Impact of Genotype and Environmental Variables on Transgene Effectiveness for Conditional Lethality Systems in Insects

Understanding the safety and environmental impact of genetically modified insects is critical for advancing their use in agriculture. Strains of pest insects have been developed that carry a conditionally lethal transgene, and these strains hold great promise in controlling pest populations through Sterile Insect Technique, and environmentally friendly pest control strategy that avoids the use of chemical insecticides. A major regulatory and public concern regarding the use of genetically modified insects is whether the transgene will persist in the environment. Males carrying conditionally lethal transgenes are extremely effective under highly controlled lab conditions, but their efficacy in a field setting remains to be seen. In the field, the transgene must be 100% effective in a range of genetic backgrounds and environmental conditions, otherwise the transgene will persist in the environment. Here, we test the hypothesis that the expression and effectiveness of conditionally lethal transgenes is impacted by environmental conditions and the genotype it is expressed in. Using Drosophila melanogaster as a model, our objectives are to 1) Test the extent to which genotype influences transgene activity by testing a conditionally lethal transgene against a worldwide panel of fly genotypes, 2) Identify the environmental conditions that impact the effectiveness of lethal transgenes, and 3) Assess the ability of natural fly populations to evolve resistance to the conditionally lethal transgene. This information will benefit scientists and regulatory agents considering field release of transgenic insects and aligns well with the USDA BRAG program area “Management Practices to Minimize Environmental Risk of GE Organisms.”