Category Archives: Varroa

Isle of Arran

Isle of Arran, September 2017

Isle of Arran, September 2017

We are conducting a trial of coordinated Varroa treatment in conjunction with the beekeepers on the Isle of Arran. In late September DJE and Luke Woodford – the EastBIO-funded student leading the project – visited Arran to present an evening lecture on Varroa and DWV: Science and Practical Beekeeping

Our studies exploit our understanding of changes in the virus population associated with Varroa transmission (rather than transmission from bee to bee during feeding) to monitor the ‘health’ of the colony.

The talk was followed by an extended question and answer session covering the project and more general aspects of beekeeping and Varroa control. 

The Isle of Arran was looking fantastic as we crossed from Ardrossan on the CalMac ferry. Goatfell, the highest point on the Arran horseshoe ridge (see image above) is a great walk and thoroughly recommended.

Drifting in honeybees

Note This post was first published on The Apiarists’ blog.

During previous research on deformed wing virus (DWV) biology and its transmission by Varroa I’ve moved known Varroa-free colonies (sourced from a region of the UK which the mite has yet to reach and maintained totally mite-free) into apiaries in the countryside. Within 2-3 weeks Varroa was detectable in sealed brood, showing that mite infestation occurs very readily. I know other researchers who have made very similar observations. Where do these mites come from?

They’re not all ‘your’ bees

The obvious source would be the phoretic mites transported on workers ‘drifting’ from nearby infested colonies, or on drones which are known to travel quite long distances and may be accepted by almost any colony. If you want to see how frequent this is try marking a few dozen drones with a dab of paint. To avoid confusion use the colour used to mark queens next year. There are unlikely to be 4+ year old queens in the apiary and the drones will all perish before the end of the current season. Over the next few days and weeks the drones will appear in adjacent colonies, and some will likely leave the apiary and be accepted in your neighbours colonies.

Hives in rows ...

Hives in rows …

Beekeepers are usually aware that colonies at the ends of rows often ‘accumulate’ bees that have drifted when returning to the hive. In shared association apiaries some crafty beekeepers will site their colonies at the ends of rows to take advantage of the ‘generosity’ of other colonies. However, many beekeepers probably do not appreciate the extent to which drifting occurs. Pfeiffer and Crailsheim report (1998) that 13-42% of the population of a colony are ‘alien’ i.e. have drifted from adjacent hives, depending upon the time of season. Remember that drifting occurs in both directions simultaneously, so the overall numbers of bees in a colony may not be adversely affected (or boosted). In other studies Sekulja and colleagues report (2014) that ~1% of marked bees drifted between colonies over a three day observation window. Interestingly, American foulbrood (AFB) infected bees drifted slightly more than uninfected bees. Spread of foulbroods during drifting is one reason the bee inspectors check nearby apiaries when there is an outbreak. These studies were all on workers where drifting primarily occurs during orientation flights before the bees become foragers. Drones drift two to three times more than workers (Free, 1958).

The likelihood of drifting must be closely related to the separation of hives and apiaries. Although workers will forage up to 2-3 miles from the hive I suspect the proportion of bees that drift this distance is small to undetectable. Drones are known to fly up to about five miles to reach drone congregation areas for queen mating and are accepted by all colonies. I’ve regularly found drones appearing in (relatively) isolated mini-nucs. I’m not aware of studies that have formally tested drifting between apiaries (though it is reported in passing in the Sekulja et al., 2014 paper referenced above).

Consequences of drifting

So, your hives contain workers and drones from many nearby colonies, and you can only really be sure that they’re all “your” bees if you live – as the sole beekeeper – on an isolated island. Not only does your neighbour generously exchange bees with you, he or she also kindly shares the phoretic mites those bees are carrying, the viral payload the bees and mites are infected with and – if you’re really unlucky – the Paenibacillus larvae spores responsible for causing AFB infection (and vice versa of course).

There are lessons here that should inform the way we conduct our integrated pest management to maintain healthy colonies. 

This post provides background information for an article (“Viruses and Varroa: Using our current controls more effectively” by David Evans, Fiona Highet and Alan Bowman) in the December 2015 issue of Scottish Beekeeper, the monthly magazine for members of the Scottish Beekeepers Association.

More later …

 

Hampshire BK autumn convention

Sparsholt College

Sparsholt College

I’m delighted to be talking at the Hampshire Beekeepers Association autumn convention at Sparsholt College this weekend. This is the first of several ‘winter talks’ to BKAs about our research on deformed wing virus and Varroa. Time permitting I hope to discuss some forthcoming studies on coordinated Varroa control that we’re doing with Alan Bowman (Aberdeen) and Fiona Highet (SASA) and that will shortly be featured in the Scottish Beekeeper. I was invited to talk at this event before accepting a post in St. Andrews … it’s a long way to travel. However, one of the advantages of flying to these events is I can’t be tempted by too many goodies from the trade stands 😉

MSWCC 2015

The Royal Agricutural University, Cirencester

The Royal Agricutural University, Cirencester

I spent Friday and Saturday attending the Midland and South West Counties Convention at the Royal Agricultural University, Cirencester. It was a good venue for a meeting, complemented by an interesting and entertaining programme of talks. I discussed our developing story about the influence of Varroa on the transmission of pathogenic strains of deformed wing virus, together with brief coverage of both high and low-tech solutions that might be useful in controlling the detrimental impact of the mite on the virus population. On the Saturday I donned my beekeepers hat (veil?) and discussed queenright queen rearing methods … lots of stakeholder engagement to keep the funders happy 😉

There were some excellent presentations on the use of pollen in forensic studies (Michael Keith-Lucas) and the use of nucleus hives (Bob Smith). I had to leave early to make sure I caught my cancelled train to Swindon (“too many passengers”), the delayed connection to Paddington (“waiting for staff to turn up”), the slow running Heathrow Express (“engineering work”) and so missed my flight back to Edinburgh … all part of the rich outreach experience.

CABK Stratford Conference

Falcon Hotel Stratford

Falcon Hotel Stratford

I’m delighted to be speaking at the  CABK Stratford Conference (the Central Association of BeekeepersBringing Science to the Beekeeper) on Saturday and Sunday 22/23 November 2014. I’ll be discussing the identification of a virulent strain of deformed wing virus, characteristics of its transmission and potential ways it might be controlled in the future. The CABK website doesn’t yet appear to list other speakers, but the provisional programme I’ve seen lists Alison Haughton from Rothamsted, Ben Jones from FERA, Jochen Plugfelder from Bern and Bob Smith from Kent.

There should be ample time for discussions so please introduce yourself if you want to chat.