Studies on the insect-resistance to insecticides : VII. Synergistic action of S-421 against the resistant housefly and mosquito larvae

Abstract

Octachlorodipropylether (S 421), a synergist for pyrethrins, was examined as a synergist for chlorinated hydrocarbons and organophosphorus compounds against the larvae of the housefly and of Culex pipiens pallens. When the ratio of octachlorodipropylether to chlorinated hydrocarbon was 0.2 to 1 or 1 to 1, it showed a marked synergistic action with DDT, γ-BHC and dieldrin against the resistant mosquito larvae. It also activated γ-BHC against both resistant and susceptible housefly larvae. A similar but smaller synergistic effect was found for organophosphorus compounds when it applied against the resistant populations.