Biodiversity of plants on and off the farm boosts natural pest control, while pest control via insecticides and vacuuming indirectly hinders it
A new study published in the Journal of Applied Ecology shows the importance of maintaining biodiversity to achieve natural pest control and reduce the use of insecticides. Specifically, the study found that natural habitat in the landscape and on-farm vegetative diversity improve natural enemy communities, which leads to improved pest control. On the other hand, using sprays and vacuuming plants indirectly hinder pest control. Vacuuming is a common, chemical-free pest control method, particularly for strawberry crops and on large farms. However, this study shows that vacuuming does not always result in fewer pests, but it does decrease beneficial insects that offer natural pest control. While spraying directly reduced pests, it also reduced natural enemies to pests, leading to an overall negative impact on pest control.
This research took place across two years on 27 organic farms that grow strawberries either as the sole crop, or one of multiple crops on the farm. The farms were selected along a gradient of diversity in the landscape, varying in the amount of nearby woody habitat, grasslands, and other agricultural land. On-farm diversification also followed a gradient with practices including the use of polyculture (multiple, different crops grown simultaneously), hedgerows, cover cropping, and flower strips for example. At the landscape scale, the driver of natural pest control came from the proportion of woody habitat near the farm, which runs contrary to popular belief that nearby natural habitat increases pest abundance and damage. The results from this work demonstrate the value in promoting plant diversity both on and off the farm, particularly woody habitats that may require policies to prioritize conservation at regional scales.
Banner Photo Credit: Pascal Debrunner; unsplash.com