Toxicity Evaluation of Three Kinds of Biogenic Pesticides and Their Mixed Preparations to Silkworm

In order to identify the toxicities of avermectins,chloronicotinyl and pyrethroid pesticides to silkworm(Bombyx mori),we determined the toxicities of the 15 biogenic pesticides(including abamectin,emamectin benzoate,imidacloprid and β-cypermethrin and their mixed formulations) to 2nd instar larvae with the leaf dipping method.At the same time,the poisoning symptoms of treated silkworm were observed.The results showed that the LC50 values of 15 biogenic pesticides to 2nd instar larvae were less than 0.5 mg/kg after 48 h of exposure respectively,the poisoning symptoms of treated silkworm were similar,which was vomiting,head or tail bending upwards,and body distorting to C or S shaped etc.It suggested that these pesticides should not be used in mulberry field because of their high toxicities.Our results indicated that pesticide with low toxicity to vertebrate is not necessarily safe to non-target insects simultaneously.