EFFICACY AND BIOCHEMICAL EFFECTS OF SOME INSECTICIDES AGAINST COTTON LEAFWORM, Spodoptera littoralis (BOISD.)

he efficiency and biochemical effects of certain insecticides belonging to different groups namely: flubendiamide (diamide), pyridalyl (phenoxy-pyridaloxy), clothianidin (neonicotinoide), fipronil (phenylpyrazole) and spirotetramat (tetramic acid) and pirimiphos-methyl (Ops) were tested against 2nd larval instar of Spodoptera littoralis laboratory strain using dipping technique. The efficacy of the tested insecticides are arranged as follows to LC50 values. The results showed that flubendiamide was the superior toxicant insecticides ( LC50 1.03 ppm) followed by pyridalyl (2.13 ppm) then fipronil (7.42 ppm), clothianidin (26.87ppm), pirimiphos-methyl (76.31 ppm) and spirotetramat (431.91 ppm). Biochemical effects of the tested insecticides on acetylcholine esterase (AChE), glutathione-s-transferases (GST), adenosinetriphosphatase (ATPase), phenoloxidase, total calcium, and total protein were determined in the treated larvae. Data showed highest significant increase at AChE activity in treatment of fipronil by change% (70.59), while treatment with pirimiphosmethyl recorded highest significant decrease by change% (-56.41). Whereas, all treatments recorded increase in GST activity except pirimiphosmethyl recorded non significant decrease. All insecticides treatments were showed a decrease in phenoloxidase activity the highest decrease recorded by pirimiphos-methyl treatment by change % (- 53.06). Regarding change percentage of ATPase, activity data recorded significant increase with pirimiphos-methyl treatment by (72.91%).  However, total protein in all treatments showed a significant decrease. On the other hand, treatment with pirimiphos-methyl recorded a significant decrease in total calcium and the corresponding change % was   (- 6.0%). Previous data confirmed the mode of action of the novel tested insecticides.