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Evaluation of Five Mosquito Traps and a Horse for West Nile Vectors on a North Florida Equine Facility

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Title:
Evaluation of Five Mosquito Traps and a Horse for West Nile Vectors on a North Florida Equine Facility
Creator:
CAMPBELL, CLINTON BRITT ( Author, Primary )
Copyright Date:
2008

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College instruction ( jstor )
Counterflow ( jstor )
Experimentation ( jstor )
Horses ( jstor )
Insects ( jstor )
Magnetism ( jstor )
Species ( jstor )
Spring ( jstor )
Surveillance ( jstor )
West Nile virus ( jstor )

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University of Florida
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University of Florida
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Copyright Clinton Britt Campbell. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
6/1/2004
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53206995 ( OCLC )

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EVALUATION OF FIVE MOSQUITO TRAPS AND A HORSE FOR WEST NILE VECTORS ON A NORTH FLORIDA EQUINE FACILITY By CLINTON BRITT CAMPBELL A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2003

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Copyright 2003 by Clinton Britt Campbell

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This document is dedicated to my parents, Stuart and Julie Campbell.

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iv ACKNOWLEDGMENTS I would like to thank Dan Kline, Jerry Hogsette, and Saundra Tenbroeck for their guidance, support, willingness to teach me, and for making themselves available whenever I needed assistance. I thank the staff of the UF Horse Teaching Unit for allowing me to use their facility. I thank Kelly Jones, Rodney Rowles, and Sarah Dilling for their assistance with horse handling. I thank Aaron Lloyd and Joyce Urban for the various tasks that they always made time to help me with. I thank Debbie Hall for all the administrative help. Finally, I thank Adam Glassman for statistical assistance.

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v TABLE OF CONTENTS Page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES............................................................................................................vii LIST OF FIGURES.........................................................................................................viii ABSTRACT....................................................................................................................... ix CHAPTER 1 LITERATURE REVIEW.............................................................................................1 West Nile Virus............................................................................................................1 Host preference.............................................................................................................4 Mosquito Trapping.......................................................................................................5 CO2-based Mosquito Traps...................................................................................5 Counterflow geometry traps...........................................................................5 Propane-based traps........................................................................................6 Equine Traps..........................................................................................................7 Summary.......................................................................................................................8 2 MOSQUITO TRAPPING TRIALS............................................................................10 Mosquito Traps...........................................................................................................10 Center for Disease Control (CDC) Trap..............................................................10 Mosquito Magnet ® X (MMX)...........................................................................11 Mosquito Magnet ® Pro......................................................................................12 Mosquito Magnet ® Liberty................................................................................12 Bugjammer™......................................................................................................14 Equine..................................................................................................................14 Trapping Protocol.......................................................................................................14 Data analysis...............................................................................................................15 Results........................................................................................................................ .16 Experiment 1.......................................................................................................16 Experiment 2.......................................................................................................18 Discussion...................................................................................................................24 Species Composition...........................................................................................24 Trap catch............................................................................................................28 Trapping Site Differences....................................................................................30

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vi Summary.....................................................................................................................31 LIST OF REFERENCES...................................................................................................32 BIOGRAPHICAL SKETCH.............................................................................................37

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vii LIST OF TABLES Table page 2.1. Mean catch and total count of mosquitoes trapped during 39 overnight trapping trials at the UF Horse Teaching Unit from May 17, 2002 to September 30, 2002..16 2.2. Percentage and total mosquito species captured by each trap during 39 overnight trapping trials at the UF Horse Teaching Unit conducted May 17, 2003 through September 30, 2003..................................................................................................17 2.4. Shannon-Weaver Diversity Index of mosquito species trapped at the UF Horse Teaching Unit. Experiment A denotes trapping conducted from May 17, 2003 through September 30, 2003, and all traps during this trial were run overnight except equine. Experiment B denotes overnight trapping conducted in April, 2003, and Experiment C denotes 30-minute trapping conducted April, 2003...................18 2.3. Percent of total count of mosquito species by site. The trapping trial was conducted at the UF Horse Teaching Unit from May 17, 2002 through September 30, 2002..19 2.5. Mean catch and total count of mosquitoes trapped during 30-minute trapping trials at the UF Horse Teaching Unit during April, 2003..................................................20 2.6. Percent of total count of mosquito species trapped during 30-minute trapping trials at the UF Horse Teaching Unit during April, 2003..................................................21 2.7. Mean catch and total count of mosquitoes trapped during overnight trapping trials at the UF Horse Teaching Unit during April, 2003..................................................21 2.8. Percent and total count of mosquito species trapped during overnight trapping trials at the UF Horse Teaching Unit during April, 2003..................................................22 2.9. Percent of total count of mosquito species by site. The trapping trial was conducted overnight at the UF Horse Teaching Unit during April, 2003.................................23

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viii LIST OF FIGURES Figure page 2.1. Aerial photograph of the University of Florida Horse Teaching Unit showing the five trap sites............................................................................................................11 2.2. Five models of mosquito traps tested at the University of Florida Horse Teaching Unit: A) The CDC 1012. B) The Mosquito Magnet X. C) The Bugjammer. D) The Mosquito Magnet Pro. E) The Mosquito Magnet Liberty...............................13 2.3. Two geldings that were sampled for mosquitoes, a cremelo (A) and a chestnut (B).15

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ix Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science EVALUATION OF FIVE MOSQUITO TRAPS AND A HORSE FOR WEST NILE VECTORS ON A NORTH FLORIDA EQUINE FACILITY By Clinton B. Campbell August 2003 Chair: Daniel L. Kline Major Department: Entomology and Nematology Field studies were conducted to evaluate the efficacy of commercially available mosquito traps to capture suspected vectors of West Nile Virus (WNV) to horses and determine the species composition and relative abundance of mosquito species in each. The traps included the Mosquito Magnet (MM) Pro, MM Liberty, and MMX (American Biophysics Corporation, East Greenwich, RI), the CDC 1012 (John W. Hock Company, Gainesville, FL), and the Bugjammer (Bugjammer Inc., Pennington, NJ). During a 30-minute period at dusk, mosquitoes were collected from a horse with a portable vacuum aspirator (Bioquip; Rancho Dominguez, CA) to assess the species attracted to the equine. All mechanical traps were operated overnight and the captured insects were collected the following morning. The trial was performed at the University of Florida Horse Teaching Unit (HTU) in Gainesville, FL, using a 5x5 Latin square

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x design during May 17 to September 30, 2002. After trap/position randomization on the first trapping night, each trap was rotated sequentially thereafter. The CDC 1012 caught significantly more mosquitoes ( P ! 0.05) than the other traps, and the Bugjammer did not catch any mosquitoes. This study resulted in a difference in the percent of WNV vector species captured in traps as opposed to those on the horse. Culex nigripalpus composed 85 – 91% in all mechanical traps and only 27% on the horse. The primary species found on the horse was Mansonia titillans ; this species composed 40% of the mosquitoes captured on the horse. The second part of the study was performed for 5 days during April 2003. During a 30-minute period at dusk, mosquitoes were collected from a horse and, during the same interval, traps were operated and collected at the end of the 30-minute period. Afterwards, the traps were allowed to operate overnight and catch was collected the following morning. The MM Pro, MMX, and CDC 1012 caught significantly ( P ! 0.05) more mosquitoes than did the MM Liberty in both the 30-minute and overnight trapping trials. All traps captured primarily Cx. salinarius, Cx. erraticus, and Anopheles crucians. During 30-minute trials performed at dusk, the equine had a greater percentage of Ma. titillans than did the traps, and less Cx. salinarius and Cx. erraticus . The results indicate that these mechanical traps capture primarily mosquitoes suspected to be vectors of WNV, e.g., Cx. salinarius , and may offer the horses some degree of protection from these species. The species of mosquitoes trapped, however, does not appear to represent the same relative abundance that is found on the horses at the facility.

