Investigating colony-level health traits in Canada’s honey bee population

The main causes of colony death, as reported by Canadian beekeepers, include high pathogen/parasite infestation levels (e.g. Varroa mites, Nosema spp.), poor quality queens and severe weather conditions. Every year, Canadian beekeepers purchase approximately 300,000 foreign queens and package bees to replace dead colonies or expand their operations. Such large-scale importation of stock has the potential to introduce undesirable pathogens or genetics and supply bees that have not been selected to survive in northern temperate climates. The overall goal of our ongoing research is to develop genomic and proteomic markers for 12 economically-valuable traits (colony phenotypes), which will enable local queen producers to rapidly select and breed healthy and productive colonies that are well adapted Canadian to conditions. Based on the rich dataset resulting from colony evaluations from this project to date, this presentation will focus on the relationships among colony phenotypes and the dynamics of diseases and parasites on colony health and productivity. We also will evaluate the relative importance of these factors on winter mortality.

In the first year of our study, 1025 colonies from across Canada were phenotyped for the following colony-level traits: Varroa mite population growth, grooming, hygienic behaviour, defensiveness, honey production, brood area, pathogen abundance, innate immunity, gut microbiota and overwintering success. As anticipated, significant correlations were found among similar productivity phenotypes such as fall and spring colony weights (r2 = 0.8374; P < 0.001), as well as between instantaneous and total honey production (r2= 0.6905; P < 0.001). We also determined that decreased hygienic behaviour was associated with higher Varroa mite population growth rates and greater DWV-A copy numbers. Increased colony mite populations were also associated with lowered mite resistance and higher levels of DWV-A and DWV-B. We further determined that increases in DWV-A and decreases colony weight were highly associated with winter mortality.

We are continuing to model and analyze these data to determine predictive relationships, which will be further discussed. Progress in identifying proteomic and SNP markers for economically-desirable traits will be reviewed along with implications for improved methods for trait selection.