolia possibly to northern South America (Berg 1989).
With few exceptions, each fig species is pollinated by a different species of wasp in
the family Agaonidae (Hymenoptera: Chalcidoidea) (Hill 1967, Ramirez 1970, Janzen
1979, Wiebes 1979). The pollination biology of monoecious species has been described
by Galil & Eisikowitch (1968, 1969). A pollen-laden female wasp enters the syconium
or "fig", an urn-shaped inflorescence which, when in the receptive stage, is lined inter-
nally with dozens or hundreds of receptive female flowers and a few immature male
flowers. The wasp lays her eggs through the styles into some of the ovaries, pollinating
most of the flowers in the process. The style lengths are variable among flowers within
each syconium, allowing the wasps to oviposit mainly in the short-styled ones (Bronstein
1988b). The wasp enters a syconium once, and dies within it. Her offspring feed and
pupate in galls formed within the floral ovaries. After four to six weeks, coinciding with
the maturation of male (pollen-bearing) flowers, the wasp offspring emerge into the fig
chamber. The wingless males emerge first, chew holes into the galls of the females, and
inseminate them. One or more males also cut a hole through the wall of the fig, rarely
exiting themselves. Rather, the females leave through this hole after being passively
dusted by pollen in some species, or actively gathering it into coxal and/or sternal
corbiculae in others (Ramirez 1969, Frank 1984), and fly away in search of receptive
young syconia.
In dioecious fig species, pollination is more complex. The "male" tree is monoecious,
having both male and female flowers in each syconium, but it has only short-styled
female flowers. Nearly all of these female flowers are used by the ovipositing wasps,
with the result that the tree produces no seeds, only pollen and agaonids. The female
tree, on the other hand, is truly female; the syconia contain only female flowers. These
flowers are all long-styled, which effectively eliminates the ability of the agaonid to
oviposit in them. These trees therefore produce only seeds.

March, 1992

Insect Behavioral Ecology '91 Nadel et al.

The association between the fig plant and agaonid is mutualistic; that is, populations
of one cannot persist without the other. Figs reproduce almost exclusively by seed, and
pollen reaches the receptive female flowers only through the action of agaonid wasps.
The wasps, in turn, develop only within syconial galls. Reproduction by the trees and
the wasps is, therefore, completely dependent on the union between the mutualistic


The exotic figs that have been reunited with their pollinators in Florida fall into two
groups: 1) naturalized, in which pollinator populations have persisted for more than a
year and which regularly produce seeds or seedlings, and 2) sporadic, in which pollinator
populations do not persist and do not regularly produce seedlings. Within the first group
(Table 1) adventive seedlings were first observed in the early 1970s growing among
potted plants in southwest Miami. In 1980 the same observer saw weedy seedlings
germinating in a roof gutter on the west coast of the peninsula, in Fort Myers. In both
cases the weeds were identified as F. microcarpa L., the Asian laurel fig. We cannot
determine whether these events mark a true spread of the pollinator from east to west
coasts or whether they resulted simply from multiple introductions. The pollinator,
Parapristina verticillata (Waterston), has since been very commonly recovered from
syconia in all areas. Its apparent spread from east to west coast spanned less than a
decade, and F. microcarpa is now naturalized for what is probably the whole of its
cultivated range.
Since the mid 1980s, seedlings of two other Asian figs have been found regularly
cropping up in Miami. Seedlings ofF. benghalensis L., the banyan, were found in 1986
(Stange & Knight 1987) and have since been found on walls and in soil. Its pollinator,
Eupristina masoni Saunders, is now abundant in the Miami area. Ficus altissima
Blume, the closely-related lofty fig, was discovered growing epiphytically at the Univer-
sity of Miami campus in Coral Gables, and has since been found throughout the Miami
area, growing on trees and on stone walls (McKey & Kaufmann, in press). Its pollinator,
Eupristina sp., probably E. altissima Balakrishnan & Abdurahian, is also well estab-
lished. Although not nearly as aggressive a weed as F. microcarpa, F. altissima appears
to be cropping up more commonly than F. benghalensis. These three species are, as far
as we know, the only figs that have escaped cultivation and become naturalized in Florida.



early 1970s F. microcarpa Miami
1980 Fort Myers
1981 Palmetto
1983 Florida City
1985 F. benghalensis Miami
1987 F. altissima Coral Gables'
F. microcarpa Homestead
Key West2
late 1980s Naples

i From McKey 1989, other observations by RJK
Observation by HN.

Florida Entomologist 75(1)

Sporadic seeding events have been recorded for a number of other figs on the east
coast (Table 2), but with no apparent perpetuity. Ficus religiosa L. (sacred fig) seedlings
were found once in Homestead in 1975 and once in Miami in 1988, but there is no
indication of successive seeding events in these areas or elsewhere. In 1975, unidentified
agaonid wasps were discovered developing in syconia ofF. septica Burmeister in Miami,
resulting in viable seeds, but no seedlings were found to occur naturally. The wasps
were never seen again. Ficus perforata L., a West Indian species not commonly planted
in Miami, has been cropping up occasionally since 1975 at the USDA station in Miami,
but its specific pollinator has never been recovered from syconia. It is questionable
whether it can be considered naturalized.


Through what was probably human cause, the established pollinators arrived from
their native ranges or even from other naturalized populations and found conditions
suitable for reproduction. They are now very common in their respective figs. The
specific pollinators of the sporadically seeding species, on the other hand, have never
been recovered in Florida. This means that conditions are either not suitable for their
reproduction, or that the seeds resulted from occasional pollination by a species that
normally pollinates another fig. Evidence for either of these cases is difficult to get
because seedlings are discovered long after the pollination event has occurred or, as in
the case of F. septica, seed set has been discovered after the female wasps had emerged
and disappeared, and the wasp remnants in the ripe syconia are too poor to identify.
It is unlikely that locally available pollinators were responsible for the observed
sporadic seeding events in Florida. The "wrong" agaonid is known occasionally to invade
syconia, especially when two trees of different species are growing nearby (Wiebes
1966). There are examples from Florida: Parapristina verticillata, the pollinator of F.
microcarpa, has been found in one of the native figs, F. aurea; the pollinator of F.
aurea, Pegoscapus jimenezi (Grandi), has, conversely, been found intruding into the
syconia of two exotic figs, F. septica and F. religiosa, and the pollinator of the native
F. citrifolia, Pegoscapus assuetus (Grandi), has been found in the exotic F. perforata.
Seed set was not studied in these instances, however, and none of these intrusions has
resulted in reproduction, except for a possible case of hybridization by F. aurea and F.
religiosa, noticed by Ramirez (personal communication). He saw apparently hybrid
seedlings growing at the USDA station in Miami in 1987. We suspect that hybridization
occurs also between the two native species, because during our examination of several
hundred trees between 1988 and the present, we noted three remarkable trees with
intermediate characters. On the whole, however, intrusion of wrong pollinators does
not appear to be an important component of reproduction by figs. Intrusion is a relatively
rare phenomenon, and hybridization is even rarer (Ramirez 1970), probably because of
further restrictions by interspecific incompatibilities.



1975 F. religiosa Homestead
F. septica Miami
1975 and later F. perforata Miami
1988 F. religiosa Miami'

SFrom Ramirez & Montero (1988)

March, 1992

Insect Behavioral Ecology '91 Nadel et al.

The first criterion for establishment of viable populations of figs and pollinators is,
of course, the union between them, although this is not at all more important than other
conditions that will be discussed later. How do agaonids find their way to distant figs?
One of the answers lies in their numbers. Each crop of figs can produce millions of
wasps, and large numbers of these tiny insects probably are transported by wind to
distant sites. The likelihood of a successful union is diminished severely by the short
life-expectancy of a female agaonid outside the syconium (Bronstein 1989). Natural
colonization of distant sites such as islands appears superficially to be a common occur-
rence, but not when the time involved is considered (McKey 1989). It is far more likely
that the high rate of recent immigration to urban areas has been caused by human
endeavor. Ficus microcarpa, for instance, probably was brought inadvertently to Miami
from Hawaii. It was introduced into Hawaii from Asia in 1921 to aid in reforestation
(Condit 1969). During the reforestation effort, five species of chalcidoid Hymenoptera
in four genera hitchhiked to Hawaii in the syconia along with the pollinator. Syconia
often are inhabited by non-pollinating chalcidoids which are either parasitic or gall
former in their own right; about 10 genera have been found in this fig in Asia (Ramirez
1970). Florida has four of the five species found in Hawaii (Odontofroggatia galili Wiebes,
Walkerella yoshiroi (Ishii), Philotrypesis emeryi Grandi, and Micranisa sp.), which
supports the assumption that the Florida subset was drawn from there (Stange & Knight
1987, J. Beardsley, personal communication).
In addition to the union of the mutualist pair, naturalization of introduced fig and
pollinator species requires a sufficiently large population of fig trees with relatively low
flowering seasonality to ensure year-round resources for the wasps. The generation
time of agaonids is usually confined to a few weeks, and the longevity of a searching
adult female is very short (Bronstein 1989). Short generation time is not always true
for dioecious figs, but discussion of these is minimized here because the established figs
in Florida are all monoecious. [For extensive treatments of monoecious and dioecious
figs, see Bronstein (1989), and Kjellberg & Maurice (1989)]. To perpetuate the pollinator
population, it is necessary for receptive syconia to be available in the fig population
throughout the year. A crop of syconia on a tree, usually two per year, is initiated
relatively synchronously except perhaps in marginal habitats (Bronstein 1989), with
long, clearly defined gaps, and is not sufficient for more than one generation of pollinators.
The pollen-laden females are rarely able to find receptive syconia on their own tree.
Pollinators persist, however, when crops are initiated asynchronously on a population-
wide basis, with different trees coming into receptivity or releasing wasps at different
times, so that availability of syconia is effectively continuous (Janzen 1979, Bronstein
The degree of crop synchrony within a population is related directly to reproductive
seasonality. Low seasonality presents a broad window of time for flowering, which
allows for temporal variability and a great degree of asynchrony. The larger the tree
population, the more asynchrony can be realized. With increasing seasonality, however,
wasps can be supported only by increasingly large populations of figs, and fig reproduction
may be affected negatively by the reduced activity of the pollinators during cool periods
(Bronstein 1989), which may explain why figs rarely spread from the tropics to temperate
zones (Kjellberg & Maurice 1989). The proximal cause of temporal variability in flowering
within a population of figs is still unknown (Michaloud 1988).
Clearly, the larger the tree population, the less frequent and shorter are the gaps
between crops. Low seasonality in flowering periodicity allows asynchrony, and asyn-
chrony within a population increases with increasing numbers of trees. Establishment
by pollinators without extirpation can occur, therefore, only when a certain critical fig
population size is reached in which no gaps exist. This critical size is affected by repro-
ductive seasonality, which is, in turn, affected by both intrinsic and extrinsic factors,
and therefore must vary from species to species and from place to place.

Florida Entomologist 75(1)

The conditions for pollinator colonization appear to have been met in certain areas
of south Florida for F. microcarpa, F. benghalensis, and F. altissima, although the
evidence remains largely presumptive. No study has been made of annual crop patterns
in any of Florida's exotic figs, although it is generally believed that crops can be encoun-
tered at any time. This is supported by periodic checks of syconia since 1987, which
always revealed the presence of pollinators. An effort by McKey & Kaufmann (in press)
led to a quantification of fig populations along 38 km of streets in Coral Gables and
South Miami, and revealed that in this area (probably reflecting most other areas in
Miami), the most abundantly planted species are, in descending order: F. benjamin
(40%), F. religiosa (30%), F. altissima/benghalensis (15%), F. microcarpa (9%), followed
by a few other minor species. Ficus altissima and F. benghalensis were not distinguish-
able under the sampling method used, but McKey & Kaufmann (in press) state that F.
altissima is more abundant, which agrees with our observations. The number of trees
encountered over the 38 km of road ranged from 192 F. benjamin to 44 F. microcarpa,
and it must be noted that this is just a fraction of a much larger contiguous population
of trees in the Miami area. For the three naturalized species, the encounter rates were
calculated as a minimum of one adult tree per km of street, which is a very reasonable
distance for travel by the agaonids (McKey & Kaufmann, in press). Although interspecific
comparisons cannot legitimately be made at this stage, it should be noted that a stochastic
simulation model developed to estimate critical population size of an African fig (F.
natalensis Hochstetter) found a median of 95 trees necessary for agaonid colonization,
although estimates ran as high as 294 trees (Bronstein et al. in press). The established
agaonids in Florida certainly have host fig populations well within or above this size.


After learning about an unsuccessful bid by fruit breeders to import pollinators for
F. auriculata Loureiro into Florida in 1937, Condit (1969) stated with apparent relief
that such an introduction would undoubtedly have caused a severe weed problem. There
is no doubt that the escape of fig trees from cultivation creates a nuisance in urban and
natural environments (Ramfrez & Montero 1988), and probably will contribute to disrup-
tion of natural ecosystems already strained to the limit in southern Florida. In the urban
environment, damage already consists in the form of added time and cost for removal
of fig seedlings from roofs, gutters, stone and brick walls, the vicinity of pools and septic
tanks, sidewalks, and from the canopies of expensive landscape trees under the threat
of strangulation. Tardy removal may also involve added costs for repair of structures
that have been invaded by the roots. The cities and the Florida Department of Transpor-
tation, responsible for removing vegetation from streets and highways, face an increased
workload. It should be mentioned that manmade structures and landscape trees already
have been under attack by the native strangler fig, F. aurea, but that the exotics in
this case represent a many-fold exacerbation of this problem. The exotics as well as F.
aurea are problematic at commercial gardens and parks. Another old nuisance, which
is being faced more frequently, is the buildup of a slippery, fermenting layer of ripe
figs on sidewalks and streets under pollinated trees (Ramirez & Montero 1988). With
few exceptions, unpollinated syconia are aborted while still small (Condit 1969). We
have observed thick layers of fruits under F. microcarpa, which generally are worse
than the other naturalized exotics.
Although the spread of exotic figs has been limited to urban areas not far from parent
trees, it is only a matter of time before they appear in the Everglades and in smaller
remnants of the natural environment. Ficus microcarpa already is known to be the
most aggressive urban weed among the exotic figs of Florida (and in Hawaii [Condit
1969]), probably because it has small ripe syconia (ca. 1.0 cm diameter), about the size

March, 1992

Insect Behavioral Ecology '91 Nadel et al.

of F. aurea fruits that are eaten by the native fauna. Many of the local birds rely either
heavily or occasionally on native figs for food, and in turn disperse and defecate the
seeds in locations suitable for germination. Ficus altissima and F. benghalensis have
much thicker-walled and larger syconia (> 2.0 cm diam) which are not preferred by
native frugivores. Their seedlings crop up much closer to the parent trees, suggesting
lack of dispersers (McKey & Kaufmann, in press). Again, this picture is liable to change
as exotic birds, especially parrots, are becoming established. The seeds ofF. microcarpa
are also dispersed by ants. These insects are attracted to an oily tissue coating the seed,
even after it passes through the gut of a frugivore (D. McKey, personal communication).
The threat to natural communities in south Florida by exotic figs should be taken
seriously. Although exotics may provide additional food and resting sites for native
animals, past indiscretions with plants such as Brazilian pepper, melaleuca, and Austra-
lian pine should cause us to err on the side of caution. These purposely introduced plants
are now serious pests in the Everglades. When the impact of introductions in natural
communities is uncertain, we feel that exclusion should be practiced rigorously to avoid
ecologically disruptive and potentially costly problems in the future.


Proposals for fig control have featured extensive pruning of mature trees during the
off season to create a gap in syconial availability with the least amount of effort. A trial
was made in Bermuda, where 30 winter-cropping trees were pruned (out of a total of
500 on the island), but it failed to eradicate the pollinators (McKey 1989). Finding every
fruiting tree is nearly impossible because syconia can be found sometimes on only one
or a few branches that are out of synchrony with the rest of the tree (personal observa-
tions, Bronstein 1989). Each syconium has the potential of contributing pollen to several
hundred others. The prospect of heavily pruning these large and beautiful landscape
trees must also present a dilemma for the tropical tourist industry; amputated fig trees
are not attractive.
Research on biological fig control is nonexistent. The problem is fairly recent and
has not received the attention it deserves. In addition to trying to break the pollinator's
reproductive cycle, or tediously pulling up weedy seedlings before they reach damaging
proportions, we suggest that a closer look be taken at the myriads of other organisms
found inside the syconia. Several lists and descriptions of such organisms from many
parts of the world have been published (e.g., Timberlake 1921, Butcher 1964, Hill 1967,
Burks 1969, Boucek et al. 1981).
Table 3 presents an example of the diverse organisms, largely unstudied, that share
their livelihoods with the pollinators of native figs or use them as food. Some of the
Hymenoptera and mites probably are parasites of agaonids. The genus of Tarsonemidae
to which the observed specimens belong has never before been collected in the New
World (H. Cromroy, personal communication), underscoring the poor state of knowledge
that exists even within our native faunas. The undescribed nematodes appear to
parasitize the agaonids, but their impact on the hosts is unknown (R. Giblin-Davis,
personal communication). Other insects may compete with agaonids for limited resources
by forming their own galls in syconia, for instance the cecidomyiid Ficiomyia perar-
ticulata Felt (Roskam & Nadel 1990), or they may be cleptoparasites; that is, they
develop in the galls created by agaonids and kill their gall mates. A role possibly beneficial
for the agaonids is played by Physothorax bidentulus Burks, which parasitizes the
cecidomyiid (Roskam & Nadel 1990). Some of the syconial inhabitants or visitors prey
on the Hymenoptera.
We have observed various ants (not included in our survey) leaving syconia, carrying
wasps away. Visiting adults and larvae of Charoxus, a New World genus of aleocharine

Florida Entomologist 75(1)

March, 1992



Pegoscapus assuetus (Grandi)
P. jimenezi (Grandi)
Idarnes care Walker
Heterandrium sp. 1
Heterandrium sp. 2
Heterandrium sp. 3
Neosycophila incerta (Ashm.)
N. bicolor(Ashmead)
Physothorax pallidus Ashmead
P. bidentulus Burks
P. russelli Crawford
Eurytoma butcheri (Burks)
Ormocerus sp.
genus et sp. indet.
Ficiomyia perarticulata Felt
Charoxus sp.
genus et sp. indet.
genus et sp. indet.
genus et sp. indet.


