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10-Minute Presentation

Systematics, Evolution, and Biodiversity

10-min: SysEB, Invasive Species, Diagnostics, and Pest Control

Assessing transgenerational phenotypic response to insecticidal stress in invasive Colorado potato beetles (Leptinotarsa decemlineata)

Sunday, November 9, 2025
8:24 AM - 8:36 AM Pacific
Location: Oregon Convention Center, E147-148, OCC
Oral Presentation
Agricultural insect pests, including the Colorado potato beetle (Leptinotarsa decemlineata; CPB), often rapidly develop resistance to anthropogenic stressors (e.g., insecticides). Such strong and repeated adaptation cannot be easily explained by selection on genetic variation. Alternatively, stress exposure may induce adaptive phenotypic responses. Individuals may inherit a “memory” of these phenotypes, perhaps via epigenetic mechanisms, increasing fitness in future generations. Although studies have documented multigenerational inheritance of stress-induced phenotypes, no one has examined how these patterns may differ across family lineages. It is important to quantify the effects of environmental stress on phenotypic variation and possible transgenerational inheritance to understand rapid evolution of stress tolerance in insect pests. Furthermore, it is necessary to account for the contribution of genetic ancestry to adaptation by tracing parentage across generations.

We assessed the effect of sublethal insecticide exposure on performance in the parental generation (exposed) and across three unexposed generations in CPB. For 12 replicate mated-pair lineages, we exposed third-instar larvae (F0 generation) to either a 10-ppm dose of imidacloprid or water (control). In F0, F2, and F3 beetles, we measured daily number of eggs (adult fecundity); larval walking rate, acceleration, and distance (mobility); leaf tissue consumed by larvae (herbivory); and time to pupation and adult emergence, pupal weight, and adult weight (development). Detecting similar stress-induced phenotypic patterns in exposed F0 and unexposed F3 beetles is particularly significant, because it would signify phenotypic inheritance without direct stress exposure. Our findings will help identify eco-evolutionary mechanisms facilitating success of CPB and other agricultural insect pests.