Ovarian development and biting frequency in Anopheles culicifacies Giles in Sri Lanka.

ABSTRACT

In order to determine the duration of the gonotrophic cycle in Anopheles culicifacies Giles in Sri Lanka, ovarian development in freshly blood-fed wild-caught females was studied in the laboratory and the findings were compared with mark-and-release recoveries in the field. In specimens of unknown parity at first capture probable feeding intervals of 1, 2 and 3 days (mean 1.7 - 2.1 days) were found. The release of freshly blood-fed nullipars bred from larvae produced two recaptures from which it could be concluded that the time required to become parous need not be more than three days. These results are of consequence in the assessment of the efficacy of insecticide spraying as an anti-malarial measure in Sri Lanka and possibly in other countries in South Asia where A. culicifacies is the vector. An equation is proposed for deriving the mosquito's daily survival rate (p) from the proportion of parous females in biting samples.