+ (2 "forms")



+ (1 "form")



These data resulted from collections of several thousand syconia from 1988 to 1991. Z. Bou6ek (British Museum)
provided preliminary names for Hymenoptera. R. Giblin-Davis and H. Cromroy, (both at Univ. Florida) identified
the nematodes and mites respectively.

staphylinids, enter syconia through the exit hole chewed by male agaonids and feed on
the newly-emerged wasps inside. One Costa Rican species is known to plug the exit
hole with debris after it enters so that its prey cannot escape (Bronstein 1988c). We
have seen the Floridian species feeding on agaonids as well as on other wasps in syconia
which we have opened (Frank & Thomas, in press). We also found that it will enter
syconia of F. microcarpa in petri dishes, but it does not enter the large and thick syconia
of F. benghalensis or F. altissima, although it does probe the agaonid exit holes. Our
understanding of the biologies of most of the non-pollinating syconial inhabitants is poor
(Bronstein 1986, Frank 1989) and should be improved, as these organisms are potential
biological control agents. In some collections of figs, non-pollinators outnumber the
pollinators (personal observation, Williams 1928, Bronstein 1986).
Currently, Florida is endowed with three species of weedy exotic figs, possibly more
if some unusual "varieties" are identified as separate species. It also has two potentially
weedy species, F. benjamin and F. religiosa, whose populations are probably large
enough to allow establishment of their pollinators in the event of their introduction.

Insect Behavioral Ecology '91 Nadel et al.

These figs are among the most abundant exotic fig species in the Miami area. Ficus
benjamin is an aggressive strangler like its close relative, F. microcarpa, and has
relatively small syconia that may easily be eaten by seed-dispersing birds. Steps must
be taken to prevent the introduction of new pollinators, and to initiate study on their
control before the weedy fig problem escalates.


We thank Doyle McKey (Univ. Miami) and Judith Bronstein (Univ. Arizona) for
their help and cooperation, and William Ramirez B. (Univ. Costa Rica) for sparking our
enthusiasm for fig insects. We are very much indebted to Z. Boucek (British Museum)
for preliminary names for Hymenoptera, to H. L. Cromroy (Univ. Florida, Gainesville)
for names for mites, and to R. M. Giblin-Davis (Univ. Florida, Ft. Lauderdale) for
names for nematodes. E. D. McCoy and P. D. Stiling (Univ. South Florida) and M. K.
Hennessey and J. R. King (USDA-ARS, Miami) kindly reviewed manuscript drafts.
This is University of Florida, Institute of Food & Agricultural Sciences, Journal Series
no. R-02090.


BERG, C. C. 1989. Classification and distribution of Ficus. Experientia 45: 605-611.
BOUCEK, Z., A. WATSHAM, AND J. T. WIEBES. 1981. The fig wasp fauna of the
receptacles of Ficus thonningii (Hymenoptera, Chalcidoidea). Tijdschr. Ent. 124:
BRONSTEIN, J. L. 1986. The nonpollinating wasp fauna of Ficus pertusa: the biology
of interlopers in an obligate mutualism, Chapter 5 in Coevolution and constraints
in a neotropical fig-pollinator wasp mutualism. Ph.D. Dissertation, Univ. Michi-
gan, Ann Arbor, MI.
1988a. Limits to fruit production in a monoecious fig: Consequences of an obli-
gate mutualism. Ecology 69: 207-214.
- 1988b. Mutualism, antagonism, and the fig-pollinator interaction. Ecology 69:
1988c. Predators of fig wasps. Biotropica 20: 215-219.
1989. A mutualism at the edge of its range. Experientia 45: 622-637.
sequences of flowering asynchrony in monoecious figs: a simulation study. Ecology
(in press).
BURKS, B. D. 1969. Redefinitions of two genera of chalcidoids from figs, with new
Florida species. Florida Ent. 52: 115-122.
BUTCHER, F. G. 1964. The Florida fig wasp, Secundeisenia mexicana (Ashm.), and
some of its hymenopterous symbionts. Florida Ent. 47: 235-238.
CONDIT, I. J. 1969. Ficus: The Exotic Species. Univ. California Div. Agric. Sci., Ber-
keley, 363 p.
FRANK, J. H., AND M. C. THOMAS. Two new species of Charoxus (Coleoptera:
Staphylinidae): predators of fig-pollinating wasps. J. New York. Ent. Soc. (in
FRANK, S. A. 1984. The behavior and morphology of the fig wasps Pegoscapus assuetus
and P. jimenezi: Descriptions and suggested behavioral characters for phylogene-
tic studies. Psyche 91: 289-308.
1989. Ecological and evolutionary dynamics of fig communities. Experientia
45: 680.
GALIL, J., AND D. EISIKOWITCH. 1968. On the pollination ecology of Ficus sycomorus
in East Africa. Ecology 49: 259-269.
- AND ---. 1969. Further studies on the pollination ecology of Ficus
sycomorus L. (Hymenoptera, Chalcidoidea, Agaonidae). Tijdschr. Ent. 112: 1-13.

38 Florida Entomologist 75(1) March, 1992

HILL, D. S. 1967. Figs (Ficus spp.) and fig-wasps (Chalcidoidea). J. Nat. Hist. 1: 413-
JANZEN, D. H. 1979. How to be a fig. Annu. Rev. Ecol. Syst. 10: 13-51.
KJELLBERG, F., AND S. MAURICE. 1989. Seasonality in the reproductive phenology
of Ficus: Its evolution and consequences. Experientia 45: 653-660.
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45: 661-673.
- AND S. C. KAUFMANN. Naturalization of exotic Ficus species (Moraceae) in
south Florida. Proceedings of the Symposium on Exotic Pest Plants, Miami,
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Sugar Planters' Assoc., Ent. Ser. Bull. 19: 3-29.


Department of Biological Sciences
Florida International University
Miami, FL 33199
Fairchild Tropical Garden
Miami, FL 33156


The terrestrial vegetation of the inland areas of the Everglades is of three main
types, occurring on oolite limestone substrate of progressively higher elevation: sawgrass
prairie, or glade; pineland; and hardwood hammock. Nectar-drinking ant abundance was
assessed using transects of honey baits, and is highest in pineland, and lowest in glade
habitat. Recruitment of ants to baits is also highest in pineland. Out of 891 species of

Insect Behavioral Ecology '91 Koptur 39

vascular plants in Everglades National Park, 78 spp. (9%) in 29 families have extrafloral
nectaries. The proportion of species with extrafloral nectaries was highest in pineland,
as was the proportion of individuals with extrafloral nectaries. The pinelands, with the
greatest nectar-drinking ant abundance, have the most plants with extrafloral nectaries.
Eight ant species have been collected at honey baits, and four species are regular visitors
to extrafloral nectaries of plants. Nectary-visiting ants are potential protectors of plants
against herbivores.


Los Everglades estan integrados por tres tipos principles de vegetaci6n terrestre,
los cuales ocurren en roca caliza del oolito con una elevaci6n progresiva: pradera, bosque
de pinos y bosque maderable. Se evalu6 la abundancia de las hormigas que se alimentan
de nectar, usando cebos con miel de abejas y fu6 mas alta en el bosque de pinos y mas
baja en la pradera. La capture de otras hormigas en cebos fu6 tambien mas alta en el
bosque de pinos. De las 891 species de plants vasculares que existen en el parque
national de los Everglades, 78 species (8%) en 29 families tienen nectar extrafloral. La
proporci6n de species con nectar extrafloral fue mayor en bosque de pinos (27%), que
en bosque maderable (22%) y que en la pradera (12%), pero la proporci6n de individuos
con nectar extrafloral fue mayor (34%) en bosque de pinos que en bosque maderable
(23%) o en la pradera (2%). Los bosques de pino, con la mayor abundancia de hormigas
consumidoras de nectar, tienen el mayor numero de plants con nectar extrafloral. Ocho
species de hormigas se han colectado en los cebos con miel de abejas y cuatro species
son visitantes frequentes de los nectares extraflorales. Las hormigas visitantes de los
nectares extraflorales protejen potencialmente la plant contra el ataque de herbivoros.

Extrafloral nectaries are plant secretary structures of diverse morphology and
anatomy (Elias 1983). They are located outside of flowers, and therefore do not usually
involve pollination. They are visited by a wide variety of animals for energy and nutrition,
and the associated effects on the plants range from beneficial (e.g., patrolling of plant
surfaces and disturbance of herbivores; enhanced predation and parasitism of plant
feeders) to harmful (e.g., attraction of herbivorous insect adults who oviposit on the
plant), depending on the ecological context (Bentley 1977, Beattie 1984, Buckley 1982,
Koptur 1992).
Extrafloral nectaries can be found on plants in both the tropics and temperate zones,
although they are more common in tropical areas. Biologists have surveyed various
habitats in diverse geographic locations and have determined the proportion of plants
that bear extrafloral nectaries (Table 1); some have sought to correlate abundance of
plants bearing extrafloral nectaries with the abundance or activity of ants at different
sites (Bentley 1976, Keeler 1979a, Koptur 1985, Koptur 1989, Koptur et al 1977), and
in general, have found fewer nectary-bearing individuals in areas with few or no ants.
This study is a contribution to this ongoing world survey. I examine the diversity
of plants with extrafloral nectaries in subtropical south Florida, and their distribution
in upland habitats of Everglades National Park. The unique combination of temperate
and tropical plants and animals has resulted in the designation of the Everglades as an
International Biosphere Preserve. The working hypothesis is that there will be an
intermediate proportion of the flora bearing extrafloral nectaries (more than temperate
sites, and less than tropical sites), and an intermediate diversity of plant species with
nectaries and ants that occur in the same habitats.
The upland terrestrial vegetation of the Everglades is of three main types: wet
prairie, pineland, and hardwood hammock. The seasonally inundated sawgrass prairie,
or glades is the lowest elevation habitat, has a substrate of marl over limestone rock,

Florida Entomologist 75(1)


% mean
cover Location Vegetation types/% cover Reference

Everglades, sawgrass prairie 2%
Florida, USA rockledge pinelands 34%
hardwood hammock 23%
N. California, native grassland 0%
USA riparian forest 0%
deciduous forest 0%
chapparal 0%
Nebraska, deciduous forest 1.8%
USA riparian forest 1.3%
tallgrass prairie 0%
sandhills prairie 8.3%
S. California, desert bush scrub 0.1-6.6%
USA desert wash 23.9-27.8%
sand dunes 0-1.4%
yucca-agave 3.7%
Korea deciduous forest


7.6-20.3% SE Brazil

forested second growth
(0 m) 28% same-at 1310 m 0%
cerrado (woody spp. only)

21.6-31.2% SW Brazil cerrado (woody spp.)

17.6-53.3% Amazonian terra firme forest 19.1%
Brazil successional forest 42.6%
buritirana 29.7%
shrub canga 50%
10-80% Costa Rica dryforest hillside 40-80%
riparian forest 10-40%
0-22% Costa Rica rain forest (0 m) 1-8%
cloud forest (1500 m) 3-22%
oak forest (3000 m) 0-3%


and is comprised mostly of herbaceous perennials and annuals, with scattered shrubs
(Fig. 1). The pineland is a subclimax community maintained by fire, on limestone rock
a few inches higher in elevation, consisting of an overstory of Dade county slash pine
(Pinus elliottii Engelm. var. densa Little & Dorman) and an understory of herbs, vines,
and shrubs (Fig. 2). Fire cleans out the developing hardwood understory every five or
so years, permitting the pines to remain the dominant feature. Without fire, the
hardwoods grow larger and eventually a hardwood forest, or hammock, is formed (Fig.
3). These habitats are intertwined into a mosaic due to small differences in topography,
fire history, and water flow.


Field observations and experiments were conducted in Everglades National Park
from 1987 1991 in Long Pine Key, in the vicinity of Redd Hammock. Extrafloral




March, 1992

Koptur 1989
(data updated)

Keeler 1980a

Keeler 1980b

Pemberton 1988

Pemberton 1990
Keeler 1979a

Oliveira & Leitao-Filho
"", Oliveira & Oliveira-
Filho 1991
Morellato & Oliveira 1992

Bentley 1976

Kopturetal. 1977

Insect Behavioral Ecology '91 Koptur

Fig. 1. Sawgrass prairie (glade) habitat in Everglades National Park.

nectaries on plants were detected by visual inspection, sometimes aided by hand-lens
and dissecting microscope. The presence of ants or sooty mold gave evidence of nectar
secretion (if ant-tended Homoptera were not present). Certain species did not have
obvious nectaries, but close examination, prompted by reports in the literature that
their families or genera possessed nectaries, often revealed tiny nectaries.

Fig. 2. Pineland habitat in Everglades National Park.



42 Florida Entomologist 75(1) March, 1992

i, Si iI 7N E

*~~~~ ~ I ^R'*' 'N'^ 1lR~f^lBB

Fig. 3. Hammock habitat in Everglades National Park.

Insect Behavioral Ecology '91 Koptur 43

Cover of plants with extrafloral nectaries was determined using three 20 m transects
in each of the three habitats. These nine transects were done during the early dry
season, when the sawgrass prairie is not covered with water, and so reflect only the
plants present during late November.
Ant activity was measured using lines of honey baits at four times during the dry
season: November, February, March, and April. Each line consisted of 20 baits spaced
at 1 m intervals, and was monitored every 5 minutes for 1 hour. The numbers and types
of ants attracted to the baits were recorded at each observation. A bait was considered
"discovered" if any ants at all were present at any time, and to have experienced
"recruitment" if the number of ants increased to greater than five. Ant voucher specimens
were determined by Dr. Mark Deyrup of Archbold Biological Station.


