Introduction.
At last, a proper old-fashioned winter with cold days and deep snow on the hills. Over the last week the temperatures haven’t got much above freezing, and some nights have been well below zero. The days are getting noticeably longer with a few more minutes of daylight which always cheers me up. Recent storms washed up a lot of uprooted trees onto the Nairn beach and the high tideline was dotted with bluebell bulbs torn from their anchorage deep within the storm-damaged soil. I’ve gathered about 20 bulbs and tried to wash out the salt but the ground is too frozen to plant them and they are sending up green leaves already.
Queen Failure.
A new season brings us new challenges along with many of the same old ones, and we continuously search for reasons why our queens fail. Fortunately, this is now a much-researched area of beekeeping and Dr Alison McAfee is one of the key scientists investigating queen failure on our behalf. Last year she worked with the lead author of a study finding out if there is balance or compromise between a queen’s high fertility and her immune system when faced with infection1. In other words, if queens need to fight an infection do their systems focus on turning on the genes that govern immunity to produce factors to fight and reduce infections at the expense of egg laying and reducing fecundity?
Queen Failure Blog.
I wrote on queen failure in 2023 ( https://www.beelistener.co.uk/queen-bees/why-do-queens-fail/ ) and today’s blog follows on with information from recent research.
We already know that queens are so important because they are the only reproductive females in a colony and are key to its stability, success and ultimate survival. Measurement of the quantity and quality of the sperm stored in a queen’s spermatheca is one way of assessing queen quality. However, there are many different factors involved and anything that causes a reduction of viable sperm will also cause a reduction in egg production. Previous research tells us that pesticide and temperature exposure damage sperm. Poor mating negatively impacts sperm storage, and failing queens producing drone brood have lowered sperm viability. In the same study, scientists found that failing queens had higher RNA virus loads, and all those queens had smaller ovaries.
Viruses Affect Queens Too.
Many honey bee viruses can be found in colonies and most of them affect queens though it might not be obvious at all to a beekeeper inspecting a colony. These are some of the common viruses: deformed wing virus (DWV), acute bee paralysis virus (ABPV), black queen cell virus (BQCV), sac brood virus (SBV), Israeli acute paralysis virus (IAPV). Interestingly, although infected with these viruses, queens rarely show symptoms and only one case of a queen having deformed wings (DWV) has been recorded to date. On dissection though, infected queens are found to have DWV in the head, thorax, gut, fat body tissue, ovaries and spermatheca. We know that high levels of DWV are associated with high levels of varroa infestations which cause ovarian degeneration and a reduction in egg laying. With the other viruses listed above, the viral levels found in affected queens were low and how they actually impacted on queens has not been so well reported.
New Virus Discovered.
A worrying recent discovery for US beekeepers has been a new honey bee virus called solinvivirus–1 which might be the cause of some queen failures. Where apiaries have tested positive for this virus they were twice as likely to contain queenless colonies than apiaries without this virus.
The recent parallel study1 involved both field and lab studies where the queens in the test groups were injected with activated live RNA viruses, and the control groups’ queens were injected with inactivated RNA viruses. The lab group queens were caged. At the end of the experiment, all queens were sacrificed and tested; both groups had raised immune proteins in their haemolymph indicating an immune response to the vaccinations. The results of this work suggest that there is a trade-off between reproduction and immunity, but it is partially – and not completely– responsible for reduced egg laying during times when queens must fight infection and turn on genes that govern immunity. There is no doubt that common viral infections reduce egg laying and are linked to premature supersedure.
An interesting observation between the caged queens was that those queens injected with the live virus had smaller ovaries and were less likely to lay eggs again. The control group given the inactive virus also had smaller ovaries but they resumed egg laying. The scientists suggest that caging queens and restricting movement caused a reduction in ovary size.
The Implications.
What does this mean for us? I think that it highlights the importance of maintaining low varroa numbers at colony level since DWV appears to the most damaging of all viruses. There are several ways to achieve this from treating with chemicals to using biotechnical methods, and selectively rearing queens from varroa resistant stock. I’d like to share the different strategies of two experienced beekeepers both focussing on doing what’s best for their bees. Steve Riley– pioneer varroa resistance beekeeper and author– shares how he achieves his goal https://www.youtube.com/watch?v=dcJO19QHAKE
Steve Donohue– bee farmer, author and popular blogger– shares his management plan here https://thewalrusandthehoneybee.com/latest-advice-on-varroa-supersedes-previous-articles/?sn=c&c=1282#comment-1282
Reference:
1Chapman, A., McAfee, A., Tarpy, D.R. et al. Common viral infections inhibit egg laying in honey bee queens and are linked to premature supersedure. Sci Rep 14, 17285 (2024). https://doi.org/10.1038/s41598-024-66286-5
Hi Ann, thanks for mentioning my blog. I am really looking forward to next season and have plans to focus on making the very best queens that I can (weather permitting). Hard to believe that in a few short months people will be talking about swarming! best wishes, Steve.
Hello, Steve. It’s handy having good information to share, and there’s no point reinventing the wheel. Please feel free to the same if the need arises. Our goals are the same so let’s cross fingers for a cracking season. Ann.
Thank you, Ann, for explaining that a viral infection will reduce a queen’s egg production even if it does not shorten her life. Makes sense… every living thing can only do so much at any one time. I wonder if a virus-infected queen, like a person infected with a cold virus, has less energy and moves around less than a queen that is not infected. I wonder, too, how we can help reduce the spread of viral infections among our colonies. Arrange our hives in ways that minimize drifting? Tom
Hello Tom, thank you for your comments and suggestions. Best wishes, Ann.