Anopheline Life-Cycles and Population Fluctuations

Abstract

INVESTIGATION of a population of adult Anopheles melas (=A.gambiœ var. melas), conducted during 1941, showed that their numbers underwent regular fluctuations, with very marked peaks at eight-day intervals, and that the only exceptions to this rule were when the rhythm was broken by the dominating influence of tides¹. At the time it was difficult to suggest a reason for the fluctuations, because work on both A. melas and its close relative A. gambiœ, by various people, indicated that the life-cycle must occupy at least ten days. Similar fluctuations were found in an A. funestus population at twelve- to fourteen-day intervals, although the supposed time for its complete life-cycle was about twenty days. I tentatively suggested that the fluctuations might be due to intraspecific competition, although this explanation seemed most unlikely.