INTERACTION OF THE CULEX-QUINQUEFASCIATUS EGG RAFT PHEROMONE WITH A NATURAL CHEMICAL ASSOCIATED WITH OVIPOSITION SITES

In laboratory bioassays, gravid Culex quinquefasciatus mosquitoes were strongly attracted and/or stimulated to oviposit by a habitat-derived chemical cue, 3-methylindole, at several concentrations ranging from 0.01 to 1 mugram/liter in water. At concentrations above 10 mugrams/li ter, 3-methylindole became repellent or deterrent. Responses to the kn own egg raft pheromone, 6-acetoxy-5-hexadecanolide, were much weaker a nd were relatively constant above a threshold dosage of about 0.1 mugr am. Responses to blends of a fixed amount of the pheromone with variab le doses of 3-methylindole were shown to be additive rather than syner gistic.