EFECTO LETAL Y SUBLETAL DE Cry2Ab Y Cry1Ac DE Bacillus thuringiensis BERLINER EN LOS ESTADOS DE DESARROLLO DE Spodoptera frugiperda J. E. SMITH.

Abstract

The fall armyworm Spodoptera frugiperda is a worldwide polyphagous insect that attacks various crops of economic importance. The control of this pest is commonly carried out with chemical insecticides which are highly polluting, a control alternative for this and other lepidopteran insects, is the use of products based on the bacteria Bacillus thuringiensis Kurstaki. The objective of this research was to evaluate under laboratory conditions, the lethal and sublethal effects of Cry2Ab and Cry1Ac proteins of B. thuringuiensis on the different developmental stages of S. frugiperda. Results showed that over time mortality of S. frugiperda increased in all stages of development, as the protein concentrations where higher. Mortality was 60.3 and 75.8% with Cry2Ab and Cry1Ac proteins, respectively. The highest concentration (5 µg mL-1) of the Cry2Ab protein, prolonged the life cycle of the neonatal larva by 7.3 days in the first generation, as compared to the control. In the case of the Cry1Ac protein at the concentration of 10 µg mL-1, the life period was extended by 6.8 days against the control. The oviposition in the F1 generation was more than 600 eggs in the controls, with 95% of larvae hatched, while with Cry2Ab (5 µg mL-1) they oviposited 161.6 eggs per female, of which an average of 111.7 larvae hatched and with Cry1Ac, they only oviposited 1.7 eggs from which no larvae hatched. These results demonstrates that sublethal effects are important to control insect populations

The results demonstrate that the lethal and sublethal effects of Bt proteins contribute to reducing the insect populations by causing low or even no offspring in the next generation.