Invertebrate biodiversity in apple orchards: agrichemical sprays as explanatory variables for inter‐orchard community differences

Invertebrates are important providers of ecosystem services to orchards and the orchards may benefit where there is greater biodiversity. Previous research has shown that apple orchards using organic or integrated pest management support different invertebrate communities, as can different orchards within the same management system. In the present study, we examined the potential for agrichemical usage to explain inter‐orchard invertebrate community differences in 10 New Zealand apple orchards under integrated pest management. Multiple regression models were used to examine relationships between spray diary data and invertebrates collected by branch tapping, pitfall and sticky traps in 2011/2012. Insecticides, fungicides, plant growth regulators and fertilizers were used as explanatory variables in these models and the most parsimonious models were identified. Plant growth regulators were significant in most of the models for inter‐orchard variability in total invertebrate diversity. Insecticides featured strongly in models explaining pest assemblages, although not so strongly for models for their natural enemies. Fungicide and fertilizer use featured in models explaining communities of decomposers and fungivores. The results generated several hypotheses about the impacts of specific agrichemicals on invertebrate biodiversity, which, if tested, could establish the feasibility of customizing spray schedules to meet both biodiversity and production goals.