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1 CHAPTER 1 LITERATURE REVIEW A new threat is upon Florida's equine industry: West Nile Virus (WNV). WNV has arrived in Florida sooner than most scientists anticipated, and is a pressing concern for many, including members of Florida's bustling equine industry. Many of the top thoroughbreds in the nation are bred and trained here in the Sunshine State, and they are now threatened by this recently introduced arbovirus. New techniques for vector control are now becoming readily available for large-scale equine facilities and backyard equine enthusiasts. Many companies are creating new traps that claim to effectively control mosquito populations, including the mosquito species that transmit WNV and other arboviruses. Some of these traps have been tested and, if proven successful, could become an effective mosquito control measure. After all, mechanical mosquito-trapping devices have been used for surveillance purposes for many years. Perhaps these traps could be used to control the nuisance mosquitoes that attack horses as well as provide an accurate portrayal of local mosquito populations. However, many questions have yet to be answered about the efficiency of these products and the mosquito species targeted. West Nile Virus West Nile Virus, an arbovirus of the family Flaviviridae, was first confirmed present in the USA in October, 1999 (Centers for Disease Control and Prevention 1999). A horse in Suffolk County, NY was diagnosed with the virus, and 24 more equine cases were diagnosed within the year. During the winter of 1999-2000, evidence confirmed that WNV was present in birds and mosquitoes in the New York City area (Garmendia et

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2 al. 2000). Various larvae of Culex spp. tested positive for the virus in the NYC area during 1999 (Kulasekera et al. 2001). WNV has been known in Africa, southern Europe, and western Asia for many years, and was first isolated in the West Nile district of Uganda in 1937 (Smithburn et al. 1940). Many of the mosquito species known to be competent vectors for WNV in these areas are Culex spp. WNV was first detected in Florida on July 3, 2001, when a dead crow in Jefferson County was confirmed positive for the virus (Stark & Kazanis 2001). During 2001, 738 clinical equine cases of WNV were reported nationwide, and 492 of these cases were in the state of Florida. Eighty-two of the horses confirmed positive in Florida during 2001 were euthanized (USDA 2001). The 2002 arbovirus season was equally as impressive, as WNV spread throughout the state of Florida and throughout the country. Of the 14,717 equine cases of WNV in the USA in 2002, 499 were reported in Florida. Of these, Alachua County, FL reported 11 horses positive for WNV in 2002 (Collins et al. 2002). Pools of mosquitoes in Florida were tested for presence of WNV using molecular assays during 2001 and 2002. Mosquito species from Florida indicated positive for WNV presence in these tests were Anopheles crucians, An. atropos, Cx. nigripalpus, Culiseta melanura, Deinocerites cancer, and Ochlerotatus taeniorhynchus (Stark & Kazanis 2001, 2002). A man in Los Angeles, CA and a horse in Island County, WA were confirmed positive for WNV in 2002, indicating WNV had spread transcontinentally in just three years (Chow et al. 2003). Cases were also confirmed in various parts of Canada in 2002 as well. The horse cases in 2002 increased twelve-fold from 2001, and occurred for the first time in nine states.

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3 Since the introduction of WNV into the United States, WNV has been detected in many mosquito species. However, few have been cited as competent vectors. Culex spp . are most often cited for WNV competence, and many have been suggested as the primary vectors to humans and mammals. Sardellis et al. (2001) tested various New England and Florida-based mosquito stock in the lab for WNV vector competence. Cx. nigripalpus, Cx. quinquefasciatus, Cx. restuans , and Cx. salinarius were all listed as competent laboratory vectors of WNV. Each of these species is known to play a role in various other enzootic cycles involving birds as amplification hosts. This further raises suspicion of their involvement in WNV transmission. Cx. nigripalpus is the primary vector of St. Louis Encephalitis (SLE) in Florida (Day & Edman 1988), and is considered to be a possible primary vector of WNV in Florida. Aedes albopictus, Ae. atropalpus, and Ae. japonicus have all been listed as potential vectors (Sardelis & Turell 2001, Turell et al. 2001), and may play an important role in the enzootic cycle of WNV. While some Culex spp. are considered to be primarily ornithophilic, they will feed on other hosts, thus transmitting the disease to other hosts, including equines. Birds serve as amplication hosts for WNV as well as similar arboviruses such as SLE. Bunning et al. (2002) tested the effectiveness of horses as amplification hosts for WNV. Equine of various breeds and ages were experimentally infected with WNV via infected Ae. albopictus and uninfected Ae. albopictus were then allowed to feed upon the infected horses. All mosquitoes that fed upon the horses tested negative for presence of WNV, and the viremia levels in the equine were low and short-lived. Given the present knowledge, horses have not been indicated as amplification hosts.

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4 Host preference A number of mosquito species are known to feed on horses. Ae. vexans seems to be readily attracted to horses, as well as various other Aedes spp. and Ochlerotatus spp. (Loftin et al. 1997). Psorophora columbiae seem to feed regularly on horses as well (Kuntz et al. 1982). Other mosquito species are also found to be attracted to and feed on equines, including Anopheles spp., Coquillettidia spp., Culex spp., Culiseta spp., Mansonia spp., and Psorophora spp. (Constantini et al. 1998, Kuntz et al. 1982, Loftin et al. 1997). Other Diptera are also known to be attracted to equines, including Simulium spp., Stomoxys calcitrans , Musca autumnalis , Tabanus spp., Chrysops spp., and Culicoides spp. (Fletcher et al. 1988). Some of these species are known vectors of equine disease, and thus are of concern. Some of the same species are also known to be attracted to other livestock, and host preference studies have been performed comparing various species of livestock, poultry, and companion animals. Loftin et al. (1997) indicates a preference of Ae. vexans , Ae. dorsalis, and Cs. inornata to equines and cattle, while Cx. quinquefasciatus shows preference toward dogs and chickens. Nelson et al. (1976) similarly shows a preference of Culex spp. for domestic fowl, while Aedes spp. prefer a mammalian host. Some of the more common Culex spp . in north Florida are known to feed on both avian and mammalian hosts, e.g., Cx. salinarius and Cx. nigripalpus . Edman (1974) reports a marked change in blood meal composition of Cx. nigripalpus according to season and relative humidity. Cx. nigripalpus seemed to be more apt to feed on birds during the spring, and a high proportion of mammals during the rainy season in the summer. Cx. salinarius is shown to be a general feeder, and is known to be a mammal

