A common pesticide used by beekeepers to kill honeybee-infecting mites temporarily leaves the bees more susceptible to a debilitating virus, new research suggests.
From parasitic flies to numerous viruses, honeybee colonies across the globe have a lot of things threatening their survival, but perhaps no stressor is as disastrous as varroa destructor mites. The tiny vampiric arachnids latch onto bees of all stages of life and suck their “blood.” Often in the process, the mites deliver to the bees deformed wing virus — which causes wing disfigurements in developing pupae, resulting in flightless bees that die shortly after their emergence. Both these mites and the deformed wing virus have been implicated in colony collapse disorder, and together they can wipe out an entire honeybee colony within a few years if left untreated, scientists have found.
The most successful weapon against these mites (at least those that haven’t developed a resistance) has been pesticides called acaricides. However, scientists know little about the chemicals’ effects on honeybee viruses. To find out, Joachim de Miranda, a bee ecologist at the Swedish University of Agriculture Sciences in Uppsala, Sweden, and his colleagues studied the effects of the common acaricide Apistanon levels of several viruses in honeybees.
To their surprise, they found that concentrations of deformed wing virus in treated bee colonies initially increased for a period, before ultimately dropping when more mites died (though the virus levels didn’t fall below those seen in untreated colonies until the last week of the 6-week treatment used in the study).
If future studies conclusively show that Apistan causes a spike in the virulence of deformed wing virus, the findings could have implications for beekeepers, the researchers say.
“Make sure that you know that you absolutely have to treat before treating with acaricides,” de Miranda told LiveScience. “If you don’t have a lot of mites, then this treatment will only cause you more damage.”
Of mites and viruses
During the winter, honeybees do not hibernate, but instead cling tightly together on the combs in the hive to form insulating “clusters.” While in the cluster, the bees still
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