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  2. Effects of Host, Pathogen, and Environmental Factors on Increased Incidence of European Foulbrood in Honey Bee

Effects of Host, Pathogen, and Environmental Factors on Increased Incidence of European Foulbrood in Honey Bee

Dr. Sarah Wood, Dr. Ivanna Kozii and Dr. Elemir Simko

Title: Effects of Host, Pathogen, and Environmental Factors on Increased Incidence of European Foulbrood in Honey Bee Colonies Pollinating Blueberries in British Columbia.

Co-principal Investigators: Dr. Sarah Wood, Dr. Ivanna Kozii and Dr. Elemir Simko, Western College of Veterinary Medicine, University of Saskatchewan

Duration: April 1, 2020 to March 31, 2022

Project Summary:

The pollination services provided by honey bees are of great importance to the BC blueberry industry. The ultimate goal of this research program is to improve health and strength of honey bee colonies which will increase efficiency in pollination services to BC blueberries.  European foulbrood (EFB) is a bacterial disease of honey bee larvae caused by the bacterium Melissococcus plutonius which can lead to larval starvation and death under conditions of colony stress. Risk factors for EFB disease during blueberry pollination include pesticide exposure, increased M. plutonius strain virulence, decreased diversity or quality of pollen, and/or inadequate brood care; however, there is a lack of scientific evidence to determine which factors are responsible for the increased incidence of EFB reported by pollinating beekeepers.  Therefore, further investigation into the environmental, pathogen, and host factors which could potentially predispose colonies to EFB disease is required.

  1. Environmental factors: Fungicide exposure in beebread has been identified as risk factor for colony mortality during blueberry pollination. In vitro larval testing of other combinations of pesticides used in blueberries will confirm or disprove the hypothesis that pesticides affect larval susceptibility to EFB.
  2. Pathogen factors: Different strains of M. plutonius harbor different virulence genes.  These genetic differences between strains may result in differences in severity and incidence of EFB disease.  M. plutonius strains from colonies placed in blueberry fields will be compared for pathogenicity and genetic profile to strains from colonies which are not used to pollinate blueberries.
  3. Host and environmental factors: The increased incidence of EFB in colonies involved in blueberry pollination is thought to be driven by poor nutritional value, low acidity level and high prevalence of agrochemical contamination in blueberry pollen.  However, the association between blueberry pollen and increased EFB has never been proven. This project will investigate the combined effects of blueberry pollen diet and colony strength/adequacy of brood care on development of EFB within a colony.

Objectives:

In vitro (in the laboratory) and in vivo (in a honey bee colony) experimental models of EFB will be used to achieve three objectives:

  1. Determine if pesticide exposure increases susceptibility of larvae to EFB in vitroI
  2. Compare the pathogenicity of different strains of EFB in vitro; and
  3. Investigate the effect of pollen and bee bread from blueberry pollination on development of EFB in vivo in the presence of i) adequate nursing bee population, and ii) reduced nursing bee population.