van Putten, Deborah2025-06-302025-06-302025-06-30https://hdl.handle.net/2077/88468To predict how populations will adapt and evolve, it is essential to understand how costly life-history traits genetically covary and trade off in response to variable environments. These trade-offs can limit the response to selection and thus can constrain adaptation in populations. Understanding these genetic trade-offs is especially important for managing pesticide resistance in pest populations. My thesis aims to quantify genetic effects between life-history traits and varying environmental conditions, in Helicoverpa armigera moth larvae infected by different doses of a fungal biopesticide. Survival, pupal mass and development rate were measured as response variables. To estimate genetic effects, a half-sibling design was used to partition sire variance from the phenotypic variation. Although the biopesticide did not appear to affect traits on a phenotypic level, including low mortality across all doses, the Bayesian model revealed some evidence for genetic effects. Genetic correlations within development rate were highest for similar doses and lowest for vastly different doses, suggesting gene-by-environment interactions. A positive genetic correlation between pupal mass and development rate was found in the highest dose, while the genetic correlations in the lower doses were closer to 0. This may suggest that certain genetic effects only influence performance under high stress conditions, and that genetic correlations can be masked at low stress environments, due to favorable conditions. Despite limited statistical power due to the number of half-sibling families, my results show that genetic effects are environment-dependent. My thesis shows the importance of considering environmental variability when predicting evolutionary responses, especially in the context of managing pesticide resistance, where hidden genetic constraints may only emerge under stress.engGene-by-environment interactions, life-history traits, trade-offs, resource acquisition, evolutionary constraints, genetic variationText