Toxicity of several δ-endotoxins of Bacillus thuringiensis against the cotton pest Earias insulana (Lepidoptera: Noctuidae)

Abstract The toxicity of nine Bacillus thuringiensis Cry proteins against neonate Earias insulana larvae was tested using a mixture of crystals and spores. The mean lethal concentration (LC 50 ) of Cry1Ac was 1.99 μg/ml. Cry1Fa, Cry1Ca, Cry1Ja and Cry2Aa were more active than Cry1Ac, with LC 50 values of 0.22, 0.24, 0.29, 0.43 μg/ml, respectively. Cry1Da and Cry1Aa were considerably less active than Cry1Ac. The remaining proteins, Cry1Ba and Cry1Ab, displayed no activity. Relative potencies were also calculated. Cry1Ja and Cry1Fa were significantly more active (7.72 and 5.71 times, respectively) than Cry1Ac, while Cry1Ca was significantly (1.95 times) more active than Cry2Aa.