Morgan Thompson

“Undercover operation: root herbivory modifies aboveground plant-herbivore interactions”

Abstract: Upon insect herbivore attack, plants initiate a cascade of defensive responses. Plant defenses locally alter plant primary and secondary metabolism and can also systemically affect distant plant tissues. Belowground insect herbivores damage plant roots, but the systemic effects of root herbivory on aboveground plant tissues remain poorly understood. Therefore, we sought to investigate how belowground insect herbivory alters aboveground plant-herbivore interactions. Specifically, our objectives were to 1) evaluate aboveground changes in plant defense following root herbivory, and 2) examine the responses of aboveground herbivores. We investigated our objectives in both greenhouse and field settings using squash (Cucurbita pepo) plants in the vegetative growth stage. We challenged plants belowground with specialist root-feeding striped cucumber beetle (Acalymma vittatum) larvae. Following 48 hours of root herbivory, we detected quantitative increases in aboveground plant volatiles, indicating altered plant defenses. We also observed decreased preference of aboveground herbivores on plants attacked by root herbivores. Overall, our results indicate belowground herbivory modifies systemic plant defenses and ultimately deters aboveground insect herbivory.

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