Of the 891 species of vascular plants recorded for Everglades National Park (Avery
& Loope 1983), 78 species in 29 families (8.8 %) have been observed to possess extrafloral
nectaries (Table 2). Common families with extrafloral nectaries include the legumes
(Fabaceae), from foliar nectaries on trees such as Lysiloma bahamensis Benth. and


Pteridium aquilinum (L.) Kuhn var. caudatum (L.) Sadebeck (1)
Tillandsia balbisiana Schult. (5)
E* Dioscorea bulbifera L. (1)
Smilax auriculata Walt. (1)
Smilax bona-nox L. (1)
Smilax havanensis Jacq. (1)
Smilax laurifolia L. (1)
Encyclia boothiana (Lindl.) Dressler var. erythronioides (Small) Luer (5)
E. cochleata (L.) Dressier var. triandra (Ames) Dressler (5)
E. tampensis (Lindl.) Small (5)
Epidendrum nocturnum Jacq. (5)
E. rigidum Jacq. (5)
Oncidium ensatum Lindl. (0. floridanum) (4,5)
0. altissimum (Jacq.) Sw. (0. luridum) (4,5)
Vanilla barbellata Reichb. f. (5)
V. phaeantha Reichb. f. (5)
E* Eragrostis barrelieri Daveau (5)
Eragrostis ciliaris (L.) R. Br. (5)
E. elliottii S. Wats. (5)

Florida Entomologist 75(1)


Annona glabra L. (8)
Sambucus canadensis L. (S. simpsonii) (1)
Chrysobalanus icaco L. (1)
Conocarpus erectus L. (2)
E* Terminalia catappa L. (2)
Ipomoea alba L. (2)
I. hederifolia L. (2)
I. indica (Burm.) Merrill (I. acuminata) (2)
I. trichocarpa Ell. (2)
I. triloba L. (2)
Diospyros virginiana L. (1)
Cnidoscolus stimulosus (Michx.) Engelm. & Gray (1,2)
Croton arenicola Small (C. glandulosus) (1)
C. linearis Jacq. (1)
Hippomane mancinella L. (1)
Manihot esculenta Crantz (1)
Acacia farnesiana (L.) Willd. (1)
A. pinetorum Hermann (1)
Albizzia lebbeck (L.) Benth. (1)
Canavalia brasiliensis Mort ex. Benth. (1)
C. rosea (Sw.) DC. (1)
Cassia aspera Muhl. ex Ell. (2)
C. chapmanii Isely (2)
C. deeringiana (Small & Penn.) Macbr. (2)
E* C. fistula L. (2)
C. ligustrina L. (2)
C. obtusifolia L. (2)
E* Delonix regia (Boj. ex Hook.) Raf. (2)
Erythrina herbacea L. (3)
E* Leucaena leucocephala (Lam.) de Wit (2)
Lysiloma latisiliquum (L.) Benth. (1)
Pithecellobium guadalupense (Pers.) Chapm. (1)
P. unguis-cati (L.) Benth. (1)
Vigna luteola (Jacq.) Benth. (5)
Scaevola plumieri (L.) Vahl (1)
Gossypium hirsutum L. (1)
E* Hibiscus rosa-sinensis L. (1)
E* Thespesia populnea (L.) Soland. ex Correa (1'
E* Urena lobata L. (1)
Swietenia mahogani (L.) Jacq. (1)
Ficus aurea Nutt. (8)
Myrsinefloridana A. DC. (1)

March, 1992

Insect Behavioral Ecology '91 Koptur

Passiflora pallens Poepp. ex Mast. (1)
P. sexflora Juss. (1)
P. suberosa L. (1,2)
Colubrina arborescens (Mill.) Sarg. (1)
C. cubensis (Jacq.) Brongn. var. floridana M.C. Johnst. (1)
C. elliptica (Sw.) Briz. & Stern (= C. reclinata) (1)
Prunus myrtifolia (L.) Urb. (1)
Hamelia patens Jacq. (9)
Morinda royoc L. (9)
Zanthoxylumfagara (L.) Sarg. (1)
Ayenia euphasiifolia Greiseb. (1)
E* Triumfetta semitriloba Jacq. (1)
Turnera ulmifolia L. var. ulmifolia (2)
Avicennia germinans (L.) L. (2)
Citharexylumfruticosum L. (1)
E* Clerodendrum speciosissimum Van Geert ex C. Morr. (1)
Cissus sicyoides L. (1)

treelets like Erythrina herbacea L. (Figs. 4 & 5) to herbs such as the rockledge-dwelling
Cassia deeringiana (Small & Penn.) Macbr.; the orchids (Orchidaceae) with nectaries
in the inflorescence; the mallows (Malvaceae) with foliar nectaries on the lower abaxial
surface of the lamina; and the passionflowers (Passifloraceae) with elevated nectaries
on leaf bases and petioles (Fig. 8). Prompted by observations by Kathy Keeler, I have
observed formless nectaries on the young inflorescences of Tillandsia balbisiana Schult.
(Bromeliaceae) (Fig. 9). And prompted by a report of nectaries in Rapanea (Myrsinaceae)
(Oliveira & Leitao-Filho 1987), Bob Pemberton and I observed foliar nectaries in Myrsine
floridana A.DC. for the first time (Figs. 10-12).
Transects revealed the greatest plant species diversity in the pinelands, followed by
glade, and then hammocks (Table 3). The pinelands had the highest proportion of species
with extrafloral nectaries (27%, vs. 22% in hammocks and 12% in glade). This difference
is even more striking when we compare cover of plants with nectaries (the proportion
of individuals with nectaries): 34% of the plants encountered in pinelands were species
that bear nectaries; 23% in hammocks; and only 2.5% in glade.
The discovery of honey baits by ants (and presumably, ant activity and/or abundance)
was greatest in pineland (a mean of 9.8 baits out of 20 discovered in one hour), inter-
mediate in hardwood hammock (a mean of 4.2 baits discovered in one hour) and lowest
in the glade (a mean of 1 bait out of 20 discovered in one hour) (Table 4). Recruitment
of ants to baits is also highest in pineland (a mean of 3.6 baits recruited to, versus a
mean of 2 in hammock, and none whatsoever in glade) (Table 4).
Of the 50 species (40 native, 10 exotic) of ants recorded from Everglades National
Park (Alan Herndon and Mark Deyrup, personal communication), I have found 8 species
visiting honey baits at my study sites (Table 5). Four of these species are regular visitors
to extrafloral nectaries of various plants.

Florida Entomologist 75(1)

Figs. 4-7. Some Everglades plants with extrafloral nectaries. 4. Habit of coral bean,
Erythrina herbacea (Fabaceae), a small tree that bears nectaries on the stipels of its
trifoliate leaves. 5. Nectar secreted from one of a pair of stipel nectaries on young leaves
of E. herbacea. Bar scale = 0.5 mm. 6. Habit of cocoplum, Chrysobalanus icaco L.
(Chrysobalanaceae). 7. Flattened nectary with nectar on abaxial leaf surface near base
on young leaf of C. icaco. Bar scale = 1 mm.


The pineland has the greatest ant activity and recruitment, and therefore, the great-
est potential for ant protection of plants with extrafloral nectaries. The pineland also
has the greatest number of plants with extrafloral nectaries. Exclusion experiments
performed on a common tree of pinelands and hammocks, the wild tamarind (Lysiloma
bahamensis), have demonstrated that the presence of ants reduces damage to leaves
(Koptur unpublished results). The role of ants and other beneficial insects visiting nec-
taries of other pineland species awaits elucidation.
The proportion of species in a flora bearing extrafloral nectaries has been calculated
for a number of habitats around the world. These values range from less than 5% in
southern California (Pemberton 1988), Hawaii (Keeler 1985), Korea (Pemberton 1990)

March, 1992

~t --

'p~a- Wi.

Insect Behavioral Ecology '91 Koptur

Figs. 8-9. Some Everglades plants with extrafloral nectaries. 8. Nectar droplet on
elevated nectary of Passiflora suberosa L. (Passifloraceae). Bar scale = 1 cm. 9. Ants
visiting formless nectaries on young inflorescences of Tillandsia balbisiana
(Bromeliaceae). Bar scale = 1 cm.

and Nebraska (Keeler 1979b) to more than 15% in various habitats of Brazil (Oliveira
& Leitao-Filho 1987, Oliveira & Oliveira-Filho 1991). The proportion of the Everglades
flora with extrafloral nectaries is intermediate, with a value of 9% (78 of 891 spp.). This
proportion may increase slightly with more field observations.
The cover of plants with extrafloral nectaries has been documented in a variety of
tropical and temperate locations (Table 4) and ranges from 0% in northern California,
Nebraska, and high elevation tropical sites to more than 50% in Costa Rica and Amazonian
Brazil. In general, there are more individuals with extrafloral nectaries in tropical
habitats than temperate habitats. Upland habitats of south Florida have from 2% to

Florida Entomologist 75(1)

Figs. 10-12. Some Everglades plants with extrafloral nectaries. 10. Ant visiting
formless nectaries of Myrsine floridana located on abaxial leaf surfaces at leaf base on
either side of the midrib. Bar scale = 1 cm. 11. Underside of leaf edge of M. floridana
with nectar droplets. Bar scale = 1 mm. 12. Leaf surface with formless nectaries of M.
floridana. Bar scale = 0.5 mm.

34% cover of extrafloral nectary-bearing plants, intermediate between temperate and
tropical extremes.
Upland habitats of south Florida are not the only ones in which ants exist, and
preliminary observations have revealed that plants with extrafloral nectaries are also
found in inundated freshwater and saltwater habitats. (These species are included in
Table 2.) Future work will compare other habitats in south Florida to upland habitats
of the Everglades, and investigate the potential ecological role of extrafloral nectaries
in various native plant species.

March, 1992

Insect Behavioral Ecology '91 Koptur


Number of Proportion Number of Proportion
species (No.) spp. individuals indivs. with
Habitat encountered nectaries encountered nectaries

glade 26 12% (3) 242 2.5% (6)
pineland 3 27% (9) 353 34% (121)
hammock 23 22% (5) 197 23% (46)


14 Nov 87 13 Feb 88 28 Mar 88 04 Apr 88 mean
Habitat D R D R D R D R D R

glade 0 0 0 0 1 0 3 0 1 0
pineland 8 1 3 0 11 5 17 5 9.8 3.6
hammock 3 1 7 2 2 1 5 4 4.2 2


Species (all native) nectar habitat

Aphaenogaster texana var. caroliniensis Wheeler B H & P
Crematogaster ashmeadi Mayr B P
Crematogaster sp. nr. ashmeadi (undescribed) B P
Cyphomyrmex rimosus (Spinola) B P
Pheidole dentata (Mayr) B&N H&P
Pseudomyrmex elongatus (Mayr) B & N H
Pseudomyrmex simplex (F. Smith) B & N H & P
Solenopsis geminata (Forel) B&N H&P


I thank Barbara Gomez and Monica Parada for help with fieldwork, and the Research
Center at Everglades National Park for permits, information, and interaction. This
research was supported with faculty development grants from Florida International


AVERY, G. N., AND L. L. LOOPE. 1983. Plants of Everglades National Park. A Pre-
liminary Checklist of Vascular Plants. National Park Service, South Florida Re-
search Center. Report T-574. 2nd ed. 76 p.
BEATTIE, A. J. 1984. The evolutionary ecology of ant-plant mutualisms. Cambridge
University Press, London.

50 Florida Entomologist 75(1) March, 1992

BENTLEY, B. L. 1976. Plants bearing extrafloral nectaries and the associated ant com-
munity: interhabitat differences in the reduction of herbivore damage. Ecology
57: 815-820.
-- 1977. Extrafloral nectaries and protection by pugnacious bodyguards. Annu.
Rev. Ecol. Syst. 8: 407-427.
BUCKLEY, R. 1982. Ant-plant interactions in Australia. Junk, The Hague.
ELIAS, T. S. 1983. Extrafloral nectaries: their structure and distribution, Ch. 6, p.
174-203 in Bentley, B. L. and T. S. Elias [eds.], The biology of nectaries. Columbia
University Press, NY.
KEELER, K. H. 1979a. Distribution of plants with extrafloral nectaries and ants at two
elevations in Jamaica. Biotropica 11: 26-29.
1979b. Species with extrafloral nectaries in a temperate flora (Nebraska).
Prairie Nat. 11: 33-38.
- 1980a. Cover of plants with extrafloral nectaries at four northern California
sites. Madrono 28: 26-29.
- 1980b. Distribution of plants with extrafloral nectaries in temperate com-
munities. American Midi. Nat. 104: 274-280.
1985. Extrafloral nectaries on plants in communities without ants: Hawaii
[USA]. Oikos 44: 407-414.
KOPTUR, S. 1985. Alternative defenses against herbivores in Inga (Fabaceae:
Mimosoideae) over an elevational gradient. Ecology 66: 1639-1650.
1989. Plants with extrafloral nectaries and ants in different habitats of the
Everglades. AIBS/BSA abstract. American J. Bot. Supplement 76: 112.
- 1992. Extrafloral nectary-mediated interactions between insects and plants,
pp. 85-132 in E. A. Bernays [ed.], Insect plant interactions Vol. IV. CRC Press,
Boca Raton.
--, P. DILLON, C. FOSTER, A. CHAVERRI, AND K. CHU. 1977. A comparison of
ant activity and extrafloral nectaries at various sites in Costa Rica. O.T.S. (Organi-
zation for Tropical Studies) coursebook, Tropical Biology 77-3: 299-302.
MORELLATO, L.P.C., AND P. S. OLIVEIRA. 1991. Distribution ofextrafloral nectaries
in different vegetation types of Amazonian Brazil. Flora (Jena) 185(1): 33-38.
OLIVEIRA, P. S., AND H. F. LEITAO-FILHO. 1987. Extrafloral nectaries: their
taxonomic distribution and abundance in the woody flora of cerrado vegetation
in southeast Brazil. Biotropica 19: 140-148.
---, AND A. T. OLIVEIRA-FILHO. 1991. Distribution of extrafloral nectaries in the
woody flora of tropical communities in Western Brazil, pp. 163-176 in Price, P.
W. et al. [eds.], Evolutionary ecology of plant-animal interactions. John Wiley &
Sons, NY.
PEMBERTON, R. W. 1988. The abundance of plants bearing extrafloral nectaries in
Colorado and Mojave desert communities of southern California. Madrono 35: 238-
- 1990. The occurrence of extrafloral nectaries in Korean plants. Korean J. Ecol.
13: 251-266.

Insect Behavioral Ecology '91 Hall


Department of Entomology and Nematology
University of Florida
Gainesville, FL 32611


African honeybees, imported to South America thirty-four years ago, have spread
throughout most of the neotropics and have replaced the resident European bees. Two
controversial views concern the nature of the neotropical African population. One view
is that the African bees have spread primarily by paternal introgression into European
colonies and the resulting population is mixture of all African-European hybrid
genotypes. The other view is that the bees have spread primarily by maternal migration
of feral African swarms and the feral population has retained, to a large extent, an
African genetic integrity. Results from recent studies, using mitochondrial and nuclear
DNA markers, support the latter view. Asymmetries in both maternal and paternal
gene flow between feral African and managed European populations favor the African
genotype. The replacement of the large extant European gene pool by a tiny introduced
African gene pool could not have occurred if the African and European populations were
panmictic and the African genotype were not favored by selective mechanisms. Some
separation of the parental genotypes and/or selection against hybrid genotypes had to
be realized. Superior fitness in a tropical environment is probably largely responsible
for the African bee success, but reduced fitness of hybrids due to genetic factors may
be involved also. As African bees approach temperate climatic regions where European
bees are better adapted, a persisting hybrid zone may be established. With DNA mar-
kers, hybrid zone dynamics can be studied which may reveal the nature of selective


Las abejas africanas, importadas a America del Sur 34 afos atras, se han expandido
a traves de la mayor parte del Neotr6pico y han reemplazado las abejas europeas. Dos
controversiales puntos de vista se relacionan con la naturaleza de la poblaci6n de abejas
africanas en el neotr6pico. El primer punto de vista sostiene que las abejas africanas se
han esparcido en las colonies europeas en base a una introgresi6n paterna dando por
resultado una poblaci6n mixta de genotipos hibridos Europeo-Africanos. El segundo
punto de vista es que las abejas se han esparcido primeramente por migraci6n materna
de emjambres salvajes de abejas africanas y que la poblaci6n salvaje ha retenido, una
integridad genetic africana. Resultados de studios recientes, utilizando marcas de
mitocondria y DNA nuclear, soportan esta teoria. Asimetrias del flujo genetico materno
y paterno entire poblaciones salvajes africanas y poblaciones europeas favorecen el
genotipo africano. El reemplazo de un fondo gen6tico minfsculo no pudo haber ocurrido
si las poblaciones africanas y europeas fueran panmiticas y el genotipo africano no
estuviera favorecido por mecanismos de selecci6n. Puede haber ocurrido una separaci6n
de los genotipos paternos y la selecci6n en contra de genotipos hibridos. El ambiente
tropical es probablemente la raz6n por la cual la abeja africana se ha adaptado tan bien
en este medio, pero la reducci6n de la adecuaci6n de los hibridos puede deberse tambien
a factors geneticos. Cuando las abejas africanas colonicen regions climaticas templadas
donde las abejas europeas estan mejor adaptadas, un hibrido persistent puede estab-
lecerse en esta zona. Con marcas de DNA, la dinamica de hibridos en esta zona puede
ser estudiada revelando la naturaleza del process selective.

52 Florida Entomologist 75(1) March, 1992

The honeybee, Apis mellifera (L.), is represented by a number of subspecies, or
races, indigenous to Europe, the Middle East and Africa (Ruttner 1988). Among the
races are profound differences in ecological adaptation between temperate and tropical
environments (Fletcher 1978, 1991, Winston et al. 1983, Rinderer 1988, Ruttner 1988).
Because African bees are adapted to the tropics, queens of the race A.m. scutellata
(Lepeletier) (initially believed to be A.m. adansonii, Latreille, Ruttner 1988) were
brought to Brazil in the late 1950s with the intention of improving commercial honey
production (Kerr 1967). African swarms that had escaped from apiaries established a
large self-sustaining feral population. The African bee population has since expanded
through most tropical regions of South, Central and North America (Michener 1975,
Taylor 1977, 1985a).
The honeybees first introduced to the Americas were primarily of the west European
subspecies A.m. mellifera (L.) and A.m. iberica (Goetze). These bees were notorious
for their stinging tendency. The more docile east European races, A.m. ligustica
(Spinola), A.m. carnica (Pollmann) and A.m. caucasia (Gorbachev), were imported later
and became the predominant stock used for beekeeping (Pellet 1938, Oertel 1976, Shep-
pard 1989). In temperate but not tropical regions, European bees established feral
populations (Michener 1975, Taylor 1977, 1985a, 1988). In the neotropics, European bees
were confined largely to apiaries. Nevertheless, they vastly outnumbered the imported
African bees. Yet within thirty-four years, African bees replaced the European sub-
species over most of one continent and part of another, without noticeable modification
of the African behavioral characteristics (Taylor 1985a). The African bee takeover has
been dramatic, with major biological and economic consequences.
The tendencies to invest honey resources into brood production, to swarm, to abscond,
and, most notably, to sting readily make African bees difficult and less profitable to
keep (Michener et al. 1972, Michener 1975, Winston et al. 1983). When African bees
invaded New World countries, the beekeeping industries were devastated (Michener et
al. 1972, Rinderer 1986a, Caron & Gray 1991). In some places, the industries have slowly
rebuilt as management practices have adapted to the African bee (Gonqalves et al. 1991).
The African bee population has been spreading into Texas since October, 1990, and
is expected soon to become well-established across the southern tier of the United
States. The northward spread of the African bees may be halted by temperate climatic
and ecological conditions. A hybrid zone may be formed between them and the persisting
European population to the north (Taylor 1977, Taylor & Spivak 1984). Within the
United States, the highest concentration of feral African bees will be in Florida. With
a large beekeeping industry, many crops dependent on honeybee pollination, and an
economy dependent on tourism, Florida will be the state most severely affected.


