Oviposition attractants and repellents of mosquitoes

Abstract

Infusions of various organic materials have been known to modify ovipositional behavior of gravid female mosquitoes. Previously, we found that an infusion of Purina Laboratory Chow elicited negative ovipositional behavior inCulex pipiens quinquefasciatus Say andCulex tarsalis Coquillett. In the present chemical studies, the Purina Laboratory Chow infusion, fermented for 10 days, was distilled to give an active distillate which, upon ether extraction, gave an active ether extract. Fractionation of the ether extract yielded an active acidic fraction and inactive nonacidic fraction. Gas Chromatographie analysis on Porapak R and AT-1200-H₃PO₄ columns of the acidic fraction showed the presence of acetic, propionic, isobutyric, butyric, isovaleric, and caproic acids. In bioassay tests, these lower aliphatic carboxylic acids, individually and in combination, exhibited ovipositional repellency against the two species of mosquitoes at the concentration of 6 × 10⁻²%. At this concentration, butyric acid caused 100% mortality in first-instar larvae ofC. p. quinquefasciatus. Gravid female mosquitoes might have acquired, through evolutional adaptation, the ability of avoiding ovipositing in unsuitable sites in which toxic compounds might be detrimental to the survival and development of their offspring.