Assessment of the role of greenhouse borders as sources of pest and beneficial insects in protected crops

Abstract

Managing pests in greenhouses and other sheltered crops requires understanding the origin of colonizing individuals. Nearby vegetation can serve as a source not only for pest insects but also for their natural enemies, making it a key factor in developing conservation biological control strategies. We conducted a study on protected strawberry crops across 50 French farms, examining the presence of major pests and their natural enemies in both greenhouses and crop border vegetation. We first identified pest and beneficial insects in greenhouses and then determined whether these insects were present in crop border vegetation. Our results showed that while crop borders primarily harboured generalist aphid species, aphids specialized in strawberry were nearly absent. Few phytophagous bugs were observed in either sampling sites. In contrast, natural enemies, such as aphid parasitoids and generalist predators, were found in both greenhouses and borders. We further analysed how factors such as seasonality, production region, surrounding vegetation characteristics influenced the presence of pest and beneficial insects in crop borders. The presence of Rosaceae plants (strawberry’s botanical family) had no effect on insect populations. Higher botanical diversity and vegetation cover in borders were associated with increased populations of generalist pests and some biological control agents. These findings highlight the crucial role of crop borders in providing resources and refuges for generalist pest and beneficial insects while having limited impact on specialized pest populations. Targeted border management could either prevent pest colonization of crops or enhance natural enemy populations, contributing to improved pest regulation in greenhouses.