Superior adaptability to tropical ecological conditions is probably largely responsible
for the amazing success of the neotropical African bees (Fletcher 1978, 1991, Winston
et al. 1983, Rinderer 1988, Ruttner 1988). Despite the phenomenal nature of the African
bee takeover, little is known about how it has happened. To understand the processes
responsible, the extent to which African and European bees have interacted must be
established. Currently, there are two major views concerning the composition and spread
of the neotropical African population.
One school of thought maintains that, because African and European bees are of the
same species, extensive hybridization has occurred. The neotropical African population
has been described as a "hybrid swarm", meaning that it represents the entire range
of hybrid genotypes (Rinderer 1986b). African drones mating with extant European

Insect Behavioral Ecology '91 Hall

queens has been assumed to be the primary driving force responsible for African bee
spread (Rinderer et al. 1985, Rinderer 1986b). As the extant bees become Africanized,
they serve to perpetuate further the spread of African genes. The term "Africanized
bees", commonly used to describe all African-derived bees in the Americas, not only
implies that the bees are hybrids but also that the bees were originally European.
The other school of thought holds that African bee spread has been through maternal
migration, that is, through queens accompanying swarms (Taylor 1977). The retention
of African phenotypic characteristics suggests that neotropical African bees have largely
retained an African genetic integrity (Michener 1975, Taylor 1985a, 1988, Fletcher 1991).
Although mating occurs between African and European bees, strong selective processes
in the tropics would favor African bees to such an extent that the presence of European-
African hybrids would only be transitory. Hybrids would exist primarily in temperate-
subtropical boundary regions, where both types of bees would be equally adapted (Taylor
& Spivak 1984, Taylor 1985a, Lobo et al. 1989, Sheppard et al. 1991). As will be discussed,
these latter views have been supported by recent studies.


Studies of hybridization have been impeded due to a lack of genetic markers that
distinguish African and European bees (reviewed by Daly 1988, 1991). Identification of
African bees has been primarily through discriminant analyses of subtle morphological
features. The genetic basis of the morphological characteristics has not been defined.
The characteristics are certainly a consequence of complex temporal and spatial interac-
tions among multiple gene products, and they are subject to pleiotropic and environmen-
tal effects. The characteristics exhibit a range of variability shared by both African and
European bees. Different distributions within the range allow assignment of probabilities
that bees belong to one group or the other. Intermediate morphometric scores in neo-
tropical bees have been used as evidence for hybridization (Buco et al. 1987, Sheppard
et al. 1991) but intermediate probabilities mean that a colony of bees cannot be identified
confidently. Such scores could be a result of hybridization but do not actually demonstrate
Hybridization is demonstrated more appropriately and accurately by the exchange
of genetic markers. Allozymes, commonly used in population genetic studies, are few
in number and lack specificity in honeybees, as in hymenopteran insects in general
(reviewed by Daly 1988, 1991). Only allele frequency differences at a few enzyme loci
distinguish African and European populations. Intensive parental analysis of individual
colonies increases the effectiveness of allozymes in following introgression (Taylor et al.
1991). Recently, understanding of the processes of African bee spread has been greatly
enhanced through the use of DNA markers seen as restriction fragment length
polymorphisms (RFLPs) (reviewed by Hall 1991). DNA differences, as a whole, are not
as subject to the selective forces that limit protein differences. Potentially, many DNA
polymorphisms can be discovered.


Two significant studies, conducted independently, found that virtually all feral
swarms caught in regions occupied by African bees carried African mitochondrial DNA
(mtDNA) (Hall & Muralidharan 1989, Smith et al. 1989). These findings were confirmed
by additional research employing a rapid method to identify the mtDNA type (Hall &
Smith 1991). In regions where the African population was well established, such as in
Venezuela, both managed and feral colonies had African mtDNA. Because mtDNA is
maternally inherited, these studies revealed that neotropical African bees have spread

Florida Entomologist 75(1)

as unbroken African maternal lineages extending back to the original queens brought
from Africa to Brazil. The speed and distance involved in the expansion of the African
bee population and the notorious swarming tendency of African bees logically implicated
maternal migration (Taylor 1977).
Analysis of both nuclear DNA and mtDNA has allowed the contributions of maternal
and paternal gene flow to be distinguished. European colonies in southern Mexico,
established before African bees entered the region and sampled fifteen months after-
wards, carried European mtDNA but carried low levels of European nuclear DNA
markers (Hall 1990). A loss of European alleles would result from daughters of the
European queens mating with African drones. Such bees can be accurately called "Af-
African paternal introgression into apiaries has been well documented. The increase
in defensive behavior in the managed colonies, shortly after African bees move into an
area, is impressive. However, Africanized apiaries are not a significant factor in the
spread of African genes and in the establishment of the African population. The absence
of European mtDNA in the feral population shows that swarms from European colonies
have not contributed to the migrating feral population, even if they have become ex-
tremely Africanized after repeated backcrossing. Apparently, European maternal
lineages in tropical apiaries eventually disappear. Unless actively maintained, they are
probably lost through attrition. Thus, Africanization of European matrilines is a dead
end process. African mtDNA in apiaries would result from beekeepers replacing dead
colonies with feral swarms and, possibly, from African queen takeovers of European
colonies (Michener 1975, Taylor 1985ab).
In feral African swarms from the same region of Mexico, the European nuclear DNA
markers were present at low levels (Hall 1990). Thus, some paternal "Europeanization"
apparently occurs at the edge of the expanding African population, where populations
of managed European bees are first encountered. In colonies from Venezuela, the mar-
kers were almost completely absent (Hall 1990). Hybrids carrying European markers
appear to be lost over time as the African population becomes established. However,
the lower level of European markers in Venezuelan colonies may indicate that the bees
had been more isolated and had encountered fewer European colonies. Samples at the
same locations must be collected over time to confirm a temporal loss of European
markers. African swarms collected in northern Mexico exhibited a dramatic change in
allozyme frequencies in less than a year, reflecting an initial European contribution that
was subsequently lost (Taylor et al. 1991). A loss of European markers would be consis-
tent also with observations in Panama of a temporal change in feral bees towards a
more African morphology (Boreham & Roubik 1987).
In the nuclear DNA studies described above, markers were used that distinguished
African from east European bees but not from west European bees (Hall 1990). Neotrop-
ical African-European hybridization was investigated recently with a DNA allele present
in almost all west European bees but absent in east European bees. This allele was
discovered at a low level in Old World African bees but at a much higher, relatively
constant, level among several New World African populations (McMichael & Hall, man-
uscript in preparation). It appears that, as a consequence of African-European hybridi-
zation, a west, but not an east, European contribution has persisted in the neotropical
African gene pool.
The mtDNA and nuclear DNA findings have demonstrated major asymmetries in
both paternal and maternal gene flow between the neotropical feral African population
and the European apiaries. Despite the overwhelming numbers of European bees present
in managed colonies at the time of African bee introduction, the genotype of the neotrop-
ical African descendents has remained largely African.

March, 1992

Insect Behavioral Ecology '91 Hall


The view that the neotropical bee population is a panmictic European-African "hybrid
swarm" (Rinderer 1986b) is difficult to reconcile with the persistence of African traits
(Michener 1975, Taylor 1985a, Fletcher 1991), the maintenance of African allozyme
frequencies (Taylor et al. 1991), and the paucity of European DNA markers (Hall 1990).
The number of African alleles contributed by the introduced bees would have been a
small fraction of the number contributed by the extant European colonies (Kerr 1967).
In a freely interbreeding African-European population, with no hybrid limitations, alleles
would be reproduced in proportion to the parental contributions (in Hardy Weinberg
equilibrium). To allow the superior fitness of the African bees to be manifested and not
be obliterated by hybridization, an African genetic integrity had to be largely retained.
Either isolation had to prevent mixing of the genotypes or, once hybrids were formed,
the proportion of European alleles had to be reduced. The alleles had to be diluted by
inward migration of more pure African bees and/or eliminated through selection.
Significant isolation has probably been realized through allopatric separation. Feral
African bee populations likely became established in many neotropical regions distantly
separated from managed colonies (Taylor 1985a). With a higher reproductive rate, the
numbers of the feral African bees would have increased in proportion to the European
bees in apiaries. If European alleles had not entered the gene pool through prior hybridi-
zation, the isolated populations could have served as sources of pure African bees.
As swarms of African bees moved from the isolated regions into areas with European
bees, they would have been subject to genetic dilution through hybridization. If there
had been no selection against hybrids, gene frequencies would have reflected the effective
size of the migrating African front and the cumulative numbers of European bees encoun-
tered enroute. As the African population spread through regions with managed European
colonies, African allele frequencies would have decreased over distance as a gradient,
that is, as a dine. At the outer edge of the African bee distribution, where African gene
frequencies would have been very low, the rate of expansion would have been limited
by short mating flight distances and by short swarm flight distances more typical of
European bees (Taylor 1977). Despite a slow rate of spread, the African bee takeover
could have occurred through this process. Continuous migration of African bees from
the more isolated areas into areas of hybridization would have diluted the European
gene pool and would have advanced the dine.
In contrast to a dine, the edge of the African population persists as a rapidly expanding
front without significant mitigation of African traits (Taylor 1977, 1985a). In African
swarms near the migrating front, European DNA alleles are found, but they represent
a minor proportion (Hall 1990). For the expanding front to be maintained, selective
processes must exist to eliminate European alleles. Long distance dispersal itself may
be a primary selective factor. Hybrids may have a reduced reproductive capability and
a lower propensity to swarm and to migrate long distances. Hybrids may tend to fall
behind the front and could persist as a more stationary population. However, the levels
of European DNA alleles are lower behind the front (Hall 1990). Lower levels could
result from continued migration of African bees from isolated regions or from selective
processes that continue to purge European alleles. Since European bees are considerably
less fit than African bees in the tropics, it is logical that hybrids may be less fit due to
a number of ecological factors (Taylor 1985a). Also, possible genetic incompatibilities
have not been ruled out which would tend to be expressed in late generation and
backcross hybrids.
In North America, most managed colonies carry east European mtDNA, whereas
some feral populations carry a large proportion of west European mtDNA (Hall & Smith

Florida Entomologist 75(1)

1991). Thus, in temperate feral populations, remnants of the early European introduc-
tions seem to persist. By encountering European bees primarily as a managed population,
the spreading African bees would have confronted a large proportion of the east European
type. Nevertheless, as in the North American feral population, west European races
may have represented a sizable proportion of the South and Central American populations
prior to African bee takeover, particularly from rustic apiary colonies and from feral
colonies that may have existed. As described above, an allele, that is predominantly a
west European marker, is present at a significant level in neotropical African populations
(McMichael & Hall, manuscript in preparation). This allele may have come from early
hybridization with A.m. mellifera or A.m. iberica before the feral African population
became established. The constant level of the allele among neotropical populations
suggests that, after entering the African gene pool, this allele has been replicated in
the same proportion and has not been selected against (that is, a neutral marker in
Hardy Weinberg equilibrium). An intriguing possibility is that the higher retention of
this marker reflects a closer relationship, hence greater genetic compatibility, between
African and west European bees than between African and east European bees. The
west European allele has not accumulated further as the African population has ex-
panded. Thus, even if there were greater compatibility, African-west European hybrid
formation and/or survival still appear to be limited in the tropics.
After intensive backcrossing with feral African drones, European matrilines should
have become more adapted to tropical conditions, and swarms from such Africanized
colonies should have contributed significantly to the feral population. However, European
mtDNA is absent in the feral population (Hall & Muralidharan 1989, Smith et al. 1989,
Hall & Smith 1991). A persisting disadvantage from a European maternal component
could be responsible. Perhaps European mtDNA limits the intense metabolic activity
required for long distance dispersal (Hall & Muralidharan 1989). Mitochondrial enzymes
are comprised of mitochondrial and nuclear DNA encoded subunits (Moritz et al. 1987).
Repeated backcrossing would create heterologous African-European subunit combina-
tions that may have reduced enzymatic activity. Suboptimal activity may be detrimental
primarily at times of metabolic stress and may not necessarily have a obvious effect on
all hybrid bee colonies. Migratory colonies would be affected more than would stationary


Selective factors will influence the distribution and character of the bees in the United
States and must be considered in control strategies. Hybridization to dilute the African
bees was attempted in Mexico (Rinderer et al. 1987, Tew et al. 1988). It would not be
feasible to introduce maladaptive genes into the feral population and expect them to
persist against strong selection. As African bees approach temperate climates, natural
factors will begin to work in favor of European bees. Where selective pressures are not
so intense, human intervention to modify the feral population may be able to overcome
weak selective forces, although such efforts would have to be continuous (Taylor 1985a,
Where selective forces are equal, a zone of hybridization will be formed naturally
(Taylor 1977, Taylor & Spivak 1984, Taylor 1985a, Lobo et al. 1989, Sheppard et al.
1991). Genotype distributions within the hybrid zone may reveal the nature of selective
processes (Barton & Hewitt 1989). If only ecological factors are involved, the genotypes
of the bees may represent a "hybrid swarm" but as reciprocal dines of African and
European alleles (Taylor 1985a). If genetic incompatibilities exist between African and

March, 1992

Insect Behavioral Ecology '91 Hall

European bees, a paucity of heterozygotes may be seen within the hybrid zone. A loss
of hybrids as a result of selection would exist in equilibrium with hybrids formed as the
parental types migrate inward.
For African bees to introgress beyond the hybrid zone and to survive northern
winters, multiple co-adapted factors would have to be inherited from European bees.
African-European hybridization within the zone would segregate critical epistatic re-
lationships among physiological, behavioral, and ecological factors. Reestablishment of
the relationships through random genetic assortment would occur at a low frequency,
especially if it must occur independently among a number of the separate patrilines that
comprise a colony. As a consequence, northern introgression of African bees would be
greatly limited (Taylor 1985a). However, unlinked neutral alleles may exhibit more
independent introgressive behavior. DNA markers under different selective influences
can potentially be found: neutral, non-neutral, and linked to non-neutral genes. An
enlarged collection of such markers will greatly enhance studies of gene flow and hybrid
zone dynamics.


The nature of the neotropical African honeybee population continues to be debated.
Is it the result of asymmetric gene flow and limited hybrid fitness favoring the African
genotype, or is it a product of unlimited hybrid formation and survival of all hybrid
genotypes as a "hybrid swarm"? Two recent reports continue to argue that there are
no limits to hybridization. This conclusion comes from finding hybrid bees in the South
American temperate hybrid zone (Sheppard et al. 1991) and from managed colonies in
Mexico shortly after African bee invasion (in effect the leading edge of the migrating
front) (Rinderer et al. 1991). Hybrids were identified on the basis of morphometric
probabilities. In the same or similar situations, hybridization has been recognized using
genetic markers (Lobo et al. 1989, Hall 1990, Taylor et al. 1991). Hybridization in
subtropical-temperate transition regions does not reflect the situation in tropical regions.
The hybridization in Mexico was not investigated as a transitory step in the dynamic
and evolving process of African bee colonization of new territory. The study in Mexico
examined only managed colonies yet concluded that feral African colonies were not
favored by asymmetric gene flow. Both studies (Sheppard et al. 1991, Rinderer et al.
1991) claimed that, because hybrids were found, no incompatibilities existed between
African and European bees. The mere existence of hybrids does not rule out the possible
existence of incompatibilities (note the mule).
New World African and European honeybee hybridization is multifaceted. Generali-
zations cannot be made about the entire process if only limited aspects are studied. The
different components must be defined and evaluated: tropical or temperate climates,
feral or managed colonies, African or European matrilines, established or transient
populations. It is even possible that hybrids between different European and African
subspecies differ in their fitness. The complex dynamics among the components must
be recognized to appreciate fully and to understand clearly New World African and
European honeybee interactions.


