Browsing by Author "W. Scott Chilton, Committee Member"

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    Effects of Synthetic Chemicals and Bacteria on the Oviposition Behavior and Electroantennogram Responses of Aedes albopictus (Diptera: Culicidae)
    (2002-07-16) Trexler, Jonathan David; D. Wes Watson, Committee Member; Coby Schal, Committee Member; Charles S. Apperson, Committee Chair; W. Scott Chilton, Committee Member
    Five volatile synthetic chemicals (dimethyl disulfide, indole, 4-methylphenol, 3-methylindole, and trimethylamine) were tested as potential oviposition attractants of Aedes albopictus (Skuse) in laboratory and field experiments. In addition, the oviposition responses of Ae. albopictus to bacterially-enriched substrates were evaluated in behavioral and electrophysiological bioassays as sources of attractants and stimulants. None of the five synthetic chemicals elicited a significant positive oviposition response. In laboratory bioassays that measured attraction of gravid females to olfactory stimuli, compounds were evaluated over a range of concentrations that spanned 4-5 logs. Three concentrations of 4-methylphenol and one concentration of 3-methylindole were significantly repellent. All other concentrations of the five chemicals tested did not attract more females than a water control. The five synthetic compounds were loaded into controlled-release packets, which were used to bait water-filled ovitraps at five suburban residences. Aedes albopictus exhibited no oviposition preference for any of the baited traps versus adjacent traps containing only water. In addition, there was no difference in the mean number of eggs laid per trap-day by Ae. albopictus among ovitraps treated with each of the five compounds. Electoantennography indicated that Ae. albopictus did not exhibit a physiological response to any of the five chemicals at 0.025 mg/L. The oviposition responses of Ae. albopictus to bacterially-enriched substrates were evaluated in laboratory bioassays. Gravid mosquitoes responded to volatiles from larval rearing water (LRW) and soil-contaminated cotton towels (T). Bacterial species were isolated from these substrates and from an organic infusion made with oak leaves (OLI). Through fatty acid-methyl ester analyses, 6 bacterial isolates from LRW, two isolates from T, and three isolates from OLI were identified to species. The response of gravid mosquitoes to these isolates was also evaluated in behavioral bioassays. Water containing Psychrobacter immobilis (from LRW), Sphingobacterium multivorum (from T) and an undetermined Bacillus species (from OLI) elicited significantly higher oviposition than control water without bacteria. Only volatiles collected from LRW elicited significant electroantennogram responses in females.