• TABLE OF CONTENTS
HIDE
 Front Cover
 Front Matter
 Table of Contents
 Acknowledgement
 Introduction
 The bromeliads
 Mosquitoes
 Bromeliad-inhabiting mosquitoe...
 Control of the mosquitoes
 Biological control research
 Other organisms inhabiting...
 Summary
 Literature cited
 Back Cover






Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; 877
Title: Mosquito production from bromeliads in Florida
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00086507/00001
 Material Information
Title: Mosquito production from bromeliads in Florida
Series Title: Bulletin - University of Florida. Agricultural Experiment Station ; 877
Physical Description: 17 p. : col. ill. ; 23 cm.
Language: English
Creator: Frank, J. H. ( John Howard ), 1942-
Publisher: Agricultural Experiment Station, University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1990
 Subjects
Subject: Mosquitoes -- Florida   ( lcsh )
Bromeliaceae -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 15-17).
General Note: Cover title.
General Note: "June 1990."
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
Statement of Responsibility: J.H. Frank.
 Record Information
Bibliographic ID: UF00086507
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 22901569

Table of Contents
    Front Cover
        Front Cover
    Front Matter
        Front Matter
    Table of Contents
        Page i
    Acknowledgement
        Page ii
    Introduction
        Page 1
    The bromeliads
        Page 1
        Page 2
        Page 3
    Mosquitoes
        Page 4
    Bromeliad-inhabiting mosquitoes
        Page 5
        Page 6
        Page 7
    Control of the mosquitoes
        Page 8
        Page 9
    Biological control research
        Page 10
        Page 11
        Page 12
        Page 13
    Other organisms inhabiting bromeliads
        Page 14
    Summary
        Page 14
    Literature cited
        Page 15
        Page 16
        Page 17
    Back Cover
        Back Cover
Full Text
00 June 1990 Bulletin 877
SMiosquito Production
from
Bromeliads in Fl1ci "t

W R.Iv e. t r d z


J.H. Frank
Agricultural Experiment Station
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
J. M. Davidson, Dean for Research















J.H. Frank is a Professor and Biological Control Specialist in the
Entomology and Nematology Department of the Institute of Food and
Agricultural Sciences at the University of Florida in Gainesville.




































Cover Photo: An imported tank bromeliad: Billbergia pyramidalis.
(Photo: J.H. Frank)











TABLE OF CONTENTS
INTRODUCTION ............................... 1
THE BROMELIADS ............................. 1
Native Bromeliads ............................. 2
Introduced Bromeliads .......................... 2
Biology of Bromeliads ........................... 3
MOSQUITOES ................. ................ 5
BROMELIAD-INHABITING MOSQUITOES ............. 6
CONTROL OF THE MOSQUITOES .................. 8
Chemical Insecticides ........................... 8
Microbial Insecticides ............................ 9
M management .................................. 9
BIOLOGICAL CONTROL RESEARCH ................ 10
Aquatic Predators and Pathogens .................. 10
Terrestrial Predators ........................... 12
Competitors ................................. 13
Outlook .................................... 13
OTHER ORGANISMS INHABITING BROMELIADS ....... 14
SUMMARY ................................... 14
LITERATURE CITED ............................ 15


















ACKNOWLEDGMENTS
Gratitude is due to Robert Noonan (professional photographer) for
permission to reproduce two of his photographs, and to Al Muzzell
(bromeliad enthusiast and grower), and Dale Habeck and Phil
Lounibos (entomologists) for reviewing manuscript drafts.











INTRODUCTION


This publication is about the natural history of the association
between bromeliads and mosquitoes in Florida. It explains the life
cycles and behavior of the mosquitoes, methods of controlling them,
and research that has been done toward biological control of them.
It also highlights laws restricting the growth of some species of
mosquitoes. This publication is not about how to grow bromeliads,
nor does it give methods for controlling pests of bromeliads.
Bromeliads are popular yard plants in central and southern
Florida. Billbergia pyramidalis (cover picture) and many other
bromeliad species and hybrids are quite easy to care for. They
provide colorful flowers, attractive foliage, or both.
Since most bromeliads grow best in partial or full shade, they are
often grown under shade trees. Thus, when dead leaves and twigs
fall, they are caught and decompose in the leaf axils of these bromel-
iads, which hold little pockets of water (tanks). The decomposing
material in these tanks provides nutrients for the bromeliad.
Larvae of certain mosquito species will live in these water-filled,
nutrient-containing tanks. The mosquito larvae do not harm the
bromeliads, but the adult mosquitoes bite warm-blooded animals in
daylight hours. An obvious way to avoid being bitten by such
mosquitoes from your yard is not to grow tank bromeliads.

THE BROMELIADS
Bromeliads (family Bromeliaceae) are a large group of plants (over
2,500 described species) of neotropical origin. They are a conspicuous
part of the flora of South and Central America and the West Indies.
Only a few bromeliad species are native to peninsular Florida, and
still fewer range north and west into other states. In South America,
bromeliads have evolved to occupy a wide range of habitats from
humid lowlands to deserts to high mountains. They grow in humus
or sand on the ground, on rocks, or as epiphytes of trees (although
many species grow on trees, none is known to be a true parasite).
Some of them are grown as crops (pineapple is a bromeliad), and
many are grown as ornamentals in the tropics and subtropics
worldwide. In more temperate climates they are grown in glass-
houses.