The work by the author cited in this article was supported by the USDA Competitive
Research Grants Office. This is Florida Experiment Station Journal Series No. R-02071.

58 Florida Entomologist 75(1) March, 1992


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60 Florida Entomologist 75(1) March, 1992


Research Institute for Nature Management, P.O. Box 9201,


Invasions by two species are analyzed, that of the collared dove (Streptopelia de-
caocto Privaldszky) invading Europe, and that of the African bee (Apis mellifera scutel-
lata Ruttner) invading tropical South America, Central America and the southern part
of North America. The analysis is made in terms of population growth and dispersal.
After this analysis, the observed parameter values are altered to investigate the sensitiv-
ity of the expected velocity to small changes in life history and long-distance dispersal.
This gives an impression of how likely it is that species, once confined to a certain
geographical region, expand their range, invading virgin regions beyond their former
range limit. The results of this approach are compared with the common theory concern-
ing invasion-proneness of species and biotypes. The present theory seems to offer a
more parsimonious explanation of invasions than does the common theory based on static

Se analizan las invasiones de dos species, la paloma collareja (Streptopelia decaocto
Privaldszky) la cual invade Europa, y aquella de la abeja africana (Apis mellifera scutel-
lata Ruttner) la cual ha invadido Sur America, America Central y la parte sur de America
del Norte. Se hace un analysis en termino de crecimiento de poblaci6n y dispersion.
Despubs de este analysis, los valores del parametro observados se alteran pra investigar
la sensibilidad de la velocidad esperada de pequefios cambios en la biologia y dispersi6n
a larga distancia. Esto da la impresi6n de que tan probable es que species, una vez
confinadas a una region geografica, expandan su actividad, invadiendo regions virgenes
las cuales estan fuera de los limits de su territorio. Los resultados de este analysis se
comparan con la teoria comun concerniente con propensidad de invasion de species y
biotipos. La present teoria parece ofrecer una explicaci6n mas parca de invasiones que
aquella explicada en la teoria coman, la cual esta basada en propiedades estaticas.

In this paper I approach the explanation of biological invasions from another viewpoint
than has been attempted so far. The common theory (e.g., Elton 1958) is static, based
on properties intrinsic and specific to invaders, as well as on functionally structured
communities offering resistance to any alien species invading it. If a species does happen
to invade, the community would be out of balance for some time, showing up from initial,
heavy fluctuations and possible local extinctions of native species, followed by a gradual
adaptation of a new equilibrium. In contrast, I want to emphasize dynamic properties
of a species' life history and its dispersal capacity, accompanied by a general openness
and spatio-temporal heterogeneity of natural communities.
To this end, I analyze the invasion of two quite different species, a bird and an insect.
Not only do these species differ in taxonomy, size, and general ecology, but also in that
the bird's dispersal propagules are the young individuals themselves, whereas in the
case of the bee a swarm is considered as a unit of reproduction and dispersal. Yet, the
two components of the invasion process, spread and population growth after settlement,
are the same. As their life-history parameters can, as usual, be expected to be sensitive

Insect Behavioral Ecology '91 Hengeveld

to environmental variation, only slight changes in their value can cause great changes
in expansiveness.
The advantage of this approach is not only that we can reconstruct an invasion and
compare that reconstructed invasion with the observed one, but also that it allows us
to understand why species with quite different properties can become invasive whereas
other ones stay where they are. Also, it explains why theories based on intrinsic prop-
erties don't work as general theories. Finally, it explains the contrasting geographical
dynamics of many invaders even expanding their range in opposite directions (Hengeveld
1989). Only by looking into the process itself, rather than at descriptions of species
properties, or at its numerical relations with other species can we understand a species'
dynamic behavior as an expression of variation in its living conditions.


The two components of the invasion process are spatial spread, and population growth
after settlement (see Hengeveld 1989). Both in the description and in the analysis of
invasions we have to estimate parameters that predict the speed with which a wave of
invasion progresses.

The Collared Dove, Streptopelia decaocto Privaldszky, in Europe

Originally, the collared dove was a subtropical bird from India. From there it spread
eastward, eventually reaching Japan, and westward covering all of Europe (see
Hengeveld 1988). As it reached Europe, it branched off after having spread across the
Balkans, westward into Italy, northward into Hungary and in a northwesterly direction
north of the Alps into Germany, via the Netherlands ending up in the British Isles
(Stresemann & Nowak 1958). At later stages, it spread out sideways from this northwes-
terly flow, southward into Spain and northeastward into Scandinavia, Poland (Glutz von
Blotzheim & Bauer 1980), and eventually into Russia (Nowak 1989). The early branch
into Italy aborted, after which Italy was invaded again only at a much later date from
the sideways colonization via France. Similarly, the colonization of the Russian plain
did not originate from the early Hungarian branch, but from the later northward coloni-
zation of Fennoscandia via the Baltic countries (Nowak 1989). On this broad scale,
therefore, the western expansion of the range of the collared dove could not be predicted
in all respects.
On the much finer scale of movements of the individual birds, the pattern of wave
progression can be formulated only in statistical terms, the individuals moving in all
directions from their birth place. Fisher (1953) reconstructed the probable birth place
of collared doves, this enabling him to connect a bird's breeding site with that where it
was born. Apart from spreading out in all directions, the birds appear to have covered
various distances from their birth place, all distances up to that of 12 km together
following an exponential decay function (Hengeveld 1988) (Fig. 1). Greater distances up
to about 300 km were scattered. Yet, though observations in the tail end were scattered,
their absolute number, 27, is rather large, and their impact on the invasion rate far
from negligible. One of them, reaching from the continent into Lincolnshire, England,
can prove this. Population growth was decayed exponentially too, giving the wave front
its shape. In the Netherlands, this exponential growth phase lasted at least 15 years,
whereas its duration in the British Isles (Hudson 1965, 1972) seems to have been only
10 years (cf. Hengeveld 1988) (Fig. 2).
These observations, however, describing the two aspects of wave progression, can
not be used for predicting this progression, as this would invoke circular reasoning. For
predictions to be made, observations should be made independently of those of wave

Florida Entomologist 75(1)

Probability of occurrence


0.05. ?



0.01. *

I *** ** *0* *

0.001. -.
1 5 10 50 100

Fig. 1. Number of new breeding sites of the collared dove as a function of the
distance to their birth place. The distances were derived from a figure by Fisher (1953).

progression. Therefore, van den Bosch et al. (in press) and Hengeveld & van den Bosch
(1991), by using ringing recovery data, constructed a frequency distribution of distances
between birth place and the place of breeding (Table 1) for measuring spread. For
measuring population growth, they constructed a matrix containing literature data on
the survival of individual birds, as well as their fertility during each phase in their life
cycle (Table 2). Thus, from the dispersal distances, the variance and kurtosis of spread
could be estimated, the mean distance because of radial spread being zero by definition.
The net-reproduction rate Ro could be estimated from the matrix. Together, these
estimates result in a combined estimate of the expected velocity of wave progression,
Cexp (van den Bosch et al. in press, Hengeveld & van den Bosch 1991). This rate can
then be compared with the observed velocity, Cobs, estimated from a map. The expected
rate, 56.3 km per year, does not differ greatly from the observed one, 43.7 km per year,

March, 1992

Insect Behavioral Ecology '91 Hengeveld

100 000 Number of Birds

10 000.






t I I I I I
1950195219541956195819601962 1964

Fig. 2. Population growth of the collared dove after settlement in the Netherlands
(0) and the British Isles (0).

which suggests that the parameters chosen describe the invasion process well; additional
parameters can alter the expected rate only marginally. The same holds for other inva-
sions analyzed the same way (Fig. 3), suggesting that the literature data, although

Florida Entomologist 75(1)


Distance Midpoint Recoveries

0-50 25 38
50-100 75 8
100-150 125 5
150-200 175 3
200-250 225 6
250-300 275 6
300-350 325 1
350-400 375 0
400-450 425 1
450-500 475 1
500-550 525 0
550-600 575 1
600-650 625 2

brought together for other purposes
the invasion of these species.

and obtained locally, are adequate for describing

The African Bee, Apis mellifera scutellata Ruttner, in America

The African bee, an African subspecies (Apis mellifera scutellata) of the honey bee,
was introduced initially into Brazil in 1956 with intention to improve the local stock of
the European subspecies (A. m. mellifera Linnaeus). After its escape in 1957 (Kerr
1967), it spread rapidly in all directions, in the 1970s reaching its southern limit in South
America (Kerr et al. 1982). Meanwhile, it also spread northward via Central America
into North America where it may reach its northern range limit in the 1990s (Taylor
1985) (Fig. 4).
The African bee causes economic loss by entering and subsequently genetically taking
over the hives of European bee (Hall & Muralidharan 1988, Smith et al. 1988). It would
be of great interest, therefore, not only to know its northern and southern range limits,
but also to be able to predict the rate at which the invasion progresses. Even more so,
one would like to know the factors influencing this progression, and eventually the
components of the process determining the within-range spatial dynamics. Unfortu-


Survival Fertility reproduction
a Age interval La Ma LaMa

1 0.0-0.5 0.86 0 0
2 0.5-1.0 0.52 0.313 0.163
3 1.0-1.5 0.31 3.125 0.969
4 1.5-2.0 0.23 3.125 0.703
5 2.0-2.5 0.13 3.125 0.403
6 2.5-3.0 0.07 3.125 0.214
7 3.0-3.5 0.03 3.125 0.123
8 3.5-4.0 0.02 3.125 0.063
9 4.0-4.5 0.01 3.125 0.031

March, 1992

Insect Behavioral Ecology '91 Hengeveld

140 Observed velocity (km per year)


/ Cattle Egret



40 / Collared Dove

House Sparrow Europe

0 House Sparrow N. America

Muskrat 1900-'30
Muskrat 1930-'60
0 20 40 60 80 100 120 140

Expected velocity (km per year)

Fig. 3. Relationship between the expected velocity and the observed one for several
animal species analyzed (after van den Bosch 1990).

nately, neither the observations nor the theory is attuned to these kinds of problems
yet. This is partly because the observations are extremely difficult to make and partly
because of the complexity of the bee's life history.
Otis (1980, 1982) conducted seminal studies on the life-history parameters of the
African bee. Yet, even after his outstanding observations, he had to admit that standard
life-table analyses could not be done, because probabilities of some colony events were
either unknown, or too variable over time. Thus, colonies could not be aged accurately
and reproduction had neither an annual nor a constant-generation basis (Otis 1982).
Also, swarming varies over time, preventing the construction of an age-specific life
table. Apart from this, mortality could not be quantified (e.g., mortality of the swarm
due to starvation or to predation by ants) or it was unknown (e.g., mortality between
swarm issue and colonization) (Otis 1982). For constructing a nest-survival curve, within-
nest population growth rate, and the increase of the density of nests, Otis therefore
relied on simulations partly based on actual observations and partly on assumptions. Of
these, the survivorship curve is most relevant to us, but again some difficulty arises.

66 Florida Entomologist 75(1) March, 1992


988 19


1980, *
1983 18',
1982 ; ;975




1957 1963

Fig. 4. Range expansion of the African bee into North and South America (after
Taylor 1985).

The higher age classes were underestimated because the study period was too short to
give reliable survival estimates of the longer-lived colonies (Fig. 5).

Insect Behavioral Ecology '91 Hengeveld 67

100- % Survivorship




0 2 4 6 8 10 12 14 16 18 20 22
Age in months

Fig. 5. Survival rate of colonies of the African bee (after Otis 1980).

Observations of a relatively static object, a colony, are difficult; estimating the dis-
persal of a colony even more so, particularly in the tropics and the subtropics of South
America. One insurmountable problem is to know how far a swarm flies before it settles.
Even after settling, a swarm may choose to fly on for some distance. It can also stop
for refuelling under way, enabling the bees to fly much farther than one engorgement
of honey would allow. A settled colony, after having produced swarms may abscond,
some 30-100% of them doing so.
All this makes systematic observations on distances travelled and on population
growth after settlement practically impossible. Theoretically, there are still some difficul-
ties because the present model assumes that the population does not move on sometime
after settling.
Yet another problem that dispersal of the African bee raises is perhaps even more
fundamental. The model assumes that reproduction during the whole life cycle (> 20
months, see Fig. 5) is relevant to the progression of the wave, although in the African
bee, swarming at such a high frequency (< 4 swarming cycles with 3.82 swarms each
per year), only the first part is relevant. This is because, after the production of one or
a few swarms, reproduction of and spread from these young swarms supersedes any
effect of subsequent ones leaving the parent colony. This makes the next swarms irrelev-
ant for the progression of the wave; they just can not reach the front, which is now
formed by the earlier sister swarms or their descendants.
Taylor (1977) approached the problem in a similar way, although he did not use a
mathematically calculated model. However, his approach has a methodological disadvan-
tage apart from some technical ones. As the component of population growth, he took
the annual number of advances of the wave front, derived from the supposed number

Florida Entomologist 75(1)

of swarms issued per year. Then, supposing an advance of the front by 100, 300 and
500 km, he derived the distance that has to be flown by a single swarm from the parent
colony to its new home, given a certain number of swarms per year. The methodological
disadvantage here is that the distances obtained are, as a next step, used implicitly or
explicitly to predict the velocity of a wave front. This cannot be done because the
estimations are derived from a supposed expansion rate rather than from independent
data on the bee's life history and spreading rate.
The technical difficulties appear from the differences in the structure of the model
developed by Taylor (1977), who divided the yearly advance of the front by the number
of successive swarms issued, and the model developed by van den Bosch et al. (1990),
that accounts for the species' life history and the shape of its dispersal distribution.
Matters are more complicated than can be represented by a simple division and as we
have seen even the more complicated model is too simple for the bee's spatial behavior.
In the next section, alterations in the original data for the collared dove will show the
importance of the structure of its life history and its dispersal distribution for the rate
at which its wave front is expected to advance.


Taylor (1977) took the various numbers of swarms produced per year as the most
important variable influencing the rate of advance of the invasion. Although he is certainly
correct in this, even more subtle changes in a species' life history can have profound
influences on the rate of advance. For example, Table 3 shows that a small, hypothetical
change in the survival rate in the collared dove affects the net rate of reproduction, R0,
considerably. This, in turn, decreases the expected velocity Cexp from 56.3 km per year
to only 32.5 km per year. Small changes in survival can occur easily under the ever-chang-
ing ecological conditions in the field as the vast population dynamic literature shows.
Similar changes in velocity can also be expected from small alterations made in the
observed dispersal distribution of the collared dove. Here, two approaches are possible,


a, L(a) % change L(a)50%

0.25 0.86 0.86
0.75 0.52 0.43
1.25 0.31 0.22
1.75 0.23 0.11
2.25 0.13 0.05
2.75 0.07 0.03
3.25 0.04 0.01
3.75 0.02 0.005
4.25 0.001 0.002

March, 1992

Insect Behavioral Ecology '91 Hengeveld


N Number (1) Cexpkm--

68 35 57.49
69 36 57.09
70 37 56.69
72 38 56.30 (x)
73 39 55.92
74 40 55.55
79 45 53.79

one starting from changing the number of birds staying close to their birth place (Table
4), and the other from changing the number of long-distance dispersers (Table 5). In
the first case (Table 4) suppose that instead of the 38 individuals observed, one or a few
individuals stay near to where they were born. As such small changes can affect the
expected velocity by 4 km per year, one can easily expect even greater changes with
normal environmental variation. In the second case (Table 5) suppose not only that one
or a few individuals are added or extracted in the tail end of the distribution, but leaving
the total number of individuals the same as they are shifted from one distance class to
the next. Effects on the velocity are dramatic; the differences between the highest and
the lowest rate amount to 23 km per year, that is about one half the rate of the lowest
velocity and about one third of the highest.
These examples show that even small changes in the parameter values used by the
model of van den Bosch et al. (1990) affect the rate of velocity of wave progression
greatly. This result shows that we need fairly precise estimations on the values these
parameters take for characterizing invasions. Estimated rates of reproduction without
proper life-table analysis (Otis 1980), or estimates of the mean and maximum flight
range as in the African bee (Otis et al. 1981, Taylor 1977), however difficult to obtain,
are insufficient.
On the other hand, the real complexities of the bee's life cycle or of its spatial dynamics
are not accounted for in the model used. The model has to be elaborated further to allow


Distance (km)
N 0.575 0.625 0.675 0.725 0.750 Cexp

69 43.8
70 1 48.0
71 1 1 51.9
71 2 51.6
72 2 1 55.6
72 1 2 56.3 (x)
72 1 1 1 57.6
72 1 2 57.6
73 1 2 1 60.6
73 1 1 1 1 61.9
74 1 1 1 1 1 66.6

Florida Entomologist 75(1)

for frequent reproduction within a species' life cycle, as well as for the sensitivity of the
expected velocity to long-distance dispersal.


