Feral colonies provide clues for enhancing honey bee tolerance to pathogens

January 21, 2021

Understanding the genetic and environmental factors that enable some feral honey bee colonies to tolerate pathogens and survive the winter in the absence of beekeeping management may help lead to breeding stocks that would enhance survival of managed colonies, according to a study led by researchers in Penn State's College of Agricultural Sciences.

Feralization occurs when previously domesticated organisms escape to the wild and establish populations in the absence of human influence, explained lead researcher Chauncy Hinshaw, doctoral candidate in plant pathology and environmental microbiology.

"In the case of honey bees, colonies that escape domestication and establish in the wild provide an opportunity to study how environmental and genetic factors affect the fitness of feral organisms compared to their domesticated counterparts," Hinshaw said. "Some have suggested that the artificial selection associated with domestication of honey bees has decreased their fitness and has made managed colonies vulnerable to pests and pathogens."

Feral honey bees frequently interact with both managed and wild bee species, playing a critical role in the dynamics of pathogens that are shared among these closely related groups, noted study co-author Margarita López-Uribe, assistant professor of entomology and Lorenzo L. Langstroth Early Career Professor.

"Both domesticated and feral honey bees face serious challenges from a large number of pests and pathogens, but feral honey bees must deal with diseases by themselves since they don't have beekeepers helping them control pest problems in the colony," she said. "This makes honey bees an ideal model to investigate the hypothesis that host-pathogen dynamics during feralization can result in higher disease pressure and pathogen tolerance in feral organisms."

The research team set out to answer three questions: Are feral colonies reservoirs of pathogens, with high pathogen levels compared to managed colonies? Do increased pathogen levels lead to higher expression of immune genes in feral colonies than in managed colonies? Is immune gene expression correlated with survival of honey bee colonies?

To address these questions, the researchers partnered with beekeepers to locate 25 feral honey bee colonies across Pennsylvania and paired each of those colonies with a managed colony within a seven-mile radius to control for climate and landscape variation. The team surveyed these colonies over a two-year period to measure winter survival, levels of three pathogens -- deformed wing virus, black queen cell virus and Nosema ceranae -- and expression of six genes that regulate immunity.

Deformed wing virus, or DWV, is considered the most serious honey bee viral pathogen because of its prevalence worldwide and its role in winter losses of colonies. DWV and other viruses often are spread by parasitic Varroa mites, requiring beekeepers to implement management strategies to minimize mite infestations among their bees.

The team's findings, recently published in Frontiers in Ecology and Evolution, indicated that feral colonies had higher levels of DWV, but it was variable over time compared to managed colonies. In addition, higher pathogen levels were associated with increased immune gene expression, with feral colonies showing higher expression in five of the six examined immune genes for at least one sampling period.

"We also found that differential expression of the immune genes hymenoptaecin and vago increased the odds of overwintering survival in both managed and feral colonies," Hinshaw said. "As a result, these two genes could be considered biomarkers of honey bee health that can be used to predict the ability of a colony to survive the winter."

López-Uribe said the results provide evidence for the role of feralization in altering pathogen landscapes and host immune responses.

"Our study was the first to show the association of host-pathogen dynamics with survival of feral colonies," she said. "Further research to identify the genetic mechanisms of virus tolerance and biomarkers of bee health can help breeding efforts to enhance these traits in selected honey bee stocks, with the goal of decreasing colony losses for the beekeeping industry."
-end-
Other researchers on the project were Kathleen Evans, doctoral candidate in entomology at the University of Maryland, and Cristina Rosa, associate professor of plant virology, Penn State.

The Penn State College of Agricultural Sciences' Strategic Networks and Initiatives Program partially funded this work through the Graduate Training Program in Integrative Pollinator Ecology. The U.S. Department of Agriculture's National Institute of Food and Agriculture also supported the research.

Penn State

Related Bees Articles from Brightsurf:

Two pesticides approved for use in US harmful to bees
A previously banned insecticide, which was approved for agricultural use last year in the United States, is harmful for bees and other beneficial insects that are crucial for agriculture, and a second pesticide in widespread use also harms these insects.

Native bees also facing novel pandemic
There is growing evidence that another ''pandemic'' has been infecting bees around the world for the past two decades, and is spreading: a fungal pathogen known as Nosema.

Bees grooming each other can boost colony immunity
Honeybees that specialise in grooming their nestmates (allogroomers) to ward off pests play a central role in the colony, finds a new UCL and University of Florence study published in Scientific Reports.

Microalgae food for honey bees
A microscopic algae ('microalgae') could provide a complete and sustainably sourced supplemental diet to boost the robustness of managed honey bees, according to research just published by Agricultural Research Service scientists in the journal Apidologie.

Bees point to new evolutionary answers
Evolutionary biology aims to explain how new species arise and evolve to occupy myriad niches -- but it is not a singular or simplistic story.

Quantifying objects: bees recognize that six is more than four
A new study at the University of Cologne proves that insects can perform basic numerical cognition tasks.

Prescribed burns benefit bees
Freshly burned longleaf pine forests have more than double the total number of bees and bee species than similar forests that have not burned in over 50 years, according to new research from North Carolina State University.

Insecticides are becoming more toxic to honey bees
Researchers discover that neonicotinoid seed treatments are driving a dramatic increase in insecticide toxicity in U.S. agricultural landscapes, despite evidence that these treatments have little to no benefit in many crops.

Neonicotinoids: Despite EU moratorium, bees still at risk
Since 2013, a European Union moratorium has restricted the application of three neonicotinoids to crops that attract bees because of the harmful effects they are deemed to have on these insects.

Bees 'surf' atop water
Ever see a bee stuck in a pool? He's surfing to escape.

Read More: Bees News and Bees Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.