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5 feeder in some habitats (Schaefer & Steelman 1969). Edman (1971) reports that Cx. erraticus , also found in north Florida, feeds primarily on birds. Mosquito Trapping CO2-based Mosquito Traps Mosquito traps have been used as a method to sample the species and number of mosquitoes in an area. A variety of traps have been used, and these have been thoroughly reviewed in Service (1993). The Center for Disease Control (CDC) trap has been a mainstay in mosquito surveillance. This is a versatile trap that can be modified a number of ways using light, octenol, etc. The ability of the CDC trap to effectively capture mosquitoes for sampling purposes is well documented (Service 1993). Counterflow geometry traps More recently traps that manipulate CO2 plumes in a different fashion have been produced. Using a counterflow of CO2, these traps are unlike typical traps that have a downdraft of CO2 as an attractant. The CO2 is usually supplied from a gas cylinder or dry ice, and two fans operate to capture mosquitoes and provide the counterflow of CO2 to attract the mosquitoes. The Mosquito Magnet X (MMX) is the current development from the first of the counterflow geometry (CFG) traps. In field studies comparing an American Biophysics Corporation (ABC) (East Greenwich, RI) CFG and the ABC PRO, a trap similar to the CDC trap, 7.8 times more mosquitoes were caught by the CFG trap (Kline 1999). Similar results were noted by Burkett et al. (2001, 2002). In trials involving numerous trap sites and a number of different trap styles, the CFG traps were more effective at trapping mosquitoes than the standard mosquito traps such as the CDC, ABC PRO, and New Jersey Light trap. Mboera et al. (2000) also found similar results.

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6 Propane-based traps Modifications of mosquito traps have begun to make traps more marketable to mosquito control districts and to the general public. The main differences in these traps is the advancement of the power and CO2 delivery mechanisms. Instead of the typical rechargeable batteries primarily used in the field, many traps now utilize standard 120 volt outlets found in virtually every household or a thermoelectric generator to allow stand-alone operation. To make CO2 more readily available, a gas cylinder or dry ice is not used in these traps; instead, CO2 is generated from the combustion of propane. The use of household energy and readily available propane makes it easier for the general consumer who is concerned about local mosquito numbers. The use of CFG combined with the propane CO2 delivery system has shown an ability to capture mosquitoes. Burkett et al. (2001) compared the MM Pro, a propane-based, stand-alone trap, to various traps, including the MMX, CDC, PRO, New Jersey trap, and Shannon trap. The MMX and Shannon traps outperformed the MM Pro, but the MM Pro was more effective than the CDC, PRO, or New Jersey traps. Similar results were obtained by Burkett et al. (2002), where the MM Pro was compared to the Shannon trap, ABC light trap, Miniature Black Light trap, and New Jersey trap. In this field study, the MM Pro captured the most mosquitoes. Kline (2002) compared two MM thermoelectric-powered propane-based traps against MMX and PRO traps in field studies. The propane-based traps caught more mosquitoes than the PRO taps, but fewer than the MMX trap. Smith et al. (2002) has done a comparison trial of eight commercially available mosquito traps, many which utilize a propane-generated CO2 source. These results were such that the Mosquito MegaCatch > MM Liberty > Lentek Mosquito Trap > Mosquito Deleto " Mosquito Deleto Prototype " Mosquito Powertrap " The Dragonfly >

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7 SonicWeb. All of these traps use CO2 as an attractant except the SonicWeb. The SonicWeb is an acoustic-based trapping device that uses the recording of the heartbeat of a dog. Most of these commercially available traps have shown an ability to capture mosquitoes, but whether or not efficient population control can be performed by the traps has yet to be determined. Equine Traps Various sampling studies, usually epidemiological in nature, have used live animals as attractants, including horses. Many live traps used recently are modifications of a trap developed by Magoon (1935). Bates (1944) used a stable trap that used an entry slits that made the mosquitoes turn and fly upwards to gain access to the animal. The slits were placed on the sides of the covered stable. This allowed entrance for the mosquitoes to feed with little possibility of escape. Samui et al. (2003) used a modified version of this trap that was portable and had more screen walls and roofing to allow for odors to escape more effectively. Mitchell et al. (1985) used a net trap constructed of bolts of nylon tulle. Ropes were used to suspend the trap; one end of the rope was tied to each corner of the screen room while the other end was tied to a tree. The horse was tethered to the ground by means of a stake. A similar design was used by Wilton et al. (1985), in which a portable, freestanding screen room was used to house a horse. Tubular frames supported the screen room, and two vertical slits were cut at the bottom of each corner to allow the insects access to the bait. Kuntz et al. (1982) used a stable trap similar to a Magoon trap, with a few adjustments. The horse was surrounded by a screened in stanchion to prevent blood feeding, and insects were trapped in collecting boxes. Stable traps were also used by Loftin et al. (1997), but these differed from the Kuntz traps in that the traps utilized a steel frame and aluminum screen sides, and the

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8 sides were modified with openings that ran the length of trap at varying heights, which could be opened or closed easily. Fletcher et al. (1988) used a different approach of sampling. The horse-baited trap was designed when open to leave the horse naturally exposed to the insects. Once closed, the insects feeding on the horse would be trapped and could then be collected. A wood frame was used as a base and support, and the sides were composed of mesh screening and polyethylene plastic. A restraining stall was placed in the middle of the trap. These traps and variations have been used to survey haemotophagous Diptera on a variety of other animals, including ruminants (Braverman et al. 1991, Loftin et al. 1997), canines (Cupp and Stokes 1973, Pinger 1985), and small mammals/avians (Turner 1972, Edman and Webber 1975, Nelson et al. 1976). Similarly, mosquito traps have been placed around animal facilities in order to survey the mosquito populations around the area (Holck & Meek 1991, Hagiwara et al. 1992). A portion of Service (1993) includes review a of various animal and human-based traps. Summary Since WNV has become a problem on such a large scale in the United States, further research in controlling the arbovirus needs to be addressed. When the primary vectors are determined, control methods can be performed by mosquito abatement districts to target vector species. Precursors of a WNV epidemic need to be determined so that early warning signs may be recognized, which would allow more time to help prevent an epidemic before it can occur. The addition of new mosquito surveillance traps could play a role in the detection and possibly control of some of the mosquitoes that transmit WNV. To determine this, the differences in species profile among different mosquito traps must be ascertained.

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9 Since WNV transmission to horses has such a large impact on the equine industry, the specific mosquito species that transmit WNV to horses should be determined. If surveillance traps are used to detect the presence of certain mosquito species in a given area, it would be helpful to know if the species profile of the mosquitoes found in a given mosquito trap mimicked that of the species profile found on horses. Also, are the suspected WNV vectors found on horses in the same relative abundance on the horses as they are in mosquito surveillance equipment? The objectives of this study are to determine if the species diversity and relative abundance of mosquitoes in north Florida, including suspected WNV vectors, varies among mosquito surveillance traps and between horses and mosquito surveillance traps.

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10 CHAPTER 2 MOSQUITO TRAPPING TRIALS Trapping was performed at the University of Florida Horse Teaching Unit (HTU) (Figure 2.1). The HTU is a 60-acre equine facility located three miles south of the University of Florida on SW 63rd Ave. The HTU maintains a Quarter Horse herd of approximately 45 head of varying ages. Traps were set in a 5 x 5 Latin square design. The traps were randomly placed at a trapping site during the first trapping interval and rotated sequentially each interval thereafter. Two traps were placed on either side of a small pond, one was near a second small pond, one was near a large oak tree and horse barn, and another was along a pasture fence line. Traps included were a Mosquito Magnet Pro, a Mosquito Magnet Liberty, a Mosquito Magnet X, a Bugjammer, a CDC 1012 light trap, and a horse. Mosquito Traps Center for Disease Control (CDC) Trap The CDC trap model 1012 (John W. Hock Company, Gainesville, FL) (Figure 2.2A), uses a 6–volt fan to capture mosquitoes, and a 6.3–volt light as an additional attractant to CO2. A rechargeable 6-volt battery was the power source. CO2 was supplied from compressed gas cylinders at a rate of 500 ml/min. The CO2 line was taped to the underside of the lid, above the fan. A polypropylene container with 30-mesh screen on the bottom was used to hold the captured mosquitoes.

