Organic mulches in highbush blueberries alter beetle (Coleoptera) community composition and improve functional group abundance and diversity

Abstract

Abstract Horticultural practices may impact invertebrates in agroecosystems, particularly natural enemies. Impacts can be better understood by grouping organisms functionally or using morphological traits in addition to taxonomic determinations. We compared the effects of mulch type (compost, pine needles, unmulched) and weeding strategy (weeded, unweeded) on beetle (Coleoptera) communities in highbush blueberries, focusing on early‐season captures that reflected overwintering habitat. Beetle diversity was similar between plot types, although functional grouping revealed differences as a result of mulching but not weeding. Predatory and granivorous Carabidae were most abundant in unmulched plots, mycetophages were most abundant in pine needles, and saprophages were most abundant in compost. Predatory Staphylinidae were most diverse in compost plots, and the diversity of granivores was greatest in unmulched plots. Carabid biomass was greater in unmulched than compost mulched plots partly as a result of larger beetle size. Beetle communities in unmulched and pine needles mulched plots were more similar than those in compost mulched plots. A combination of compost mulched and unmulched areas should benefit all predatory taxa, although mulch use for pest control will need to be evaluated within the context of other production goals.