This is a wide-ranging article, part of an occasional series, intended to touch on recent developments in beekeeping that have caught my attention – discussion welcomed!
Topics covered here include:
- Hygienic behaviour
- Varroa virus blocking – important new research just published
- Sumps/eco floors and fashionable fungi
- Small Hive Beetle management
- and more…
Hygienic behaviour is key to the bee’s ability to manage varroa and this has been attracting more attention recently. Of course there is Ron Hoskins and the Swindon honeybee conservation group, to whom we devoted an article in June. Now, the BBKA is gathering funding for a 3-year investigation into what happens when a UK population of varroa-tolerant bees is moved to other areas (i.e. can the trait persist and be spread).
However, UK efforts are dwarfed by European and American ones. BBKA News carried an article in October about researcher Gianluigi Bigio who is now helping breed a hygienic strain in Italy; there is a German initiative to develop such characteristics, by the conservation group SMARTBEES, and the aristabeeresearch.org initiative – this seems to be being participated in by the British BIBBA group. In the USA, scientists with links to these European initiatives have developed strains like Baton Rouge, which exhibit varroa hygiene and are becoming more widespread (see map here). The BeeSource forum has been promoting organic, treatment-free beekeeping since 1999; and Stateside queen rearers such as Zia bees are selling other strains of hygienic bees. Other US mite resistant strains are mentioned in passing in stories like this one (see end of 3rd para).
The queen rearers and academics tend to be focussed on intensive queen rearing and controlled breeding. But, since my and others’ experience shows that it doesn’t seem too difficult to run treatment free colonies, especially providing you start with feral stock, it seems likely, to me, that hygienic behaviour is an innate behaviour of bees which has been epigenetically “switched off” to conserve resources until needed again recently.
I’ve come across claims, backed up by a 2001 research paper, that Foulbrood and chalkbrood are virtually non-existent in mite resistant bees. The life cycle of American Foulbrood requires it to go through a vegetative and spore state. Spores are transferred via the mouth parts of an adult bee to the brood when she feeds it. But spores are only formed after capping of an infected larvae, and it dies in the capped cell. So hygienic bees will remove and take infected larvae far from a hive before capping, and dying. This breaks the foulbrood cycle, making it impossible for it to reproduce.
Kevin Mewis of OBKA makes an interesting observation on hygienic bees. He’s trying non-treatment of bees in some hives, and notices that the hives with the fewest deformed wings (i.e. varroa) have spotless, clean floors – which goes against the recent trend with some for ‘eco-floors’ or sumps.
Varroa virus blocking – important new research just published
There is a new development concerning varroa-tolerant bees, with research on the presence of Deformed Wing Virus (DWV), which is largely spread by the varroa mite and one of the chief reasons varroa can so effectively sap a colony’s strength.
In this blog’s earlier article about Ron Hoskins and the Swindon Honeybee Conservation Group’s hygienic bees, we were not at that point permitted to mention that there was ongoing research by a virologist into these bees. That research has just now been made public as of 27th October 2015 in a scientific paper by the virologist group led by Declan Schroeder, with lead author Gideon Mordecai, in the ISME Journal (International Society of Microbial Ecology); you can read the full paper on the journal website or there is a non-technical press-release on the work. There was also a 10 minute report within the BBC TV programme Inside Out West on 26th Oct. (If you are in the UK, and viewing within~28 days of this post going up, you can see the programme on the BBC iPlayer here: the report starts after about 19 minutes 10 seconds.)
In essence, it turns out that as well as Ron’s bees grooming and biting mites, and ejecting infected larvae, these bees have evolved another advantage. For those of you who can’t see the programme, the gist is: the varroa mites in these Swindon colonies carry a mix of the variant strains of DWV – some of the dangerous type A, but more of type B which is asymptomatic (harmless) in bees – but the bees themselves ONLY carry the harmless type B, in high levels. The researchers attribute this to a known process called superinfection exclusion (SIE) – where the overwhelming dominance of one pathogen suppresses the presence of another. The harmless Type B viruses have become dominant within the bees in such high numbers that the Type A cannot gain a hold – either due to direct blocking of the Type A virus at the cellular level or due to some adaptation of the immune system, the research is not yet clear on the operating mechanism.
The results of the virologists’ analysis is highly important and could prove to be key in a better understanding of why certain colonies are more robust to the presence of varroa and resistant to Colony Collapse Disorder, and perhaps lead to deliberate introduction of Type B DWV virus as a vaccine-like treatment.
So the question arises, why has type B become dominant in the Swindon bees? A similar analysis on bees from Hawaii, where varroa was introduced ~3 years ago and many colonies died, shows that in that instance it was type A which dominated and type B which became absent.
