Pests and extreme weather events: How heat wave timing, potato variety, and predator presence influence Colorado potato beetle suppression

Integrated pest management programs that incorporate multitrophic ecological interactions are facing an increasingly frequent threat: extreme weather events, such as heat waves. Such extreme events, though brief, have the potential to alter ecological interactions such as those that contribute to pest control in agroecosystems. Understanding how the timing of an event such as a heat wave interacts with plants, herbivorous insects, and predatory insects is essential to developing pest control strategies that are more resilient to extreme weather. We used two varieties of potato — one that shows resistance to Colorado potato beetle (CPB) and a conventional variety that does not ­— to ask how plant resistance traits influence the survival and performance of CPB in the context of heat waves that occurred at four different timings throughout the ontogeny of the plants and insects, and with or without augmenting predatory insect populations. We observed a strong main effect of the resistant potato variety reducing CPB larval survival, though the reduction in survival to adulthood was minimal. A heat wave that occurred when the CPB larvae and potato plants were young reduced beetle survival regardless of potato variety and predator presence. Predators were successful in reducing CPB survival only in the absence of heat waves. Our results suggest that heat waves may pose both challenges and potential benefits for ecologically-based pest control, meaning that management programs will need to incorporate novel strategies that are informed by the reality of more frequent extreme weather events.