Early herbivory attracts and facilitates subsequent specialist herbivores with consequences for plant performance

Authors: BARRETT, MATTHEW - Cornell University; BRENNAN, NATALIE - Montana State University; Weber, Donald; RAGUSO, ROBERT - Cornell University; THALER, JENNIFER - Cornell University

Submitted to: Ecological Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Several insects are pests of cucurbit (squash, pumpkin, melon crops) in North America. Among key pests these include striped cucumber beetle and squash bug. How these species affect the crop, based on their colonization and feeding on the crop, affects crop production and damage over time. The aim of this study was to determine how damage and other cues, including pheromone production, by striped cucumber beetles, typically the first herbivore (pest) to arrive on the crop, affect the subsequent colonization and reproduction and damage by squash bug over the course of the season in summer and winter squash crops. We found that squash bug colonization depends on cucurbit species and variety, as well as stong association with cucumber beetle presence and damage. Pest feeding affected onset of male flowering and ultimate crop yield. These results give insight into the different response by the crops over the course of the growing season, and the impact of multiple pest species feeding over time. The results will be of interest to cucurbit researchers and pest managers, and provide underpinning for pest management thresholds for use in protection of this important group of vegetable crops.

Technical Abstract: Early arriving herbivores can influence the attraction and performance of later-arriving species through both direct interactions and plant-mediated effects. During initial attack, herbivores and plants release cues that may be exploited by subsequent herbivores sharing similar resources. Later-arriving herbivores may also benefit from prior damage or tailored plant responses to first herbivores. These interactions can variably affect plant reproductive traits depending on the timing, identity, and sequence of herbivore attacks. In this study, we examined interactions between two insect herbivore pests, striped cucumber beetle (Acalymma vittatum) and squash bug (Anasa tristis), which often arrive in succession on cultivated Cucurbitaceae plants. We aimed to determine: (1) how cues from A. vittatum and damaged plants influence the abundance, distribution, and host selection of A. tristis; (2) how prior damage affects A. tristis growth and survival; and (3) how sequential herbivory impacts crop reproductive traits and yield. We found that higher A. vittatum abundance and foliar damage were associated with increased A. tristis presence, but only on Cucurbita species, the preferred host genus of A. tristis. In bioassays, A. tristis adults preferred Cucurbita pepo seedlings with actively feeding A. vittatum, and hatchlings showed a 25.7% increase in growth on previously damaged plants. Field experiments showed that sequential herbivory by both species delayed male blooming, reduced male floral abundance, and negatively affected yield. These reproductive impacts, however, were more pronounced in the early-maturing C. pepo variety (Saffron Summer Squash) than in the later-maturing (Jack-o-Lantern) variety. Our results highlight how the order of herbivore arrival can shape plant-insect interactions and ultimately affect crop performance and reproductive traits.