Determination of Toxicity of Organophosphorous and Pyrethriod Insecticides to the Silkworm Bombyx mori

In order to provide scientific basis for selecting and applying pesticides reasonably in mulberry gardens and in surrounding agricultural fields,acute toxicity of 10 organophosphorous and 19 pyrethroid pesticides to Bombyx mori was determined using leaf-dipping method.The toxicity was compared based on their active ingredient of organophosphorous and pyrethroid pesticides or on the same active ingredient but made by indifferent manufactures and was graded according to LC50 value.The results showed that 5 organophosphorous pesticides such as Zhudi(20% Triazophos EC) and 16 pyrethroid pesticides such as Biqi(4.5% Beta cypermethrin EC) were highly toxic to Bombyx mori with LC50 value between 0.1 mg/L and 10 mg/L.Other 5 organophosphorous pesticides such as Nongsite(48% chlorpyrifos EC) and other 3 pyrethroid pesticides such as Jiagong(2.5% Beta cypermethrin EC) have moderate toxicity to Bombyx mori with LC50 between 10 mg/L and 1 000 mg/L.And the toxicity of organophosphorous and pyrethroid pesticides which have different active ingredients or have the same active ingredient but made by different manufacturers was different.Therefore,one must be clear about where the pesticides were made and what active ingredients they have,thus avoiding using the pesticides with high toxicity to silkworm in mulberry garden.