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11 Figure 2.1. Aerial photograph of the University of Florida Horse Teaching Unit showing the five trap sites. Mosquito Magnet ® X (MMX) The MMX is an American Biophysics Corporations (ABC) counterflow geometry trap (Figure 2.2B). The CO2 source was compressed gas cylinders, and the CO2 flow rate was 500 ml/min. The shell of the trap is composed of a clear PVC container, the top and bottom lids of which are removable for access to the trap catch. Two fans are mounted

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12 between a PVC tube to produce CO2 flow vertically downward while maintaining an upflow of air to capture mosquitoes. A 12-volt battery was used to power the fans. An inner mesh keeps the mosquitoes inside the trap and prevents the mosquitoes from being forced through the opposite fan. A lip extends over the top to form a roof to inhibit moisture build-up inside of the trap. Mosquito Magnet ® Pro The MM-Pro (Figure 2.2D) is a counterflow geometry trap that creates attractants by catalytically converting propane into CO2, heat, and moisture. The propane is supplied by a standard 20 lb. commercial propane tank. The MM-Pro generates its own power through a thermoelectric module, which allows for stand-alone operation. The trap is 40 x 33 x 22 in., and is constructed of stainless steel with a PVC shell. A nylon net traps mosquitoes within the unit. Mosquito Magnet ® Liberty The MM Liberty (Figure 2.2E) is similar in form and function to the MM Pro with a few exceptions. The power supply of the MM Liberty is a 120-volt US outlet. For this project, the trap needed to be more portable, thus, the electric line was spliced and connected to a rechargeable 12-volt battery. The MM Liberty has a push-button start and lights to indicate when the machine is operating and if service is needed. Like the MM Pro, the MM Liberty creates a CO2 source from propane and the mosquitoes are captured in a nylon net located inside the machine. The dimensions of the MM Liberty are 25" x 18" x 33", and the frame is composed of PVC and marine specification powder-coated steel.

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13 A. B. C. D. E. Figure 2.2. Five models of mosquito traps tested at the University of Florida Horse Teaching Unit: A) The CDC 1012. B) The Mosquito Magnet X. C) The Bugjammer. D) The Mosquito Magnet Pro. E) The Mosquito Magnet Liberty.

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14 Bugjammer™ The Bugjammer (Figure 2.2C) is a trap that relies primarily on acoustics to lure mosquitoes and other insects to the trap. The primary attractant of the Bugjammer is a heartbeat lure, which is a speaker that emits a recording of the heartbeat of a dog. Four, D-cell batteries were used to supply electricity. Close range attractants for the Bugjammer include reflected ultraviolet light and contrasting stripes. The insects are captured by an adhesive pad that surrounds the housing over the speaker. Equine Two adult geldings were used in this trial. From July 17 – August 18, 2002, a cremelo gelding was used (Figure 2.3A), and from August 19-September 30, 2002, and April 2003, a chestnut gelding was used (Figure 2.3B). Mosquitoes that landed on the equine were captured with a BioQuip (Rancho Dominguez, CA) portable vacuum aspirator. The vacuum was powered by plugging it into a cigarette lighter in a vehicle. The vacuum contained canisters that fit snugly inside. The vacuum held the mosquitoes inside the canister when the power was on, and a cap was placed over the canister after it was removed from the vacuum. Trapping Protocol The first trial consisted of all the mechanical traps, and each trap was operated overnight at each location. This part of the trial ran from May 17, 2002 through July 16, 2002. Traps were turned on one night per week and one consecutive 5-night period each month. Traps were turned on 2-3 hours before sunset and collected 2-3 hours after dawn. The traps were collected and the captured mosquitoes were euthanized in a freezer.

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15 A B Figure 2.3. Two geldings that were sampled for mosquitoes, a cremelo (A) and a chestnut (B). In the second part of the trial the Bugjammer was removed and a live equine was used in its place. The equine was led to the respective collecting site each collecting night, and mosquitoes were collected from the equine. The collection from the equine was done for 30 minutes, starting approximately 15 minutes before sunset and ending 15 minutes after sunset. The remainder of the traps were operated as in the first trial. This trial was performed from July 17, 2002 through September 30, 2002. The third trial was performed April 7, 8, 9, 15, and 16, 2003. The MM Pro, MM Liberty, MMX, CDC 1012, and a horse were utilized as traps. All traps were started approximately 15 minutes before dusk, and all traps were collected 15 minutes after dusk. Mosquitoes were vacuumed from the horse during the same interval. After they were emptied, the mechanical traps remained on overnight and the contents were collected the following morning. The traps were rotated so that each trap was at each position once during the five-day trial. Data analysis Count data from the traps was converted using a log transformation (log10=count + 1) and then analyzed with the DuncanÂ’s multiple comparison procedure. Significance

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16 was placed at P ! 0.05. Shannon-Weaver index (Shannon & Weaver 1963) was performed using the function: HÂ’ = # pi ln pi where pi = the proportion of the number of individuals of species i in the total sample number ( ni/N). Results Experiment 1 The total number of mosquitoes collected during the extent of the fall trial was 273,538 . During these overnight trials, the CDC 1012 caught significantly more mosquitoes than the other traps that ran the entirety of the trial ( P ! 0.05), but CFG traps were not significantly different from one another (Table 2-1). The Bugjammer did not catch any mosquitoes during the trial. Table 2.1. Mean catch and total count of mosquitoes trapped during 39 overnight trapping trials at the UF Horse Teaching Unit from May 17, 2002 to September 30, 2002. Trap N Mean Catch Total Catch CDC 1012 38 2874.7a 109238 MMX 37 1555b 57535 MM Pro 34 1401.1b 47639 MM Liberty 35 1646.3b 57622 Note: Means followed by the same letter are not significantly different ( P ! 0.05) N=Number of trapping intervals operating properly Mosquito species catch was rather homogeneous during experiment 1. Culex nigripalpus dominated trap catch percentages of all mechanical traps, while Mansonia titillans was the most prominent species captured on the equine (Table 2-2). Ma. titillans

