Manure inputs affect composition of predatory beetle assemblages in vegetable fields

Recent evidence indicates that resource subsidies in the form of manure can affect the abundance and diversity of predatory insects and spiders in agroecosystems. In 2010, we examined the effects of this treatment on three organic vegetable farms in Burlington, Vermont. Manure was applied to the field margins at a rate of 10 tons/acre and compared to a control plot on each farm. Arthropods were sampled by pitfall trapping over the course of the summer. Here we describe the relationship between detrital subsidies, phenology, arthropod abundance and assemblage composition. Arthropod responses were taxon-specific, with Carabidae having the strongest response.