U of S research collaboration with Saskatraz honeybee breeding program helps breed bees resistant to Varroa mites

A University of Saskatchewan research collaboration with the Saskatraz Honeybee Breeding Project has identified how the Varroa destructor parasite suppresses the immune system in honeybees, a species that helps produce about one third of the world's food crops through pollination. They have also developed a tool to help breeders select bees resistant to the parasite and associated disease-causing microorganisms.

"Our study offers insights into why Varroa-susceptible bees run into trouble," said Scott Napper, one of the lead authors of a study published May 21 in the journal Frontiers in Genetics. Napper is a professor of biochemistry at the U of S and senior scientist at the Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac).

"Once they are Varroa infested they become more immune compromised," he said. "This leads to a number of secondary infections that likely leads to the death of the bees and the collapse of the colony."

Saskatraz was founded in 2004 by honeybee breeder and molecular biologist Albert Robertson, working in cooperation with Saskatchewan beekeepers. By putting bee colonies under pressure of Varroa infestation without treatments to protect them from the mites, then breeding the survivors, the project has had success in identifying Varroa-resistant bees.

"Our breeding and research work is recognized globally," said Robertson, who is also CEO and senior scientist with Meadow Ridge Enterprises near Saskatoon. "To my knowledge, we are the first to combine naturally selected stock, that is, survivors, with defined behavioral traits for Varroa resistance. Selection of these phenotypes allowed us to use established molecular techniques to identify potential molecular markers."

These techniques marry tools from biochemistry and computer science - a field called bioinformatics - to shed light on bee genetics. The team had already developed a microarray and associated software to allow researchers to screen for many molecular markers from any organism (a microarray looks like a standard microscope slide with rows of tiny spots, each spot representing a different molecular test).

The team analyzed whole bees using microarrays, looking for differences in susceptible and resistant hives. One challenge was to find markers specific to honeybees, which had yet to be identified.

Enter DAPPLE, a tool developed by computer science PhD student Brett Trost. Working under the supervision of professor and bioinformatics specialist Tony Kusalik, he scoured extensive online databases for molecular markers. While there were none in the catalogues specific to bees, DAPPLE could identify candidates for further testing and evaluation.

"The software spits out suggestions with references to (research) papers and you can go to the paper and see if enough evidence exists to pursue it," Trost explained. "You still need a biologist in the end; the computer can only suggest 'this looks like a likely candidate.' It's up to the biologist to make the final selection (of the molecular marker)."

From the microarray experiments, the team identified five molecular targets that reliably distinguish between Varroa-resistant and susceptible honeybees. This eliminates the need to establish a hive, expose it to Varroa, and see how it does - a process that can take several years.

Robertson explained the technology will allow bee breeders to supply queen producers with breeding stock (bees) showing Varroa resistance traits. Further advances could help identify markers for other desirable traits such as honey production and ability to survive the winter.

Funding for the research was provided by Saskatchewan Agriculture, the Agriculture Council of Saskatchewan, Meadow Ridge Enterprises, the Natural Sciences and Engineering Research Council of Canada, and the Canada Research Chairs program.


For more information, contact:

Jennifer Thoma

Media Relations Specialist

University of Saskatchewan Marketing and Communications Team


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