Bees, Beer, and Dead Mites

Bees and Beer (Source

Bees and Beer   (Source: YouTube)

Can beer save the bees? No, but with enough beer, bees may not care that mites are crawling all over them.  There have been headlines over the past month suggesting that beer will save the honey bees, but that’s not quite the real story.

Instead, there is a new natural miticide that kills Varroa mites. It’s based on hops, a product used to make beer.  A study from the Carl Hayden Bee Lab in Tucson showed that a solution of 1 per cent hops beta acid swabbed on worker bees’ backsides killed Varroa mites but not honey bees. Cardboard tabs dipped in a hops beta acid solution also eliminated mites when inserted into a beehive.

Alpha and beta hops acids are used in beer making. The beta acid is even more bitter than the alpha line. Bees avoid sipping bitter stuff, so they are unlikely to imbibe the brew material. Further, it appears to be safe for honey bees when used in the beehive. In the USA, the Environmental Protection Agency (EPA) recently approved the use of a commercially made hops beta acid application. This is important because it clears the way for yet another mite killer, this time a natural product, to be used inside the beehive.

Flowering Hops Plant

Flowering Hops Plant Source: Wikipedia

The new product is a biochemical miticide, Potassium Salts of Hops Beta Acids, which is derived from the cones of female hop plants, Humulus lupulus. The EPA registration allows beekeepers to use it in the fight against varroa mites. Significantly, it should allow beekeepers to take a break from other chemicals, disrupting the mite’s cycle of resistance which grows if the same products are repeatedly used to fight mites. The registrant is Beta Tech Hop Products,  which will make plastic strips containing the biopesticide.  According to a news release from the EPA itself, a biopesticide is a “naturally-occurring substance with minimal toxicity and a non-toxic mode of action against the target pest(s). There are numerous advantages to using biopesticides, including reduced toxicity to other organisms (not intended to be affected), effectiveness in small quantities, and reduced environmental impact.” That sounds good.

It’s not surprising that mites succumb to hops acid. Some of the other standard miticides are also acid-based. Oxalic acid and formic acid are examples. All of these – hops, oxalic, formic, and other acids – even pass the test for “organic” in most cases. (It depends on who’s rules you’re following.) But the difficult thing about these natural acids is that you have to use them at high enough concentrations to kill mites but low enough concentrations to not slaughter bees. And that can be really tricky. Air temperature, draft, and colony populations need to be factored in when preparing to fumigate with acids. Plus, beekeepers are notoriously inept at following instructions. Although these treatments usually work, they can kill your bees. Perhaps hops acid will not be so finicky to apply.

Initial reports about the safety and efficacy of hops is encouraging. The December 2012 report from  the Arizona bee lab shows Gloria DeGrandi-Hoffman as the contact researcher. Dr Hoffman is noted as a careful and thorough scientist. Her work was made public three years ago and already a commercial product has been derived from the research and is now available to beekeepers. A big hurdle was EPA approval, which was granted in October, 2015. Here is a summary of the research:

“Hop (Humulus lupulus L.) beta acids (HBA) were tested for miticidal effects on varroa destructor Anderson and Trueman, a parasitic mite of the honey bee (Apis mellifera L.). When varroa were placed on bees that had topical applications of 1 % HBA, there was 100 % mite mortality. Bee mortality was unaffected. Cardboard strips saturated with HBA and placed in colonies resulted in mite drop that was significantly greater than in untreated hives. HBA was detected on about 60 % of the bees in colonies during the first 48 h after application. Mite drop in colonies lasted for about 7 days with the highest drop occurring in the first 2-3 days after treatment. There was a reduction in the percentages of bees with HBA and in the amounts on their bodies after 7 days. Bee and queen mortality in the colonies were not affected by HBA treatments. When cardboard strips saturated with HBA were put in packages of bees, more than 90 % of the mites were killed without an increase in bee mortality. HBA might have potential to control varroa when establishing colonies from packages or during broodless periods.”

In late October, the EPA released its ‘tolerance’ exemption for hops acid, apparently offering a free pass if any is later found in honey. Here is part of what the government released:  “This regulation establishes an exemption from the requirement of a tolerance for residues of the biochemical pesticide potassium salts of hops beta acids in or on honey and honeycomb for the control of Varroa mites in accordance with label directions and good agricultural practices. This is good news for beekeepers – they can use what they need without risking contamination to their honey by a harsh chemical. Hope hops works as well as a cold beer to reduce everyone’s concerns about mites.

Varroa destructor on a honey bee, photographed by USDA Ag Research Service, using an electron microscope.

Varroa destructor on a honey bee,
photographed by the USDA Ag Research Service, using an electron microscope.

About Ron Miksha

Ron Miksha is a bee ecologist working at the University of Calgary. He is also a geophysicist and does a bit of science writing and blogging. Ron has worked as a radio broadcaster, a beekeeper, and Earth scientist. (Ask him about seismic waves.) He's based in Calgary, Alberta, Canada.
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7 Responses to Bees, Beer, and Dead Mites

  1. Emily Scott says:

    I thought HopGuard had been around a few years – how much of an advance is this new formulation? And have instructions being given on whether it can be used in combination during the year with the other acids you mention, such as oxalic or formic (MAQs)? There have been some warnings given to UK beekeepers by the bee inspectors here that we should be careful about giving both MAQs and oxalic acid to a colony because of the potential effect on the queen (even several months apart).


    • Miksha says:

      Thanks Emily! It’s the ARS research that’s new and last month’s EPA approval of the strips. Be sure to read te linked articles from the manufacturer, from ARS, and from the EPA.
      Things are likely different in the UK. Do you find it effective in England? Maybe the new delivery system will help reduce queen losses, which I’ve seen with oxalic acid.


  2. Emily Scott says:

    My beekeeping partner Emma wrote that Ealing Bees post! But the concern has only been about combining the two acids. I wonder whether the Canadian beekeepers could have overused OA, either by using it more than once in a year in dribble form or applying a high dosage. Beekeepers here often buy it premixed in sugar solution at the right syrup to acid strength ratio (though this will be changing now that a new ApiBoxal product is the only approved product in the market), whereas I imagine it’s easier to get wrong if you’re having to mix it up yourself at home.


  3. john middleton says:

    I dried some hops out and ground them down to flour, for my wife to use as a natural yeast in baking, July this year I decided to try some with my bees, I sprinkled half a teacup over the frames of each of my hives, the bees loved it, there was a good varroa drop, and the bees have thrived.

    Liked by 1 person

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