In this paper I have analyzed the invasions of two species, that of the collared dove
invading Europe and that of the African bee invading the Americas. I have shown that
for clearly defined life histories and dispersal events, neat observations can be made,
resulting in reasonably accurate predictions of the rate at which invasions progress in
geographical space. However, for less clearly defined life histories and dispersal events,
and for relatively crude observations, the model soon has obvious limitations. Yet,
knowing these limitations is important as they show us where to improve either the
model structure or the observational accuracy.
Comparison of the model with another approach has shown us that, for two reasons,
it is methodologically more advanced than previous approaches. First, by distinguishing
sharply between information to be used for characterizing the observed velocity of the
invasions and that needed for calculating the expected rate, it is possible to test the
model predictions. For less sharply distinguished information this distinction is not
feasible, however, because reasoning becomes partly or wholly circular.
Second, by applying this model, we have looked into the dynamic process itself,
rather than having relied on species or community properties supposedly influencing
this process directly or indirectly as is done in the traditional invasion theory (Elton
1958). In previous approaches, species are characterized as invaders versus non-invaders
on the basis of genetics, morphology, and the like (Hengeveld in prep.). The invasion
process is seen as a dynamic response to altered ecological conditions. Invasions are
just the opposite of extinctions, but nobody would divide species into intrinsic "extincters"
versus "non-extincters".
Similarly, communities should not be distinguished into invadable and non-invadable
ones. They can be invaded by species fitted to the local conditions. Using the present
approach, therefore, I have defined a dynamic process in terms of parameters liable to
change under the influence of variable environmental conditions.
The present results, showing both the potential and the limitations of the model
used, are therefore important as seen in this light. The results do show that the model
works under certain conditions. They also show where and why it does not work and
where it should be improved. The model's advantages make it worth the effort to make
further improvements. Thus, applying a model that accounts for dynamic responses to
a variable environment not only opens the way to analyze individual invasions, starting
from another, more ecological point of view. This strongly argues for the use of this
kind of model or, when it fails, for improving either the field observations required or
the model structure itself.


BOSCH, F. VAN DEN. 1990. The velocity of spatial population expansion. Thesis, Leiden
--, J. A. J. METZ, AND O. DIEKMANN. 1990. The velocity of spatial population
expansion. J. Math. Biol. 28: 529-565.
--, R. HENGEVELD, AND J. A. J. METZ. in press. Analyzing the velocity of animal
range expansion. J. Biogeogr.
ELTON, C. S. 1958. The ecology of invasions by animals and plants. Methuen, London.
FISHER, J. 1953. The collared turtle dove in Europe. British Birds 56: 153-181.
GLUTZ VON BLOTZHEIM, U. N., AND K. M. BAUER. 1980. Handbuch der Vogel Mittel-
Europas, Vol. 9. Akademische Verlagsgesellschaft, Wiesbaden.

March, 1992

Insect Behavioral Ecology '91 Hengeveld 71

HALL, H. G., AND K. MURALIDHARAN. 1988. Evidence from mitochondrial DNA that
African honey bees spread as continuous maternal lineages. Nature 339: 211-213.
HENGEVELD, R. 1988. Mechanisms of biological invasions. J. Biogeogr. 15: 819-828.
1989. Dynamics of biological invasions. Chapman & Hall, London.
,AND F. VAN DEN BOSCH. 1991. The expansion velocity of the collared dove
Streptopelia decaocto population in Europe. Ardea 79: 67-72.
HUDSON, H. F. 1965. The spread of the collared dove in Britain and Ireland. British
Birds 58: 105-139.
- 1972. Collared doves in Britain and Ireland during 1965-1970. British Birds
65: 155.
KERR, W. E. 1967. The history of the introduction of African bees to Brazil. South
African Bee J. 39: 3-5.
---, S. DE LEON DEL RIO, AND M. D. BARRIONUEVO. 1982. The southern limits
of the distribution of the Africanized honey bee in South America. American Bee
J. 122: 196-198.
NOWAK, E. 1989. Ausbreitung der Turkentaube (Streptopelia decaocto) in der UdSSR:
Umfrage 1988. J. Ornithol. 130: 513-527.
OTIS, G. W. 1980. Population biology of the Africanized honey bee, p. 209-219 in P.
Jaisson [ed.], Social insects in the tropics. University Paris-Nord, Paris.
- 1982. The swarming biology and population dynamics of the Africanized honey
bee. PhD. dissertation. Univ. Kansas, Lawrence, Kansas, 197 p.
--, M. L. WINSTON, AND O. R. TAYLOR. 1981. Engorgement and dispersal of
Africanized honey bee swarms. J. Apic. Res. 20: 3-12.
SMITH, D. R., O. R. TAYLOR, AND W. M. BROWN. 1988. Neotropical Africanized
honey bees have African mitochondrial DNA. Nature 339: 213-215.
STRESEMAN, E., AND E. NOWAK. 1958. Die Ausbreitung der Turkentaube in Asie
und Europa. J. Ornithol. 99: 243-296.
TAYLOR, O. R. 1985. African bees: potential impact in the United States. Bull. Ent.
Soc. America 31: 14-24.
- 1977. The past and possible future spread of Africanized honey bees in the
Americas. Bee World 58: 19-30.


The model used is a type of reaction-diffusion process, where the "reaction" part
stands for local population growth after settlement, and the "diffusion" part for spatial
spread. The simplest equation in two dimensions reads:

an 1 a2n a2n
rn + D(- + -)
at 2 ax2 ay2

or (growth rate at point x,y) = (reproductive rate) + (diffusion) where r is the intrinsic
rate of natural increase, n is the number of individuals, D is the diffusion coefficient,
and n(t,x,y) is the population density at time t at location (x,y) in the two-dimensional
plane. Thus, rn represents the growth component and the remainder the spread compo-
nent. From this model it follows that:

C = /-2-rD

from which the velocity of spreading, C, can be calculated from mapped observations.
The calculations therefore concern the net-reproduction rate, Ro, and the diffusion coef-
ficient, D. Ro is defined as:
Ro = af L (a) m (a) da

72 Florida Entomologist 75(1) March, 1992

where is the proportion of females in the population, L(a) is the age-specific survivorship
- or the probability that an individual is still alive at age a, and m(a) is the age-specific
fertility that is the rate of offspring production at age a. Apart from Ro we also need
to know the mean age at child-bearing, from which p is defined as:

L = --faL(a)m(a)da
Ro 0

Spatial spread is defined by the variance of the marginal density of the distances between
a nesting bird and its parent's nest:

00 00
r2 = f S x2D(x,y)dxdy
0 0

where x and y are spatial coordinants and D the diffusion coefficient. Then, the expected
velocity of population expansion becomes:

Cexp = V2Log (R)

(van den Bosch et al. in press). Van den Bosch et al. (in press) applied this model to
more extensive data; Hengeveld and van den Bosch (1991) show the actual calculations,
and van den Bosch et al. (1990) give the mathematical derivations.


'Department of Entomology and Nematology
University of Florida
Gainesville, Florida 32611-0740

2Citrus Research and Education Center
Lake Alfred, Florida 33850-2299

3Southwest Research and Education Center
Immokalee, Florida 33934-9716


A model of the attack rate for a grazing herbivore, the citrus rust mite, is obtained
as a Type 2 functional response analogous to Holling's disc equation. The attack rate is
given by

Insect Behavioral Ecology '91 Allen & Yang 73

A' = (cells mite-1 d-')
1 + CthX'

where c is the maximum cell attack rate given by c = qvV_. th, q, v and 5 are the
handling time attack-', probability of attack, the velocity while grazing, and the total
cell density cm-2 respectively. x' is the proportion of the total cells which remain alive.
A' needs to be multiplied by the proportion of time spent "grazing" if this is less than
one. If y is the mite density in any area having perimeter/area ratio P/a then the
emigration rate is given by

P v
m' y (mites cm-2d-)
a 1 + CthX1

m' also needs to be multiplied by the proportion of time spent grazing. Egg production
rate, E, was assumed proportional to A' so that

A' (1 + cth)x'
E = Emax Emax (eggs d-1)
A'max 1 + cthx

where Emax is the maximum egg production rate when food is maximum (x' = 1).


Se obtuvo un modelo de la rata de ataque de un herbivoro, el acaro tostador de los
citricos, como una respuesta funcional tipo 2 analoga a la equaci6n de disco de Holling.
La rata de ataque es especificada por:

A' =-
1 + cthX'

donde c es la rata de encuentro de la celula especificada como c = qv V8. th, q, v y 8
son el tiempo de ataque-1, la probabilidad del ataque, la velocidad de pastoreo, y la
densidad total de la celula en cm2, respectivamente. x' es la proporci6n de todas las
celulas que permanencen vivas. A' necesita ser multiplicado por la proporci6n de tiempo
dedicado a el pastoreo si es menos que uno. Si y es la densidad del acaro en cualquier
area con un perimetro/proporcion area P/a, entonces la rata de emigraci6n es especificada

P v
m = y
a + cthX

m/ tambien necesita ser multiplicado por la proporci6n del tiempo dedicado a el pastoreo.
La rata de producci6n de huevos, E, fu6 asumida como proporcional aA' de tal forma que

A' (1 + cth)x'
E = Emax = Emax (eggs d-1)
A/max 1 + CthXe

donde Ema es la rata de producci6n mAxima de huevos cuando el alimento esta al maximo
(x/ = 1).

Florida Entomologist 75(1)

Whenever we attempt to model the attack of one species upon another, we are faced
with the problem of how to construct a trophic transfer function describing the flow of
material between the two species. These trophic coupling functions are commonly called
the functional response of the "predator" species to the "prey" species density after the
term used by Holling in his classical early work on the subject (Holling 1959a, 1959b,
1965). Many such functions have been suggested in the literature (May 1978, Table 5.1,
gives a list of possibilities), but the major emphasis has been on true predator-prey
rather than herbivore-plant interactions (Caughley & Lawton 1978, Noy-Meir 1975).
The problem we discuss here is one of a herbivore, Phyllocoptruta oleivora (Ashm.)
(the citrus rust mite), feeding on the surface of citrus fruit. Our objective is to derive
expressions for the functional response in terms of fruit cells killed mite-1 day' as a
function of the cells cm- remaining alive, and to relate the functional response to the
rates of movement and reproduction. While the rust mite is used as an example, the
situation is rather general and could, with only slight modification, be applied to most
grazing herbivores.
The citrus rust mite is a tiny eriophyid mite about 180 rLm in length which feeds on
individual epidermal cells on citrus fruit and leaves. For calculation purposes, we assume
that the epidermal cells are about 10 pm in diameter, and the feeding punctures made
by the mite are about 0.7-1.0 iLm in diameter (McCoy & Albrigo 1975, Achor et al.
1991). Given the scale at which the attack occurs, one is tempted to take a "regression"
approach as the senior author did in an earlier study (Allen 1976). It was found that
visual estimates of the percent damage on the orange surface accumulated linearly with
mite-days with the caveat that the slope increased with time in a roughly sigmoid fashion
over the maturity cycle of the orange.
In the current paper, we adopt a more detailed process-oriented approach involving
cells cm- and mites cm-2 as system variables whose interaction is to be modelled as part
of a dynamic system which will ultimately include the mite fungal pathogen, Hirsutella
thompsonii (Fisher) (Allen et al. in press). With the process-oriented approach, one can
examine the possibility that the time-varying damage rate observed in the field was a
result of cell expansion during fruit growth.


Holling obtained his original "disc" equation by having a blindfolded subject search
for sandpaper discs on a tabletop by tapping with one finger, and upon finding a disc,
remove it and place it to one side (Holling 1959a). This process was used to model the
attack rate (= functional response) of a predator, and the function exhibited a saturation
effect (leveling-off) as the prey density became high. This was because the "predator"
(subject) became saturated with "prey" and spent all the time just handling prey, i.e.,
time was assumed to be conserved and was divided by type of activity. Thus

T, = T At (1)

where T, is time spent searching for prey, Tt is total time and Ath is total time spent
handling prey, A being the number of prey attacked and th being the handling time per
attack. In addition it was assumed that

A = aT,x (2)

where a = proportion of available prey encountered (or area searched) per time unit,
and x was the prey density. Upon substituting eq.(1) into eq.(2) and solving for A we
obtain the now famous disc equation or Type 2 functional response

March, 1992

Insect Behavioral Ecology '91 Allen & Yang

A ax
= A' (3)
Tt 1 + athx

where we have written the equation with total time in the denominator on the left-hand-
side so that we have the attack rate which we will call A'.
We now proceed to the case of a grazing herbivore moving with scalar velocity
(unspecified direction) v over a food substrate which has density x per unit area. We
will consider epidermal cells cm-2 in our study of the rust mite, but one could talk about
plants or mass per unit area just as well. As our herbivore moves over the substrate,
the number of "prey" encountered is equal to the distance covered (vT,) divided by the
average distance between prey (d). In the rust mite situation the cells are relatively
uniform in their spatial distribution and we assume a mean cell diameter of about 10
Jm and consequently a cell density of about 106 cm-2. Contagious (i.e., clumped) distri-
butions of plants or other resource objects might be handled by combining the approach
used here with the negative binomial probability of being found (1 zero class) as per
Holling (1988). In our case

Distance Covered vT,
Number of Cells Encountered = = T,
Mean Cell Diameter d

but at least approximately

cell density = 8 = -

sod = and therefore the Number of Cells Encountered = vT, V-. We now assume

Cells Attacked = (Probability of Attack) (Cells Encountered) (Proportion Alive)

or in symbolic form

A = qvT, V = qvT, V8 (4)
where q is the probability of attack and x' is the proportion alive. Since time is conserved

T, = Tt- Ath To (5)

where To is time spent on activities other than searching and feeding. By substituting
eq.(5) into eq.(4) we obtain

qv V (1- T )x'
A T,
Al = (6)
Tt 1 +qvV thx'

where (1- -- ) is the proportion of time spent on "grazing", i.e., the feeding-moving
t t
cycle, and the extension of the disc equation, eq.(3), is obvious. Much of the attraction

76 Florida Entomologist 75(1) March, 1992

of eq.(6) is that for many herbivores the parameters can be obtained by independent
observation. For example, McCoy & Albrigo (1975) observed that rust mite "searching"
time averaged 11.3 7.3 s and mouthpart insertion time averaged 26.0 20.0 s.
Although these measurements are just a crude beginning, they serve as an example
that the parameters of eq.(6) can be obtained by direct observation even for an animal
as small as the rust mite.
We assume that eq.(6) represents the attack rate mite ', and therefore the total
mortality rate for cells under attack by y' mites cm 2 is eq.(6) multiplied by y'. If we
now plot eq.(6) for different mite and cell densities, the form of the classical Type II
functional response emerges (Fig. 1). The ratio is held constant at 0.5 (this is simply a
guess), and cell encounter rate and handling time are varied to illustrate the effect of
these parameters on the placement and shape of the curve. We hasten to emphasize
that the exact placement of the curve is not known to any great degree of certainty,
and the values shown are simply order-of-magnitude estimates from what little is known.
Field estimates of damage rates (% mite d 1) by visual inspection of fruit surfaces
indicate that the damage rate increases with fruit maturity from about 0.001% to 0.01%
mite-' d-1 (Fig. 5) and (Allen 1976). The curves of Fig. 1 assume a cell density of 106
cm-2) and their maxima (when x' = 1) vary from about 100,000 to 30,000 cells (100 mites)-1
d-1 which corresponds to 0.1% to 0.03% mite-1 d-1. Thus, the parameters used in Fig. 1
give cell mortalities which, on a percentage basis, are at least 3-fold larger than observed
visual estimates of % damage from the field. This apparent disagreement may simply
mean that visual % damage is not equal to % cell mortality, i.e., the model may be
"right" and the visual data may be "wrong"! Alternatively, q or v may be too large or

the proportion of time spent feeding (1- ) may be too large. Regardless of parameter

uncertainty, eq.(6) finally gives us a mechanistic model of the interaction between the
mite and the fruit for which data can be obtained by direct observation of the feeding


When modelling populations, it is often of interest to have a submodel of movement
into and out of some spatial region of interest, a field, a leaf, or a unit of area. We will
consider the rust mites emigrating from a cm2 of fruit surface. We assume that the
number of mites moving across one side of the cm2 is proportional to their velocity, v,
the time spent searching, T,, and their density, y. The effect of this movement on the
density in the cm2 is 4 times this amount however, since there are 4 sides, and in general,
one needs to multiply the movement across a unit of boundary by the perimeter/area
(P/a) ratio (= 4 in a square unit of area) (Brewster & Allen 1991). Thus, the total
emigration effect on density in our case is

m= vT,y (mites cm-)

But, since T, = T, Ath To, and A = cTx where c = qv V-, then

T + ct,
1 + cted

and our density change due to emigration from the cm2 becomes

Insect Behavioral Ecology '91 Allen & Yang

Cell Mortality From Citrus Rust Mite Feeding

cell density = 106 cm-2
qvV/6 = 5000 cells d-1
To/Tt = 0.5
th = 100 see

To/Tt = 0.5

Fig. 1. The attack rate (functional response) of the citrus rust mite on citrus epid-
ermal cells. Cell density is expressed as proportion of 106 cells cm- y is the density of
all feeding stages of the mite cm-. From eq.(6) in the text.

v(1- To
m P Tt
m =- y
Tt a 1 + qv thX1

(mites cm-2 d-1)

We look at this graphically as a function of rust mite and cell densities in Fig. 2, where
the parameter values are identical to those of Fig. 1, and we note that the more saturated
(leveled-off) is the functional response of Fig. 1, the more nonlinear is the emigration
rate (eq.(7)) as food diminishes (Figs. 1B and 2B). Of course, what we would really like
is the net change in density in our cm2, and so we must calculate the difference between
input and output using eq.(7) and take the difference. The price one pays for this is
that the densities outside the cm2 must be known or modelled.


