Selection and genotype analysis of Bt isolates with high virulence against Athetis lepigone (Moschler)
Author of the article:YANG Yun-He1** SONG Ping1 WANG Zhen-Ying2 DONG Zhi-Ping3 WANG Qin-Ying1***
Author's Workplace：1. College of Plant Protection, Agricultural University of Hebei, Baoding 071000, China;2. Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing 100093, China;3. Institute of Millet Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China
Key Words：Bacillus thuringiensis, Athetis lepigone, genotype identification, insecticidal activity, Vip3Aprotein, Cry1Acprotein
Abstract： [Objectives] To obtain Bt strains and insecticidal proteins with high insecticidal activity against Athetis lepigone (Möschler). [Methods] The insecticidal activities of 36 Bt strains and an engineered Pseudomonas putida with a cry1Ab gene were evaluated on second instar larvae of A. lepigone by bioassay. PCR-RFLP analysis was performed to verify the genotypes of all Bt isolates. [Results] The bioassay results indicated obvious differences in the insecticidal activities of the different Bt isolates tested. The results also revealed that the Bt strains with high insecticidal activity all contained the cry1Acgene. Furthermore, the results of a comparison of the toxicities of Bt SC-40 (cry1Ac, cry2Ac, cry1I, vip3A) and Bt HD-73 (cry1Ac) showed that the LC50 of BT HD-73 (188.51 μg/g) was lower than that of Bt SC-40 (418.13 μg/g). The supernatants from the vegetative stage of Bt SC-40 and Bt HD-1 with the vip3A gene showed certain insecticidal activities (42.5 % and 57.4 % mortality, respectively) to second instar larvae of A. epigone. However, the supernatants of Bt HD-73 with no vip3A gene did not show obvious insecticidal activity. [Conclusion] These results imply that the Cry1Actoxin encoded by the cry1Ac gene play an important role in the resistance of plants to A. lepigone larvae. Vip3Amay also have some insecticidal properties with regard to this pest.