INTRODUCTION


This publication is about the natural history of the association
between bromeliads and mosquitoes in Florida. It explains the life
cycles and behavior of the mosquitoes, methods of controlling them,
and research that has been done toward biological control of them.
It also highlights laws restricting the growth of some species of
mosquitoes. This publication is not about how to grow bromeliads,
nor does it give methods for controlling pests of bromeliads.
Bromeliads are popular yard plants in central and southern
Florida. Billbergia pyramidalis (cover picture) and many other
bromeliad species and hybrids are quite easy to care for. They
provide colorful flowers, attractive foliage, or both.
Since most bromeliads grow best in partial or full shade, they are
often grown under shade trees. Thus, when dead leaves and twigs
fall, they are caught and decompose in the leaf axils of these bromel-
iads, which hold little pockets of water (tanks). The decomposing
material in these tanks provides nutrients for the bromeliad.
Larvae of certain mosquito species will live in these water-filled,
nutrient-containing tanks. The mosquito larvae do not harm the
bromeliads, but the adult mosquitoes bite warm-blooded animals in
daylight hours. An obvious way to avoid being bitten by such
mosquitoes from your yard is not to grow tank bromeliads.

THE BROMELIADS
Bromeliads (family Bromeliaceae) are a large group of plants (over
2,500 described species) of neotropical origin. They are a conspicuous
part of the flora of South and Central America and the West Indies.
Only a few bromeliad species are native to peninsular Florida, and
still fewer range north and west into other states. In South America,
bromeliads have evolved to occupy a wide range of habitats from
humid lowlands to deserts to high mountains. They grow in humus
or sand on the ground, on rocks, or as epiphytes of trees (although
many species grow on trees, none is known to be a true parasite).
Some of them are grown as crops (pineapple is a bromeliad), and
many are grown as ornamentals in the tropics and subtropics
worldwide. In more temperate climates they are grown in glass-
houses.








Native Bromeliads


Bromeliads considered as native to Florida belong to three genera
(Catopsis, Guzmania, and Tillandsia) and all of them are epiphytic.
The three native species of Catopsis and one of Guzmania are
restricted in Florida to the extreme south, where all of them are
listed as endangered (5). Most of the dozen or so native species of
Tillandsia have quite restricted distributions; one (Tillandsia
pruinosa) is listed as endangered, and all but four of the remainder
are listed as threatened (5). Two of these four are the "wild pines"
(Tillandsia fasciculata and Tillandsia utriculata), which are listed as
commercially exploited plants, a protected category (Figure 1). They
are the most common native examples of tank bromeliads that
harbor mosquito larvae. The endangered, threatened, and commer-
cially exploited plants are protected under Florida law and U.S. law
(5, 28). The remaining two species, which are not protected, are
"Spanish moss" (Tillandsia usneoides) and "ball moss" (Tillandsia
recurvata); these are the most common native examples of bromeliads
that do not form tanks, and therefore do not harbor mosquito larvae.

Introduced Bromeliads
Numerous bromeliad species have been introduced into cultivation
in Florida from South and Central America and the West Indies.
Among them are species of the genera Aechmea, Androlepis,
Billbergia (see cover photo), Canistrum, Catopsis, Guzmania,


Figure 1. A native tank bromeliad: Tillandsia fasciculaa. (Photo: J. H. Frank)








Hohenbergia, Neoregelia (Figure 2), Nidularium, Orthophytum,
Portea, Quesnelia, and Vriesea, many of which form tanks; species of
Acanthostachys, Ananas, Araeococcus, Bromelia, Cryptanthus, Dyckia,
Fosterella, Hechtia, Navia, Pitcairnia, and Pseudoananas, most of
which do not form tanks; and species of the genus Tillandsia,
containing bromeliads with and without tanks.
Many nurseries in south Florida sell bromeliads, and a few
nurseries specialize in bromeliads. They sell natural species,
cultivars, interspecific hybrids, and even intergeneric hybrids with
such names as Neomea 'popcorn.' Bromeliad cultivation has become
so popular that a society [The Bromeliad Society International (BSI),
which publishes The Bromeliad Society Journal] was formed in 1951.
There are now 11 local bromeliad societies in Florida alone, some of
which publish newsletters such as the "Bromeliadvisory" (monthly,
from the Bromeliad Society of South Florida).

Biology of Bromeliads
Bromeliads are monocotyledonous plants that share biological
characteristics of related families such as Cannaceae and Musaceae.
Although a few members of some plant families other than bromel-
iads (e.g., Agavaceae, Araceae, Cannaceae, Marantaceae, Musaceae,
Strelitziaceae) accumulate little tanks of water in their leaf axils,
hundreds of species of bromeliads have this characteristic. The
arrangement of these tanks varies: in some species water accumulates


Figure 2. An imported tank bromeliad: Neoregelia marmorata. (Photo: J.H.
Frank)







in a few or in many separate leaf axils, yet in others the central
leaves together form a large tank surrounded by a few, separated
tanks provided by outer leaf axils.
Bromeliad leaves bear special epidermal cellular structures
(trichomes) that absorb water and minerals from the leaf surface.
This ability to absorb from leaf surfaces explains why some bromel-
iads (sometimes called "air plants") can live with their roots attached
to telephone lines and power poles. These air plants gain their
nutrition from whatever mineral particles, blown about in the wind
and rain, happen to land on their leaf surfaces. They seem to live
"on the air," and their feeble-looking roots serve merely to anchor
them.
Most cultivated bromeliads are epiphytic (22), and thus have a
natural association with trees. During and after rains, water
dripping from trees is no longer just rainwater, but is enriched with
minerals leached from tree leaves: bromeliads absorb it either
through trichomes on their leaf surfaces or through trichomes on the
leaf surfaces forming their tanks. The tanks also trap pollen, dead
leaves, and twigs and seeds falling from the trees; these materials
break down in the tanks to form a nutritive soup available to
bromeliads and mosquito larvae.


