Large regional variation in global impacts of agriculture on terrestrial insects and other arthropods

Many insects and other arthropods are reported to be in rapid decline worldwide, mainly driven by changes in land use and climate. At the same time, arthropods provide many important services that benefit agriculture, and thus their losses may pose risks to food security. Although biodiversity responses vary between global realms, this spatial heterogeneity is not well-understood and is rarely addressed in global analyses. To understand the geographical variation of biodiversity change better, we investigated the responses of arthropod diversity to agricultural land use and intensity for six geopolitical regions, using a global dataset of biodiversity records. We show that agricultural intensification generally leads to average biodiversity declines, but we find large variation in responses per region. Notably, responses in Europe are minimal or even significantly positive. Further investigation suggests that responses in Europe may be attributable to a combination of a primary vegetation baseline that is subject to comparatively high levels of disturbance and fragmentation, and significant compositional changes that have favoured widespread generalists and non-native species. Conversely, narrow-ranging habitat specialists, particularly of forests, are associated with significant declines. These findings have important consequences for global biodiversity assessments and associated predictions of ecosystem service delivery, which are likely underestimating land use impacts on biodiversity by relying on statistical model coefficients that are heavily biased towards Europe and may fail to report important compositional changes by focussing analyses solely on species richness and total abundance.