Abiotic environments can modify the penetrance of a transgene-based lethality system for genetic biocontrol of insect populations

Authors: PEREZ-GALVEZ, FERNAN - University Of Kentucky; Handler, Alfred; HAHN, DANIEL - University Of Florida; BREDLAU, JUSTIN - University Of Kentucky; TEETS, NICHOLAS - University Of Kentucky

Submitted to: Proceedings of the Royal Society of London B
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: The availability of genetically modified insects presents an attractive alternative to conventional pest control methods especially in regards to Sterile Insect Technique. One concern for the use of genetically modified insect strains is the potential for the expression of genetic modifications, resulting in lethality for population control, to be altered in response to variable environmental conditions. In particular, are conditions that suppress lethality when total lethality is expected or required for a self-limiting status, ensuring that genetically modified insects do not survive in the field. Scientists at USDA, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, and collaborators at the University of Kentucky and the University of Florida have therefore examined the influence of two environmental variables, temperature and nutrition, on the efficiency of an early embryonic conditional lethality system in the vinegar fly, Drosophila melanogaster. These environmental variables were manipulated in parental and offspring environments with the finding that the genetically modified lethality system has distinct responses to each variable, that the effects of each variable are greatest when administered to embryos, and that the most extreme levels of exposure have the most negative effect on transgenic lethality. These results highlight the need to evaluate the field application of genetic modifications to insect species in the context of variable environmental conditions previous to commercial use.

Technical Abstract: Genetic biocontrol approaches in insect pest management offer high specificity at the species level and reduced insecticidal chemical pollution, but this approach requires the release of genetically modified organisms that must perform across a variety of environmental conditions. Because organisms often display phenotypic and gene expression variability when exposed to stressful conditions, it is reasonable to expect that transgenic systems may be prone to environmentally mediated variation in expression and function. In this study, we examined the influence of two abiotic variables, temperature and nutrition, on the penetrance of an early embryonic Tet-off conditional lethality system in the fly Drosophila melanogaster. We manipulated parental and offspring environments independently to determine the impact of life stage of exposure on transgene performance by estimating the probability of larval hatching and measuring transcript abundance of the transgenic system components. Our findings reveal that: 1) transgene performance has distinct norms of reaction to each environmental variable, 2) that the effects of abiotic challenge are greatest when exposure occurs in the embryos expressing the transgene, and 3) that exposures at the extreme limits of permissible conditions can dramatically decrease the penetrance of transgenic lethality. While variation in transcript abundance of the transgenic system was observed in some environments, these changes were not fully congruent with patterns of phenotypic penetrance, suggesting that the observed variation in lethality is likely driven by processes downstream of transcription.