Varroa-resistant honey bees developed by ARS will survive winter better: USDA ARS



Varroa-resistant honey bees developed by ARS will survive winter better

Contact person: Kim Kaplan
Email: Kim Kaplan

Baton Rouge, Louisiana, April 7, 2022—According to a study published in Scientific reports.

Although ARS developed the Pol lineage bees in 2014, this study was the first time they had been tested head-to-head with standard honey bee stocks in commercial apiaries providing pollination services and producing honey. honey. The ability of colonies to survive the winter without being treated for Varroa mites was monitored in four states: Mississippi, California, and North and South Dakota.

In this study, colonies of the Pol line that received no treatment to control Varroa mites in the fall had a survival rate of 62.5% compared to standard bee colonies in commercial apiaries that did not. also had not received Varroa treatment in the fall, which had a winter survival rate of 3%. percent.

When colonies of the Pol line and standard colonies were treated against Varroa mites in the fall and in December, the bees of the Pol line had a winter survival rate of 72%, while the standard bees had a rate 56% survival. Thus, the bees of the Pol line always had a better winter survival rate, even after receiving a double treatment against Varroa mites.

“These survival results continue to underscore the importance for beekeepers of managing Varroa infestations. The ability to have high colony survival with reduced or no Varroa treatments can save beekeepers time and money. money,” said molecular biologist Michael Simone-Finstrom, co-lead of the study with research entomologist Frank Rinkevich, both from the Honey Bee Breeding, Genetics and Physiology Research Laboratory. ARS in Baton Rouge, Louisiana.

This research was the culmination of breeding efforts to develop honey bee colonies with naturally low Varroa populations that began at the Baton Rouge laboratory in the late 1990s.

The survival of winter colonies is crucial for beekeepers because in February each year, approximately 2.5 million honey bee colonies are needed in California to pollinate almond crops. Larger, healthier colonies earn beekeepers premium pollination contracts at around $220 per colony.

A line of bees developed by ARS that naturally has low levels of Varroa mites is more than twice as likely to survive the winter as standard honey bees.

Varroa mites can cause massive colony losses; they have been the biggest problem beekeepers have faced since they spread to the United States from Southeast Asia in 1987. Although there are acaricides used to control Varroa, resistance is developing to some of them.

“We would like to replace reliance on chemical controls with honey bees like Pol-line which themselves have high resistance to mites and perform well, including high honey production, in commercial beekeeping operations. Pol-line mites is based on their behavior to eliminate varroa mites by expelling infested pupae — where varroa mites breed — a trait called varroa-sensitive hygiene (VSH),” Rinkevich said.

“Beyond Pol-line bees, we need to create advanced and easy breeding selection tools that beekeepers can use to select resistance traits in their own bees to promote VSH behavior in honey bees across the world. country,” Simone-Finstrom said. “The great thing about this particular trait is that we’ve learned that honey bees of all types express it at some level, so we know that with the right tools it can be promoted and selected for in bees from everybody.”

Evolutionary ecologist Thomas O’Shea-Wheller, now at the University of Exeter in England, who worked on the study while a post-doctoral fellow at Louisiana State University under the supervision of the Professor Kristen Healy, pointed out: “This type of resistance provides a natural and long-lasting solution to the threat posed by Varroa mites. It does not rely on chemicals or human intervention.

In addition to overall winter survival, scientists looked at virus levels in colonies of Pol and standard lineage bees that are commonly transmitted by varroa mites.

Pol lineage colonies had significantly lower levels of three major viruses: deformed wing virus A, deformed wing virus B and chronic bee paralysis virus, all of which can cause problems important to colonies.

“Interestingly, when we looked at viral infection levels separately from mite infestation levels, we found that there was no strong correlation between viral loads and colony survival. You couldn’t use the level of these viruses as good predictors of the colony. losses,” Simone-Finstrom said.

The Agricultural Research Service is the principal internal scientific research agency of the United States Department of Agriculture. Daily, ARS focuses on solutions to agricultural problems affecting America. Every dollar invested in agricultural research translates into $17 of economic impact.

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