A HIGH INCIDENCE OF DIELDRIN-RESISTANCE IN ANOPHELES GAMBIAE GILES FROM AN UNSPRAYED AREA IN NORTHERN NIGERIA.

Abstract

IN the course of recent investigations in the northern Guinea savannah of Nigeria on the ecology1 of Anopheles gambiae Giles and A. funestus Giles and on their behaviour in huts sprayed with insecticides2, determinations were made of the susceptibility of both species to DDT and to dieldrin in a area near the town of Kaduna. Apart from very small-scale trials in which a total of 8 village huts were sprayed with DDT and a mixture of DDT and malathion, and apart from the fairly regular use of DDT (but not dieldrin or BHC) as a larvicide on streams in the township of Kaduna, the whole of the northern Guinea savannah can be considered an unsprayed area. The nearest area receiving regular insecticidal house-spraying is the Western Sokoto area, about 200 miles north-west, where DDT has been used since 1957. Prior to this both BHC and dieldrin had been used and dieldrin-resistance in A. gambiae shown to be prevalent from 19553. Dieldrin-resistance was also found in A. gambiae in 19564 in the township of Kano, some 150 miles north-east of Kaduna, and was attributed to the use of BHC mainly for agricultural purposes.