Trade-offs and synergies in management of two co-occurring specialist squash pests

Co-occurring herbivorous pests may have shared or divergent responses to plant- and insect- derived cues, creating challenges for effective pest management in agroecosystems. We examined how behaviors of two endemic specialist herbivores of Cucurbitaceae crops, squash bugs (Anasa tristis, Hemiptera: Coreidae) and striped cucumber beetles (Acalymma vittatum, Coleoptera: Chrysomelidae) are affected by cues in the Cucurbita pepo agroecosystem. We evaluated plant resistance to squash bugs and beetles using cultivars that typify the two domesticated subspecies C. p. pepo (e.g., zucchini) and C. p. ovifera (e.g., straightneck summer squash), and tested how squash bugs respond to beetle aggregation and feeding. Across several field experiments, we demonstrated that squash bugs prefer to oviposit on C. p. ovifera over C. p. pepo, while beetles had the opposing preference. Nonetheless, there was no link between preference and squash bug nymphal survival or development. While squash bugs and beetles diverge in preference, we found that squash bugs positively respond to beetle-derived cues. More squash bug oviposition was observed on plants with greater beetle damage and, using both actively feeding beetles and synthetic lures, we demonstrate that bugs eavesdrop on and respond to vittatalactone, the male-produced beetle aggregation pheromone. Thus, squash bugs appear to exploit the cue of a co-occurring specialist beetle for host choice and this has implications for management: while there are trade-offs in varietal preference, synergistic trapping of both pests may be possible. By evaluating the behavior of co-occurring pests, management strategies with multi-species efficacy can be identified and applied in agroecologically-based pest management.