RESIDUAL EFFECT OF CHEMICAL INSECTICIDES USED AGAINST THRIPS THROUGH REARING PERFORMANCE OF SILKWORM Bombyx mori L.
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Date
2022-12-29
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Abstract
A study was conducted to evaluate the safety period and residual effect of chemical insecticides used against thrips through rearing performance of silkworm Bombyx mori L. Insecticides were sprayed on mulberry at an interval of 25 (20 DAS), 30 (15 DAS) and 35 (10 DAS) days after pruning. Among the treatments acetamiprid 20 SP @ 0.2 g / l recorded highest larval mortality per cent even upto 20 DAS, Mortality was zero in buprofezin 25 SC @ 2 ml / l, fipronil 5 SC @ 2 ml / l, dimethoate 30 EC @ 2 ml / l at 15 and 20 DAS. Where as in acephate 75 SP @ 1 g / l and imidacloprid 17.8 SL @ 0.3 ml / l there was zero mortality at 20 DAS. Acetamiprid 20 SP @ 0.2 g / l adversely affected the rearing performance of silkworm with residual toxicity symptoms like vomiting gut juice, rectal protrusion, stiffening of larval body and twisting of larval body in agony which was followed by acephate 75 SP @ 1 g / l which recorded hook shaped larvae with shrunken body and buprofezin 25 SC @ 2 ml / l recorded death of larvae without moulting, incomplete moulting and ripened larvae. Further acetamiprid
also recorded minimum cocoon and reeling parameters followed by acephate. Fipronil and dimethoate had a reasonably good safety period of 15 days and resulted in better rearing, cocoon and reeling parameters.
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