Honey bees and native pollinators occupy distinct climatic niches in a spring-blooming crop

Insect-mediated pollination is critical to our food supply. However, pollinators are threatened by a complex mixture of stressors, including extreme weather and climate change. The production of some fruit crops, particularly those that bloom in the unstable weather of spring, is currently limited by a lack of pollinators. In this study, we assessed how climatic preferences varied among the taxa involved in apple pollination in the Midwestern US, with the ultimate goal of determining how resilient these pollination services will be to climate change. To monitor pollinator foraging activity in the field, we used AutoPollS, a camera trap technology that employs computer vision to detect and identify pollinators. AutoPollS units were placed in apple orchards during bloom along with weather-monitoring equipment. The units took photos of insects as they visited flowers, and offline analysis identified the insects to genus. Comparing activity among wild bees, honey bees, and flies, we found that wild bees had the narrowest climatic niche, only foraging at the warmest temperatures and in sunny conditions. Honey bees also preferred warmer temperatures, but showed more tolerance for sub-optimal weather conditions than wild bees. Flies were the most tolerant of sub-optimal conditions, such as lower temperatures, lower light levels, and higher humidities. These results show that different types of pollinators occupy distinct climatic niches, providing a mechanistic understanding of niche complementarity in apple pollination. Ensuring the presence of a diversity of pollinators will help spring-blooming crops be resilient to climate change in the future. Supported by NSF PRFB DBI-2305941.