Becoming a beekeeper can be overwhelming at times. One of the most difficult things for me is figuring out how and when to treat the hives to prevent pathogens and parasites from becoming too numerous. We have attended an Integrated Pest Management course but only walked away with a list of offenders and their chemical treatments, which we had already learned through online research. Why not just treat for all, as often as possible? I'd rather not dump these chemicals (several of which are antibiotics) into the hives unless we need to, since they're expensive to buy and their overuse can result in pathogen/parasite resistance.

One of the most prevalent bee parasites is a mite: Varroa destructorVarroa mites attach to developing bees and feed off the nutrients in bee hemolymph (similar to blood). Although they don't immediately kill the bees, they weaken individuals and eventually the whole colony. The mites can also transmit viruses that are harmful to the bees. In the face of these challenges, sometimes it can only take a little push (e.g., harsh winter) for the colony to die.

Treatment for Varroa usually occurs in the Spring and Fall, and involves adding either organic chemicals such as Formic Acid or specially developed miticides.  Unfortunately, the organic chemicals often do not clear the mites and the mites can quickly evolve resistance to the miticides.  Thus, treatment often leaves me feeling like we're only buying time before the mites win.

But new treatments are in the pipeline, and an exciting possibility was just published in the most recent issue of PLoS Pathogens.  Garbian et al. tested whether RNA interference (RNAi) could be used to reduce the pathogenicity of Varroa.  RNAi involves the experimental addition of double-stranded RNA that can bind to a complementary RNA in the mite. These target mite RNAs can be chosen such that important functions needed for mite survival will be affected.  Garbian et al. described experiments where they fed bees sugar water containing mixtures of these RNAs.  The RNAs were able to pass through the bee hemolymph into the mites, and reduce the number of mites per bee by ~2-fold.  However they were only able to follow the hives for 7 weeks, and were unable to determine whether the RNA treatments would result in fewer hive collapses, which often take 2-3 years.

The most exciting thing about using these RNAs as a treatment is that it is unlikely the mites will evolve resistance to the RNAs.  And, if they do over the generations, it is relatively easy to design new RNAs that match the evolved target. Perhaps one drawback is that RNAs are not very stable in the environment, and Garbian et al. even show that the RNAs they use as treatments only lasted six days at the most.  However, this can also be seen as a positive aspect of the treatment as lingering effects on non-target organisms would be short-lived.

Although the results from this particular paper are not yet able to change the treatment regimes for maintaining healthy hives, I think they will have a strong impact in the future.  RNAi-based technology has moved steadily forward in the last decade, making it possible to optimize the experimental approach of Garbian et al. to reduce mite levels further. Additionally, maintaining the health of our most important pollinator, the honeybee, has become an international goal with many governments shuffling funds to prioritize research into enemies of the bees.

Despite the optimism I have for these research directions, I am still a bit nervous about our own bee hives.  We've seen mites in two of the three hives, and have treated using miticides and formic acid.  But we know from the experiences of other beekeepers that treatment alone is not a guarantee. Here's to our bees, and hoping I'll hear their beautiful buzzes next spring.