Impact of semi-natural habitat restoration in agro-ecosystems on pest and beneficial insect biodiversity and abundance

Numerous studies have demonstrated that agricultural intensification and ecosystem simplification have detrimental impacts on the diversity of beneficial insects. Indeed, the ability for pest outbreaks to be suppressed by beneficial "natural enemy" insects is greatly reduced in simplified agricultural ecosystems. One potential solution to this problem is the implementation of semi-natural habitat amendments to provide the resources that natural enemy insects require. This idea stems from Root's 1973 Enemy Hypothesis, which posits that diverse plant communities provide a diverse range of habitats and resources that cascade upwards to support a greater diversity and abundance of beneficial predatory and parasitic insects. To get a sense of the kinds of habitats important to promoting biodiversity in these agricultural systems, our team sampled 4 different types of amendments across 28 field sites in Delta, British Columbia. By utilizing three sampling methods, we aimed to capture a large subset of the insect diversity present in these ecosystems. Additionally, we conducted vegetation surveys to better understand the links between vegetative traits and trends in insect diversity. We predict that ecosystems with semi-natural habitat amendments will support a higher diversity and abundance of beneficial predatory and parasitic insects while suppressing the diversity and abundance of pest insects by providing natural enemies with supplemental food resources, nesting locations, and refuge habitat from weather and pesticides. Our research will provide growers with the information they need to make better informed decisions about the management of their land and how best to sustainably control pest insects.