Susceptibility of Diatraea saccharalis Populations (Lepidoptera: Crambidae) to Bt Toxins Expressed in Genetically Modified Corns for Development of Transgenic Sugarcane in Argentina

The sugarcane borer, Diatraea saccharalis, is one of the most important pests of sugarcane and corn crops in Argentina. In general, there are no control methods to manage this insect in the cane fields in the country. So, the development of borer resistance in sugarcane through transgenic technology could be the best approach, as in the case of Bt corn derived of the Bacillus thuringensis bacterium that has been the primary tool for managing this borer in the field. However, sugarcane borer control has been threatened by observations of resistance to certain varieties of Bt corn and the protein used in many new varieties. The susceptibility of two populations of sugarcane borer to different Bt toxins expressed in five genetically modified corns (two single and three pyramided genes) was determined for the development of a transgenic sugarcane. In laboratory bioassays, larval mortality of both populations on Bt corn leaf tissue containing Cry1F toxin was lower than other Bt technologies at 3 days of exposure. However, there were no significant differences between larval mortality of the five Bt corns at 7 days after infestation. In a greenhouse trial, larval survival and plant injury were not significant in Bt corns. The results suggest that any Bt protein could be incorporated into sugarcane crops for managing D. saccharalis.