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17 and Ochlerotatus infirmatus were also caught in the mechanical traps, but they did not compose more than 5% of any mechanical trap catch. Cx. nigripalpus, Oc. infirmatus, and Psorophora. spp . were found on the equine in different percentages than in any of the mechanical traps. A total of 18 different species were trapped during this period of time, including Aedes aegypti, Ae. vexans, Anopheles crucians, An. quadrimaculatus, Cx. erraticus, Cx. nigripalpus, Cx. salinarius, Cx. quinquefasciatus, Coquillettidia perturbans, Ma. titillans, Ochlerotatus infirmatus, Oc. mitchellae, Ps. ciliata, Ps. columbiae, Ps. cyanescens, Ps. howardii, and Uranotaenia lowii. Table 2.2. Percentage and total mosquito species captured by each trap during 39 overnight trapping trials at the UF Horse Teaching Unit conducted May 17, 2003 through September 30, 2003. Species CDC 1012MM LibertyMM Pro MMX Horse Cx. nigripalpus 88.39 90.98 86.11 85.45 27.26 Ma. titillans 4.76 1.84 2.32 4.42 39.76 Ae. vexans 0.23 0.07 2.89 0.27 0.66 An. crucians 1.38 0.45 0.65 0.99 0.07 Cq. perturbans 0.28 0.37 0.17 0.22 3.06 Cx. erraticus 1.58 1.60 1.79 1.39 0.27 Cx. salinarius 0.21 0.12 1.27 0.72 0.40 Ps. ciliata 0.03 0.09 0.15 0.17 0.73 Ps. columbiae 1.10 2.17 2.43 2.18 3.86 Ps. cyanescens 0.04 0.04 0.09 0.24 6.65 Oc. infirmatus 1.54 1.63 1.61 1.52 15.63 Other 0.45 0.65 0.51 0.59 1.66 Total Catch 109238 57622 47639 57535 1504

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18 The percent of mosquitoes trapped per site was also very homogeneous. Between 85 and 92 percent of all mosquitoes captured at all sites was Cx. nigripalpus (Table 2.3 ). Ma. titillans, Oc. infirmatus, and Psorophora spp . were all at similar abundances at each site as well. Other various species were in relatively low abundance at all sites. Diversity also differed among the traps. Shannon-Weaver analysis of the data show that the index of mechanical traps was between 0.49 and .70 for all mechanical traps (Table 2.4). The Shannon-Weaver index for the equine during this period was 1.62. Table 2.4. Shannon-Weaver Diversity Index of mosquito species trapped at the UF Horse Teaching Unit. Experiment A denotes trapping conducted from May 17, 2003 through September 30, 2003, and all traps during this trial were run overnight except equine. Experiment B denotes overnight trapping conducted in April, 2003, and Experiment C denotes 30-minute trapping conducted April, 2003. A B C MMX 0.71 1.12 1.18 MM Pro 0.69 0.64 0.85 CDC 1012 0.57 1.25 1.46 MM Liberty 0.48 1.11 1.05 Equine 1.62 1.59 Experiment 2 Thirty-minute trapping trials showed a distinction among different traps in relation to mean catch. There was no significant difference between the MM Pro, CDC 1012, MMX, and the horse, and no significant difference between the horse and the MM Liberty ( P ! 0.05) (Table 2.5). Mean catch counts ranged from 21.8 to 91.6 per 30 minutes, with the horse catching a mean of 28.4 mosquitoes per 30 minutes. The total catch count for all traps for 5 catch periods was 1098.

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19Table 2.3. Percent of total count of mosquito species by site. The trapping trial was conducted at the UF Horse Teaching Unit from May 17, 2002 through September 30, 2002. Site # Total Mosquitoes Cx. nigripalpus Ma. titillans Oc. infirmatus Psorophora spp . Other A 74742 85.30 3.70 2.65 3.14 5.21 B 56415 84.54 4.69 1.61 1.86 7.34 C 57780 90.41 3.28 1.47 0.91 5.07 D 47702 88.07 5.42 0.69 2.03 5.50 E 36899 91.82 1.70 1.19 1.77 4.87

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20 Table 2.5. Mean catch and total count of mosquitoes trapped during 30-minute trapping trials at the UF Horse Teaching Unit during April, 2003. Trap Mean Catch (± Std) Total Catch MM Pro 91.6 ± 91.6a 458 CDC 1012 72.6 ± 22.3a 264 MMX 52.8 ± 86.3a 363 Equine 28.4 ± 17.4a, b 142 MM Liberty 21.8 ± 32.3b 109 Note: Means followed by the same letter are not significantly different ( P ! 0.05) The percent of total mosquitoes captured during the 30-minute trials differed between the traps and the horse. While the most abundant species for all traps was Cx. salinarius, the range of percent capture differed between traps (Table 2.6). The CFG traps captured between 65.84 and 70.64 percent, while Cx. salinarius only composed 40.14 and 49.24 percent of the total mosquitoes found on the horse and the CDC 1012, respectively. The horse and the CDC 1012 captured 29.58 and 19.7 percent Ma. titillans, respectively, and the CFG traps captured between 4.13 and 9.17 percent. The horse also had more Ae. vexans than did mechanical traps, while the mechanical traps had more Cx. erraticus than did the horse. An. crucians abundance was varied between all traps, ranging from 4.37 to 13.26 percent. The overnight trial mean catch showed a distinct division between the MM Liberty and the other traps with the MM Liberty catching significantly less mosquitoes (114.6 per night) than any other trap (Table 2.7). Traps other than the MM Liberty

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21 caught between 342.4 and 493.4 mosquitoes per night. The total catch for all traps during the 5 night trapping period was 6693 mosquitoes. Table 2.6. Percent of total count of mosquito species trapped during 30-minute trapping trials at the UF Horse Teaching Unit during April, 2003. Mosquito Species CDC 1012MM LibertyMM Pro MMX Horse Ae. vexans 1.52 0 2.4 1.38 7.04 An. crucians 13.26 8.26 4.37 16.8 9.86 An. quadrimaculatus 0.38 0 0 0.28 3.52 Cq. perturbans 1.52 0.92 0 2.75 3.52 Cx. erraticus 9.09 6.42 2.18 6.06 1.41 Cx. nigripalpus 0 0.92 3.71 0.28 0 Cx. salinarius 49.24 70.64 80.13 65.84 40.14 Ma. titillans 19.7 9.17 5.02 4.13 29.58 Oc. infirmatus 5.3 3.67 1.97 1.93 4.93 Other 0 0 0.22 0.55 0 Total Catch 264 109 458 363 142 Table 2.7. Mean catch and total count of mosquitoes trapped during overnight trapping trials at the UF Horse Teaching Unit during April, 2003. Trap Mean Catch (± Std) Total Catch CDC 1012 493.4 ± 353.8a 2467 MMX 388.2 ± 273.5a 1941 MM Pro 342.4 ± 256.7a 1712 MM Liberty 114.6 ± 297.9b 573 Note: Means followed by the same letter are not significantly different ( P ! 0.05) The mosquito relative abundance differed somewhat between traps in the 2003 overnight trial. The differences were primarily between the MM Pro and the other traps. Cx. salinarius composed more than half of all mosquitoes in each of the other traps

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22 (Table 2.8). The MM Pro, however, had 84.58 percent Cx. salinarius , and no other species composed more than 7 percent of the total count. The other traps caught a greater percentage of Cx. erraticus and An. crucians than did the MM Pro. Ma. titillans did not compose more than 3 percent of the mosquito species composition in any trap. Relative abundance was similar for all sites. Cx. salinarius was the primary species captured at each site, composing between 60.76 and 75.21 percent of the species composition (Table 2.9). Other species of higher percent capture were Cx. erraticus and An. crucians , and the percent composition among these species differed little between sites. Table 2.8. Percent and total count of mosquito species trapped during overnight trapping trials at the UF Horse Teaching Unit during April, 2003. Mosquito Species CDC 1012 MM Liberty MM Pro MMX Ae. vexans 0.49 0.52 0.58 1.08 An. crucians 17.67 10.82 6.19 15.35 An. quadrimaculatus 0.32 1.05 0.53 1.44 Cq. perturbans 1.78 2.27 0.41 1.8 Cx. erraticus 21.24 16.23 6.31 9.02 Cx. nigripalpus 0.04 0 0.06 0.26 Cx. salinarius 54.2 65.97 84.58 67.59 Ma. titillans 2.92 1.4 0.82 2.11 Oc. infirmatus 1.13 1.05 0.35 0.77 Other 0.2 0.7 0.18 0.57 Total Catch 2467 573 1712 1941

