biology of larval and adult mosquitoes (diptera: culicidae)

174 Pages·2016·3.31 MB·English

Clemson University
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All Dissertations Dissertations
8-2011
ZOOS AS EXPERIMENT ENVIRONMENTS:
BIOLOGY OF LARVAL AND ADULT
MOSQUITOES (DIPTERA: CULICIDAE)
Holly Tuten
Clemson University, [email protected]
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(DIPTERA: CULICIDAE)" (2011).All Dissertations. 769.
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ZOOS AS EXPERIMENT ENVIRONMENTS: BIOLOGY OF LARVAL AND ADULT
MOSQUITOES (DIPTERA: CULICIDAE)

A Dissertation
Presented to
the Graduate School of
Clemson University

In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy
Entomology

by
Holly Coleen Tuten
August 2011

Accepted by:
Peter H. Adler, Committee Chair
William C. Bridges, First Reader
Kimberly S. Paul, Second Reader
William Wills, Third Reader
ABSTRACT

Zoos are a unique environment where humans and animals are in close daily contact,
potential mosquito habitats exist, exotic plants and animals are introduced regularly, and
wild animals roam. Studies of mosquito behaviors in zoos will lead to a better
understanding, both within and outside zoos, of disease transmission routes and mosquito
biology. To investigate whether the unique assemblage of habitats in zoos affects
mosquito behavior, I sampled larvae and adults in the Greenville Zoo and the Riverbanks
Zoo, South Carolina, USA, from March 2008 to January 2011. The objectives of my
study were to investigate mosquito oviposition behavior, blood-host usage, and
transmission of the causative agent of dog heartworm (Dirofilaria immitis); document the
structure of the mosquito pyloric armature; and provide zoos with suggestions for
mosquito control. My results underscore the medical and veterinary importance of
studying mosquito blood feeding ecology in zoos, and the experimental utility of zoos for
studying mosquito behavior.

A total of 1,630 larvae and 4,349 adults representing 16 species was collected and
identified. The most common species were Aedes albopictus, Ae. triseriatus, Culex
erraticus, Cx. restuans, and Cx. pipiens complex. Principal components and multiple
logistic regression analyses showed that across both zoos the overall larval mosquito
presence (regardless of species) was predicted by ambient and site temperature,
precipitation, dissolved oxygen, presence of natural habitats, and absence of aquatic
vegetation. Pairwise species associations indicated significant habitat-based relationships
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between larvae of Ae. albopictus and Ae. triseriatus, and Cx. pipiens complex and Cx.
restuans. Recommendations to zoo personnel, regarding larval mosquito habitat
management, were to reduce or eliminate artificial containers and shade sources greater
than or equal to 2 m above standing water, use mosquito larvicides when source
reduction is not possible, and receive training in recognizing and mitigating larval
mosquito habitats. Mosquitoes fed on captive animals, humans, and wild animals, and
took mixed bloodmeals. Blood hosts included 1 amphibian species, 16 bird species, 10
mammal species (including humans), and 2 reptile species. Minimum flight distances
(dispersal) from host locations ranged from 15.5 m to 327.0 m, with a mean of 94.1 m ±
13.4 m. No mosquitoes tested (n = 45) were positive for D. immitis. The pyloric spines of
Ae. albopictus, Ae. j. japonicus, Ae. triseriatus, An. punctipennis, Cx. pipiens complex,
Cx. restuans, Or. signifera, and Tx. rutilus were photographed and measured.
Differences exist in qualitative and quantitative spine structure, with Aedes spp. forming
one general group, Culex spp. another, and An. punctipennis and Or. signifera a third.
The one specimen of Toxorhynchites rutilus examined was most like Culex spp.
mosquitoes.

Larval mosquito-habitat, adult mosquito-host associations, and pyloric armature and
spine structures generally conformed to previously published accounts, indicating that
mosquito biology inside zoos represents mosquito biology outside zoos. Therefore, zoos
can be used for experiments not feasible in the field. However, novel variation (e.g., new,
exotic host records) recorded in mosquito species warrants further investigation in zoos.
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My study demonstrates that zoos can be used as experiment environments to study
mosquito behaviors (e.g., oviposition cues, innate versus learned host preferences,
mosquito dispersal, and home range memory), and that findings can be extrapolated to
non-zoo areas, while also providing medical and veterinary benefits to zoo animals,
visitors, and the public.