MOSQUITOES

Adult mosquitoes (family Culicidae) are winged, terrestrial insects,
and their immature stages (eggs, larvae, and pupae) are aquatic.
Larvae and pupae are strictly aquatic, but the eggs of some mosquito
species are laid in damp places to await flooding before the larvae
can hatch from them.
Larvae molt their skins four times during their development, and,
at the fourth molt, they become pupae. Adult females of most
mosquito species take blood from warm-blooded animals; this
provides proteins needed for the development of eggs. Adult male
mosquitoes, and females of some species, do not take blood. Adult
mosquitoes of both sexes feed on plant nectars, which they use as an
energy source. Mosquito larvae feed by filtering particles from the
water, by rasping particulate debris from underwater surfaces, or by
preying on other small organisms, depending upon the species. Eggs
and pupae do not feed. In general, all stages (eggs, larvae, pupae,
adults) of mosquitoes are short-lived, but there are exceptions.
The animal (or person) on which an adult female mosquito feeds
is termed the host. Adult female mosquitoes of some species are
capable of transmitting vectoringg) certain infectious diseases from








host to host. Thus, certain Aedes mosquitoes are capable of vectoring
yellow fever and dengue; certain Culex mosquitoes are capable of
vectoring filariasis and encephalitis; and certain Anopheles mosquitoes
are capable of vectoring malaria. Whether a particular female
mosquito carries such a disease organism depends upon its previous
exposure to the disease. Yellow fever, malaria, and dengue have
been eradicated from Florida by control of the mosquitoes carrying
them, but all three diseases exist in parts of South America.

BROMELIAD-INHABITING MOSQUITOES
Larvae of over 200 mosquito species have been found in water in
bromeliad tanks in the neotropics; some are specialists to that habitat
and others are generalists that occur in a variety of habitats (9).
Among the specialists are larvae of certain Anopheles species, whose
adults are important vectors of malaria. Cleanliness of bromeliads
shipped from the neotropics is essential, not just to avoid importation
of pests that may damage bromeliads and other plants, but also to
avoid importation of vector mosquitoes.
Bromeliads (and other plants) imported to the United States from
abroad are required to undergo agricultural inspection (for plant
pests and plant diseases) by USDA-APHIS at ports of arrival, in
accordance with two U.S. laws (26, 27). If plant pests are found, the
infested plants are destroyed or fumigated. The efficacy of fumiga-
tion in killing mosquito eggs in bromeliads has not been determined.
The U.S. Surgeon General is empowered to regulate movement of
vectors of human disease across state and national boundaries (29).
However, at this time inspection is not made by U.S. Public Health
Service employees, but by USDA employees who examine imported
bromeliads for all organisms, not just plant pests.
Only two native Florida mosquito species have larvae specialized
for existence in bromeliad tanks: Wyeomyia vanduzeei and Wyeomyia
mitchellii. Adult females of both species bite warm-blooded animals,
including man. This causes pruritis (itching) rather than pain. The
peak of the biting cycle is in the late afternoon, in contrast to other
species which bite mainly after dark (3). These two Wyeomyia
species are not known to vector any disease of humans, although
some neotropical Wyeomyia species vector Wyeomyia virus and nIheus
encephalitis virus. Because of this, Wyeomyia vanduzeei and
Wyeomyia mitchellii may be looked upon simply as pests of man
(albeit with some suspicion until research is more complete).
Larvae of other mosquito species occur occasionally in bromeliads
in Florida, but in tanks of Billbergia pyramidalis these other species
form less than 1 percent of the total number of mosquito larvae -







unless the water in the tank is fouled by decaying materials such as
clippings (16). Infusions made from grass clippings seems to attract
female Culex quinquefasciatus and Aedes aegypti to lay eggs; if grass
clippings get into the water in the bromeliad tanks, then larvae of
these species may be found there. People producing these species in
their bromeliads are in violation of Florida law because Culex
quinquefasciatus and Aedes aegypti are known as vectors of human
disease, and represent a threat to public health (4). Local laws also
may apply. Life cycles and behavior of the two Wyeomyia share
generalities with those of other mosquitoes, but there are some
important differences. Male and female adults prefer shaded
locations and do not fly far (15). They are among the smallest
mosquitoes in Florida, and their maximum life span is about three
weeks. The hind pair of legs (of the three pairs) is held upward and
forward over the thorax and head as if to act as an additional pair
of antennae (Figure 3). Females lay eggs during daylight hours; they
drop the eggs while hovering over bromeliad tanks (14). If the eggs
hit the water surface in a bromeliad tank, they hatch in two to three
days (10). If the eggs land on dead tree leaves in a bromeliad tank,
they may be stranded until washed downward by rain, but some can
survive being stranded for more than three weeks (10).
Larvae (Figure 4) feed by filtering small particles of food, mostly
at the water surface. They take a minimum of about two weeks to
develop to the pupal stage; this is more than twice as long as many
mosquitoes in Florida. Pupae take four to five days to develop


