‘Trojan hives’ carry parasites to native bees

Many bumblebee colonies imported into the UK for crop pollination are infested with parasites, a study in the Journal of Applied Ecology suggests.

More than a million bumblebee colonies are shipped around the world each year. When the bees alight on the same flowers as native insects, they can transmit parasites. Some countries now require imported colonies to be tested for diseases, and companies “often claim that their colonies are free of parasites,” the study authors write.

Not so, the team found. The researchers tested 48 colonies imported into the UK in 2011 and 2012 and found parasites in 77 percent of them. They also investigated whether the parasites could infect other insects. The survival of bumblebees exposed to feces from the diseased colonies dropped from 61 to 44 percent, and honeybee survival dropped from 70 to 40 percent.

The results “are genuinely alarming,” the researchers write. They urge countries to adopt stricter checks on colonies “to reduce the pathogen spillover threat from commercially produced bumblebees.” Roberta Kwok | 18 July 2013

Source: Graystock, P. et al. 2013. The Trojan hives: pollinator pathogens, imported and distributed in bumblebee colonies. Journal of Applied Ecology doi: 10.1111/1365-2664.12134.

Image © simongaberscik | Shutterstock



  • Joshua July 21, 2013 at 7:00 pm

    Varoa Mites are what I assume they are referencing https://en.wikipedia.org/wiki/Varroa_destructor

    They are prevalent in almost every bee hive in North America and most countries around the world. Why they wouldn’t identify the “parasite” I don’t know, but I’m not an expert in these things, just a beekeeper.
    They do affect the health of Honeybees and Bumbles, but not significantly if appropriate measures are taken.
    I can’t read the full study, but I would suggest the researchers need to study up on their beekeeping perhaps?


    • Roberta Kwok July 23, 2013 at 12:14 pm

      Hi Joshua,

      Here’s what the authors say about the parasites they looked for:

      “We screened the bees for the three main bumblebee parasites [the trypanosome Crithidia bombi, the microsporidian Nosema bombi and the neogregarine Apicystis bombi, all of which are faecal–orally transmitted parasites of adult bees, (Schmid-Hempel 1998)], four widespread honeybee parasites [the faecal–orally transmitted microsporidian parasites of adult bees Nosema apis and N. ceranae and the orally infecting foulbrood bacteria Melissococcus plutonius and Paenibacillus larvae of bee larvae, (Morse & Flottum 1997)], deformed wing virus (DWV), which is a common parasite in honeybees and bumblebees (Evison et al. 2012), and the orally infecting fungal parasite Ascosphaera of bee larvae (Aronstein & Murray 2010).”

      And here’s what they say about the parasites they found in the colonies:

      “The parasites included three specialist parasites of bumblebees (Apicystis bombi, Crithidia bombi and Nosema bombi) that can negatively affect their health (Schmid-Hempel 2001)… There was also evidence of two parasites (DWV and N. ceranae), which can infect bumblebees and honeybees (Genersch et al. 2006; Graystock et al. 2013), and three other honeybee-specific parasites, including P. larvae.”


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