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DEDICATION
To my friends and family and the ―World‘s Greatest Medical Entomologist‖,
William Wills
&

To Chris M. Stone, this work would not be what it is without your enthusiastic support
and our rambling conversations. I can‘t wait to see where our adventures take us next.
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ACKNOWLEDGMENTS
I will forever be gladly indebted to W. Wills for guiding me into this profession. Thank
you for finding me in the forest.

I gratefully acknowledge the guidance of P.H. Adler, a graceful leader and outstanding
person. ―The best of leaders when the job is done, when the task is accomplished, the
people will say we have done it ourselves.‖ – Lao Tzu.

I would like to thank the staff of both zoos including K. Benson DVM, H. Miller DVM,
J. Bullock, B. Foster, K. Gilchrist, J. Lineberger, A. Norris, and S. Reno. Additionally,
my thanks go to C. Beard, T. Brewer, C. Climer (―Exo-AP‖ protocol), C. Evans
(Richland Co. DHEC collections), K. Korneva, J. McCall, J. McCreadie, M. Nelder, D.
Swanson (identifications of Ceratopogonidae and Corethrellidae), and P. Vigueira. And, I
am grateful to the lab of Dr. W. Foster at The Ohio State University for serving as my
surrogate lab. I would also like to thank the W.C. Nettles Endowed Research Grant for
partial research funding, the Nettles Travel Grant and Clemson GSG Professional
Enrichment Grant for funding most of my professional presentations, the Terminix and
Cochran Fellowships, the Filaria Research Reagent Repository in Athens, GA for
materials and training (thank you E. Burkman), the SC Department of Health and
Environmental Control for equipment, and the National Science Foundation Graduate
Research Fellowship Program for financial support.

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TABLE OF CONTENTS
Page

TITLE PAGE .................................................................................................................... i

ABSTRACT ..................................................................................................................... ii

DEDICATION ................................................................................................................. v

ACKNOWLEDGMENTS .............................................................................................. vi

LIST OF TABLES .......................................................................................................... ix

LIST OF FIGURES ......................................................................................................... x

CHAPTER

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

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

Mosquitoes in zoos .................................................................................. 5
Environmental characters of larval mosquito habitats ............................. 8
Blood hosts of mosquitoes ..................................................................... 16
Mosquitoes vectors of Dirofilaria immitis ............................................. 19
Pyloric armature of mosquitoes ............................................................. 23

III. HABITAT CHARACTERISTICS OF
LARVAL MOSQUITOES IN SOUTH CAROLINA ZOOS ................ 27

Materials and methods ........................................................................... 29
Results .................................................................................................... 34
Discussion .............................................................................................. 40

IV. MOSQUITO HOSTS IN SOUTH
CAROLINA ZOOS ............................................................................... 46

Materials and methods ........................................................................... 48
Results .................................................................................................... 56
Discussion .............................................................................................. 67

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Table of Contents (Continued)

Page

V. PYLORIC ARMATURE OF MOSQUITOES ............................................ 72

Materials and methods ........................................................................... 75
Results .................................................................................................... 80
Discussion .............................................................................................. 90

VI. CONCLUSION ............................................................................................ 95

Public summary ................................................................................... 103

APPENDICES ............................................................................................................. 104

A: Pictures of larval mosquito habitats in the zoos......................................... 105
B: Pictures of gravid collection sites in the zoos ............................................ 111
C: Pictures of aspiration sites in the zoos ....................................................... 116
D: GPS coordinates and descriptions of collection locations ......................... 120
E: Annual updates to the zoos 2008-2010 ...................................................... 125

REFERENCES ............................................................................................................ 146

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LIST OF TABLES

Table Page

2.1 Species of mosquitoes previously captured at the
Greenville Zoo and their larval habitats................................................... 7

2.2 Records of Dirofilaria immitis infection in captive
animals at zoos ....................................................................................... 22

3.1 Total number of larvae collected at SC zoos ............................................... 35

3.2 Aquatic habitat types positive for larvae at SC zoos .................................. 36

3.3 Continuous variables used in Principal Components Analysis.................... 37

3.4 Logistic regression on habitat variables ....................................................... 39

3.5 Coefficients of species pairwise associations .............................................. 40

4.1 Primers used in molecular analyses ............................................................. 55

4.2 Mosquito species collected for bloodmeal analyses .................................... 58

4.3 GenBank percent identities and flight distances
by Sella stage ......................................................................................... 60

4.4 Mosquito hosts at SC zoos ........................................................................... 63

4.5 Forage ratios of mosquitoes at SC zoos ....................................................... 64

5.1 Mean comparisons of female mosquito pyloric spines ................................ 89

5.2 Mean comparisons of male mosquito pyloric spines ................................... 90

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