Small numbers of bee and non-bee pollinators detected moving between on-farm native plantings and neighbouring grass cropland

Abstract

On-farm native plantings support insect pollinator diversity, however, they must move between this habitat and crops grown elsewhere on the farm if they are to have any possibility of delivering pollination services that benefit growers. To determine whether pollinator movement occurs, sticky traps to capture verified crop pollinating insects (bees and non-bees species) were placed at distances of 0, 50, 100, 150 and 250 m from 5 year old native plantings into adjacent grass crops on three farms in New Zealand. These were activated twice for 48 h in Dec 2017 and Jan 2018. Captured pollinators were examined for pollen originating from the native plantings. A total of 993 individuals from 13 crop pollinating species were counted of which 506 were examined for pollen. Eight individuals representing three pollinator species were found with pollen sourced from the plantings. Of these, the native bee Lasioglossum sordidum (n = 4) was found to have travelled up to 250 m, while the native flies Melangyna novaezelandiae (n = 3) and Odontomyia sp. (n = 1) travelled up to 150 m. Despite finding few pollinators moving between these habitats, we recommend further studies to assess (1) whether the current study is truly indicative of limited pollinator movement across these habitats at broader temporal (e.g. seasonal and yearly), spatial and system scales (e.g. a broader range of agriculture systems and regions). Such knowledge can inform farmers on whether or not it is worthwhile establishing on-farm native plantings to support pollinators.