Oviposition-Modifying Substances for Mosquitoes.
Rept. no. 3 (Final), Apr 79-Mar 81,
CALIFORNIA UNIV RIVERSIDE DEPT OF ENTOMOLOGY
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The objectives of this research project are to study the chemistry and the biology of oviposition-modifying substances for mosquitoes, to investigate the possibility of applying them in the management of mosquito populations, and to evaluate the role of oviposition attractants in sampling populations offemale mosquitoes and ovipopulations. To prepare for the field evaluation of the previously identified oviposition repellents, their concentration-activity relationship and species specificity were studied. The magnitude of repellency of the repellents was found to be directly proportional to their concentrations. Butyric acid, the major repellent component, was repellent to Cx. p. quinquefasciatus, Cx. tarsalis, Ae. aegypti, and An. quadrimaculatus at various concentrations. The acid was repellent to Cs. incidens at higher concentrations but attractive at lower concentrations. The study on the structure-activity relationship of homologous, straight-chain, aliphatic carboxylic acids as oviposition repellents revealed that octanoic, nonanoic, and decanoic acids were the most active against gravid females of Culex quinquefasciatus, Cx. tarsalis, and Aedes aegypti. Other types of compounds, such as skatole, 1-hexadecanol, and 2-methylnonanoic acid, were also repellent against Cx. quinquefasciatus. The semi-field evaluation of oviposition repellents in experiment field ponds showed that nonanoic acid was able to repel ovipositing females for about 8 days at the 150 ppm, 4 days at 75 ppm, 2 days at 50 ppm, and 1 day at 25 ppm.