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23Table 2.9. Percent of total count of mosquito species by site. The trapping trial was conducted overnight at the UF Horse Tea ching Unit during April, 2003. Site Total Catch An. cruciansCq. perturbansCx. erraticus Cx. salinariusMa. titillans Other A 2159 12.69 1.57 15.15 65.63 2.45 2.52 B 2225 16.9 1.21 16.67 60.76 2.38 2.06 C 923 10.83 1.41 8.78 73.35 0.76 4.88 D 1198 11.27 1.67 7.76 75.21 1.59 2.5 E 188 9.04 2.66 14.89 68.09 1.6 3.72

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24 The April trapping trial yielded 16 species of mosquitoes. These included Ae. albopictus, Ae. vexans, An. crucians, An. quadrimaculatus, Cq. perturbans, Cx. erraticus, Cx. nigripalpus, Cx. salinarius, Ma. titillans, Ps. ciliata, Ps. columbiae, Ps. ferox, Oc. infirmatus, Oc. mitchellae, Ur. lowii, and Ur. sapphrina. Shannon-Weaver diversity indexes do not differ more than 0.21 between the 30-minute and overnight trials for any trap (Table 2.4). The horse had the highest diversity (1.59), while trap diversity ranged from 0.64 to 1.46. Discussion Species Composition North Florida contains a unique mosquito population where Cx. salinarius occurs in high numbers during the winter and spring, and Cx. nigripalpus occurs primarily in the summer and fall. In particularly warm springs, Cx. nigripalpus has been abundant earlier than in years of normal temperature ranges in north Florida. It is speculated that WNVpositive Cx. salinarius are overwintering the virus, and in particularly warm springs, a large outbreak of WNV could occur in north Florida due to early occurrence of Cx. nigripalpus (Zyzak et al. 2002). This is one reason that monitoring devices, such as the traps used in this study, are important for early detection of a possible viral outbreak. Both trials performed at the HTU contained Cx. salinarius in spring and Cx. nigripalpus as the primary mosquito captured in the summer months. This is in agreement with data from other areas in Florida (O'Meara and Evans 1983, Zyzak et al. 2002), and previous research performed at the HTU (Gentry 2002).

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25 The relative composition of mosquito species feeding upon the horses differed from that of any of the mechanical traps, despite being placed at the same trapping sites. The composition of species in the spring would indicate that Cx. salinarius was the vector of interest most readily trapped in mechanical traps on the HTU. Cx. salinarius is known to feed readily on both avian and mammalian hosts (Cupp & Stokes 1973), thus the possibility of finding it both in the traps and on the horse seems quite probable during periods of peak emergence. A higher percentage of Cx. salinarius was found in the mechanical traps (49.24-80.13%) than on the horse (40.14%), but Cx. salinarius was the primary species captured for the horse as well as the traps. An. crucians , another species known to have a broad range of hosts, was found in varying percentages in all traps. Cx. erraticus , an ornithophilic species (Edman 1979), was found in higher percentages in the traps, and in very low numbers on the horse. So, the data acquired during the spring would point more towards mechanical traps catching primarily species of mosquitoes that have a broad pattern of both avian and mammalian hosts. In contrast, the horse had a greater variety of species, most known to feed on mammalian hosts. While Cx. salinarius was the most abundant species (40.14%) found on the horse, Cx. salinarius was found in a greater abundance in the mechanical traps (66.5%). Mammalian-feeding mosquitoes were found in higher abundance on the horse than that of the mechanical traps. Ma. titillans composed 29.58% of the total catch from the horse during the spring, while the CDC 1012 trap captured 19.7 % and CFG traps captured between 4.13 and 5.02 % during the 30-minute spring trials (Table 2.6). Ae. vexans , another species known to feed primarily on mammals (Edman 1971, Cupp & Stokes 1973), was found in greater percentages on the horse (7.04%) than in the traps (0-

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26 2.4%). This would be expected, since many mosquito species known to feed on mammals will feed on horses. During the spring, the relative abundance of species captured during the 30minute trial was found to be similar to the overnight trial with a few exceptions. The primary species captured in both trials was Cx. salinarius, and the difference in proportion of Cx. salinarius captured in the 30-minute trial compared to the overnight trial does not differ by more than 5% for any trap (Table 2.6, 2.8). The primary differences lies in the percentage of Cx. erraticus captured; the presence of Cx. erraticus is lower at dusk than during the remainder of the evening. Activity throughout the night by Cx. erraticus has been noted previously (Snow 1955). The percent of Ma. titillans captured was also lower in the overnight collection when compared to the 30-minute period, especially between the CDC 1012 and the MM Liberty. The percentage of Ma. titillans comprising the CDC 1012 results declined from 19.7 to 2.92% from dusk to overnight, and the MM Liberty changed from 9.17 to 1.4%. The percentage of An. crucians increased in all traps except the MMX. Differences in percentages of mosquito species captured during the summer were even more dramatic than in the spring, but suggest a similar trend to that found in the spring. Mechanical trap capture during the summer consisted primarily of Cx. nigripalpus , a species known to shift host preference from birds to mammals (Edman 1974). For all mechanical traps, Cx. nigripalpus was between 85 and 91% of the total catch (Table 2.2). Other species, some of which are mammalian feeders, were captured during this experiment, such as Ma. titillans, Cx. erraticus, and Oc. infirmatus , but none of these species composed more than 5% of the total catch of any trap in overnight trials.

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27 All mechanical traps showed the ability to attract and capture large numbers of a primary north Florida WNV vector, such as Cx. nigripalpus, but they did not trap any other species in similar numbers during this trial. The horse had a very different species composition during the summer trial. Similar to the spring trial, mosquito species found on the horse were typically mammalian feeders or had an affinity for both avian and mammalian hosts. Ma. titillans was found in the greatest abundance on the horse, composing 40% of the total catch. Cx. nigripalpus, a suspected WNV vector in the area, composed 27% of the species found on the horse, which is different than that of the high percentages (85.45 90.98 %) found in the mechanical traps during this period of time. Other mammalian feeders were also found on the horse in higher abundance than the traps. Oc. infirmatus , a mammalian feeder, composed 16% of the horse species, and Psorophora spp . composed 11% of the total species. Ps. cyanescens , a species rarely found in mosquito traps in the area, composed 6.65% of the total horse count. This is much different than that of the composition found in the mechanical traps. The Shannon-Weaver index calculations for all traps indicate that in both trials, the horse had a greater diversity of species than the mechanical traps (Table 2.4). The Shannon-Weaver index was higher for all traps during the spring except the MM Pro, but the index did not increase or decrease more than 0.21 for any trap from the spring 30minute trial to the spring overnight trial. The horse's index is very similar for both the spring and summer trials at 1.59 and 1.62 respectively. Since there was little change in the index between dusk and overnight measurements in the spring, it is likely that similar results would have been obtained in the summer.