We assume that egg production by our herbivore (the rust mite) is proportional to
food intake up to some maximum egg production rate (Emax when x' = 1 in eq.(6)). In

eggs d-1 = (eggs attack-') (attacks d-1)

or symbolically

Florida Entomologist 75(1)

March, 1992

Movement Rate Function for Citrus Rust Mite
cell density = 106 cm-2

qvV/6 = 5000 cells d-1
To/Tt = 0.5
th = 25 sec

qv/6 = 5000 cells d-1
To/Tt = 0.5
th = 100 sec

qvV6 = 2000 cells d-1 qvV6 = 2000 cells d-1
To/Tt = 0.5 To/Tt = 0.5

Fig. 2. The movement rate out of a cm2 containing living cell proportion x/ by mites
at density y cm2. Parameters are identical to Fig. 1. From eq.(7) in the text.

E = eA' = e -x-
1 + Ctex'

where c = qv E can be obtained from observed maximum egg production rates
when x' = 1, i.e., E = mawhere A'/x is eq.(6) with x' = 1. By substituting for e in the
above equation the reproductive rate becomes

E = Emax

(1 + cth)x/
Ema +
1 CtX'

Note that we have tacitly assumed for simplicity that (1 T ) cancels in the ratio of
attack rates in eq.(8), i.e., that proportion of "other" time is the same regardless of the
food supply (an assumption which needs to be checked). We currently have the total
egg output over the life of a female rust mite as a function of temperature (T) (C) given by

total eggs = 66.811 11.979T + 0.69897T2 0.011925T3

and the length of the reproductive period is given by

adult time = 29.74e-0.743T


Insect Behavioral Ecology '91 Allen & Yang

Reproductive Function for the Citrus Rust Mite
cell density = 106 cm-2

qvV6 = 5000
th = 25 sec

qvV6 = 5000 cells d-l
th= 100 sec

Fig. 3. The reproductive rate of the citrus rust mite (eggs female-1 d ) as a function
of temperature and proportion of epidermal cells alive. Parameters are identical to Fig.
1. From eq.(8) in the text.

total eggs
so the average adult egg production rate is given by Emax from laboratory
adult time
data where we assume x' = 1. Using this as our Emax, we plot the reproductive rate
from eq.(8) in Fig. 3 over the temperature range of 13 to 33'C. These curves have a
maximum at about 280C of 4.8 eggs female-' d-1 when living cell density is maximum (x'
= 1) and drop off in somewhat different ways with declining food supply depending on
the details of the functional response parameters. Again we hasten to emphasize the
approximate and preliminary nature of these curves due to omission of some factors
(e.g., differences in To with food supply and sex ratio effects) and outright guesses at
others (e.g., q = 0.5 and v = 10 cm d-1), nevertheless they serve as a starting point for
a model of this system and indicate where data are needed.


Throughout the development of eqs.(6), (7) and (8) it was assumed that epidermal
cell density, 6, was known, e.g., in Figs. 1, 2 and 3 it was assumed that cell diameter
was about 10 im and therefore that 8 was about 106 cells cm-2. This was based on
estimates by McCoy & Albrigo (1975) that "epidermal cell thickness ranged from 6-12
Rm" and by micrographs in their paper suggesting cell diameters of about 10 pm. In
addition, leaf epidermal cell sizes appear to be on the order of 10 pm (Achor et al. 1991).
However, it is known that fruit epidermal cells stop dividing and undergo an expansion
phase in the later stages of fruit growth (Bain 1958). In addition, recent preliminary

80 Florida Entomologist 75(1) March, 1992

measurements indicate that mature grapefruit and navel oranges have epidermal cell
diameters of 40-80 pxm (D. Achor, pers. communication). Good measurements of fruit
surface area (S) are available for Valencia orange (Allen 1976) where it was found that

S(t) = (9)
1 + et (9)

in cm2 where t is days since 1 Jan. of the starting year, k = 153 cm2, a = 4.8, and P =
0.03592 d-1. Could cell expansion be proportional to surface expansion and therefore cell
density be some inverse form of this sigmoid growth function? If we assume that cell
density starts at 8m.x and ends at wnn, and decreases as the inverse of surface expansion,
then we can write an equation for cell density with time as

ea- pt
8(t) = (8max-min) + 8min (10)
1 + e4-3t

where the exponential fraction part is the inverse of eq.(9), i.e., 8(t) declines in sigmoid
fashion from 8max to 8min in phase with fruit surface expansion from eq.(9). The % damage
mite d 1 should now be given by (100), and using eqs. (6) and (10) to calculate this
ratio, the result is plotted in Fig. 4 against time of year for comparison with visual %

Effect of Cell Expansion on

Z Damage Mite-1 Day-1


7 q=0.10
Lt 0.0110
Sv = 5 cm/sec
th 100 sec
& 0.0095


Q 0.0065

0 93 186 279 372 465

Time (Days from Jan. 1)

Fig. 4. The attack rate of the mite expressed as % damage mite-' d-1 varying through
time due to epidermal cell expansion during fruit growth. Obtained by dividing eq.(6)
by eq.(10) and multiplying by 100. (Compare with Fig. 5).

Insect Behavioral Ecology '91 Allen & Yang

damage estimates from the field in Fig. 5 (reprinted from Allen 1976). We assumed that
6max = 2 x 106 and n- = 5 x 105 cells cm-2 respectively, and parameters as shown in
Fig. 4 were chosen to give a fairly low attack rate. Thus one can, by appropriate choice
of parameters, generate the time-varying damage rate effect much like that observed
in the field from cell expansion alone.
This exercise does not prove that the time-varying damage rate observed visually
in the field is strictly due to cell expansion, but it does illustrate what we can do once
more accurate information is available on cell density with time, 8(t). Thus, the models
developed here indicate what data are needed in the rust mite system before models of
the system can be reliable tools for population dynamics studies and economic predictions.
Finally, in the more general case of a grazing herbivore, we have developed a func-
tional response equation (eq.(6)) which is analogous to Holling's disc equation (eq.(3)).
The constant a in the disc equation is equal to qv V/ in our case of uniformly distributed
In the case of randomly distributed plants at density x, the mean distance between
them is -- (Clark & Evans 1954), and the functional response of a grazing herbivore

A 2qv V
- A + 2qvt
Tt 1 + 2qvthN

Except for the factor 2, this is our eq.(6) without considering "other" time (To) or
proportion of plants alive (x'). Thus one obtains basically the same functional response

(t) 01 15/( I + exp (6.92-0.03592t))

200 300
t = JULIAN DAY (1 =JAN1)


Fig. 5. % damage mite-' d' by visual observations in the field. From Allen (1976).
Reprinted with permission from the ESA.





I, *O

Florida Entomologist 75(1)


Variable/Parameter Description Units





proportion of area searched
number of attacks during T,
attack rate (A/Tt)
maximum attack rate
fruit growth constant
fruit growth rate constant
mean cell diameter
cell density
maximum cell density
minimum cell density
egg production rate
maximum egg production rate
eggs produced attack-'
final fruit surface area
density change due to movement
movement rate
perimeter/area ratio
probability of attack
fruit surface area
days since 1 Jan.
handling time attack-'
total time
searching time
"other" time
"grazing" velocity of rust mite
living epidermal cell density
proportion cells alive (x/8)
density of mite moving stages
density of mite feeding stages

for either uniform or random resource units (plants, cells, etc.). We will leave for future
research the question of a clumped distribution of resource units ...


We would like to thank C. S. Holling, J. W. Jones, and H. L. Cromroy for their
comments on the manuscript. D. S. Achor did some last-minute measurements on citrus
fruit epidermal cell density from her lunchbox which indicate the need for more informa-
tion on cell density. The patience of J. Howard Frank was much appreciated. We are
also grateful to Julio Arias for translating the abstract into Spanish. This is Florida
Agricultural Experiment Station Journal Series No. R-02104.


ACHOR, D. S., L. G. ALBRIGO, AND C. W. MCCOY. 1991. Developmental anatomy of
lesions on 'Sunburst' Mandarin leaves initiated by citrus rust mite feeding. J.
American Soc. Hort. Sci. 116: 663-668.
ALLEN, J. C. 1976. A model for predicting citrus rust mite damage on Valencia orange
fruit. Environ. Entomol. 5: 1083-1088.

attacks d-'
attacks d-'
cells cm2
cells cm-
cells cm-2
eggs female-1 d1
eggs female-' d-
eggs attack-'
mites cm-2
mites cm2 d-'
cells cm-
mites cm-2
mites cm-2

March, 1992

Insect Behavioral Ecology '91 Allen & Yang

--, Y. YANG, J. L. KNAPP, AND P. A. STANSLY. (in press). The citrus rust mite
story: A modeling approach to a fruit-mite-pathogen system, in D. Rosen, F.
Bennett and J. Capinera (eds.), Integrated Pest Management and Biological Con-
trol: A Florida Perspective. Intercept Press, London.
BAIN, J. M. 1958. Morphological, anatomical, and physiological changes in the develop-
ing fruit of the Valencia orange, Citrus sinensis (L.) Osbeck. Australian J. Botany
6: 1-24.
BREWSTER, C. C., AND J. C. ALLEN. 1991. Simulation of plant resistance in a celery-
leafminer-parasitoid model. Florida Entomol. 74: 24-41.
CAUGHLEY, G., AND J. H. LAWTON. 1978. Plant-herbivore systems, p. 132-166 in R.
M. May (ed.), Theoretical ecology: Principles and Applications. Blackwell Scien-
tific Publications, Oxford.
CLARK, P. J., AND F. C. EVANS. 1954. Distance to nearest neighbor as a measure of
spatial relationships in populations. Ecology 35: 445-453.
HOLLING, C. S. 1959a. Some characteristics of simple types of predation and
parasitism. Canadian Entomol. 91: 385-398.
- 1959b. The components of predation as revealed by a study of small mammal
predation of the European pine sawfly. Canadian Entomol. 91: 293-320.
--. 1965. The functional response of invertebrate predators to prey density. Mem.
Entomol. Soc. Canada 48: 1-86.
--. 1988. Temperate forest insect outbreaks, tropical deforestation and migratory
birds, in The Wellington festschrift on insect ecology, (ed.) Sahota and C. S.
Holling. Mem. Entomol. Soc. Canada 146: 21-32.
MAY, R. M. 1978. Models for two interacting populations, p. 78-104 in R. M. May (ed.),
Theoretical ecology: Principles and Applications. Blackwell Scientific Publications,
McCoY, C. W., AND L. G. ALBRIGO. 1975. Feeding injury to the orange caused by
the rust mite, Phyllocoptruta oleivora (Prostigmata: Eriophyoidea). Ann. En-
tomol. Soc. America 68: 289-297.
NOY-MEIR, I. 1975. Stability of grazing systems. J. Ecol. 63: 459-481.

84 Florida Entomologist 75(1) March, 1992


School of Natural Sciences, Liverpool Polytechnic
Byrom St.
Liverpool L3 3AF, U.K.


Limataphalara brevicephala gen. et sp. nov. is described from Florida. Its separation
from other New World Aphalarinae is discussed and a key to genera is provided. The
probable host plant is Nectandra coriacea (Lauraceae).


Se describe en Florida Limitaphalara brevicephala gen. et sp. nov. Se discute su
separacion de otros Alphalarinae de el nuevo mundo y se describe una clave para estos
generous. Se consider que Nectandra coriacea (Lauraceae) es la plant hospedera de
este insect.

Psyllids belonging to the subfamily Aphalarinae (sensu White & Hodkinson 1985)
display high diversification in the north temperate regions of the Holarctic, particularly
in the arid regions of Central Asia (see Loginova 1964, Klimaszewski 1973). They are,
by contrast, poorly represented in the tropical/subtropical zones. Within the New World,
species belonging to the genera Alphalara F6rster (1848) and Craspedolepta Enderlein
(1921) are particularly abundant throughout the U.S.A. and Canada (Russell 1973,
Journet & Vickery 1979). Tropical/subtropical representatives are scarce, the fauna
comprising the genera Gyropsylla Brethes (5 species, Argentina to the southern U.S.A.),
Neaphalara Brown & Hodkinson (1 species, Panama), Burckhardtia Brown & Hodkinson
(1 species, Panama and Mexico) and probably Lanthanaphalara Tuthill (1 species, Peru)
(Brbthes 1921, Tuthill 1959, Hodkinson & White 1981, Burckhardt 1987, Hodkinson
1988, Brown & Hodkinson 1988). The Aphalarinae are characterized primarily by the
presence of long finger-like posterior lobes on the male proctiger and the absence of
genal processes.
This paper describes a new monotypic genus, Limataphalara gen. nov., type species
brevicephala sp. nov., from Florida and discusses its relationship to other New World
Aphalarinae. A key to genera is provided.

Limataphalara gen. nov.
(Figs 1-11)

Type species: Limataphalara brevicephala sp. nov.


Head (Figs 1 & 2) weakly deflexed from the general plane of the body, very short,
vertex convex, about 1/3 as long as broad, with 2 large distinct fovea, fore-margin almost
straight, hind margin excavate; lateral ocelli large, mounted on distinct tubercles adjacent
to the eye; eyes hemispherical; preocular sclerite well-developed, at least anteriorly;

Hodkinson: New Florida Psyllid

V r1

0 0

2 4

o ^^^^ 4

Figs. 1-11. Limataphalara brevicephala sp. nov. 1. Head and thorax, lateral view.
2. Head, dorsal view. 3. Antenna. 4. Clypeus, lateral view, with labium attached. 5.
Propleurites. 6. Forewing. 7. Metacoxa with meracanthus. 8. Male terminalia, lateral
view. 9. Male right paramere, inner view. 10. Apical portion of aedeagus. 11. Female
terminalia, lateral view.

median ocellus small, lying at the apex of thin ribbon-like frons, not fully visible in dorsal
view; genae barely swollen, merging with vertex just below front margin of head;
antennae (Fig. 3) 10-segmented, short, stout, segment 3 the longest, with a single large
rhinarium on each of segments 4 to 9, apical segments with fields of sensoria as in
Gyropsylla but with the 2 terminal setae having an acute apex; clypeus (Fig. 4) small
and rounded, not extending to fore-margin of head.
Thorax (Fig. 1) with dorsum weakly arched, pronotum short, collar-like, descending
to the mid point of the eye; propleurites (Fig. 5) quadrate, divided by a branched suture.
Forewing (Fig. 6) oblong-oval, with a well developed pterostigma and a costal break,
venation as in figure, gap in anal vein immediately adjacent to point at which vein Culb
meets the marginal vein; vein C + Sc, along basal leading edge of wing, strongly thic-
kened, colored bright shining black, the pigment extending into cell c + sc and giving a
conspicuous black band along the wing margin; wing membrane slightly thickened,

Florida Entomologist 75(1)

semitransparent, veins concolorous; hindwing membraneous, a little shorter than fore-
Fore- and mid- legs simple, without characteristic features. Hind leg with coxal
meracanthus short, stout and broadly rounded at the apex; area beneath the meracanthus
forming a rounded swelling as in Gyropsylla (Fig. 7); metafemora without a genual spine
or swelling, with an apical crown of 7-9 thick black spurs; basal metatarsus with 2 similar
spurs, shorter than apical metatarsus.
Male proctiger (Fig. 8) with elongate sinuous posterior processes that lack the inner
hook-like process that occurs in many aphalarines, although the lower margin appears
somewhat swollen in the region where the hook normally occurs; subgenital plate simple,
paramere (Fig. 9) of complex form, with a basal interior process; aedeagus (Fig. 10)
unusual, with apex only weakly expanded but bearing a long and strongly sclerotized
ductus ejaculatorius; point of articulation of apical segment set some way from base.
Female terminalia (Fig. 11) wedge shaped, lacking diagnostic features.
Derivation of name: refers to the shiny black coloration and indicates a polished form
of the type genus Aphalara.

Limataphalara brevicephala sp.n.
(Figs 1-11)

Characters additional to the generic description are listed below.

Coloration. Dorsal surface of head and thorax bright shining black, underparts usually
of similar coloration but occasionally deep red. Antennal segments 1-2 and 9-10 black,
remainder creamy white. Forewing membrane yellow, veins concolorous, shining black
area present along basal leading edge of wing. Legs black. Abdomen and terminalia
pale green to yellow.