Figure 3. An adult Wyeomyia mosquito engorged with human blood. (Photo:
Robert Noonan)









































Figure 4. Larval Wyeomyia mosquitoes in a Billbergia pyramidalis tank.
(Photo: Robert Noonan)
into adults.
A remarkable thing about Wyeomyia larvae is their ability to resist
starvation for many weeks. Larvae of other mosquitoes, under
similar circumstances, would die. Despite decomposed leaves and
other materials in bromeliad tanks, the water usually is very clear,
suggesting a scarcity of nutrients. Thus, Wyeomyia larvae do not
have an abundant supply of food; often large numbers exist in tanks
with sufficient food for only a few. In some cases there seems to be
intense competition among them for food, and only a few survive.
Therefore, the presence of many larvae in bromeliad tanks does not

7







guarantee that many adult mosquitoes will be produced from the
bromeliads.
When faced with an inadequate diet, the larvae delay their
development. It is to their advantage to do so because extra food
may fall into the tank from the tree canopy above, and this extra
food may enable more of them to complete development to the pupal
stage (11). This food-limited survival of the larvae has important
implications for most forms of biological and chemical control.
Larvae of these two Wyeomyia species have been studied mainly
in tanks of Tillandsia utriculata (10), but are likely to be found in
tanks of all imported tank bromeliads. Production from Billbergia
pyramidalis is estimated at about 100 adult Wyeomyia per plant per
year, based on a survey of plants in Daytona Beach, Tampa, Vero
Beach, and Miami (16). A yard with 100 plants would therefore be
expected to produce about 10,000 adult Wyeomyia per year, about
half of which (the females) would attempt to bite.
Adult Wyeomyia do not fly far, so they bother mainly the people
on whose land the plants grow, as well as people on neighboring
properties, especially in cities. For the grower of bromeliads who
does not mind being bitten by mosquitoes, there is no problem; for
family, friends, and neighbors, there may be a problem. This should
be a problem for the owner of the bromeliads to solve, not a problem
to be solved at public expense by mosquito control district employees.
In general, people enthusiastic about growing bromeliads should be
knowledgeable about this problem, take care of their plants, and
minimize mosquito production from them. People who have little
interest in bromeliads, and no time to care for them, would do better
not to grow tank bromeliads.

CONTROL OF THE MOSQUITOES
Chemical Insecticides
Adult Wyeomyia mosquitoes fly during daylight hours. They are
not affected by insecticidal fogging conducted at dusk and after dark,
and are not even affected by experimental daytime fogging (30).
In general, reliance on chemical pesticides to kill Wyeomyia
mosquito larvae is a poor control strategy. Introduction of chemical
pesticides into bromeliad tanks will kill Wyeomyia larvae and provide
temporary relief from the adult mosquitoes that would develop.
When the larvae are killed by pesticides, food accumulates, uneaten,
in bromeliad tanks until the breakdown of the pesticides. At that
time, Wyeomyia larvae newly hatched from eggs have an abundant
food supply, and they can develop rapidly with little or no mortality
from starvation, producing adults that are larger than normal. These








larger adults are capable of producing more eggs than the typical
small adults, so the population size returns to normal in short order.
The only effective chemical control is obtained by repeatedly
applying chemicals, causing, in effect, a chemical treadmill at a high
cost of labor and pesticides. Some improvement may be found in the
use of slow-release chemicals carried on inert substances, but labor
costs are still considerably higher than applying chemicals in large
bodies of water such as ponds and ditches, and the consequence still
leads to the resurgence of Wyeomyia numbers after the treatment
cycle stops. Such treatments also provide opportunity for the
development of Wyeomyia larvae that are genetically resistant to
chemicals. Chemical insecticides applied against scale insects and
other pests of bromeliads probably will kill Wyeomyia larvae because
the chemicals will get into the bromeliad leaf axils.

Microbial Insecticides
Spore-forming bacteria of the genus Bacillus have been developed
as microbial insecticides against mosquito larvae, which the bacteria
kill by releasing toxins. Bacillus sphaericus offers advantages over
Bacillus thuringiensis israelensis because it can reproduce in the
mosquito larvae of some species, and can persist in some aquatic
environments for several weeks (24). Laboratory tests showed the
pathogenicity of Bacillus sphaericus strain 1593 against Wyeomyia
mitchellii but not against chironomid midge larvae (1); Bacillus
thuringiensis israelensis did not exhibit a pathogenicity against
Wyeomyia vanduzeei (2). Bacillus sphaericus strain 1593, sprayed
experimentally at 108 spores/ml against Wyeomyia larvae in tank
bromeliads, suppressed Wyeomyia populations for up to two months
(25). Further field tests of Bacillus sphaericus against Wyeomyia
larvae also gave promising results (31).
This microbial insecticide, may perhaps be safe to non-target
chironomid midge larvae in bromeliad tanks. If so, this selective effect
would be beneficial not only because midge larvae are harmless, but
also because they may reduce nutrients in bromeliad tanks.
Commercial sale of Bacillus sphaericus may begin in 1989 or 1990.

Management
With rare exceptions, larvae of these two Wyeomyia species have
been found only in bromeliad tanks. The numbers of these mosqui-
toes in any given area depend primarily on the number of tank
bromeliads in that area, and secondarily on the nutrient supply in
the bromeliad tanks. Reduction in the number of tank bromeliads
will cause a corresponding reduction in the number of Wyeomyia.








