A mushroom extract could save bees from a killer virus

Bees, as you have probably heard, are dying, in large numbers. Known as Colony Collapse Disorder, wasting is one of the causes of a well-known pest Varroa destructor. A flat, button-shaped beast with eight legs and a maximum length of 2 millimeters Varroa The mites invade bee hives around the world en masse, catch their inhabitants and feed on their tissues, transmitting devastating RNA viruses.

The most serious of these diseases is the deformed wing virus, considered one of the most important contributors to the devastation of honeybees in the world. Named for the shrunken and misshapen wings that develop in affected bees, DWV deprives its guests of theft, weakens their immune system and halves their lifespan. The more a bee is sick, the more vain the wings are, the less it pollinates plants. In addition, what flora an infected bee Is manage to become infected with the virus, transmitting the infection to future pollinators. As if a bee-debilitating virus, transmitted by intangible parasites, was not terrifying enough, beekeepers currently have no effective means of fighting the virus.

But in a study reported today in Scientific reports on nature, researchers present evidence of a surprising solution to DWV: fungi. The discovery has implications not only for honeybees populations, but also for food systems, economies and ecosystems that depend on healthy activity.

The mushrooms in question belong to the genera Fomus and Ganoderma, better known mushroom lovers like tinder and reishi. The former usually grow on horse-shoe shaped trees. They have long been popular with traditional medicine and are widely available in Asian markets and health food stores. Both belong to an order of fungi known as polypores, many of which have shown that extracts possess powerful antiviral properties against dangerous infections such as swine flu, smallpox virus and HIV.

"I wanted to see if these extracts had a similar antiviral effect in bees," says Paul Stamets, lead author of the study. A leading mycologist, author of Cultivate gastronomic and medicinal mushroomsand a passionate proselytist of all that is fungal (his talk on TED, "6 ways mushrooms can save the world", has been viewed millions of times), Stamets has long suspected that bees took advantage of fungi.

He remembers a scene taking place in his garden in July 1984 – the first time that he noticed bees from his personal hive that were flying backwards to turn into a pile of wood chips covered with mushrooms. The bees, he says, drank droplets of liquid oozing from the fungus mycelium, the fuzzy web of spider webs through which the mushrooms absorb nutrients.

At the time, he thought the droplets contained sugar (fungi break down the wood into glucose). "But a few years ago, I had an epiphany – a waking dream, actually," says Stamets. And if the bees received more than a shot of sugar? He began to wonder if they were healing themselves.

This question led him to Walter Sheppard, chairman of the entomology department of Washington State University and one of the world's leading experts on bees. With the help of researchers from the Sheppard Laboratory and the US Department of Agriculture, they spent several years administering sweetened water suckers with mycelial extracts of various species of fungi and analyzing them. their effects on infected bees.

In both indoor experiments and outdoor trials, honeybees fed mycelium extracts performed better than those who drank only sugar water. In caged DWV-infected bees, researchers observed a 800-fold decrease in viral titers (a measure of the level of virus in the bee system) among bees treated with DWV extract. # 39; tinder. The effect was less potent in the field, which is less strictly controlled than laboratory tests (colonies fed with reishi extract recorded a 79-fold reduction in DWV, those fed on extract tinder, a reduction of 44 times), but the results were still very significant. (In other field trials, bees fed on reishi extract found a remarkable 45,000 – fold reduction in the Sinai Lake virus, another disease that is currently ravaging populations in the Philippines. honey bees.)

"This has shown a powerful effect, stronger than anything I've seen," says geneticist Jay Evans, head of the USDA's Bee Research Laboratory, who analyzed the virus levels. More powerful yet than RNA interference, another promising – but expensive – approach to fighting the bee virus on which Evans is conducting an investigation. "I'm a little jealous," he says.

Stamets has received numerous patents on the excerpts in the past year and plans to sell them on his website, fungi.com, an area he says he has owned since 1994. "I'm not that money for money, "he says. . "I walk in my conversation and I use my company to fund further research."

More studies are always a good idea, especially for something as apparently effective as these snippets. On the one hand, it is not clear if they will help save bee colonies in the long run. Stamets' field studies took place over two months in summer – but the most difficult time of year for bees is in the winter. Future studies will need to consider how other colonies fed with the extracts bought for six months or more, and how many survived this cold and deadly season.

It is also difficult to know how these extracts reduce viral titers in infected bees. They could strengthen the immune system of insects. Or inhibit the virus directly. Or affect how it replicates inside bees. Or it could be something else. Whatever mechanism is used, it would be useful to understand it better before deploying the extracts on a larger scale. After all, there are also unintended consequences to consider.

"Whenever I hear about something like this, I immediately think about the risks and drawbacks," says Lena Wilfert, evolutionary ecologist at Ulm University in Germany. , which studies the spread of viruses in bees. Among the known viral pathogens that affect insects, she says, the DWV represents the biggest threat, so she understands the potential benefits of powerful anti-virus agents. "But every time you apply a drug on a large scale, you will have a potential for changing resistance in what it targets." These questions have yet to be probed.

"We have to prove all this, you know, and, fortunately, I became more disciplined as a scientist, rubbing shoulders with other scientists," said Stamets, who acknowledged that there was still much to be done. "We are currently testing hundreds of hives and we are building up."

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