Differential response to oviposition site by feral and domestic populations of Aedes aegypti (L.) (Diptera: Culicidae)

Low fecundity in the laboratory was found in populations of Aedes aegypti (L.) exhibiting Black tergite (Bt), a phenotype characteristic of the feral A. a. formosus (Wlk), whereas high fecundity was found in six domestic populations of A. a. aegyptiin which the phenotype was absent. An investigation of the cause of low oviposition by the feral population indicated that behavioural differences in mating and feeding were not responsible; egg retention was identified as the major factor. Introduction into laboratory procedure of a variable simulating the feral environment, i.e., coconut-shell infusion at the oviposition site, induced a highly significant increase in feral fecundity both through its chemical constituents and visual attraction. Differential response to oviposition site is discussed in relation to the evolution of subspecies of A. aegypti.