Treatment and supplemental feeding on colony production and survival in Canada

We examined what effect management factors, specifically treatment for Nosema spp. with fumagillin and provision of supplemental nutrition, had on honey bee colony productivity, pathogen levels, and survival. The study was conducted at three locations: 125 colonies in northern Alberta, Canada, managed for honey production; 120 colonies in southern Alberta managed for hybrid canola seed pollination; and 76 colonies on Prince Edward Island, managed for lowbush blueberry pollination. Protein patty supplements with 25% pollen were provided to half the colonies continuously during the active beekeeping season, except during the bloom period of the major crop. Fumagillin was provided in sugar syrup to half the colonies each fall. Colony populations were assessed at 11 time intervals between May 2014 and May 2016, and samples of adult bees were collected for determination of parasite, pathogen and virus loads.

Sites differed in colony survival over two years, adult and brood populations, and seasonal population patterns. Colony performance in blueberries was poorest overall. Supplemental protein feeding had no general effect on colony productivity measurements and neither protein supplementation nor fumagillin treatment influenced overall colony survival at the two-year time point. Treatment with fumagillin did suppress Nosema spp. loads in colonies after treatment, but was only associated with improved rates of winter survival and honey production for specific site-year combinations. Overall, our results provide modest, conditional support for the use of protein supplements and fumagillin.

Parasite loads in adult bee samples showed that colonies originating from New Zealand packages were initially predominantly infected with N. apis., however after one year, N. ceranae was found to be the dominant species. The trypanosomatid Lotmaria passim was found to be common among colonies. Increased frequency of L. passim detection over the experiment was also associated with greater infections of Nosema spp., as well as increased colony weight loss during winter. Overall, increased incidence of clinical disease symptoms in colonies were found to be highly associated with decreases in honey production and reduced fall adult bee populations, suggesting that disease status may be the most influential determinant of colony outcomes in cold temperate climates.