Joint action of insecticides against houseflies.

Mixtures of DDT, lindane, endrin, isobenzan, malathion, thiometon, and carbaryl were formulated on an equitoxicity basis. The joint action of 14 mixtures of insecticides was studied against the female housefly (Musca nebulo L.) by a topical application method. In general, the intragroup combinations of the chlorinatophosphate plus a chlorinated hydrocarbon insecticide exhibited no loss in either potency or synergism. An independent joint action was observed only in those mixtures containing DDT and either malathion or thiomethon. The toxicity of all the formulations containing carbaryl and a chlorinated hydrocarbon insecticide was found to be more than additive. The mixture of isobenzan plus carbaryl exhibited the highest degree of synergism of all the combinations tested, while those containing carbaryl and either malathion or thiometon showed a slight antagonism.