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

Authors: BRZOZOWSKI, LAUREN - Cornell University; Weber, Donald; WALLINGFORD, ANNA - University Of New Hampshire; MAZOUREK, MICHAEL - Cornell University; AGRAWAL, ANURAG - Cornell University

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2021
Publication Date: 5/3/2021
Citation: Brzozowski, L.J., Weber, D.C., Wallingford, A.K., Mazourek, M., Agrawal, A. 2021. Tradeoffs and synergies in management of two co-occurring specialist squash pests. Journal of Pest Science. https://doi.org/10.1007/s10340-021-01379-y.
DOI: https://doi.org/10.1007/s10340-021-01379-y

Interpretive Summary: Squash is an important group of crops native to the Americas. Squash crops host multiple native insect pests such as cucumber beetles and squash bugs that damage the crop by feeding and also by vectoring plant pathogens. These pests use volatile odors from the crop plants as well as from other insects, to find and aggregate on the crop. Crop damage may be mitigated by choice of crop cultivars, as well as manipulating the pests' responses to plant and insect odors. However, different pests differ in their plant preferences and in what attracts and retains them on the crop. Knowledge of these behaviors is important for sustainable management of squash pests. In a series of field experiments, we demonstrated that striped cucumber beetles and squash bugs prefer to lay their eggs on different squash types. In addition, we discovered that the aggregation pheromone of striped cucumber beetle, vittatalactone, is also attractive to squash bugs. Thus, squash bugs eavesdrop to exploit the pheromone signal of the cucumber beetle, enabling crop location and potentially altering crop preference and damage. The results offer the potential for synergistic trapping of both pests, and should be of interest to researchers and practitioners of pest management in squash and other cucurbit crops such as pumpkins, cucumbers, and melons.

Technical Abstract: 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., 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 tradeoffs 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.