An effective method of controlling Wyeomyia is to limit the number
of bromeliads, and this is a viable option for people who have neither
an interest in bromeliads nor the time to maintain them.
For people who have a real interest in bromeliads, and time to
care for them, there are alternatives. If the number of Wyeomyia
larvae developing depends on the food supply in bromeliad tanks, a
reduction in the food supply will cause a reduction in the number of
larvae developing. In general, bromeliads grown in glasshouses and
shade houses will not receive dead tree leaves and twigs, which form
the basis of the food chain on which the mosquito larvae feed. Thus,
fewer Wyeomyia should develop under those conditions.
If bromeliads have to be grown under the shade of trees for lack
of other shaded sites, then removal of fallen leaves and twigs from
the tanks should reduce the food available to the mosquito larvae.
Pressure from a garden hose with appropriate nozzle can be used to
flush the majority of Wyeomyia eggs out of the tanks of bromeliads
growing on the ground (17) and may be expected to flush out
nutrients available to Wyeomyia larvae. This method must be used
frequently to cause much suppression of adult mosquito production.
Bromeliad tanks can be provided with artificial fertilizers to
compensate for natural organic materials removed. Such fertilizers
do not provide food for mosquito larvae.
Successful biological control methods against Wyeomyia might
eliminate the need for any other control method. Integrated pest
management for Wyeomyia would use management methods in
conjunction with biological control methods. Some research into
biological control methods for Wyeomyia has been conducted as
described below, but has not yet been brought to a satisfactory
conclusion and, as of this writing, there is no research program
leading to that objective.

BIOLOGICAL CONTROL RESEARCH
Biological control is the deliberate effort by man to control pests
by manipulation of antagonistic organisms (called biological control
agents). Typically, it is a treatment highly specific to the target
(pest) organism and thus differs from chemical control because
chemicals tend to hit target and non-target organisms rather
indiscriminately. Biological control is based on an understanding of
the population dynamics of the pest organism as regulated by
antagonistic organisms and other factors in nature. Some forms of
biological control against some targets can offer a permanent control
solution and a remarkably good cost to benefit ratio.








Aquatic Predators and Pathogens


Use of predators and pathogens as biological control agents is
especially difficult where survival of the target pests is limited by
food supply. Put simply, if there is only enough food in the water
held by a bromeliad tank to allow for the development of 10 (pest)
mosquito larvae, but 100 mosquito larvae are present, then 90 will
die of starvation. If a predator (or pathogen) kills 70 mosquito
larvae, only 20 will die of starvation and still 10 will develop to the
pupal stage. Only if the predator (or pathogen) succeeds in killing
more than 90 of the mosquito larvae will there be any reduction in
the number of mosquito larvae developing.
Larvae of some mosquito species are predatory on other or-
ganisms, including other mosquito larvae. In Florida, two such are
the larvae of Toxorhynchites rutilus and Corethrella appendiculata.
Normally found in water-filled treeholes, they also have been found
occasionally in tanks of bromeliads such as Billbergia pyramidalis
(16). Adults of these species do not bite warm-blooded animals
(adults of Toxorhynchites rutilus do not feed on blood at all). The
natural rarity of the larvae in tanks of Billbergia pyramidalis denies
them the opportunity for any important effect on Wyeomyia larvae.
The reason for their rarity in bromeliad tanks is that they are
adapted for existence in treeholes, and the adult females search for
treeholes in which to lay their eggs (7, 15). Rarely the adult females
make "mistakes" and lay a few eggs in bromeliad tanks; these eggs
have little or no effect on Wyeomyia larvae (12).
In feeding experiments, Toxorhynchites rutilus larvae left a few
Wyeomyia prey larvae untouched, no matter how many they were
offered (12). Toxorhynchites larvae may conserve their prey in the
manner of stock-rearers (23), and may be unsuitable as biocontrol
agents where survival of the prey is limited by food availability.
It has been suggested that eggs of Toxorhynchites rutilus or exotic
relatives (Toxorhynchites brevipalpis from Africa and Toxorhynchites
amboinensis from Asia) should be mass produced and distributed to
bromeliad tanks for control of pest mosquitoes. However, the high
labor costs of such mass production, the short "shelf life" of the eggs
(they hatch in less than two days), and the high labor costs of
distribution make this approach impracticable in Florida. Females
of these three species do not search for plant leaf axils in which to
lay their eggs, so mass production and releases of these mosquitoes
as adults would do little or nothing to reduce the problem caused by
mosquito production from bromeliads.
Collection records suggest that Toxorhynchites guadeloupensis
from the West Indies and Toxorhynchites superbus from Mexico








