A press release from the University of Guelph, announces a newly published scientific paper describing recent varroa mite research conducted in Canada. Researchers tested a species of fungus as a possible biological control for varroa, with promising results. One of the researchers, Dr. Ernesto Guzman, is a frequent speaker at beekeeper meetings in the United States, including the Heartland Apicultural Society conference in Indiana in 2011.
Keep in mind that commercial control products based on such research will take years to develop, or may never materialize. I recall sitting in a meeting in 1999 and hearing a scientist report on her research, using a different fungus from the one in the Canadian study, and on its potential as a varroa control product. Here is a report on that research, conducted at the USDA Weslaco Bee lab. Scientists in England also looked a varroa eating fungus over ten years ago. A varroa control product has yet to be developed as a result of either of these studies. Read the press release, but don’t start looking in the beekeeping catalogs for a varroa eating fungus product any time soon.
Below is the press release on the new Canadian research.For Immediate Release University of Guelph
Fungus Fights Deadly Bee Mites in a Two-Pronged Attack
Fungi used in the biological control of a destructive honey bee parasite may protect bees by both infecting the mites and preventing suppression of the bee’s own immune response.
(October 22, 2012) – Guelph, ON
A fungus normally used to control insect pests may help honey bees protect themselves from a destructive mite by both infecting the mites and preventing suppression of the bee immune system, says a team of bee researchers at the University of Guelph.
The Varroa mite is a devastating bee pathogen that, if left untreated, can kill an entire honey bee colony. Beekeepers typically treat their colonies with miticides to control the mites, but resistance to these chemicals has become widespread. The Varroa mite is believed to be a leading factor in the high winter mortality experienced in Canadian bee colonies in recent years.
“Beekeepers have an urgent need for effective, bee-friendly Varroa treatments. Naturally-occurring entomopathogenic fungi could be an effective, biologically-based control method. They are non-toxic to humans and can be mass-cultured,” explains Mollah Md. Hamiduzzaman, a post-doctoral researcher in the School of Environmental Sciences and lead author of the study.
Hamiduzzaman and colleagues looked at gene expression in honey bee larvae exposed to regular mites and mites inoculated with fungus. Infection with Varroa typically leads to lower expression of genes involved in the bee immune response, leaving bees less able to fend off the parasite. When mites were first inoculated with the fungus, however, expression of three important immunity genes jumped 2-3 fold over normal levels. “The results suggest that the fungi could reduce damage from Varroa mites by both infecting the parasites, and preventing the mites from suppressing the bee’s natural immune response,” says Hamiduzzaman.
Because the fungi are natural insect pathogens, however, the honey bees can also be vulnerable to infection from the fungus. According to Ernesto Guzman, an entomologist and collaborator on the study, “the trick is to find a fungus that kills Varroa at doses that are relatively harmless to the bees”. The team looked at several strains of fungus and identified one strain of Metarhizium anisopliae that causes high mite mortality (over 90%) and relatively low bee mortality (24%). Guzman says it may be possible to find other strains that are just as effective against mites but less harmful to honey bees.
Another interesting possibility, adds Guzman, is to isolate the factors that trigger the enhanced bee immune response from the fungus. “These compounds could potentially then be applied to hives to trigger a natural defense against Varroa infections.”
Graduate student Alice Sinia and pathologist Paul Goodwin also collaborated on the study. The results have been published in the most recent issue of the Journal of Invertebrate Pathology.
This project was supported with funds from the Natural Sciences and Engineering Research Council of Canada and the Ontario Ministry of Food and Rural Affairs. The study is contribution #61 to the Canadian Pollination Initiative (NSERC-CANPOLIN).
Hamiduzzaman, M.M., A. Sinia, E. Guzman-Novoa and P. Goodwin. 2012. Entomopathogenic fungi as potential biocontrol agents of ecto-parasitic mite, Varroa destructor, and their effect on the immune response of honey bees (Apis mellifera L.). Journal of Invertebrate Pathology 111(3) 237-243. (published online: http://dx.doi.org/10.1016/j.jip.2012.09.001 )
what do you recommend that we do use to control them?
Greg
We have two classes of products to control varroa. The older, more toxic chemicals, Apistan – active ingredient fluvalinate and CheckmitePlus – active ingredient coumaphos. These are traditional agricultural pesticides, which have been used for many years and most beekeeping professionals have great concerns about negative effects upon honey bees from their use. In addition, due to the long length of time they have been used to control varroa, varroa mites have become resistant to them in varying degrees, so they are not as effective as they once were. There is a newer generation of varroa control products on the market, products like Api Life Var, ApiGuard, the Miteaway Quick Strip and Hop Guard. These products use more natural materials like thymol, formic acid and hop oil. These ingredients considered easier on the bees, if used correctly and are effective. I recommend these newer products. I also recommend that you contact your apiculture extension specialist or your local bee inspector for advice. Some products may work better than others in your area and some are not legal in all states. Also, always follow the label instructions that come with the product.
Phil