The succession of mosquito species (Diptera, Culicidae) in rice fields in the Kisumu area of Kenya, and their possible control
| Autor: | R. B. Highton, J. A. Chandler |
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| Rok vydání: | 1975 |
| Předmět: | |
| Zdroj: | Bulletin of Entomological Research. 65:295-302 |
| ISSN: | 1475-2670 0007-4853 |
| DOI: | 10.1017/s0007485300005988 |
| Popis: | Thirty-five species of mosquitoes (10 782 adults) were caught in modified CDC ilight-traps during the 27-week rice cultivation cycle at Ahero, Kenya, in the period September 1972 to March 1973. Only 0.8% were blood-fed and 5-l % gravid, indicating that the traps were sampling newly emerged adults. During weeks 1-7, before rice seedlings were transplanted, catches were small, but increased markedly from then until harvest (week 20). Two groups of mosquito species were recognised : the fist, including Mansonia uniformis (Theo.), M. africana (Theo.) and Mimum yia splendens Theo., bred throughout the rice cycle; the second, including Anopheles gambiae s-l., A. pharoensis Theo., A. ziemanni Griinb., Culex poicilipes (Theo.) and C. antennatus (Becker), were affected by water depth and height of the rice crop. The slurry of shallow muddy pools which follows transplanting stimulated intense breeding of A. gambiae and A. pharoensis. Once the young plants were established, reflooding of the fields and subsequent growth of water plants and algae favoured the breeding of A. ziemanni and C. poicilipes. Towards the end of the rice cycle large numbers of C. antennatus were caught. It is concluded that mosquito control by means of insecticides or by irrigation management would be possible. Large scale irrigations, particularly rice fields, can increase the incidence of mosquito-borne disease in associated human populations (Surtees, W’Oa). The importance in Cahfornian rice fields of Culex tarsalis Coq., a vector of western equine and St. Louis encephalitis (Reeves 8z Hammon, 1962), and C. tritaeniorhynchus Giles, a vector of Japanese encephalitis in the Far East (Smith, 1970). illustrates the need for an understanding of the intimate relationship between irrigation and mosquito breeding. Relatively little information exists on rice fields as a habitat for mosquitoes in East Africa Grainger (1947) found larvae of Anopheles gambiae Giles and A. pharoensis Theo. common in rice fields in the Kisumu area of Kenya; he attempted to control them by intermittent irrigation. In Tanzania, Webbe (1961) found that water impoundment favoured mosquito breeding, particularly of Anophelines, and that the periodic drying out of the fields, due to poor water husbandry, resulted in prolific breeding of A. gambiue, A. pharoensis and C. tigripes Grp. & Charm. In 1968 the Kenya Government completed a Pilot Rice Scheme at Ahero near Kisumu, and the following year a preliminary study was made of the area, as part of the Medical Research Council’s programme on Viral Epidemiology Overseas (&u-tees |
| Databáze: | OpenAIRE |
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