Mosquitoes of the colony and protectorate of the Gambia

Abstract 1. (1) A mosquito survey of the Colony and Protectorate of the Gambia was carried out mainly in the rainy season, July to September. The survey was primarily concerned with conditions in rural villages near the extensive tidal brackish swamps, with Rhizophora and Avicenmia mangrove, along the river Gambia and its creeks, but some account is given of the mosquitoes of the semi-urban European residential area at Fajara at the coast. 2. (2) Fifty-four species and varieties, of which 24 are new published records for the Gambia, were taken including a female of uncertain identity but probably a form of Aedes pseudoafricanus and several females, biting man in shade in the late afternoon, of a new species close to Aedes palpalis , to be described elsewhere. Combined with new records from neighbouring Senegal and Casamance in recent surveys by French workers, the mosquito faunal list for Sene-Gambia as a whole is increased from 37 to 89 species and varieties. 3. (3) The mosquitoes predominantly associated with man and his habitations were Anopheles gambiae and A. g. var. melas for which further evidence is given of their role as vectors of malaria, and of bancroftian filariasis in the absence of Culex pipiens fatigans . 4. (4) A. gambiae bred in typical small collections of fresh water. Growths of sea-purslane ( Sesuvium portulacastrum ) on the extensive sand flats of the brackish water swamps of the river Gambia and its creeks are, besides the well-known association of A. g. var. melas with Avicennia mangrove, additional important indicators of its breeding places. 5. (5) Domestic cattle in the Gambia, many infected with Setaria cervi , are staked out-of-doses at night near the village to which they belong. The vector of the infection is not known but the literature suggests mosquito transmission. Several mosquito species feeding on man, including those of the A. gambiae-A. g. var. melas complex, feed also on the domestic cattle. There is need to establish the vectors for cattle setariasis to clarify the identity of infective filarial larvae, presumed to be W. bancrofti , in A. gambiae and A. g. var. melas . 6. (6) Dirofilaria aethiops , a filarial parasite experimentally transmissible by culicine and anopheline mosquitoes, is known from a monkey from the Gambia and from Cercopithecus aethiops johnstoni in East Africa. The related common West African green monkey ( C. a sabaeus ) is common in the Gambia. Mosquitoes of the A. gambiae-A. g. var. melas complex were, in a brief collecting period, the most numerous of several mosquito species taken after dark on a tree-platform in bush known to be frequented by monkeys. Facts are fragmentary. 7. (7) The behaviour of some of the anophelines and culicines in the Gambia with special reference to those biting man, those resting by day indoors, and those concerned in periodic massive invasion of, at least European, houses in the rains is briefly discussed.