Effects of a heat wave event on the chemical ecology of species interactions in the potato agroecosystem

Authors: Carvajal-Acosta, Alma; SNOOK, JOSHUA - Louisana State University; SZENDREI, ZSOPHIA - Michigan State University; WETZEL, WILLIAM - Montana State University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2025
Publication Date: 10/27/2025
Citation: Carvajal-Acosta, A.N., Snook, J.S., Szendrei, Z., Wetzel, W.C. 2025. Effects of a heat wave event on the chemical ecology of species interactions in the potato agroecosystem. Environmental Entomology. 54(6):1196-1206. https://doi.org/10.1093/ee/nvaf104.
DOI: https://doi.org/10.1093/ee/nvaf104

Interpretive Summary: Heat wave events are becoming increasingly common with important implications for agricultural pest management. As a result, we currently have a poor understanding of how heat waves impact pest management. Therefore, experiments were conducted in Michigan using simulated heatwaves and potato plants to assess heat wave impacts on the performance of the Colorado Potato Beetle (CPB), which is a serious pest of potatoes in the United States. Additionally, researchers in Michigan wanted to determine whether these effects are influenced by the presence of pest competitors and beneficial microbes. Potato plants were exposed to CPB larvae that were untreated or treated with anti-biotics (to remove gut microbes), and that were alone or in the presence of another pest insect. Analyses were also conducted to determine if heat waves affect the production of glycoalkaloids (toxic chemicals to herbivores), plant hormones that control plant response to herbivore damage and environmental stress, and volatiles compounds involved in the attraction of predators or parasitoids damaging to insect pests. Results demonstrated that the heat wave increased CPB larval and adult performance when crops were damaged by both insect pests, but only when CPB lack beneficial microbes. The improved CPB performance was explained by a decrease in glycoalkaloids in plants exposed to the heat wave and multiple pest damage. Heat stressed potato plants also showed increasing levels of jasmonates (a class of plant hormone) suggesting that plants prioritized response to heat stress over producing defensive chemicals. Finally, we found that the heat wave affected plant’s ability to produce volatiles, but we observed no changes in predator/parasitoid communities. These results provide critical knowledge on the impacts of temperature extremes on pests, crop chemistry and physiology under more realistic field conditions. These new insights will allow researchers to develop and plan agroecological pest management strategies that are more resilient to heat waves.

Technical Abstract: Heat waves, brief periods of unusually high temperatures, are increasing in frequency and intensity globally. Such extreme weather events can alter plant chemistry, disrupting species interactions that contribute to pest suppression or increase their performance. Yet, most heat wave studies focus on pairwise interactions, leaving us with a poor understanding of how complex agroecosystems respond to temperature extremes. We addressed this knowledge gap by simulating an experimental heat wave in the field on potato plants (Solanum tuberosum L.) and the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), in the presence or absence of their mutualistic microbial symbionts and another pest, the potato aphid (Macrosiphum euphorbiae (Thomas)). We assessed beetle performance alongside changes in volatile organic compounds (VOCs) and glycoalkaloids from host plants. Beetle performance declined in the absence of their microbial symbionts and under aphid competition, but this effect was reversed under heat wave conditions. These results corresponded with a downregulation in glycoalkaloids, suggesting that potato prioritizes heat stress response over herbivore attack by divesting resources from the production of defensive compounds. The heat wave strongly affected VOCs composition, reducing emissions of multiple compounds while increasing others, but these changes were not directly linked with CPB performance. Overall, our results demonstrate that heat wave effects on crop–pest dynamics are dependent on the agroecological context and mediated by specialized metabolites. Importantly, under dual herbivore pressure, potato crops appear to prioritize coping with heat over defending against pests, underscoring the urgent need for pest management strategies that account for extreme climate events.