A German “crowd sourcing” fund wanted 10,000 Euros to build honey bee saunas. Within a few weeks, they had over 60,000 Euros in pledges – that’s about $75,000. I guess that the contributors don’t realize bees can die in a sauna. Back to that in a minute.
Varroa mites kill bees. To eat, the nasty mite-creatures grab hold of bees and suck up their insides. Eventually, all colonies with booming varroa mite infestations die. That’s why beekeepers try to poison varroa mites – usually treating their bees with pesticides. Pesticides can leave trace chemicals inside the hive and become dangerous to bees and bee handlers. Further, the mites may evolve resistance against the poisons. Unfortunately, various chemical treatments seem to be the only currently effective and widespread weapon against the deadly varroa mites. But other methods are being tested.
Just as mites evolve to resist chemicals, honey bees may evolve to resist mites. This is the idea behind the celebrated Russian bee. Honey bees found in eastern Russia seemed to have evolved to live with mites. The claim is that most untreated honey bees will die, but a small subset will have some genetic quirk that will allow them to survive varroa attacks.
Genetically quirked bees will reproduce and repopulate the ecological niche lost by their vanquished sisters. This may have happened in isolated areas, such as Siberia. Unfortunately, when the Russian bee was brought to North America, its genetic advantage was quickly diluted by other honey bees already extant in the hives of commercial beekeepers. You see, queen and drone bees fly many kilometres to clandestine rendezvous hangouts where they indiscriminately mate. This evolved habit prevents honey bees from becoming inbred and fosters genetic diversity – within the same colony any two randomly selected co-working workers are likely to be half-sisters, not full sisters. Although this diversity gives many advantages to a colony, it almost kills the idea of maintaining pure-bred naturally mated lines of pest-resistant bees. It takes a good queen breeding program to maintain stock that keeps a line of honey bees imbued with hygienic behaviours and other qualities that suppress varroa populations. There are such queen breeders around and it can be done – but without discipline and diligence, varroa will creep back into an operation.
So, if chemical treatments eventually fail and genetic solutions are hard to maintain, what might be done to fight the dreaded varroa mites? Some beekeepers have lured mites to drone brood, then discarded the comb; others have reported some success dusting powdered (icing) sugar on bees to extricate mites. Greasy vegetable oil sprayed on the bees may slow down mite infestations. A completely different idea – heat – has been occasionally promoted and seems to be going through a bit of a popularity renaissance. Varroa mites, it seems, can’t cling to honey bees if the temperature is hot. This has led to a number of schemes that warm the inside of a hive (or a cage of bees) until the mites fall off. Unfortunately, this does not kill the varroa mites, it just dislodges them – chances of success are likely pretty sketchy using this system.
The USDA studied this idea 15 years ago. You can read their report at this link. Here’s the problem: at temperatures of 40ºC (104ºF) and higher, mites slowly fall off honey bees but bees begin to suffer heat stress. Honey bees, as you likely know, try to keep their nest temperature at about 35ºC (95ºF). Way back in 1791, Francis Huber discovered that even on the hottest summer days, bees did not allow their nest to rise above 99ºF. Remember, mites fall off at 104ºF. So it is hard to get a high enough temperature inside a hive to dislodge varroa mites. The bees will fan and evaporate water and reduce the hive temperature so they do not die of heat exhaustion and so their wax home doesn’t melt into a candle-like blob. High air temperatures dislodge mites if the temperature is warm enough for a long enough period of time. Higher temperatures (over 45ºC or 113ºF) will make the mites fall in just a few minutes, but will also kill honey bees more quickly. The USDA study shows that bees get crispy if they are exposed to too much heat – or even a little heat for too long a time. Quoting the USDA 2001 study: “Overall, heat treatment is a risky procedure. Even 40ºC, the lowest temperature that can remove all the mites is perilously close to temperatures that kill bees.”
With these potential problems in mind, I was surprised to see that a German Crowd Sourcing Fund was able to quickly raise a huge amount of money to build a Bee Hive Sauna. The crowd sourcing goal was 10,000 Euros. They have over 60,000 Euros in pledges – that’s about $75,000. Their self-promotion site includes the non-Einstein quote (“…if all the bees die, in 4 years you will too…”) and it includes lots of Wir retten Bienen (“We save Bees”) subtexts. So, the promoters know how to appeal to the heart-strings of the misinformed. My guess is that the contributors/donators/funders don’t realize that bees can die in a sauna. The trick that keeps the bees alive, according to the inventor, is that (with his Bienen Sauna) “The Bees do not roar.” (OK, maybe it’s the Google Translator. The original German is Die Bienen brausen nicht.) I have never heard of roaring bees, but roaring seems like a problem to be solved. I will probably get the story wrong, so let’s allow the inventor, Engineer Richard Rossa, to explain:
“The bees do not roar.” “In my trials I came to the realization that roar of bees is not caused by a slow heating of the ambient temperature, but by increased CO2 content of the air. However, this effect does not occur in the treatment with the bees sauna. If necessary, fresh air is supplied at any time. This is done controlled so that no draft is produced. “Holding the air temperature constant between 40°C and 42°C, all Varroa mites, which are long enough exposed to this temperature, irreversibly damaged. Should any of Varroa mites survive, they are so damaged that they can no longer reproduce. Broodless colonies are treated for 45 to 60 minutes. Those with brood take two hours because it takes longer to warm through the brood cells. Then the device switches off automatically. In the entire time temperature and humidity are constantly monitored and regulated in the hive.”
It appears that by ridding CO2 from the hive, the bees won’t roar. If you read their website, you will see that (for about $1,000 per unit) it will be just the varroa mites that do the roaring. Rossa says that the temperature inside the hive/sauna will be kept at 40 to 42ºC. As we have already seen, this is a good bit warmer than the bees like, so I suspect some energy will be wasted by the bees as they gather water and circulate air to get the hive temperature down to their preferred 35ºC. Or I could be wrong. It could be that I am just an old-fashioned cynic who is spouting off about any product that has been tried in a number of commercially available guises over the past few years (see the Mite Zapper and the Varroa Controller).
Maybe I am cynical because some gullible people will quickly fund any cool yuppish idea – even if the procedure has been shown problematic by USDA researchers. However, I do not have a PhD in “Co-operative Communication Strategies for Politics and Media”, whereas Richard Rossa’s partner, Dr Florian Deising does. He was “a management consultant, financial manager [who] led international projects in large corporations… [But 2 years ago, he] got out to make as it were full time our world a better place”. I suppose these guys have their heart in the right place and they obviously know how to work a crowd for money. And perhaps they know how to keep bees from roaring in the sauna. It would be great if some sort of well-engineered hot-hive can actually kill varroa mites without hurting bees. That would eliminate chemical treatments. But at almost $1,000 for each device, the Bee Sauna will probably meet limited success. Personally, I think the long-term future for varroa control will be in genetic manipulation, not in heat. But check out the Bee Sauna at wir-retten-bienen.org (“WE SAVE BEES.ORG”) for yourself and make your own informed decision.