Epidemiology of Nosema spp. and the effect of indoor and outdoor wintering on honey bee colony population and survival in the Canadian Prairies

PLoS One. 2021 Oct 25;16(10):e0258801. doi: 10.1371/journal.pone.0258801. eCollection 2021.

Abstract

The epidemiology of Nosema spp. in honey bees, Apis mellifera, may be affected by winter conditions as cold temperatures and differing wintering methods (indoor and outdoor) provide varying levels of temperature stress and defecation flight opportunities. Across the Canadian Prairies, including Alberta, the length and severity of winter vary among geographic locations. This study investigates the seasonal pattern of Nosema abundance in two Alberta locations using indoor and outdoor wintering methods and its impact on bee population, survival, and commercial viability. This study found that N. ceranae had a distinct seasonal pattern in Alberta, with high spore abundance in spring, declining to low levels in the summer and fall. The results showed that fall Nosema monitoring might not be the best indicator of treatment needs or future colony health outcomes. There was no clear pattern for differences in N. ceranae abundance by location or wintering method. However, wintering method affected survival with colonies wintered indoors having lower mortality and more rapid spring population build-up than outdoor-wintered colonies. The results suggest that the existing Nosema threshold should be reinvestigated with wintering method in mind to provide more favorable outcomes for beekeepers. Average Nosema abundance in the spring was a significant predictor of end-of-study winter colony mortality, highlighting the importance of spring Nosema monitoring and treatments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alberta / epidemiology
  • Animals
  • Beekeeping / methods*
  • Bees / growth & development*
  • Bees / microbiology
  • Mycoses / epidemiology*
  • Mycoses / microbiology
  • Nosema / isolation & purification
  • Nosema / pathogenicity*
  • Seasons*
  • Temperature*

Grants and funding

Alberta Crop Industry Development Fund (ACIDF) M.N. Alberta Beekeepers Commission R.C. https://www.albertabeekeepers.ca/ Growing Forward 2 (a federal-provincial-territorial initiative) M.N University of Manitoba R.C. https://umanitoba.ca/ Canadian Bee Research Fund (CBRF) R.C., S.H. https://honeycouncil.ca/industry-overview/canadian-bee-research-fund/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.