Managed fly pollinators ensure berry crop yields under variable weather conditions

Insect pollination is essential for global fruit and vegetable production, yet rising climate variability and widespread declines in bee populations threaten the reliability of this service. Flies (Diptera), despite their abundance and tolerance to different environmental conditions, remain largely overlooked as managed pollinators in agriculture. Here, we present field-based evidence from commercial farms in Australia showing that certain fly species can deliver effective and climate-resilient pollination services to high-value berry cropping systems. In replicated cage trials, European hover flies (Eristalis tenax) produced fruit comparable in weight and marketability to those pollinated by European honey bees (Apis mellifera) and Australian native stingless bees (Tetragonula carbonaria), whereas brown blow flies (Calliphora stygia) showed more variable performance. When scaled to full-sized commercial polytunnels, hover flies consistently produced market-quality blackberry fruit, matching open (mainly bee) pollination in spring and outperforming open pollination under the cooler, more variable conditions of winter. Hover fly-pollinated fruit equaled or exceeded the quality of hand-pollinated flowers and consistently outperformed self-pollinated controls. Across spring and winter floral visitation field surveys, hover flies maintained higher flower visitation than honey bees across cooler temperatures, broader humidity ranges, and early tomidday time periods, indicating greater climatic tolerance under field conditions. Together, these findings demonstrate that the hover fly, E. tenax, can provide scalable, climate-resilient pollination services and highlight the value of integrating flies into diversified pollination strategies to support resilient crop production under a changing climate.