Various straight-chain unsaturated fatty acids from C14 to C24 were evaluated for their ovipositional repellency against gravid females of the southern house mosquitoCulex quinquefasciatus Say, and the relationship between the structures of the fatty acids and their ovipositional repellency was determined. A double bond withZ configuration was prerequisite for an unsaturated fatty acid to be highly repellent;E isomers were less active or even inactive. No relationship was found between the repellency and the number of double bonds in the unsaturated fatty acids. In C18 monounsaturated fatty acids, (Z)-9 acid was more active than (Z)-11 and (Z)-6 acids, indicating that a double bond at the 9 position rendered an acid highly repellent. Among (Z)-9-alkenoic acids of different chain lengths, the most repellent was C18 acid which was also more active than (Z)-11-C20, (Z)-13-C22, and (Z)-15-C24 acids. Oleic[(Z)-9-octadecenoic]acid, which met all these criteria, was the most ovipositionally repellent among the unsaturated fatty acids tested.

Abstract--Organic infusions have been shown to elicit discriminatory responses in ovipositing mosquitoes. Previously, we found that a Purina| Lab Chow infusion induces negative oviposition behavior in Culexpipiens quinquefasciatus Say and Culex tarsalis Coquillett. Six aliphatic carboxylic acids isolated from the active fraction of this infusion were acetic, propionic, isobutyric, butyric, isovaleric, and caproic. In the present studies, we have quantified the negative ovipogition responses of Culex mosquitoes to these carboxylic acids in a laboratory bioassay system and have also tested the main acid component, butyric acid, against Culiseta, Aedes, and Anopheles mosquitoes.

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Four chemical compounds previously shown to be attractants toHippelates eye gnats and houseflies were evaluated againstFannia femoralis (Stein). Two of the compounds, trimethylamine hydrochloride andn-butyric acid, were determined to be the principal attractants against this fly. A composition containing trimethylamine hydrochloride (yielding trimethylamine in presence of water),n-butyric acid, and an anchovy meal inert carrier proved highly attractive. To evaluate the practical use of the synthetic fly attractant (SFA) formulation, a large-scale trial over an entire poultry ranch was implemented using SFA formulation and a sugar toxicant (as a killing agent) in specially designed traps. Within 2 weeks after initiation of SFA-toxicant treatments, significant reduction inF. femoralis population from the pretreatment level occurred. This high level of reduction prevailed during the remainder of the treatment period.

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