Impact of fagopyrum esculentum on Agriotes obscurus (Coleoptera: Elateridae) development and orientation

Abstract Wireworms (Coleoptera: Elateridae), larvae of click beetles, form a complex of significant subterranean pests damaging important crops such as potatoes and corn, with Agriotes obscurus being prevalent in Switzerland. Buckwheat acts as a biofumigant and affect wireworms, reducing their feeding and their juvenile growth. This study aimed to evaluate the effects of common buckwheat ( Fagopyrum esculentum ) on the development of A. obscurus larvae, comparing four buckwheat varieties (Grauer Heiden, Val Pusteria, Kitawasesoba, Drushina) against a barley control. Larvae were subjected to no-choice feeding tests under controlled conditions, with measurements of weight, length, and head capsule width taken over 12 weeks. Behavioral responses to different buckwheat varieties were assessed via double-choice olfactometry to examine attraction and preference. Results indicated no significant differences in weight or head capsule width between treatments, though barley-fed larvae showed a slight growth advantage. However, larval length exhibited significant varietal differences, with certain buckwheat varieties inhibiting growth more markedly. Mortality rates were unaffected, likely due to the advanced larval stage tested. Olfactometry revealed no clear preference towards any buckwheat variety, suggesting volatile profiles do not strongly influence larval attraction. These findings suggest that while buckwheat can impair wireworm development, especially larval length, variation among buckwheat varieties offers potential for optimizing integrated pest management strategies. The observed lack of behavioural attraction differences may suggest an incorporation of buckwheat as a cover crop, may disrupt wireworm life cycles and suppress damage sustainably.