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28 The data indicate that all mechanical traps, save the Bugjammer, are able to capture mosquitoes, specifically suspected WNV vectors, during the spring and summer months. If mechanical traps are proven to be an effective means of control against mosquitoes, perhaps this would be useful to farm owners to effectively reduce the number of WNV vectors in their area. The mechanical traps have the ability to attract Culex spp . in a given area and, on average, hundreds to thousands of these mosquitoes can be captured in a single night (Table 2.1, 2.7), but do these traps give a true reflection of the total mosquito population as a whole? If species diversity on a primary host in a particular area differs from that of the species diversity caught in mechanical traps in the same area, then which is providing a more accurate representation of the population as a whole? If traps were suitable for reduction of WNV vectors such as Cx. nigripalpus on equine facilities, perhaps the virus could be somewhat controlled in a given area. However, reduction of the primary species that are feeding on the horses would be less likely. Thus, the serious problem of WNV would be reduced, but the irritation of the horses due to the feeding activity of other mosquitoes, such as Ma. titillans, would likely be reduced by a lesser extent. Trap catch Previous data suggest that the latest CFG traps are superior to CDC light traps in mosquito capturing ability. These traps create a CO2-enriched plume that mosquitoes navigate to the source and become trapped by fans once in the vicinity of the trap. In previous studies, CFG traps have shown to have a higher mosquito yield than non-CFG traps (Kline 1999, Burkett et al. 2001, Burkett et al. 2002). However, the data in this study suggest that the CDC light trap performed as well or better than CFG traps in spring (Table 2.5, 2.7) and in the summer (Table 2.1) under the conditions of this study.

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29 In all experiments, the primary mosquitoes captured were Culex spp. , Cx. nigripalpus in particular. Cx. nigripalpus is known to be attracted to light (Lewis & Teller 1967). This provides a possible to the explanation for the larger mean catches with the CDC 1012 light trap over the other traps, because the CDC 1012 was the only trap in this study to utilize light as an attractant. This study shows that CDC and CFG traps have the ability to capture hostseeking mosquitoes despite the presence of large mammalian hosts in the immediate vicinity. The Bugjammer model tested did not capture any mosquitoes. Although the CDC trap did average a higher catch rate during the 2002 trial than the other traps, the ABC traps were able to catch mosquitoes each night as well. For the average consumer, the ABC propane-based traps are more user-friendly due to the high availability of propane, bulk and low availability of CO2 tanks, etc. Among the CFG traps, the MM Liberty captured significantly less ( P ! 0.05) mosquitoes in the 2003 trial than other mechanical traps tested. The MM Pro and MMX had similar mean catch rates throughout both studies, despite a different source of CO2 for each trap. A possible explanation for the MM Liberty's poor performance may be due to a flaw in the machines that was noticed after the completion of this trial. The flaw was not in the mosquito capturing ability of the machine, but rather a malfunction in the net apparatus. ABC noticed a marked change in total mosquito count in a group of MM Liberties due to this malfunction, and the MM Liberty used in the spring trial came from this group of machines. No trap used in this study utilized 1-octen-3-ol, a mosquito-attracting substance that is commonly used in commercial mosquito traps to increase total catch. Octenol was

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30 not included because some of the WNV vectors targeted in this study, such as Cx. nigripalpus , do not show an high affinity for octenol (Kemme et al. 1993, Kline 1994, Kline & Mann, 1998); the exception is Cx. salinarius (Kline 1994, Rueda et al. 2001). The results for the 2002 trial (Table 2.2) would suggest that there is a large population of Cx. nigripalpus at the HTU. However, many species of Aedes, Anopheles, Coquillettidia, Mansonia, Psorophora, and Ochlerotatus show an increased catch when CO2 is coupled with octenol (Kemme et al. 1993, Kline 1994, Rueda et al. 2001). This perhaps would have changed the relative abundance of mosquito species comprising the mechanical trap catches. Trapping Site Differences The HTU is a 60-acre facility, and trap sites were located in unique areas. Some trap sites were located within a few feet of a water source, while other sites were located in open pasture. The mean number of mosquitoes trapped by site differ significantly ( P ! 0.05). Site A had a higher mean catch than the other four in 2002, and site A and B had a higher mean catch than the other three sites in 2003. All traps, however, were rotated sequentially and each trap was stationed at each site a similar number of trap nights. Relative abundance of mosquito species trapped did not differ much by site in any trial. During the 2002 trial, Cx. nigripalpus was the primary mosquito captured at every site, and all sites had relatively similar results for every mosquito species (Table 2.3). The 2003 trial resulted in similar results, where Cx. salinarius was the primary mosquito captured at each site and all species had similar abundance at all sites (Table 2.9).

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31 Summary A different relative abundance of mosquito species exists on horses than what is captured in typical mosquito surveillance traps in north Florida. But which truly represents the actual mosquito species population? If, for instance, Cx. nigripalpus is found on horses in relatively low abundance, the possibility of transmission of WNV to the horse is still present because it only takes a single WNV infected mosquito to transmit WNV. So, if mechanical traps are being used for surveillance, then detecting the presence of a given mosquito feeding on horses may not be a problem, despite the fact that the relative abundance of species found in the traps may not represent that of what was found on the horse. Given the high abundance of Ma. titillans found on the horse, further research should be performed in order to determine if this species could be a competent WNV vector. At the present time, Ma. titillans has not been ruled out as a possible vector. This knowledge would aid in understanding WNV in more detail and possibly in controlling vectors more effectively. Research should also focus on the possibility of using mechanical traps as control methods for mosquitoes. Traps are a non-chemical alternative to a dwindling number of registered adulticides available for mosquito control. Mechanical traps do have the ability to catch thousands of mosquitoes per night in certain situations such as the one presented in this paper, and perhaps, in some situations, could be used as control. Trap placement can make a difference in the number of mosquitoes captured, and perhaps placement can become a factor in whether these traps can make a difference in the control of mosquito populations. If traps were an effective method of control in some situations, they could become an important tool in the IPM arsenal of mosquito control.

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32 LIST OF REFERENCES Bates, M. 1944. Notes on the construction and use of stable traps for mosquito studies. J Natn Malar Soc 3: 135-145. Braverman, Y., U. Kitron, and R. Killick-Kendrick. 1991. Attractiveness of vertebrate hosts to Culex pipiens (Diptera: Culicidae) and other mosquitoes in Israel. J Med Entomol 28: 133-138. Bunning, M., R. Bowen, C. Cropp, K. Sullivan, B. Davis, N. Komar, M. Godsey, D. Baker, D. Hettler, D. Holmes, B. Biggerstaff, and C. Mitchell. 2002. Experimental infection of horses with West Nile virus. Emerg Infect Dis 8: 380386. Burkett, D., W. Lee, K. Lee, H. Kim, H. Lee, J. Lee, E. Shin, R. Wirtz, H. Cho, D. Claborn, R. Coleman, and T. Klein. 2001. Light, carbon dioxide, and octenolbaited mosquito trap and host-seeking activity evaluations for mosquitoes in a malarious area of the Republic of Korea. J Am Mosq Control Assoc 17: 196-205. Burkett, D., W. Lee, K. Lee, H. Kim, H. Lee, J. Lee, E. Shin, R. Wirtz, H. Cho, D. Claborn, R. Coleman, W. Kim, and T. Klein. 2002. Late season commercial mosquito trap and host seeking activity evaluation against mosquitoes in a malarious area of the Republic of Korea. Korean J. Parasit. 40: 45-54. Centers for Disease Control and Prevention. 1999. Update: West Nile-like viral encephalitis – New York, 1999. MMWR Morb. Mortal. Wkly. Rep. 48:890-892. Chow, C., S. Montgomery, D. O'Leary, R. Nasci, G. Campbell, A. Kipp, J. Lehman, K. Olson, P. Collins, and A. Marfin. 2003. Provisional surveillance summary of the West Nile virus epidemic--United States, January-November 2002. JAMA 289: 293-295. Collins, C., L. Conti, C. Blackmore, and D. J. Harris. 2002. Florida Arboviral Activity Summary – 2002. Retrieved July 28, 2003 from http://www9.myflorida.com/Environment/hsee/arbo/data/2002/Annual%20Arbovir al%20Activity%20Summary%20for%202002.pdf Constantini, C., N. Sagnon, A. Della Torre, M. Diallo, J. Brady, G. Gibson, and M. Coluzzi. 1998. Odor-mediated host preferences of West African mosquitoes, with particular reference to malaria vectors. Am J Trop Med Hyg 58: 56-63.

