Toxic effects of triorganotin compounds on the Anopheles steprensi mosquito and larvae

Nineteen triorganotins were studied for their long term effects against the second instar larval stages of Anopheles stephensi, a mosquito that is a v ector for hurnan malaria. In the residual activity studies, the most effect ive compound was triphenyltin chloride, which was effective for 10 weeks. T he residual toxicities of the triorganotins were comparable or better than the residual effects of some commonly used larvicides. The compound that sh owed the highest delayed effect was also triphenyltin chloride where pupati on did not occur until the tenth week at which time 33% of the larvae pupat ed with a 75% emergence rate. In the studies on the adult female mosquitoes , the fluoro derivatives were the most effective. It was further observed t hat the anion group attached to the tin atom played a significant role in t he toxicity of the compounds in the adult studies.