Toxicity and Effect of Sublethal Dosage of Several Common Pesticides to Growth and Development of the Silkworm,Bombyx mori

In order to provide reference for choosing safe pesticides in controlling pests in mulberry gardens of silkworm(Bombyx mori) raising area,the toxicity of 6 common pesticides,namely pyridaben,propargite,chlorfenapyr,DDVP,phoxim and imidacloprid,to silkworm was assayed through feeding the larvae with poisoned leaves,and the effect of two sublethal dosages(LC5 and LC15) of 4 pesticides,namely propargite,chlorfenapyr,DDVP and imidacloprid,to silkworm growth and development was investigated.The results indicated that the toxicity of pesticides to the silkworm larvae were in the order of imidaclopridphoximDDVPpyridabenchlorfenapyrpropargite.Their LC50 to silkworm at 96 h after treatment was 0.256,0.556,8.912,50.689,119.715 and 351.691 mg/L,respectively.And the toxicity increased with the prolongation of time.The developmental stages,body weight of molting larvae,cocoon weight and cocoon shell weight of survived larvae from treatments at LC5 and LC15 of propargite,chlorfenapyr and DDVP showed no significant difference compared with the control.Moreover,no significant difference was observed between treatments at LC5 and LC15 of the same pesticide.