Research Update Winter 2023

Effect of diet amendments on health of honey bees (Apis mellifera) 

Tests to evaluate the effect of diet amendments on health parameters of honey bees were conducted last Summer and Fall of 2022. We screened several doses of potential beneficial compounds in artificial protein diets provided to caged honey bees as follows: omega 3, 6, and 9 (essential fatty acids), beta-carotene (a precursor of vitamin A), and several nutraceuticals, to investigate their effect on food consumption and survivorship. We found that the essential fatty acids and a hi-dose of beta-carotene resulted in high mortality and were no longer tested. The low dose of beta-carotene and several nutraceuticals that had positive effects on bee health were selected for screening on infection levels of Nosema disease and effects on other health parameters. We are analyzing samples and data. 

Research project: Breeding for Low Varroa Growth (LVG) in Ontario Honey Bee Colonies 

The parasitic mite Varroa destructor has been associated to most overwinter colony losses in Canada, which exceeded 45% during winter 2021-2022, according to the Canadian Association of Professional Apiculturist (CAPA). At the Honey Bee Research Centre, University of Guelph, we implemented a breeding program to select honey bees for varroa mite resistance. The breeding program has been implemented in collaboration with the Ontario Beekeepers Association (OBA), Ontario Queen Breeders Association and Purdue University, and it is focused on selecting bee colonies based on low and high Varroa population growth (LVG and HVG, respectively), by using sticky bottom boards. Preliminary results have shown that in comparison with HVG colonies, LVG colonies had lower rates of varroa mite population growth, more mite mutilation, adult bees had lower levels of Deformed wing virus (DWV), showed more concentration of haemocytes (immune cells) in the haemolymph (insects’ blood), and started performing grooming instances faster (grooming behaviour is a mechanism associated to natural mite resistance). The future steps of this breeding program aim to identify differences in gene expression, metabolome, and gut microbiome between bees from both genotypes, after fourth generations of selection. Also, we aim to find more funding to continue breeding additional generations of selected bees to understand better the mechanisms involved in mite resistance.