Attack and aggregation of a major squash pest: parsing the role of plant chemistry and beetle pheromones across spatial scales

1. Successful management of insect crop pests requires an understanding of the cues and spatial scales at which they function to affect rates of attack of preferred and non-preferred host plants. A long-standing conceptual framework in insect-plant ecology posits that there is hierarchical structure spanning host location, acceptance, and attack that could be exploited for integrated pest management.

2. We investigated how plant- and insect-derived chemical cues affect successive decisions of host choice in aggregating insects, and tested predictions in the Cucurbita pepo - Acalymma vittatum system. Acalymma vittatum is an aggregating specialist beetle pest that strongly prefers zucchini (C. p. pepo) to summer squash (C. p. ovifera), two independent domesticates of C. pepo. We hypothesized that subspecies-specific plant traits, especially volatile cues, interact with the male-produced aggregation pheromone to amplify beetle preference for C. p. pepo.

3. Differential beetle attack ...