New Light Shed on Bee Parasites, Pathogens
With all the discussion about honey bee health, the implication is that a wealth of information exists about what is normal or healthy for a honey bee. Sadly, there is not. Very little information exists detailing the presence of honey bee pests in the US. Finally we are getting some answers.
The National Honey Bee Disease Survey was initiated in 2009 to document honey bee pests and pathogens throughout the US in the response to concerns over declining honey bee populations and to meet import/export requirements for international trade. A report summarizing the first five years of sample collection has just been published. Researchers detailed their observations on mites, fungal pathogens, and viruses. A critical component of the survey is to also analyze pesticide residues in apiaries; however, this information was not included in this report.
During the first five years of the survey, populations of Varroa mite and Nosema spp. (a fungal pathogen of honey bees) were far greater than expected. From 2009-2014, Varroa mites were positively identified in 87 – 98% of the sampled apiaries, and their populations were surprisingly seasonal. The highest monthly Varroa mite loads were observed in August through November. Furthermore, 55-70% of all sampled apiaries had mite populations over the critical economic threshold level at the critical time right before winter. Nosema spp. incidence ranged from 42-79% of sampled apiaries during 2009-2014, and was greater in migratory colonies (than stationary colonies).
Varroa mites are closely linked to virus infections; so, it follows that researchers saw a high incidence of viral infections associated with high mite populations. Eight viruses were monitored each year. Dwarf wing virus consistently had the greatest incidence with detected levels above 80% each year, while chronic bee paralysis virus doubled annually since 2010.
There is some good news: three exotic pest problems of, Tropilaelaps mite, slow paralysis virus, and Apis cerana (Asian honey bee), have not yet been detected in the US.
Researchers at the University of Maryland and USDA lead this multiyear effort. This first summary will serve as a baseline to measure trends and patterns over time, bringing much needed information to identify drivers of poor bee health. Plus it will be useful for detection of changes and new pests. Researchers also plan to correlate colony health to in-hive pesticide residues.
Share This Post
