Wild Honey Bees in a US Forest Show Resilience to a Deadly Virus, Researchers Report

A new study by Penn State researchers revealed that a forest-dwelling honey bee population in New York has evolved to resist a virus that has been decimating managed colonies across the world.

The findings could have implications for preventing or treating the virus in commercial apiaries, the researchers said.

The deformed wing virus and its mite vector

(Photo : ANTHONY WALLACE/AFP via Getty Images)

The deformed wing virus (DWV) is one of the most serious threats to honey bees, according to the researchers.

The virus is transmitted by the Varroa destructor mite, a tiny parasite that infests honey bee colonies and feeds on their blood.

The virus causes severe deformities in the wings and other body parts of infected bees and often leads to their premature death.

It is especially harmful when it infects bee pupae, the developmental stage between larvae and adults. The infected pupae grow up to have twisted wings and other abnormalities and usually die shortly after reaching adulthood.

The virus also weakens the immune system of adult bees, making them more susceptible to other diseases and environmental stressors.

The virus and the mite have been spreading rapidly across the world, causing massive losses of honey bee colonies in many regions.

In the United States, the virus and the mite are considered to be the main factors behind the phenomenon of colony collapse disorder (CCD), which has been affecting beekeepers since 2006.

CCD is characterized by the sudden disappearance of most of the worker bees from a colony, leaving behind the queen and a few young bees.

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The wild honey bees of Arnot Forest

However, not all honey bee populations are equally vulnerable to the virus and the mite.

The researchers discovered that a wild honey bee population living in the Arnot Forest, a 4,000-acre research forest owned by Cornell University near Ithaca, New York, has developed a natural resistance to the virus.

The researchers compared the rates and severity of DWV infection in the wild honey bees from the forest to those in managed colonies from New York and Pennsylvania.

They found that while the infection rates were similar across all groups, the virus genotype--or variant of a virus--found in the wild honey bees resulted in milder infections than the virus found in the managed colonies.

The researchers speculated that the virus may have evolved to be less virulent in the forest because of the lower density and diversity of honey bee colonies in the area.

In contrast, in areas where beekeepers keep many colonies close together, the virus can spread more easily and rapidly to new hosts, and thus has no incentive to become less harmful to its host.

The researchers also suggested that the wild honey bees may have developed some behavioral or physiological adaptations to cope with the virus and the mite, such as grooming, hygienic behavior, or immune responses.

They noted that the wild honey bees have been living in the forest for at least 40 years, and have likely been exposed to the virus and the mite for a long time.

The researchers said that the findings could have implications for preventing or treating the virus in managed colonies.

According to them, learning how different virus genotypes could result in more or less severe infections could help them better understand the infection dynamics and epidemiology of the virus.

They also said that identifying the factors that enable the wild honey bees to survive the virus and the mite could help them develop strategies to enhance the resilience of commercial colonies.

The study was published in the Proceedings of the Royal Society B. The lead author of the study was Allyson Ray, a postdoctoral scholar at Vanderbilt University who researched while a graduate student at Penn State in the Molecular, Cellular, and Integrative Biosciences Graduate Program.

The co-authors of the study were Christina Grozinger, Publius Vergilius Maro Professor of Entomology and director of the Center for Pollinator Research at Penn State, and Harland Patch, assistant research professor of entomology at Penn State.

The study was funded by the U.S. Department of Agriculture and the National Science Foundation.

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