Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Screening and insecticidal activity of Bacillus thuringiensis strains with high toxicity against Spodoptera frugiperda.

Abstract

Spodoptera frugiperda (J. E. Smith), a major agricultural pest in the world, causes serious damage to many major food and economic crops, such as corn. It is urgent to screen highly virulent Bacillus thuringiensis (Bt) strain resources to achieve high-efficiency, green and sustained control of S. frugiperda. Based on the difference of insecticidal genes and the evolutionary relationships among strains, 172 candidate strains were obtained from the 363 wild strains by eliminating repetition strains, which were stored in the laboratory and showed insecticidal activity against Spodoptera litura and Agrotis ypsilon. The spores and crystal mixtures of these strains were obtained by culture. Their virulence against S. frugiperda was tested after quantification of insecticidal proteins, and 27 Bt strains were obtained for their high virulence. The most virulent strain was B14-D2, with LC50 of 0.155 μg/g. The cry1Ea3 gene in this strain was cloned and expressed in crystal-free mutant HD73-. The LC50 of Cry1Ea3 protein against neonates of S. frugiperda was 1.789 μg/g. This research adds to the Bt strain resources for the development of new Bt products.