Warmer autumns and winters could reduce honey bee overwintering survival with potential risks for pollination services

Authors: RAJAGOPALAN, K. - Washington State University; DeGrandi-Hoffman, Gloria; PRUETT, M. - Washington State University; JONES, V.P. - Washington State University; Corby-Harris, Vanessa; PIREAUD, J. - Washington State University; CURRY, R. - Crystal River Consulting Llc; HOPKINS, B. - Washington State Potato Foundation; NORTHWOOD, T. - Washington State University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2024
Publication Date: 3/25/2024
Citation: Rajagopalan, K., Hoffman, G.D., Pruett, M., Jones, V., Corby-Harris, V.L., Pireaud, J., Curry, R., Hopkins, B., Northwood, T. 2024. Warmer autumns and winters could reduce honey bee overwintering survival with potential risks for pollination services. Scientific Reports. 14. Article 5410. https://doi.org/10.1038/s41598-024-55327-8.
DOI: https://doi.org/10.1038/s41598-024-55327-8

Interpretive Summary: Pollinators are critical for food and nutritional security but face multiple stresses including climate change. Climate change research has largely focused on unmanaged pollinators, and the effects of a warming climate on plant-pollinator interactions, forage availability, and ranges where the pollinators can establish. Overlooked are managed pollinators such as honey bees and the subtle but important impacts that changes in autumn and winter temperatures have on overwintering colonies. Using a population dynamics model and historical and future climate data, we show that warmer autumns and winters, that are occurring with increasing frequency in northern latitudes, increase late-season honey bee flight, alter the overwintering colony age structure, skew the population towards older bees, and lead to greater risks of colony failure in the spring. Focusing on the Pacific Northwest, we show that geographic areas where warmer fall temperatures affect overwintering colony survival will expand throughout the century. We also show that overwintering hives in cold storage facilities will likely become a critical tool to reduce colony losses and insure the availability of hives for pollination.

Technical Abstract: Pollinators are critical for food and nutritional security but face multiple stresses including climate change. Climate change research has largely focused on unmanaged pollinators, and the effects of a warming climate on plant-pollinator interactions, forage availability, and ranges where the pollinators can establish. Overlooked are managed pollinators such as honey bees and the subtle but important impacts that changes in autumn and winter temperatures have on overwintering colonies. Using a population dynamics model and historical and future climate data, we show that warmer autumns and winters, that are occurring with increasing frequency in northern latitudes, increase late-season honey bee flight, alter the overwintering colony age structure, skew the population towards older bees, and lead to greater risks of colony failure in the spring. Focusing on the Pacific Northwest, we show that geographic areas where warmer fall temperatures affect overwintering colony survival will expand throughout the century. We also show that overwintering hives in cold storage facilities will likely become a critical tool to reduce colony losses and insure the availability of hives for pollination.