Category Archives: Species

Apis mellifera aquaticus

Early June 2017 ...

Early June 2017 …

June in Fife was the wettest year on record. It started in a blaze of glory but very quickly turned exceedingly damp. The photo above was taken on the 7th of June. One of my apiaries is in the trees at the back of the picture. Six queens emerged on the 2nd or 3rd of June to be faced with a week-long deluge. The picture was taken on the first dry morning … by the afternoon it was raining again, so delaying their ability to get out and mate (hence prompting the recent post).

And so it continued …

Early July 2017 ...

Early July 2017 …

Here’s the same view on the 1st of July. Almost unchanged … ankle deep water en route to the apiary, the burn in flood and some splits and nucs now being fed fondant to prevent them starving.

A beautiful morning though 😉

Retrospective weather reports

Of course, you shouldn’t really worry about weather that’s been and gone, though comparisons year on year can be interesting. At the very least, knowing that the June monthly rainfall in Eastern Scotland was 223% of the 1961-99 average, I’ll have an excuse why queens took so long to mate and why the June gap was more pronounced than usual. Global warming means summers are getting wetter anyway, but even if you make the comparison with the more recent 1981-2010 average we still got 206% of the June monthly total.

The Met Office publishes retrospective summaries nationally and by region. These include time series graphs of rainfall and temperature since 1910 showing how the climate is getting warmer and wetter. If you prefer, you can also view the data projected on a map, showing the marked discrepancies between the regions.

June 2017 rainfall anomaly from 1981-2010

June 2017 rainfall anomaly cf. 1981-2010 …

Parts of the Midlands and Lewis and Harris were drier than the June long-term average, but Northern England and Central, Southern and Eastern Scotland were very much wetter.

It would be interesting to compare the year-by-year climate changes with the annual cycle of forage plants used by bees. Natural forage, rather than OSR where there is strain variation of flowering time, would be the things to record. As I write this (first week of July) the lime is flowering well and the bees are hammering it. The rosebay willow herb has just started.

Rosebay willow herb

Rosebay willow herb

Prospective weather forecasts

Bees are influenced by the weather and so is beekeeping. If the forecast is for lousy weather for a fortnight it might be a good idea to postpone queen rearing and to check colonies have sufficient stores. If rain is forecast all day Saturday then inspections might have to be postponed until Sunday.

If you have a bee shed you can inspect when it’s raining. The bees tolerate the hive being opened much better than if it were out in the open. Obviously, all the bees will be in residence, but their temper is usually better. They exit the shed through the window vents and rapidly re-enter the hive through the entrance.

I don’t think there’s much to choose between the various online weather forecast sites in terms of accuracy, particularly for predictions over 3+ days. They’re all as good or as bad as each other. I cautiously use the BBC site, largely because they have an easy-to-read app for my phone.

Do I need an umbrella?

For shorter-term predictions (hours rather than days) I’ve been using Dark Sky. This can usefully – and reasonably accurately – predict that it will start raining in 30 minutes and continue for an hour, after which it will be dry until 6pm.

The forecast in your area might be different 😉

Dark Sky via web browser

Dark Sky via web browser

There’s a well designed app for iOS and Android as well that has neat graphics showing just how wet you’re likely to get, how long the rain will last and which direction the clouds will come from.

Dark Sky on iOS

Dark Sky on iOS

It’s far from perfect, but it’s reasonably good. It might make the difference between getting to the apiary as the rain starts as opposed to having a nice cuppa and then setting off in an hour or two.

Rain stopped play

I’ve posted recently on delays to queen mating caused by the poor weather in June. I’ve now completed inspections of all the splits. Despite both keeping calm and having patience I was disappointed to discover that the last two checked had developed laying workers. Clearly the queen was either lost on her mating flight or – more likely (see the pictures above) – drowned.

I’ve previously posted how I deal with laying workers – I shake the colony out and allow those that can fly to return to a new hive on the original site containing a single frame of eggs and open brood. If they start to draw queen cells in 2-3 days I reckon the colony is saveable and either let them get on with it, or otherwise somehow make them queenright.

One of the laying worker colonies behaved in a textbook manner. A couple of days after shaking them out there were queen cells present. I knocked these back and united the with a spare nuc colony containing a laying queen.

Lime can yield well in July

Lime can yield well in July

The second colony behaved very strangely. I didn’t manage to inspect them until a week after shaking them out. There were no queen cells. Nor was there any evidence of laying worker activity in the frames of drawn comb I’d provided them with. Instead, they’d filled the brood box with nectar from the nearby lime trees. Weird. I united them with a queenright colony and I’ll check how they progress over the next week or two.

Apis mellifera aquaticus

My colonies are usually headed by dark local mongrel queens. My queen rearing records show that some are descended from native black bees (Apis mellifera mellifera) from islands off the West coast of Scotland, albeit several generations ago. These bees are renowned for their hardiness, ability to forage in poor weather and general suitability to the climate of Scotland.