Structure. Head (Fig. 2) with antennae mounted on the front margin which bears a row
of short setae. Antennae 0.73-0.88 times head width, in one male specimen only 9-seg-
mented. Labium (Fig. 4) elongate, not expanded apically. Forewing (Fig. 6) 1.96-2.11
times as long as broad, 2.19-2.44 times head width, with surface spinules occupying all
cells, not leaving spinule-free bands along the veins; vein R, weakly sinuous; cells cula
and mI +2 subequal. Metatibia 0.57-0.63 times head width. Male subgenital plate shallow
sparsely hairy; paramere (Fig. 9) irregular in shape, with a basal inner process developed
into a large inwardly directed tooth, which is just visible in lateral view but very obvious
in posterior view, with the inner teeth meeting along the mid-line. Outer part of paramere
with a roughly pentagonal base giving rise to a slender, posteriorly curved apical process
that bears a linear region of sclerotization along its inner apex; inner surface of paramere
with scattered stout setae.
Female proctiger (Fig. 11) of moderate length, 0.63-0.64 times head width, with sinuous
dorsal margin; circumanal pore field consisting of a double row of pores, almost half as
long as proctiger; subgenital plate roughly triangular, bluntly acute at apex; ovipositor
broad basally, tapering into a narrowly acute apex; lateral valves large and somewhat
truncate at apex.

Measurements. Head width d 0.56-0.59mm, 9 0.59-0.60mm. Antennal length C0.43-
0.50mm, 2 0.48-0.51mm. Forewing length 61.23-1.32mm, 9 1.42-1.44mm. Proctiger
length d (ignoring lobes) 0.15-0.16mm, ? 0.37-0.38mm. Paramere length 30.21-0.23mm.
Apical portion of aedeagus length 60.14-0.16.

Host plant. Larval material is not available but the collection of adults from Nectandra
coriacea (Lauraceae) at two separate localities suggests that this is the host plant.

March, 1992

Hodkinson: New Florida Psyllid 87

Type material. Holotype d: U.S.A., Florida, Miami, 13.iv.1982 (T. Loyd) from Nec-
tandra coriacea. Paratypes: 1I, 49 same data as holotype. 19 U.S.A., Florida, St.
Lucie Co., Ankona, 11.v.1984 (K. L. Hibbard) from Nectandra coriacea. All type material
is deposited in the USNM collections, Beltsville, Maryland.

Derivation of name: refers to the short transverse head.


The tropical/subtropical New World Aphalarinae comprise an assemblage of small
or monotypic genera that appear taxonomically isolated from each other. This suggests
that they may represent relict forms from a much larger fauna.
Limataphalara resembles Gyropsylla in the form of the swollen metacoxa, in the
small rounded meracanthus and in the presence of fields of small sensoria on the antennal
flagellum. Furthermore, Nectandra, the probable host plant genus of Limataphalara,
has also been recorded as a host for Gyropsylla cannela (Crawford) (Crawford 1925,
Hodkinson & White 1981). As all other Gyropsylla species for which the host plant is
known feed on Ilex (Aquifoliaceae) some doubt has previously been expressed as to the
veracity of the record from Nectandra (Brown & Hodkinson 1988). It may, however,
now represent another shared character between related genera.
Amongst other New World aphalarine genera Lanthanaphalara and Neaphalara
share the similar form of coxa and meracanthus to Limataphalara and also lack the
small inner hook-like process on the posterior projection of the male proctiger. Neaphal-
ara also possesses a male paramere with an inner basal process, although it differs
somewhat in form from that in Limataphalara. Otherwise the genera differ markedly
in the general form and details of the head, forewing and terminalia.
The remaining tropical/subtropical genus, Burckhardtia, appears to feed on Aralia
(Araliaceae). It differs from Limataphalara in most details of the head, legs, forewing
and terminalia. The New World aphalarine genera can be separated using the following
simplified key.


1 Forewing with a conspicuous pterostigma .............................................. 2
1' Forewing without a pterostigma ........................................................... 6
2(1) Forewing with brown color pattern in apical half ....................................... 3
2' Forewing without brown color pattern in apical half, at most with a black
streak along the leading edge of cell c + sc ............................................. 4
3(2) Forewing with gaps present basally in veins Rs, M and Cu, corresponding
to the position of the nodal line. Male proctiger with inner hook-like processes
on the posterior projection. Clypeus elongate. Paramere in lateral view with
basal anterior process ................................ Neaphalara Brown & Hodkinson
3' Forewing without gaps in veins along nodal line. Male proctiger lacking
inner hook-like processes. Clypeus shorter, rounded. Paramere without basal
process, with an inner tooth arising at mid-length.
............................................................. Burckhardtia Brown & Hodkinson
4(2') Vertex elongate, almost as long as broad, each half extended forward into
triangular-shaped extensions that reach well forward of the median ocellus.
........................................................................... Lanthanaphalara Tuthill
4' Vertex much broader than long. Front of head either straight or with gently
rounded anterior lobes on each side of median ocellus ................................ 5

88 Florida Entomologist 75(1) March, 1992

5(4') Forewing membraneous, clear. Clypeus usually elongate. Posterior lobe of
male proctiger long and thin, with 2 small ventral hook like processes, extend-
ing well beyond the paramere which is usually clavate. Apex of aedeagus
somewhat expanded, hooked anteriorly, without a prominent ductus
ejaculatorius .............................................................. Gyropsylla Brethes
5' Forewing semi-thickened, yellow, with a shiny black streak along the leading
edge of cell c + sc. Clypeus short and rounded. Lobe of male proctiger stout,
without ventral processes, barely extending to the paramere. Paramere of
more complex form, with an inner basal tooth. Apex of aedeagus linear,
with a prominent sclerotized ductus ejaculatorius.
............ .......................................... ..... Limataphalara gen. nov.
6(1') Anterior margin of each half of vertex strongly angular. Genae expanded
into rounded tubercles below the eye. Clypeus often elongate.
.................................. .................................. ...... Aphalara F6rster
6' Anterior margin of each half of vertex more gently rounded. Genae not
developed into distinct tubercles. Clypeus rounded, not elongate.
......................................................................... Craspedolepta Enderlein


I thank Dr. Douglass R. Miller for providing access to the USNM collections. Financial
support was provided by the Natural Environment Research Council (U.K.).

BRtTHES, J. 1921. Un nuevo Psyllidae de la Republica Argentina (Gyropsylla ilicicola
Brethes). Rev. Fac. Agron. Univ. Nac. La Plata. 14: 82-89.
BROWN, R. G., AND I. D. HODKINSON. 1988. Taxonomy and ecology of the jumping
plant-lice of Panama (Homoptera: Psylloidea). 304pp. E. J. Brill, Leiden. En-
tomonograph 9.
BURCKHARDT, D. 1987. Jumping plant lice (Homoptera: Psylloidea) of the temperate
neotropical region. Part 1: Psyllidae (subfamilies Aphalarinae, Rhinocolinae and
Aphalaroidinae). Zool. J. Linn. Soc. 89: 299-392.
CRAWFORD, D. L. 1925. Psyllidae of South America. Broteria, Ser. Zool. 22: 56-74.
ENDERLEIN, G. 1921. Psyllidologica VI. Zool. Anz. 52: 115-123.
FORSTER, A. 1848. Ubersicht der Gattungen und Arten in der Familie der Psylloden.
Verh. naturh. Ver. press. Rheinl. 5: 65-98.
HODKINSON, I. D. 1988. The Nearctic Psylloidea (Insecta: Homoptera): an annotated
check list. J. Nat. Hist. 22: 1179-1243.
HODKINSON, I. D., AND I. M. WHITE. 1981. The Neotropical Psylloidea (Homoptera:
Insecta) an annotated check list. J. Nat. Hist. 15: 491-523.
JOURNET, A.R.P., AND V. R. VICKERY. 1979. Studies on Nearctic Craspedolepta
Enderlein (Homoptera: Psylloidea). Taxonomic revision. Mem. Lyman Entomol.
Mus. Res. Lab. 7: 1-164.
KLIMASZEWSKI, S. M. 1973. The jumping plant-lice or psyllids (Homoptera: Psyllodea)
of the Palaearctic. An annotated check-list. Annls zool., Warszawa 30: 155-286.
LOGINOVA, M. M. 1964. Suborder Psyllinea-Psyllidae or leafhoppers. pp. 437-482 in
Bei-Bienko, G. Ya. (Ed.). Keys to the insects of the European part of the USSR.
Volume 1. Zool. Inst. Akad. Nauk SSSR, Moscow (English translation: Israel
Programme for Scientific Translation, Jerusalem, (1967)).

Flowers & Yamamoto: Feeding by Maxillectomized Manduca 89

RUSSELL, L. M. 1973. A list of the species of Craspedolepta Enderlein recorded from
North America (Homoptera: Psyllidae: Aphalarinae). J. Washington Acad. Sci.
63: 156-159.
TUTHILL, L. D. 1959. Los Psyllidae del Peru Central (Insecta: Homoptera). Revta
Peruana Entomol. Agric. 2: 1-27.
WHITE, I. M., AND I. D. HODKINSON. 1985. Nymphal taxonomy and systematics of
the Psylloidea (Homoptera). Bull. Brit. Mus. Nat. Hist. (Entomol.) 50: 153-301.

(MANDUCA SEXTA: Lepidoptera: Sphingidae)

Agricultural Research Programs
Florida A&M University
Tallahassee, FL 32307


Tobacco hornworm larvae reared on diet or jimsonweed and with one or both pairs
of maxillary sensillae styloconica removed were given feeding tests with four non-host
plants (collard, dandelion, cowpea and mullein). Increased feeding was observed for all
larvae lacking medial, lateral, or both pairs of sensillae; these increases were greater
for larvae that had been reared on jimsonweed. For larvae with both pairs of sensillae
removed, all test plants were highly acceptable. For larvae with only the lateral sensillae
removed, the test plants were only slightly more acceptable. Diet-reared larvae with
the median sensillae removed found test plants slightly more acceptable than did control
larvae. Jimsonweed larvae lacking only the median sensillae found dandelion, normally
a rejected plant, almost completely acceptable. Possible physiological reasons for these
behavior changes are discussed.


Se hicieron pruebas alimenticias con cuatro plants no hospederas a las larvas de
Manduca sexta criadas con dieta artificial o con hierba hedionda Datura stramonium
y con uno o dos pares de las sensilas styloconicas estirpadas de las maxilas. Las plants
experimentales fueron berza coming, Brassica oleracea, amarg6n, Taraxacum officinale,
caupi, Vigna sinensis y gordolobo, Verbascum thapsus. Se observ6 alimentaci6n mas
extensive para las larvas a las cuales les faltaron ambos o uno u otro par (medio o lateral)
de sensilas. El aumento de alimentaci6n fu6 mas grande en las larvas que habian comido
hierba hedionda. Todas las plants fueron aceptadas por las larvas sin ambos pares de
sensilas. Las larvas sin las sensilas laterales, aceptaron un poco mas dichas plants. Las
plants experimentales fueron un poco mas aceptables a las larvas crecidas con dieta y
sin las sensilas medias, pero las larvas criadas en hierba hedionda y sin las sensilas
comieron casi completamente el amarg6n (el cual normalmente es una plant no acept-
able). Se discute la posibilidad de una base quimiosensorial que explique este compor-

90 Florida Entomologist 75(1) March, 1992

Studies on feeding behavior of Lepidoptera have emphasized electrophysiology and
much progress has been made in determining the electrical responses of specific receptor
cells to specific chemicals. Because of its large size, economic importance and ease of
rearing, the tobacco hornworm, Manduca sexta (L.), has become a favorite experimental
animal for feeding studies. Much of the research has centered on the median and lateral
sensilla styloconica of the maxillae (Waldbauer & Fraenkel 1961, Waldbauer 1962,
Schoonhoven & Dethier 1966, Schoonhoven 1969, Stadler & Hanson 1976) which function
as both gustatory and olfactory receptors.
While electrophysiological studies tell us much about the responses of individual
receptor cells, they still leave open the question of how these responses are integrated
by the insects into behavior patterns. One possible approach is to surgically alter the
receptors and observe how feeding behavior changes. Several experiments have been
done in which the maxillae of M. sexta were removed or destroyed (Waldbauer &
Fraenkel 1961, Waldbauer 1962). These showed that without their maxillae, M. sexta,
normally oligophagous on the Solanaceae, became effectively polyphagous and fed on a
wide range of plants that they would not accept under normal circumstances (however;
de Boer et al. 1977 found that even M. sexta lacking both maxillae and antennae still
showed some feeding selectivity because of receptors in the preoral cavity). In this
paper we report the results of experiments in which M. sexta fed on two different diets
had their sensillae styloconica removed in various combinations and then were tested
for feeding on four non-host plants.


M. sexta larvae were obtained from a culture at North Carolina State University
and two groups, one reared on artificial diet and the other reared on jimsonweed as
described previously (Flowers & Yamamoto 1982), were used in these experiments. On
entering the fourth instar, sensillae styloconica in three combinations were removed by
confining the larvae to a block of paraffin in a dish which was then filled with water.
This caused the larva to close its spiracles, thus building up CO2 in the tracheal system
which anesthetized the animal. (Using CO, gas directly proved unsatisfactory and caused
a high mortality rate.) Sensillae were pinched off with sharpened jeweler's forceps under
200X magnification. Four treatments were used: all four sensilla styloconica removed,
the lateral pair removed, the median pair removed, and a control group which were
anesthetized but without an operation. All larvae were returned to their respective
diets (artificial or jimsonweed) and allowed to feed until fifth instar.
After the moult to the fifth instar, acceptance of four non-host plants to the treated
larvae was determined by placing individual larvae in a petri dish with an 8 mm diameter
leaf disk of each of four test plants. Feeding after 24 hours by each larva was recorded
to the nearest quarter of a disk for each test plant (further details in Flowers and
Yamamoto 1982). Plants tested were collard (Brassica oleracea L., Cruciferae), dandel-
ion (Taraxacum officinaleL., Asteraceae), mullein (Verbascum thapsus L.,
Scrophulariaceae), and cowpea (Vigna sinensis L., Fabaceae). De Boer & Hanson (1984)
have proposed a hierarchy of acceptability for plants: under their system, cowpea and
collard would be considered "acceptable non-host plants" since M. sexta can be reared
on them in the laboratory, while dandelion and mullein would fall into the category of
unacceptable non-host plants. As in our previous paper, feeding indices (Flowers &
Yamamoto 1982) were obtained from scoring fractions of the test plants consumed by
larvae and multiplying by 100. Data were analyzed as a split-plot design with the larvae
as a whole plot and the 4 test plants as sub-plots. Feeding indices and their 95% confidence
limits are shown in Fig. 1-2.

Flowers & Yamamoto: Feeding by Maxillectomized Manduca 91



e 70
d 60 I -
g 50

I 40
e 30
20 -

L-M- L- M- Control
# larvae/group (43) (40) (64) (83)

Fig. 1. Responses of diet-reared larvae with the sensillae styloconica removed in
different combinations: L-M-, both pairs of sensillae removed; L-, lateral pair removed;
M-, medial pair removed. Test plants: P, cowpea; D, dandelion; C, collard; M, mullein.
Vertical bars give 95% confidence limits.


Feeding by intact control larvae on the four test plants roughly paralleled the results
obtained earlier (Flowers & Yamamoto 1982): collard was highly acceptable, followed
by mullein, with cowpea and dandelion showing low to very low acceptablilty. As in our
previous study, cowpea and dandelion were slightly more acceptable to jimsonweed-
reared larvae than to diet-reared larvae. Removal of both lateral and medial sensillae
styloconica (L-M-; Fig. 1,2) resulted in dramatic increases in feeding on all test plants
except collard (which was already almost completely acceptable), although cowpea re-
mained slightly less acceptable than the other three in most cases. Removal of the lateral
sensillae styloconica (L-; Fig. 1,2) increased feeding on cowpea, dandelion and mullein
for both diet- and jimsonweed-reared larvae, with the jimsonweed-reared larvae showing
slightly greater increases in consumption than the diet-reared larvae. Removal of the
median sensillae (M-) resulted in small increases in feeding on cowpea and mullein, and
a large increase in feeding on dandelion for diet-reared larvae (Fig. 1); while for jimson-
weed-reared larvae (Fig. 2), there was a proportionally similar increase in feeding on
dandelion, while increases in feeding on cowpea and mullein were somewhat greater
than for diet-reared larvae.
These results suggest that both the median and lateral receptors respond to deterrent
chemicals since removal of either one caused an increase in feeding. Schoonhoven and
Dethier (1966) also postulate the presence of a stimulant receptor in the median sensilla;
our experiments neither confirm nor disprove such a function for the median sensilla.
The greater increase in acceptance of dandelion by L- and L-M- diet-reared larvae as
compared to those reared on jimsonweed suggests that jimsonweed was desensitizing
the deterrent receptors and that removal of these receptors caused a smaller change
than did removal of the same receptors in diet-reared larvae.

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