Climatic predictors of varroa destructor, melissococcus plutonius, and vairimorpha detections in honey bee colonies

Authors: MCAFEE, ALISON - University Of British Columbia; Walsh, Elizabeth; TRAN, LAN - Agriculture And Agri-Food Canada; LABUSCHAGNE, RENATA - Alberta Agriculture And Rural Development; CUNNINGHAM, MORGAN - University Of British Columbia; TSVETKOV, NADEJDA - University Of British Columbia; COMMON, JULIA - University Of British Columbia; HIGO, HEATHER - University Of British Columbia; PERNAL, STEPHEN - Agriculture And Agri-Food Canada; GIOVENAZZ0, PIERRE - Laval University

Submitted to: PLOS Climate
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2024
Publication Date: 8/29/2024
Citation: Mcafee, A., Walsh, E.M., Tran, L., Labuschagne, R., Cunningham, M., Tsvetkov, N., Common, J., Higo, H., Pernal, S., Giovenazz0, P. 2024. Climatic predictors of varroa destructor, melissococcus plutonius, and vairimorpha detections in honey bee colonies. PLOS Climate. https://doi.org/10.1371/journal.pclm.0000485.
DOI: https://doi.org/10.1371/journal.pclm.0000485

Interpretive Summary: Honey bees are afflicted with various pests and pathogens, but little has been published about the climactic impact on pest and pathogen trends. In a survey of several hundred colonies across five provinces in Canada, correlations between weather factors (namely temperature, rainfall, and wind) and the causative agents of EFB and Nosemosis, in addition to the ectoparasitic mite Varroa destructor. We found the EFB generally increased seasonally in addition to with inclimate weather events. Vairimorpha (formerly Nosema spp.) spores went down after spring and were negatively correlated with temperature, but positively correlated with wind and precipitation. Wind speed and rain were linked with lower Varroa loads, which may be due to patterns of honey bee brood rearing. These data contribute to building a larger dataset of disease agent detections that is needed in order to predict how incidence may change in our future climate. Understanding how climatic variables influence parasite and pathogen incidence is critical as weather patterns continue to rapidly shift under climate change.

Technical Abstract: Honey bee (Apis mellifera) pathogens and parasites are some of the most damaging agents affecting colony productivity. While the prevalence of diseases and their etiological organisms vary according to regional and seasonal patterns, the influence of specific climatic predictors is rarely formally assessed. We therefore analyzed how Varroa destructor, Melissococcus plutonius, and Vairimorpha spp. detections varied according to regional, temporal, and climatic factors in honey bee colonies across five Canadian provinces. We found strong regional effects for all disease agents, with consistently high Varroa and M. plutonius incidence in British Columbia, and year-dependent regional effects on Vairimorpha spore loads. Increasing wind speed and precipitation were linked to lower Varroa detection probability, whereas warmer temperatures were linked to higher detection probability. Analysis of an independent dataset shows that these trends for Varroa are consistent within a similar date range, but temperature drives season-long patterns. Vairimorpha spore loads decreased over the course of the summer, with the lowest levels found at later dates when temperatures were warm. Spore loads increased with wind speed and precipitation, consistent with inclement weather limiting defecation flights. M. plutonius detections generally increased across the spring and summer, but were also positively associated with inclement weather. These data contribute to building a larger dataset of disease agent detections that is needed in order to predict how incidence may change in our future climate. Understanding how climatic variables influence parasite and pathogen incidence is critical as weather patterns continue to rapidly shift under climate change.