Nevertheless, without further natural selection and evolution they will have still needed water wings, a snorkel and flippers to get mated last month 😉

Not waving but drowning


Colophon

Carl Linnaeus

Carl Linnaeus

The taxonomic scheme ‘developed’ by Carl Linnaeus (1707 – 1778) is a rank-based classification approach actually dates back to Plato. In it, organisms are divided into kingdoms (Animals), classes (Insecta), order (Hymenoptera), family (Hymenoptera), genera (Apis) and species (mellifera).

The subspecies is indicated by a further name appended to the end of the species name e.g. Apis mellifera capensis (Cape Honey bees), Apis mellifera mellifera (Black bees)

Apis mellifera aquaticus doesn’t really exist, but might evolve if it remains this wet 😉

Worker laying workers

A few months ago I wrote about problems encountered with laying workers, and ways to overcome those problems. Laying workers occur when a colony lacks sufficient open brood pheromone to suppress egg laying by the workers. One solution, though not one I favour, is to repeatedly add frames of open brood to suppress egg laying and then either add a queen, or allow the colony to raise their own.

The article was titled ‘drone laying workers’ and, in the comments, Tim Foden correctly pointed out that the prefix ‘drone’ was probably superfluous. Since the workers were unmated they would only be able to lay haploid eggs which would inevitably develop into drones.

Without intervention a laying worker colony is doomed. However, drones from a laying worker colony are fertile. Therefore, from an evolutionary perspective you could consider the rearing of drones is a last-gasp effort to pass on some of the genes to successive generations.

But … there’s always a but

The Cape honey bee (Apis mellifera capensis) is a subspecies usually restricted to the Western Cape region of South Africa. Laying workers of Cape honey bees can lay eggs that develop into workers (or queens). Since these ‘mother’ workers are unmated and their resulting progeny workers are diploid, this takes some genetic trickery. This mechanism is snappily titled thelytokous parthenogenesis.

Cape honey bees

Cape honey bees

Parthenogenesis is most simply defined as reproduction without fertilisation. Thelytoky is derived from the Greek thelos, meaning ‘female’, and tokos, meaning ‘birth’. The next time you’re asked to define thelytokous parthenogenesis in the pub quiz your team will have the edge – it means giving birth to females without reproduction. The female progeny capensis workers produce can be reared as workers – essentially clones of their mothers – or, with a change in diet for the early larvae, queens.

The genetic trickery involves the haploid pronucleus of the egg fusing with one of the polar bodies that are generated during oogenesis (egg production). Polar bodies are small haploid cells that bud off during ovum development. Fusion of the two haploid cells creates a diploid, which can go on to become a female bee.

No laying worker problems then … ?

Quite the opposite. You’d think that by encouraging this type of activity in Cape honey bees your laying worker problems would be a thing of the past. In fact, your problems become a thing of the future. Laying workers of capensis are socially parasitic. They invade – through drifting for example – unrelated neighbouring colonies, such as those of Apis mellifera scutellata (another subspecies, the African honey bee). Once there, the eggs they lay are reared by the new colony, but the resulting workers do not contribute to foraging or other hive activities. Instead they also become laying workers (worker laying workers that is 😉 ), eventually leading to the collapse of the host colony.

Capensis has been spread widely from its original range through migratory beekeeping, leading to large-scale colony losses and significant economic impact to the beekeeping industry in regions of South Africa distant from the Western Cape. Capensis also hybridises with scutellata in areas where their ranges overlap.

Divide and conquer

Honey bees are social insects. Cape honey bees, for all their unsociable parasitic activities are also social. However, their unsociable activities aren’t restricted to parasitism. They also exhibit a trait called worker policing. A Cape honey bee colony might contain several laying workers. The workers they rear are able to discriminate between eggs laid by their ‘mother’ and those laid by her half-sisters – effectively their aunts – in the same hive. Once they detect a foreign egg, they either eject it or eat it.

This worker policing can lead to sub-division of the hive, with territories being established in separate parts of the hive, each containing genetically clonal populations of laying workers. However, unless the colony rears a new queen its long-term prospects are very limited. The prodigious egg-laying ability of a queen far outstrips that of even multiple laying workers, meaning the colony – and all its sub-divisions – will eventually dwindle and be lost.

Worker policing is an interesting phenomenon and has some relevance to queen rearing and larval selection which I’ll address later in the season.

Pedantically speaking … and wind

Laying workers colonies in the UK characteristically rear large numbers of drones. This is why Tim Foden correctly commented that the prefix ‘drone’ is superfluous. However, to be absolutely pedantic it is needed. This is because, irrespective of the strain of bee, up to 1% of eggs laid by laying workers are diploid. All bees exhibit thelytokous parthenogenesis but it’s only in capensis the trait is common.

Why is it only in capensis that this trait is common? It’s been suggested the selection for thelytokous parthenogenesis is due to the strong winds that occur in the southern region of South Africa in which capensis is the native honey bee. As a consequence of this, queens are often lost on mating flights, rendering the colony queenless. Without “worker laying workers”  – or, more correctly, diploid laying workers from which new queens can be raised – colonies would be doomed.