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33 Cupp, E., and G. Stokes. 1973. Identification of bloodmeals from mosquitoes collected in light traps and dog-baited traps. Mosq News 33: 39-41. Day, J., and J. Edman. 1988. Host location, blood-feeding, and oviposition behavior of Culex nigripalpus (Diptera: Culicidae): Their influence of St. Louis encephalitis virus transmission in southern Florida, pp. 1-8. In T. Scott and J. Grumstup-Scott [eds.], Proceedings of a Symposium: The Role of Vector-Host Interactions in Disease Transmission. Misc Pubs Entomol Soc Am. Edman, J. 1971. Host-feeding patterns of Florida mosquitoes. I. Aedes, Anopheles, Coquillettidia, Mansonia, and Psorophora . J Med Entomol 8: 687-695. Edman, J. 1974. Host-feeding patterns of Florida mosquitoes. III. Culex ( Culex ) and Culex ( Neoculex ). J Am Mosq Control Assoc 11: 95-104. Edman, J. 1979. Host-feeding patterns of Florida mosquitoes (Diptera: Culicidae). VI. Culex ( Melanoconion ). J Med Entomol 15: 521-525. Edman, J., and L. Webber. 1975. Effect of vertebrate size and density on host-selection by caged Culex nigripalpus . Mosq News 35: 508-512. Fletcher, M. G., E. C. Turner, J. W. Hansen, and B. D. Perry. 1988. Horse-baited insect trap and mobile insect sorting table used in a disease vector identification study. J Am Mosq Control Assoc 4: 431-435. Garmendia, A., H. Van Kruiningen, R. French, J. Anderson, T. Andreadis, and A. Kumar. 2000. Recovery and identification of West Nile virus from a hawk in winter. J Clin Microbiol 38: 3110-3111. Gentry, A. B. 2002. Evaluation of protection systems and determination of seasonality for mosquito and biting flies at the University of Florida Horse Teaching Unit. M.S. thesis, University of Florida, Gainesville. Hagiwara, S., M. Suzuki, S. Shirasaka, and T. Kurihara. 1992. A survey of the vector mosquitoes of Setaria digitata in Ibaraki Prefecture, central Japan. Jpn J San Zool 43: 291-295. Holck, A. R., and C. L. Meek. 1991. Nocturnal distribution of Louisiana riceland mosquito adults. J Am Mosq Control Assoc 7: 628-632. Kemme, J. A., P. H. A. Van Essen, S. A. Ritchie, and B. H. Kay. 1993. Response of mosquitoes to carbon dioxide and 1-octen-3-ol in southeast Queensland, Australia. J Am Mosq Control Assoc 9: 431-435. Kline, D. L. 1994. Olfactory attractants for mosquito surveillance and control: 1-octen-3ol. J Am Mosq Control Assoc 10: 280-287.

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34 Kline, D. 1999. Comparison of two American Biophysics mosquito traps: The professional and a new counterflow geometry trap. J Am Mosq Control Assoc 15: 276-282. Kline, D. 2002. Evaluation of various models of propane-powered mosquito traps. J Vector Ecol 27: 1-7. Kline, D. L., and M. O. Mann. 1998. Evaluation of butanone, carbon dioxide, and 1octen-3-ol as attractants for mosquitoes associated with north central Florida bay and cypress swamps. J Am Mosq Control Assoc 14: 289-297. Kulasekera, V., L. Kramer, R. Nasci, F. Mostashari, B. Cherry, S. Trock, C. Glaser, and J. Miller. 2001. West Nile virus infection in mosquitoes, birds, horses, and humans, Staten Island, New York, 2000. Emerg Infect Dis 7: 722-725. Kuntz, K. J., J. K. Olson, and B. J. Rade. 1982. Role of domestic animals as hosts for blood seeking females of Psorophora columbiae and other mosquito species in Texas USA ricelands. Mosq News 42: 202-210. Lewis, L. A. and L. W. Teller. 1967. The use of fluorescent tubes in a modified New Jersey light trap. Proc New Jers Mosq Exterm Ass 54: 163-170. Loftin, K. M., R. L. Byford, M. J. Loftin, M. E. Craig, and R. L. Steiner. 1997. Host preference of mosquitoes in Bernalillo County, New Mexico. J Am Mosq Control Assoc13: 71-75. Magoon, E. 1935. A portable stable trap for capturing mosquitoes. Bull Entomol Res 26: 363-369. Mboera, L., W. Takken, and E. Sambu. 2000. The response of Culex quinquefasciatus (Diptera: Culicidae) to traps baited with carbon dioxide, 1-octen-3-ol, acetone, butyric acid and human foot odour in Tanzania. Bull Entomol Res 90: 155-159. Mitchell, C. J., R. F. J. Darsie, T. P. Monath, M. S. Sabattini, and J. Daffner. 1985. The use of an animal-baited net trap for collecting mosquitoes during western equine encephalitis investigations in Argentina. J Am Mosq Control Assoc 1: 4347. Nelson, R., C. Tempelis, W. Reeves, and M. Milby. 1976. Relation of mosquito density to bird:mammal feeding ratios of Culex tarsalis in stable traps. Am J Trop Med Hyg 25: 644-654. O'Meara, G., and F. Evans. 1983. Seasonal patterns of abundance among three species of Culex mosquitoes in a south Florida wastewater lagoon. Ann Entomol Soc Am 76: 130-133. Pinger, R. R. 1985. Species composition and feeding success of mosquitoes attracted to caged dogs in Indiana. J Am Mosq Control Assoc 1: 181-185.

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37 BIOGRAPHICAL SKETCH Clinton Britt Campbell was born in Leesburg, Florida on December 4, 1978, to Stuart and Julie Campbell. He graduated from South Lake High School in Groveland, Florida, in 1997. Clinton graduated from Lake-Sumter Community College in August 1999 with an Associate of Arts degree. He graduated from the University of Florida in May 2001 with a Bachelor of Science Degree in entomology. Clinton will begin attending school at the University of Florida College of Veterinary Medicine in August 2003 in pursuit of a Doctor of Veterinary Medicine degree.