A method for the investigation of susceptibility to insecticides in Anopheles larvae

Abstract

The difficulties associated with the testing of insecticides on Anopheles larvae are discussed, especially those applying to the small tropical species. A method is described which is distinguished principally by the adoption of a short exposure period of I hour, followed by 5 hours for recovery or for death to take place. Results obtained with two strains of A. gambiae and with A. maculipennis atroparvus are described, in which the susceptible strain of A. gambiae and the A. maculipennis strain are shown to have a similar pattern of response to different toxicants ; while the resistant strain of A. gambiae departs from this very markedly in its response to the cyclodiene insecticides and to a less extent as regards BHC and DDT. It is suggested that the method may prove to be a useful supplement to the established methods of testing for the presence of insecticide resistance in mosquitoes, and for its measurement when found.