Synergistic effects on the toxicity of organotins on cotton leafworms.

Piperonyl butoxide, sulfoxide and MGK 264 were found to act as synergists for certain organotin compounds; with respect to their toxicity on the larvae of a susceptible strain of the cotton leafworm, Spodoptera littoralis (Boisd.). High degree of synergism was obtained when either piperonyl butoxide or MGK 264 was combined with Plictran and/or MGK 264 when combined with Duter. The 3 synergists were equivalent in their synergistic action with Brestan. In all cases, the relatively high degree of synergism was brought about when organotins and synergists were mixed at ratio of 10 : 1. On the basis of synergistic ratios, data indicated that detoxification mechanism of Plictran may be more sensitive to synergistic effects than that of Duter and Brestan. Testing organotin compounds against the more tolerable field strain provided probable evidence of negative correlation between different insecticides and organotins, especially Plictran.