Influence of temperature during the treatment period on the susceptibility to dieldrin of adult Aëdes aegypti.

Seasonal variations in the susceptibility of adult mosquitos to some chlorinated-hydrocarbon insecticides appeared, in some countries, to be due to the differences in temperature at the time the tests were carried out. This also seemed to apply to Aëdes aegypti adults tested with dieldrin at Arusha, Tanganyika. Tests were therefore carried out throughout the various seasons and the results showed that when there was a decrease in the temperature at the time of treatment, the susceptibility of the adults was considerably decreased; consequently, A. aegypti adults are unlikely to be a satisfactory standard insect for tests with dieldrin. The possibility of a connexion between the activity of the mosquito at different temperatures and the susceptibility must be considered.