A BEHAVIORAL AND ELECTROPHYSIOLOGICAL STUDY OF OVIPOSITION CUES FOR CULEX-QUINQUEFASCIATUS

Both the synthetic oviposition pheromone. erythro-6-acetoxy-5-hexadeca nolide (0.01-80 mug) and a polluted water sample (0.01-80%) significan tly increased oviposition by gravid female Culex quinquefasciatus Say (Diptera: Culicidae) in a laboratory assay against clean water. An add itive effect resulted when 0.05 mug oviposition pheromone was combined with the polluted water dilution series. Undiluted, however, both the oviposition pheromone and the polluted water sample, alone and in com bination, reduced the oviposition response to control levels. A previo usly reported oviposition site odour component, 3-methylindole, also s ignificantly increased oviposition at 1 x 10(-11) to 1 x 10(-8) g but at 1 X 10(-7) g significantly less oviposition occurred than in contro l treatments. The biological activities of the compounds were addition ally evaluated electrophysiologically by an EAG assay. Female mosquito es were electrophysiologically sensitive to the oviposition cues, both pheromone and habitat-related; EAG responses of males were considerab ly lower than of females with 3-methylindole.