south to Colombia are primarily inhabitants of bromeliads (9). They
might be considered as biocontrol agents for bromeliad-inhabiting
mosquitoes, but a performance assay has been made of only one
bromeliad-inhabiting Toxorhynchites species. Toxorhynchites haemor-
rhoidalis (which, despite the different name, is very possibly the
same species as Toxorhynchites superbus) larvae inhabit flower bracts
of Heliconia, leaf axils of aroids, and tanks of the bromeliads
Aechmea nudicaulis and Aechmea aquilega in coastal Venezuela (21).
Experiments performed produced no evidence to support the theory
that Toxorhynchites haemorrhoidalis larvae reduced the abundance
of pest mosquito larvae in tanks of either of these bromeliad species
(19). There is still no evidence that larvae of any Toxorhynchites
species are useful biological control agents of pest mosquitoes in
bromeliad tanks.
In Florida, small predatory fly larvae (Stenomicra: Aulacigastridae,
Neodexiopsis: Muscidae) have been found in water held in tanks of
Tillandsia utriculata, but their effect on populations of Wyeomyia
larvae is thought to be negligible (6).
In Venezuela, larvae of a damselfly, Leptagrion siquierai, occur in
water held in tanks of Aechmea aquilega and, to a lesser extent, in
Aechmea nudicaulis. They are predatory and amphibious. Unlike
larvae of Toxorhynchites, these damselfly larvae can crawl from one
tank to another, so they may be better adapted to survive in
Aechmea aquilega than in Aechmea nudicaulis because the former is
more compartmentalized. Their effectiveness as predators against
populations of pest mosquito larvae has not yet been demonstrated
(20).
Predatory water beetles have been recorded in bromeliad tanks in
the neotropics (6), but their effects on mosquito larval populations
have not been evaluated.
Wyeomyia larvae infected with the protozoan pathogen Pilosporella
fishi or the fungal pathogen Coelomomyces sp. are rare in Florida (8,
18). Clearly these pathogens have a negligible effect on the number
of Wyeomyia larvae surviving. Their rarity has hindered research on
their life cycles, and no explanation is available as to why they are
not more common.

Terrestrial Predators
In Florida, spiders and ants are common among the leaves of
native and imported bromeliads, but are not specialized to this
habitat. They may contribute to the limitation of Wyeomyia
populations, by capturing some of the Wyeomyia adults emerging
from the aquatic pupal stage, but no evaluation of this has been








made. Predation by such organisms on adult Wyeomyia may be
useful because adult populations (unlike larvae) are not suspected of
being limited by food resources.
Ants have been seen to prey on Wyeomyia eggs in the laboratory,
but no evaluation has been made in nature. Some species of preda-
tory beetles of the families Carabidae and Staphylinidae are known
to be specialized to the habitat provided by bromeliads in the neo-
tropics (10), but their life cycles are unknown or poorly known, and
no evaluation of their effect on mosquito populations has been made.

Competitors
Mosquito eggs, larvae, and pupae are not the only organisms that
inhabit bromeliad tanks. However, just as Florida has few native
species of bromeliads, in contrast with neotropical countries such as
Costa Rica (6), and just as Florida has few bromeliad-inhabiting
mosquito species, in contrast with neotropical countries such as
Jamaica (9), so it seems to have relatively few sorts of other
organisms (6). Tank bromeliads in a few acres of coastal Venezuela
were found to have more mosquito species and more species of other
organisms than in all of Florida (19 to 21), but each bromeliad
contained far fewer larvae of any pest mosquito than is typical of
bromeliads in a natural habitat in Florida (12). Nutrients in
neotropical bromeliads are shared among a diversity of organisms.
Thus, it can be surmised, fewer nutrients are available to mosquitoes
and, consequently, smaller mosquito populations are produced.
Reduction of nutrients suitable for mosquito larvae in bromeliad
tanks in Florida could perhaps be accomplished by the introduction
of innocuous organisms to consume these nutrients. These innoc-
uous organisms would be from neotropical tank bromeliads, and they
would act as competitors with the mosquito larvae. This seems a
rational approach to biological control, when survival of the target
organisms is limited by food. However, research toward this
objective has not yet begun, and thorough characterization of the
specialized diet of any of the organisms in bromeliad tanks has not
been accomplished.

Outlook
Damage caused to plants by plant pests can be quantified in terms
of loss in value of the plants and in costs of control measures taken.
Such loss figures are important in drawing up lists of priorities for
publicly-funded research on biological control. Damage caused by
human disease vectored by mosquitoes can be quantified in terms of
medical costs and lost wages. Methods for quantifying damage








caused by mosquitoes that are almost entirely a nuisance lack
persuasion, and public funds for biological control research are much
more likely to be awarded to projects of perceived higher priority (of
which there is no shortage). Nevertheless, Wyeomyia mosquitoes rate
highly as pest mosquitoes in south Florida, and if funds are available
for research into control of pest mosquitoes, then Wyeomyia should
receive a share.

OTHER ORGANISMS INHABITING BROMELIADS
Use of chemicals against scale insect pests of bromeliads is likely
to kill any and all of the other organisms associated with bromeliads,
whether they are scale insects feeding on the leaves, mosquito larvae
and adults, innocuous organisms inhabiting bromeliad tanks, or
beneficial natural enemies. Innocuous organisms inhabiting bromel-
iad tanks are very poorly known; although two hundred or so species
have been recorded from bromeliad tanks in various parts of the neo-
tropics, these are just a small part of the total, and undescribed
species occur even in Florida.
Aquatic, bromeliad-inhabiting organisms show great diversity in
form. They range from simple organisms (fungi, algae, and proto-
zoa), aquatic worms and insects, to tadpoles of frogs specialized for
existence in bromeliad tanks (6, 32). The life cycles of only a few
have been studied at all. Even among the relatively few species of
such organisms in Florida, fascinating discoveries remain to be made.
Aquatic organisms that are the immature stages of winged insects
evidently are distributed among bromeliads by their winged mothers,
but a question of considerable interest is how other organisms get
from one bromeliad to another (13). Other questions concern to
what extent these organisms use the tanks of imported bromeliads,
and whether their populations are expanding or decreasing with the
urbanization of southern Florida.

