Notes on the Bionomics of Anopheles elutus, Edw. (Dipt., Culic.)

Abstract

(1) A. elutus females in Palestine show seasonal variations of fertility, but these do not appear to explain fully the distribution of adults throughout the year.(2) Females of the overwintering generations show low fertility. This depends probably on conditions of larval life.(3) The seasonal changes in the egg of A. elutus in Palestine are due to temperature variations. It is suggested that these changes are protective adaptations against cold in winter and excessive heat and irradiation in summer.(4) The entering of the hibernation stage of A. elutus in Palestine cannot be considered as a pure consequence of the low temperature in autumn, since spring activity begins at a much lower temperature.(5) During hibernation the females feed, but do not bring eggs to maturity ; the blood is used for fat accumulation.(6) During the second half of the hibernation period the females lose their reserve materials.(7) Full fat females starved in the laboratory lose their fat-body reserves, and simultaneously their ovaries develop to stage 2. Under the prevailing temperature the process requires about 3 weeks.(8) A slow development of the ovary is going on during hibernation, but never proceeds beyond the second stage. The ovaries in a large percentage of females reach this stage at all times when reactivity occurs at the end of the hibernation period.