It is clear to me (and the paper considers this, though as their study is limited they cannot say for sure) that this situation has not arisen serendipitously, but ONLY because Ron has not chemically treated his bees, and has encouraged and bred only from successful strains for many years (he has been doing this for ~19 years now). That by not treating chemically, but allowing varroa in effect to exist at a low-level alongside his hygienic bees, this has allowed for a continual “innoculation” of the bees which, over time, has resulted in the evolution of a sustainable balance arising between the bees, varroa, and their viruses.
Sumps / eco floors, and fashionable fungi
The idea behind sumps, also known as eco floors, is to have a pile of sawdust and other natural debris on the hive floor in the belief that it resembles what is found in many colonies inside hollow trees, and so allows a natural ecosystem to thrive, including creatures that predate upon varroa. But, as noted in the section on Small Hive Beeetle (SHB) below, other not so helpful side-effects of sumps can occur. Also, I and some others are not convinced as to the naturalness of a messy hive floor as some feral colonies have been observed to keep their tree hollow floors clean, and propolise over the and loose or rotted wood at the bottom. Opinions seem to vary as to whether clean floors are ‘normal’.
Furthermore, there has been mention of ‘some studies’ implying some fungi might help bees’ immune systems. As far as I can tell, this is based on the experience of one beekeeper who happens to be an expert on fungi, and has very healthy bees which have access to fungi he raises, but there were no control studies outside his apiary. This seems to have become amplified by the rumour mill to a conclusion that “wood rots with fungi… bees live in hollows in tree trunks …so decomposing sawdust on the floor of the hive must therefore be a good thing per se”.
Meanwhile, it has been found that some fungi do have antiviral properties, so some people are extending this to “fungi must be good for bees” – but does this antiviral property extend to viruses that affect bees? The answer is that that no one knows yet as the results are not in.
Another confusing factor is that bees sometimes preferentially gather rust spores instead of pollen. No one knows why – it doesn’t seem to be as nutritious so perhaps it has useful medicative properties, but it could be for reasons we do not understand.
Steve Sheppard at Washington State University is looking into the possibility of developing lines of fungi to help bees, but it’s implied this would be a treatment you’d pay for.
However, overall an interesting area, so expect to see more about fungi and bees in the press and forums, but don’t assume anything has been proven yet.
Small Hive Beetle (SHB)
Small Hive Beetle (SHB), originally an African pest, has been causing problems in the USA for some time, and has just recurred in Italy. It is only a matter of time before we have to manage it in the UK. A key point here is that eco-floors have been found to give SHB somewhere to hide (in the detritus, often under a varroa mesh).
Consider this: the varroa mesh on the bottom of many hives needs gaps large enough that varroa, which are up to 2mm long, fall through. However, adult SHB are only about 3.2mm wide, which is less than a 2mm square mesh’s diagonal dimension, so it is almost certain that they can wiggle through. In other words, varroa meshes give SHB somewhere to hide beyond the reach of the bees, which would otherwise harass them.
Prediction: expect varroa meshes to fall out of favour once SHB reaches your country, unless you are in a country so hot they are vital for ventilation.
How bees harass SHB: workers can haul the larvae out, but they cannot grab the quick, armoured adults. However, a strong hive can “corral” them instead and even trap them in propolis prisons! But opening a hive gives the beetles an opportunity to scatter, so low intervention beeks may have an edge over conventional beeks there.
SHB control methods are worth being aware of. One technique is oil filled traps. The beetles take refuge from bees harrying them in the traps’ convenient crevices, fall into the oil and drown. A low tech version is corrugated cardboard – the bees chase the beetles into the tubes, then propolise them inside!
In general, minimise nooks and corners where the beetles can hide, and don’t make the hive cavity far too large for the size of colony. Some “SHB hygienic” bees are better at resisting the pest than others – it remains to be seen if varroa and SHB “hygiene” traits are the same, i.e. will people with varroa-tolerant bees find they have less trouble with SHB?
Old comb attracts SHB; freezing comb kills SHB (and wax moth eggs). So the advice in SHB regions is to melt down comb you harvested for wax promptly so as not to attract them. (This is more of an issue for large scale honey farmers who have sheds full of supers awaiting processing.)
It’s the larvae which cause damage, eating stores and brood, leaving leaking honey in their wake. They’re up to 1cm long white grubs and are distinguished by ridges of small spines along their length. Unlike wax moth larvae they tunnel through comb, not along its surface.
SHB is now in the almond growing region of Australia, where the authorities have just relaxed controls on migratory beeks, freeing them to spread it all over Australia – to the fury of small scale beeks there.
And finally, in other news …
- A bee researcher has won an ig Nobel prize for research into which part of the body hurts most when stung!
- Thefts of bees are increasing in the USA because Colony Collapse has reduced their numbers, and farmers will pay a lot for pollination services. Sometimes thieves just shake bees into a box, leaving the hive and frames; so don’t assume unusual hive types are immune. It sometimes happens in the UK too, and there is a dedicated sub-forum for UK beeks to discuss this.
- Talking of thefts… here’s a newspaper article showing a really exotic hive robber.