Published online by Cambridge University Press: 10 July 2009
Dieldrin, γ BHC, DDT, Telodrin and Baytex have been applied topically in oil solutions to G. swynnertoni Aust. caught as wild adults. The order of toxicity of these compounds was the same as that to laboratory-emerged G. morsitans Westw. and all were relatively more effective. Wild females were 2–3 times as tolerant of the chlorinated hydrocarbons as the males, and pregnant females required nine times as much DDT as the males. Greater tolerance to Baytex did not exceed the difference in body weights between the sexes. These results confirm those obtained with G. morsitans and are attributed to the increased tolerance to chlorinated-hydrocarbon insecticides shown by females as they age and become fertilised and pregnant.
There is no such increase in tolerance of females to Baytex and the importance of this in planning practical control measures is indicated.