Buckwheat (Fagopyrum esculentum) floral strips support natural enemies and maintain yields in organic green bean (Phaseolus vulgaris) crops

Abstract

Arthropod natural enemies can contribute to pest management by consuming crop pests, but populations of these natural enemies may be low within crops due to a lack of resources. Floral strips can provide these resources and support natural enemy communities, which in turn can suppress pest populations and thereby improve crop yields. Buckwheat (Fagopyrum esculentum Moench) floral strips were added to experimental plots of organic green beans (Phaseolus vulgaris L.) and paired with control plots, without floral strips, to determine their impact on arthropod communities, crop yields, and pest control costs. Crop yields were maintained, but costs of pest control significantly lower (16%) in plots with floral strips. This was not explained by an increased abundance or diversity of natural enemies or a decrease of pests (i.e. all herbivores). Instead, the composition of arthropod natural enemy communities were similar between buckwheat floral strips and the crop, suggesting that the floral strips support natural enemies already present within crops. Semi-natural edge habitat in control plots, had a unique community of natural enemies, which had little spillover into the crop and therefore may have little impact on biological control. These results suggest that higher crop yields can be achieved with reduced inputs, such as insecticides, by adding floral strips to crops as they may support the natural enemies present within crops. Future studies should consider the impacts of specific natural enemies, rather than diversity, and direct measurements of biological control to connect the impact of floral strips to crop yields.