SUMMARY
Among the native and imported bromeliads ("air plants") common
in southern Florida are tank bromeliads, which catch and hold water
in little pools (tanks) in their leaf axils. Many different tank bromel-
iads are grown as ornamental plants.
Mosquito larvae grow in the bromeliad tanks. Almost all of them
are Wyeomyia mosquito larvae, but sometimes others are found,
especially when grass clippings get into the bromeliad tanks and foul
the water. Besides the mosquito larvae, various harmless aquatic
organisms live in bromeliad tanks.
The mosquito larvae do not harm the bromeliads, but they








caused by mosquitoes that are almost entirely a nuisance lack
persuasion, and public funds for biological control research are much
more likely to be awarded to projects of perceived higher priority (of
which there is no shortage). Nevertheless, Wyeomyia mosquitoes rate
highly as pest mosquitoes in south Florida, and if funds are available
for research into control of pest mosquitoes, then Wyeomyia should
receive a share.

OTHER ORGANISMS INHABITING BROMELIADS
Use of chemicals against scale insect pests of bromeliads is likely
to kill any and all of the other organisms associated with bromeliads,
whether they are scale insects feeding on the leaves, mosquito larvae
and adults, innocuous organisms inhabiting bromeliad tanks, or
beneficial natural enemies. Innocuous organisms inhabiting bromel-
iad tanks are very poorly known; although two hundred or so species
have been recorded from bromeliad tanks in various parts of the neo-
tropics, these are just a small part of the total, and undescribed
species occur even in Florida.
Aquatic, bromeliad-inhabiting organisms show great diversity in
form. They range from simple organisms (fungi, algae, and proto-
zoa), aquatic worms and insects, to tadpoles of frogs specialized for
existence in bromeliad tanks (6, 32). The life cycles of only a few
have been studied at all. Even among the relatively few species of
such organisms in Florida, fascinating discoveries remain to be made.
Aquatic organisms that are the immature stages of winged insects
evidently are distributed among bromeliads by their winged mothers,
but a question of considerable interest is how other organisms get
from one bromeliad to another (13). Other questions concern to
what extent these organisms use the tanks of imported bromeliads,
and whether their populations are expanding or decreasing with the
urbanization of southern Florida.

SUMMARY
Among the native and imported bromeliads ("air plants") common
in southern Florida are tank bromeliads, which catch and hold water
in little pools (tanks) in their leaf axils. Many different tank bromel-
iads are grown as ornamental plants.
Mosquito larvae grow in the bromeliad tanks. Almost all of them
are Wyeomyia mosquito larvae, but sometimes others are found,
especially when grass clippings get into the bromeliad tanks and foul
the water. Besides the mosquito larvae, various harmless aquatic
organisms live in bromeliad tanks.
The mosquito larvae do not harm the bromeliads, but they









produce mosquito pupae which, in turn, produce biting adult
mosquitoes. Adult Wyeomyia mosquitoes bite during daylight hours
and often are a pest problem. They are not controlled by pesticidal
fogging conducted by mosquito control districts.
Reduction of the number of tank bromeliads grown is a practical
way of controlling Wyeomyia mosquitoes. Because the mosquito
larvae feed on organic materials such as dead leaves that have fallen
into the tanks, then keeping tank bromeliads in glasshouses and
shade houses will lessen adult mosquito production from them.
Pressure from a garden hose will wash out some mosquito eggs and
organic materials in bromeliad tanks.
In general, use of chemical insecticides to kill Wyeomyia mosquito
larvae is not a reliable strategy. The microbial insecticide Bacillus
sphaericus has given promising results in preliminary tests and may
be harmless to non-target organisms; applications of it may have to
be repeated about six times per year. It may be available commer-
cially in 1989 or 1990 as a mosquito larvicide.



LITERATURE CITED
1. Ali, A. and J.K. Nayar. 1986. Efficacy of Bacillus sphaericus Neide
against larval mosquitoes (Diptera: Culicidae) and midges (Diptera:
Chironomidae) in the laboratory. Fla. Entomol. 69: 685-90.
2. Ali, A., D.M. Sauerman and J.K. Nayar. 1984. Pathogenicity of
industrial formulations of Bacillus thuringiensis serovar israelensis to
larvae of some culicine mosquitoes in the laboratory. Fla. Entomol. 67:
193-97.
3. Edman, J.D. and J.S. Haeger. 1978. Host-feeding patterns of Florida
mosquitoes V. Wyeomyia. J. Med. Entomol. 14: 477-79.
4. Florida Statutes. 1987. 386.041. Nuisances injurious to health.
5. Florida Statutes. 1987. 581.185. Preservation of native flora of
Florida.
6. Frank, J.H. 1983. Bromeliad phytotelmata and their biota, especially
mosquitoes. Pp. 101-128 in J.H. Frank & L.P. Lounibos (eds.) Phytotel-
mata: terrestrial plants as hosts for aquatic insect communities. Plexus;
Medford, New Jersey. vii + 293 pp.
7. Frank, J.H. 1985. Use of an artificial bromeliad to show the
importance of color value in restricting colonization of bromeliads by
Aedes aegypti and Culex quinquefasciatus. J. Am. Mosquito Control
Assoc. 1: 28-32.
8. Frank, J.H. and G.A. Curtis. 1977. On the bionomics of bromeliad-
inhabiting mosquitoes. VII. Incidence and effect of Pilosporella fishi,
a parasite of Wyeomyia vanduzeei. Mosquito News 37: 487-89.
9. Frank, J.H. and G.A. Curtis. 1981. On the bionomics of bromeliad-
inhabiting mosquitoes. VI. A review of the bromeliad-inhabiting
species. J. Fla. Anti-Mosquito Assoc. 52: 4-23.









