Behavioral responses of mosquitoes to toxicants Miriam Cooperband, PhD Research Entomologist Center for Medical, Agricultural, and Veterinary Entomology

Topics to be discussed Laboratory study of facultative landing and resting behavior on pyrethroid-treated surfaces Collaborative field study with USAF Reserve- impact of Dibrom sprayed from 500 ft on mosquitoes in cages with refugia and prallethrin volatiles Prallethrin volatility Spray entry into cages Novel field cage design

Behavioral Investigations Objective: Examine facultative landing, resting, and alighting behavior on surfaces treated with pyrethroid insecticides Military relevance: –Treated bednets, walls, and barriers used by the military rely on facultative contact with residual pyrethroid insecticides to deliver a lethal dose –Pyrethroid insecticides produce varying levels of “excito-repellency” –Does this “excito-repellency” affect mosquito landing behavior on these treated surfaces?

Methods Glass cage, 30 cm 3 One inner surface with 2 filter papers: ½ treated, ½ control Release 60 females and make a video recording of their activity for 30 min Analysis using Observer XT software (Noldus)

Behavioral Investigation Species tested: –Aedes aegypti –Anopheles quadrimaculatus –Culex quinquefasciatus Compounds tested: –Bifenthrin –Deltamethrin –Lambda-cyhalothrin –Acetone used as a “control”

Anopheles quadrimaculatus

Differences in Landing Patterns Cx. quinquefasciatus Control Bifenthrin Ae. aegypti Control Bifenthrin

An. quadrimaculatus Control Bifenthrin Differences in Landing Patterns

Preliminary Conclusions There appear to be differences in landing, alighting, and resting behaviors between: –all three species studied –different pyrethroid insecticides Different behavioral responses may influence which insecticides are best utilized for barrier or residual wall treatments (facultative landing), as compared to bednet treatments (attractant) Analysis of data continues

Collaboration with USAF Field study in Florida –Application of Dibrom at 500 ft –Spray entry into cages –Refugia –Prallethrin volatiles –Mortality of Cx. quinquefasciatus Novel cage design

Prallethrin Volatility Emmrich et al 2003

Novel Bioassay Cage Design Easily assembled Cylindrical, spacious interior Easy placement and retrieval of mosquitoes in the field Collapsible Inexpensive

Aerial Spray Study Treatments Dibrom, refugia, no prallethrin Dibrom, refugia, prallethrin No Dibrom, refugia, prallethrin Dibrom, no refugia, no prallethrin Dibrom, no refugia, prallethrin

Prallethrin and Refugia

Avon Park Bombing Range Sebring, Florida Avon Park Bombing Range Sebring, Florida

Preliminary Results Spray drift applied at 500 ft was not as accurate or predictable as when applied at 150 ft because of shifts in wind direction Few droplets detected on spinners either inside or outside of bioassay cages Periphery of plume reached cages; producing only 14-19% mortality Slightly lower mortality with refugia than without, but not significant with N=6 Presence of prallethrin papers showed no effect

Summary Facultative landing responses to residual pyrethroid insecticides may differ between species and active ingredient Complex behaviors can be analyzed using sophisticated behavioral analysis software Collaboration established with USAF to study the effects of prallethrin volatiles and refugia on mortality when combined with Dibrom ULV Droplet collections should be made inside and outside of bioassay cages

Special Thanks Sandra AllanSandra Allan Gary ClarkGary Clark USAFUSAF DWFPDWFP Sandra AllanSandra Allan Gary ClarkGary Clark USAFUSAF DWFPDWFP Karl HaagsmaKarl Haagsma Mark BreidenbaughMark Breidenbaugh Brian SpearsBrian Spears Mark FredlakeMark Fredlake Karl HaagsmaKarl Haagsma Mark BreidenbaughMark Breidenbaugh Brian SpearsBrian Spears Mark FredlakeMark Fredlake