Western Cape Fynbos region of South Africa

Western Cape Fynbos region of South Africa

Capensis queen mating flights have been documented at wind speeds in excess of 30 mph … another adaptation to the climate of the region. In contrast, scutellata queens, from more northerly regions in South Africa won’t go on mating flights if the wind speed exceeds ~12 mph.

Cape honey bees are wonderfully well adapted to the Western Cape Fynbos region of South Africa. They are the strain beekeepers choose to use for honey production and pollination in an area with huge biodiversity and ~6000 endemic plant species. In trials using alfalfa, capensis-pollinated plants set twice as much seed as those pollinated by scutellata. This suggests they are particularly thorough plant ‘visitors’, a conclusion supported by their ability to collect pollen which was also twice that of scutellata. They have additional unique characteristics. In a publication pre-dating the introduction of Varroa to South Africa, Hepburn and Guillarmod (PDF) describe how readily capensis absconds in summer and migrates in winter, both characteristics the reflect adaptation to the climate and the regular wildfires in the region, and not seen in other strains of bees.

Finally, in much the same way that moving capensis colonies elsewhere has caused problems, the introduction of American foulbrood to the region in 2008 (again through beekeeper activity) has resulted in the loss of 40% of Cape honey bees.

 

Take one for the team

You know it makes sense

You know it makes sense

… would have been a much better title for an interesting recent paper on the impact of Varroa on honey bee colonies. More specifically, the snappily titled “Social apoptosis in honey bee super organisms” (Page et al., 2016 Scientific Reports 6: 27210 doi:10.1038/srep27210) attempts to answer how and why the natural host of Varroa, the Eastern honey bee (Apis cerana), copes with mite infestation whereas ‘our’ bees (Apis mellifera), the Western honey bee, succumbs within 2-3 years without mite-control? The paper is Open Access so you don’t need to pay to read it and you can find it here.

Only the good damaged die young 

The authors demonstrate that A. cerana mite-associated pupae die before they emerge, whereas those of A. mellifera do not. As a consequence of this the mite levels are unable to build up to damaging levels in the colony. Essentially the pupae on which the mites feed die very quickly, meaning the mite also dies. They determined this by uncapping and examining age-matched pupae one day before natural emergence (see below) in Varroa-infested or uninfested colonies. Varroa-associated pupae (upper row in the image below) had all died during pupation.

Infested (above) and control (below) A. cerana pupae

Infested (above) and control (below) A. cerana pupae

In an extension to this study the authors showed that puncturing pupae with a sterile glass needle and then re-sealing the cell (you can do this with gelatin) also results in the pupae dying. The needle used had the same diameter as the chelicerae of the Varroa mite, so this treatment recapitulated the physical damage caused by the mite. Since the needle was sterile it was unlikely that the pupae were dying from exposure to the viruses (or other pathogens) transmitted by the Varroa mite. Instead, it seems that the Eastern honey bee has evolved mechanisms of “self-sacrifice” in response to wounding that result in the death of damaged pupae before the infesting mite has had a chance to multiply. Clever.

Social apoptosis

Apoptosis is the term used by cell biologists to describe a series of events that are also called programmed cell death seen, for example, in virus-infected cells. If a cell detects that it is virus infected, a cascade of signalling events result in it undergoing apoptosis (it dies), so preventing the infecting virus from replicating properly and spreading to neighbouring cells in the organism. Social apoptosis is a similar process, the death of an infected – or infested – member of the superorganism, the honey bee colony.

Immunity is a term meaning ‘having resistance to’, for example immunity to measles due to prior vaccination or infection. Generally, immunity is a reflection of strength of the recipient or exposed to the ‘abuse’ caused by the infectious agent. In contrast, the mechanism described for A. cerana is the opposite of this, instead being a form of immunity through weakness or susceptibility.

A. cerana has additional resistance mechanisms that help it combat Varroa infestation including enhanced grooming, removal of mites from unsealed brood, entombing multiply mite-associated drone brood (it’s not clear to me whether this is the same mechanism as the social apoptosis reported here), increased hygienic behaviour and shorter developmental cycles. These will have evolved over the millennia that the mite and bee have associated.

Any chance A. mellifera will evolve a similar mechanism?

Possibly, but I’m not holding my breath. There are already hygienic strains of A. mellifera – for example, VSH bees developed by the USDA group at Baton Rouge. These typically uncap and discard Varroa-associated pupae. This isn’t the same process as the social apoptosis reported here in A. cerana. The latter pupae die prematurely, thereby preventing mite reproduction. While we’re on the subject of Varroa and genetic resistance – do VSH A. mellifera strains open and discard mite-associated pupae … a) early enough to prevent significant levels of mite replication, and b) without releasing progeny mites from the cells they were raised in? I’m aware of the rates at which they clear out Varroa infested cells, but not either the timing of these events or the fate of any Varroa released at the same time.

It’s difficult to imagine a practical strategy to select for A. mellifera honey bee pupae that are more sensitive to Varroa infestation … our bees are currently too robust.


Billy Joel wrote Only the good die young which appeared on his 1977 album The Stranger. “[Not] so much anti-Catholic as pro-lust” Joel explained when it was censored, inevitably ensuring its chart success. The song has more to do with the birds and the bees …  😉