10. Frank, J.H. and G.A. Curtis. 1982. Bionomics of the bromeliad-
inhabiting mosquito Wyeomyia vanduzeei and its nursery plant
Tillandsia utriculata. Fla. Entomol. 64: 491-506.
11. Frank, J.H., G.A. Curtis and J.T. Rickard. 1985a. Density dependent
sex ratio distortion and developmental bimodality in Wyeomyia
vanduzeei. Pp. 155-65 in L.P. Lounibos, J.R. Rey & J.H. Frank (eds.)
Ecology of mosquitoes: proceedings of a workshop. Florida Medical
Entomology Laboratory; Vero Beach, Fla. xxi + 579 pp.
12. Frank, J.H., G.A. Curtis and G.F. O'Meara. 1984. On the bionomics
of bromeliad-inhabiting mosquitoes. X. Toxorhynchites r. rutilus as a
predator of Wyeomyia vanduzeei (Diptera: Culicidae). J. Med. Entomol.
21: 149-58.
13. Frank, J.H. and L.P. Lounibos. 1987. Phytotelmata: swamps or
islands? Fla. Entomol. 70: 14-20.
14. Frank, J.H., H.C. Lynn and J.M. Goff. 1985b. Diurnal oviposition by
Wyeomyia mitchellii and W. vanduzeei (Diptera: Culicidae). Fla.
Entomol. 68: 493-96.
15. Frank, J.H. and G.F. O'Meara. 1985. Influence of micro- and
macrohabitat on distribution of some bromeliad-inhabiting mosquitoes.
Entomol. Exp. Appl. 37: 169-174.
16. Frank, J.H., J.P. Stewart and D.A. Watson. 1988. Mosquito larvae in
axils of the imported bromeliad Billbergia pyramidalis in southern
Florida. Fla. Entomol. 71: 33-43.
17. Gettman, A.D. and J.H. Frank. 1989. A method to reduce Wyeomia
mitchelli eggs in Billbergia pyramidalis bromeliads. J. Fla. Anti-
Mosquito Assoc. 60: 7-8.
18. Hall, D.W. and D.W. Anthony. 1979. Coelomomyces sp. (Phyco-
mycetes: Blastocladiales) from the mosquito Wyeomyia vanduzeei
(Diptera: Culicidae). J. Med. Entomol. 16: 84.
19. Lounibos, L.P., J.H. Frank, C.E. Machado-Allison, P. Ocanto and J.C.
Navarro. 1987a. Survival, development and predatory effects of
mosquito larvae in Venezuelan phytotelmata. J. Trop. Ecol. 3: 221-42.
20. Lounibos, L.P., J.H. Frank, C.E. Machado-Allison, J.C. Navarro and P.
Ocanto. 1987b. Seasonality, abundance and invertebrate associates of
Leptagrion siqueirai Santos in Aechmea bromeliads in Venezuelan rain
forest (Zygoptera: Coenagrionidae). Odonatologica 16: 193-99.
21. Machado-Allison, C.E., R. Barrera R., J.H. Frank, L. Delgado and C.
Gomez-Cova. 1985. Mosquito communities in Venezuelan phytotelmata.
Pp. 79-93 in L.P. Lounibos, J.R. Rey & J.H. Frank (eds.) Ecology of
mosquitoes: proceedings of a workshop. Florida Medical Entomology
Laboratory; Vero Beach, Fla. xxi + 579 pp.
22. Padilla, V. 1973. Bromeliads. Crown Publ.; New York. viii + 134 pp.
23. Reiter, I.P. 1985. Discussion. P. 142 in L.P. Lounibos, J.R. Rey & J.H.
Frank (eds.) Ecology of mosquitoes: proceedings of a workshop. Florida
Medical Entomology Laboratory; Vero Beach, Fla. xxi + 579 pp.
24. Service, M.W. 1983. Biological control of mosquitoes has it a future?
J. Am. Mosquito Control Assoc. 43: 113-20.
25. Stewart, J.P., W. Ehrhardt and E. Shepard. 1981. Control of
bromeliad-inhabiting mosquitoes. Unpubl. talk at Annl. Mtg. of Am.
Mosquito Control Assoc. (San Antonio, TX, 1981) and pers. comm. from









J.P. Stewart (Daytona Beach, FL, 1988).
26. United States Code. 1912. Plant quarantine act.
27. United States Code. 1957. Plant pest act.
28. United States Code. 1973. Endangered species act.
29. United States Code. 1982. Public Health Service act.
30. Unpublished information from D.B. Carlson and G.A. Curtis, Indian
River Mosquito Control District, Vero Beach, Florida.
31. Winner, R.A., S.K. Chamberlain, and R.E. Parsons. 1989. Use of Raid
Yard Guard, Vectobac-G, or Vectolex-G to control Wyeomyia mitchellii
(Theobald) in bromeliads at a residential site in Sarasota, Florida. J.
Fla. Anti-Mosquito Assoc. 60: 71-72.
32. Zahl, P.A. 1975. Hidden worlds in the heart of a plant. National
Geographic 147: 389-97.








































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This publication was promulgated at a cost of $2,945.40, or
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bromeliads and mosquitoes.



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