Field Observations on Competitive Displacement, at the Preimaginal Stage, of Culex Quinquefasciatus Say by Culex Cinereus Theobald (diptera: Culicidae) at the Kenya Coast

AbstractIn certain areas of the Kenya coast, Culex quinquefasciatus Say is unable to maintain itself in breeding sites (flooded pit latrines) which it has to share with C. cinereus Theo. The pattern of settlement of the two species and the replacement of C. quinquefasciatus by C. cinereus were studied from May to November 1980 by monitoring newly emerged males as they departed from two breeding sites located in a small village near Mombasa. C. quinquefasciatus was the first species to be recorded from both sites, soon after they were flooded by the early rains. C. cinereus came later and did not increase markedly until after the late rains. The pattern of replacement of C. quinquefasciatus by C. cinereus was similar in the two breeding sites; the former species was unable to maintain itself once C. cinereus started to increase. Studies in another village showed that, after displacement, egg laying by C. quinquefasciatus continued but at a much reduced level. It is suggested that this is an example of competition-mediated succession occurring annually, with C. quinquefasciatus being better adapted to exploit rapidly the newly flooded sites but unable to sustain later competition from C. cinereus.