An international team of researchers has discovered honey bee colonies in Newfoundland, Canada, that are free of the invasive parasites that affect honey bees elsewhere in the world. Nancy Ostiguy, associate professor of entomology at Penn State University, was lead author on a paper about these findings, published June 23 in the journal PLOS ONE. She said:
Our ability to find European honey bee populations free of invasive parasites is shrinking. These parasite-free populations in Newfoundland are essential for our ability to understand the interactions among various parasites and pathogens of honey bees.
Invasive parasites — such as Nosema ceranae, a fungus, and Varroa destructor, a mite — have incurred heavy economic penalties on the honey bee industry via colony losses and reduced productivity of surviving colonies, and both parasites threaten global food security because of reduced pollination services to agriculture.
The extent to which these detriments are attributable to specific parasite species is difficult to assess, however, because of the occurrence of multiple parasites within honey bees. Studying the effects of these parasites is even more challenging because few areas in the world have western honey bee colonies that are free of invasive parasites.
Ostiguy and her colleagues found a geographical area in Newfoundland, in which a number of important invasive honey bee parasites, including Varroa destructor and Nosema ceranae, do not exist. The researchers used molecular techniques to test for the presence of viruses and Nosema ceranae in honey bee colonies managed by beekeepers. They used a visual screening method to search for insect parasites, including Varroa destructor. They then assessed the colonies for visual signs of illness and related the illness data with the presence or absence of parasites or viruses.
In the Newfoundland colonies, the researchers found the parasite Nosema apis, the species that has been displaced by Nosema ceranae elsewhere, and the pathogens, black queen cell virus and deformed wing virus. Ostiguy said:
Despite the presence of these parasites and pathogens, colony losses in Newfoundland are very low — similar to the mortality rates reported in the United States before the introduction of Varroa destructor.
Ostiguy said her team will continue to investigate the relationships between various pathogens and parasites of honey bees, along with various stressors, such as pesticide exposure, with the goal of providing information to help keep honey bees healthy.
Bottom line: Scientists say the Newfoundland populations of bees offer them a unique opportunity to investigate honey bee health.