Study on the Toxicity of Bacillus thuringiensis LY30 to Cotton Bollworm

The study aimed to explore the toxicity of Bacillus thuringiensis(Bt) LY30 to cotton bollworm.A high toxicity Bt strain against larvae of cotton bollworm named as LY30 was isolated from over 400 wild-type strains by bioassay.The initial comparison of LY30 with HD-1 by morphological,physiological,biochemical features showed that LY30 belongs to H3a3b3c serotype.SDS-PAGE electrop horesis atlas showed that they were composed of two kinds of protein of 135kD and 65kD components.There were no differences between growt hmorphology,fermentation culture features,physiological and biochemical characteristics between HD-1 and LY30.However,toxicity difference between them was examined with bioassay,the result showed that LC50 of LY30 fermented liquid against neonate,second and third instar larvae of cotton bollworm were 0.32,0.62,and 2.58 μL/ml respectively.LY30 possesses high toxicity against larvae of cotton bollworm younger than third instar.