Seasonal changes in populations of phlebotomine sandflies (Dipt., Psychodidae) in Kenya

Abstract

An account is given of seasonal changes in the incidence and relative abundance of a number of Phlebotomine sandflies which rest in termite hills in two widely separated areas of Kenya.The annual pattern of rainfall distribution is shown to be of greater importance than the total precipitation in influencing the gross distribution and local abundance of many sandflies.Kenya sandflies fall readily into ‘ perennial ’ and ‘ rainy-season ’ groups: the former have a wide distribution and appear to breed throughout the year. The distribution of the ‘ rainy-season ’ sandflies is relatively restricted, since these species are found almost exclusively in areas with a bimodal pattern of annual rainfall; it is suggested that they may survive the intervening dry periods in larval diapause. The length rather than the severity of the dry seasons is thought to be the limiting factor in the distribution of ‘ rainy-season ’ species.Examples are given of the seasonal changes in structure of populations made up of several species sharing, in the adult form, the same termite-hill habitat.