COMPETITIVENESS OF CHEMO-STERILIZED MALES AND CYTOPLASMICALLY INCOMPATIBLE TRANSLOCATED MALES OF CULEX-PIPIENS-FATIGANS WIEDEMANN (DIPTERA, CULICIDAE) IN FIELD

A technique, based on the release and recapture of marked females, was used to measure the mating competitiveness of sterile males of C. pipiens fatigans in villages in Delhi Union Territory, India. Experiments were carried out with chemosterilized and cytoplasmically incompatible translocated (IS-31B) males simultaneously with prolonged release trials with these 2 types of male. The fertile males in the tests were the indigenous population and the females used were in most cases of wild origin. With each type of male, 1 test was conducted with a moderate (.apprx. 13:1) ratio of released to wild males and the other tests used high (.apprx. 40:1) ratios. The estimated mean mating competitiveness of IS-31B males was somewhat higher than that of chemosterilized males, but the difference was non-significant based on a specially devised method of testing statistical significance. In the 4 experiments, 77-94% of the egg rafts laid by recaptured females were sterile, indicating that both types of sterile male were sufficiently competitive to induce a high level of egg sterility in an isolated wild population.