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Varroa is now endemic in UK bee hives, high infestations of which can decimate colonies. There have been various claims of resistance to varroa in some colonies and there is certainly a desire to selectively breed from colonies that show resistance.
What does resistance mean? Since it’s not the mites themselves that kill bees, rather the viruses they carry (deformed wing viruses being the most common), is it resistance to these? Or is it behaviour that prevents mite numbers from building up too much. Most probably the latter.
Varroa is so destructive to Western Honey Bees (Apis mellifera) because their longer brood cycle and larger colony size enable them to multiply more quickly that the shorter brood cycle of the Asian honey bee (Apis cerana) from which they came. Documented wild bee colonies that apparently show resistance are often small colonies (where mite populations take longer to reach dangerously high levels) that swarm often (leaving mite-ridden brood and bees behind), so it is often unclear if it is the same colony. It may be that colonies disturbed less by beekeepers can withstand disease and infestation better and it may be that some wild colonies can probably self-select on behaviourial traits that help keep mite levels down.
Last summer, I went to a workshop at LASI (Laboratory of Apiculture and Social Insects, University of Sussex) about “breeding hygienic bees”. In this context, hygienic behaviour is when bees are effective at removing dead or diseased material from the hive.
The workshop demonstrated a method of assessing the extent to colonies’ hygienic behaviour by killing a area of brood and monitoring how quickly the colony removes the dead. The method demonstrated was to remove a brood frame from the hive, press a metal ring (about 10cm across and 10cm high) into an area of fully capped brood, carefully pour liquid nitrogen into the ring to kill the brood without otherwise damaging them, place the frame back in the hive and monitor proportion of brood removed by the bees. The assumption is that colonies able to detect and removing duff brood are more likely to survive varroa attack, because they are more likely to remove infected brood, but I’m not sure if this assumption has been verified Selectively breeding from hygienic colonies over several years is a way to improve colonies’ chances against the varroa mite.
This was advocated as a method which local beekeeping associations with the resources for queen-rearing could employ. However, the open-mating that exists in most areas makes such programmes difficult.
Thanks to Sally for tipping the group off about this hard-hitting investigative documentary about neonicotinoid pesticides. Though based on the USA, it’s extremely relevant to the UK.
In the UK, oilseed rape seed is now routinely pre-treated with neonics, like maize in the USA. ‘Better than spraying,’ I read recently, but this film shows that dust from the sowing machines is as bad as spray drift. Anyway, as the poison is systemic, it will be in the nectar and pollen regardless of the application method.
It seems to me that the case for banning neonicotinoid use is very strong, and on the basis of the precautionary principle is unanswerable. It is curious that the BBKA refuses to oppose the use of neonics. If I were a member, I would be agitating for a change of policy. PAN-UK, the local sister of PANNA in the film, campaigns against neonics.
As for why neonics are permitted under UK regulation, well, the pesticides approval system has parallels with that for pharmaceuticals, as described by Ben Goldacre.
For a British view, listen to Phil Chandler’s Barefoot Beekeeper podcast of 17 May, Talk at Trill Farm. Among other things,
“Neonicotinoids applied as seed dressings kill most invertebrate life UNDER the ground as well as ABOVE. These poisons eradicate earthworms, beetles and insect larvae from the soil – which means there is no food for birds which probe the soil: lapwings, curlews, starlings etc”
The talk covers other aspects of sustainable beekeeping and is quite a good introduction to Phil’s views.
Phil also covered neonics in more detail in an interview with Dr Henk Tennekes last year.
I’m not seeing many honeybees in my garden at the moment — richer pickings elsewhere I suspect — but there was one on my solitary veronica yesterday.
She moved on to the verbena bonariensis. Then 40 minutes later she (or a sister) was back on the veronica, which maybe suggests that veronica replaces nectar continuously (unlike e.g. dandelions which I believe offer their nectar as an early breakfast and then are dry till the next morning).
Later, another h/bee on white clover in Millfields cricket field. Quite a golden Italian look to her, though perhaps created as much by the low evening sun (7pm) as by her colouring.
Back in my garden, a pair of wool carder bees (anthidium manicatum) have been tucking into the giant dead nettle for the past few weeks. Now that’s finished, they’re on the hybrid woundwort. Evidently there is enough moss around my garden, or nearby, for their nest. I’m about to plant lamb’s tongue for them for next year, just in case.
Wool carders live right into September, when several conspicuous solitaries such as the hairy footed, the miners and masons, have died. The leaf cutters should be around too, till August, though they’ve stopped carving those elegant slices out of my rose leaves now.
A common carder bumblebee, which is different (bombus pascuorum), is spending time on the common bittersweet. One thing about appreciating bees is that you start to appreciate also the often insignificant flowers that can attract them. Alder buckthorn is a case in point – its tiny flowers in June bring the bumbles as readily as a foxglove.
Out on the street the Pride of India is flowering, attracting another h/bee. Congratulations for that go to LBH’s street trees officer who carried out a prolific and imaginative (and well maintained) planting in lower Clapton’s streets a few winters ago.