Synergism of Insecticidal Action by Some Benzo 1,3-Dioxole Compounds in Spodoptera Litura (Fabricius)

Toxicity of different insecticides with synergists was evaluated against 4 and 7 day old larvae of Spodoptera litura (Fabricius). Based on the LC50 obtained, the 4 day-old larvae was of 8.0, 2.1, 4.4 and 11.2 - times susceptible than that of 7 day- old larvae to cypermethrin, fenvalerate, lambdacyhalothrin and profenophos, respectively. The joint action ratios for different insecticides synergist mixture indicates that piperonyl butoxide and dihydrodillapiole increased the toxicity of all the pyrethroids to the 4 day- old larvae, whereas dillapiole synergised only cypermethrin. However, an additive action w s obtained when vanillin oxime ether was used in mixed formulations with each of the insecticides viz., cypermethrin, fenvalerate, and lambdacyhalothrin. Synergist bioassays with the organophosphorous insecticide; profenophos resulted in additive action only with each of the synergists. The combination of piperonyl butoxide with each of the four insecticides viz., cypermethrin, fenvalerate, lambdacyhalothrin and profenophos, indicated synergistic effect against 7 day- old larvae. Also, plant based insecticide synergists i.e. dillapiole and the more stable reduced derivative dihydrodillapiole exhibited synergistic action when mixed with cypermethrin, lambdacyhalothrin and profenophos. Yet only an additive action was obtained when combined with fenvalerate. On the other hand, vanillin oxime ether synergised only cypermethrin and lambdacyhalothrin