Temperament

If there’s been a theme to this season, so far, it’s been grumpiness. I can’t think of a year when I’ve heard of, or met, so many colonies turning grumpy and starting to sting and follow for apparently no reason at all.

There’s no shortage of advice on how to tackle aggressive colonies. It’s always the same, and it always involves re-queening, unless there’s no queen to hand, or the colony is in a public space, in which case the hive should be destroyed.

The reason for this advice is that grumpiness is apparently caused by Bad Genes and, because Bad Genes are passed down to the members of a colony through the queen, then putting in a new queen with Good Genes is clearly the only approach that will work. Moreover, according to some, it’s by far the quickest, and re-queening can change the temperament of a colony for the better within an hour.

That last bit begs a question.  Given we know that the genes are the blueprint for new bees, and that constructing a new bee takes about three weeks, if the answer was in the genes, you’d expect a colony’s temperament to change substantially after about six weeks, rather than an hour. The answer to that is that life is complicated, and that queens put out a bunch of pheromones, and that a gentle queen gives out especially gentle ones, that turn even grumpy workers into stripey little angels in no time flat.

But wait. We know the temperament of a colony can change from week to week, even when there’s no queen at all, and get better even with the same queen. So perhaps, as in other areas of life, pinning the blame on poor breeding, or the single parent, isn’t quite as sensible as it seems.

There are a few things we definitely know can provoke bees into grumpy behaviour. Poor weather, clumsy beekeeping, the threat of robbing and competition for forage can all affect colonies. It’s possible that other stress factors, such as hive congestion or disease, might be involved (as well as high levels of grumpiness, there’s also a lot of sacbrood about, though it’s not necessarily related). So how is it that changing the queen, which does nothing for dexterity, security, competition, weather and isn’t likely to immediately affect the health of a whole colony, always has such a good effect?

When a queen is changed, it’s not just the genes in the eggs she lays that are different. It’s the strength and mixture of pheromones that she produces. And pheromones, together with a bunch of other olfactory stimuli (smells) in and out of the hive have a powerful influence on bees, especially regarding grumpiness. We can see this, according to some, when we use smoke to calm bees or to mask the smell of a stung finger.

QMP (queen mandibular pheremone) is one queen pheromone, and arguably the most important. It seems to do a lot of different things, such as suppressing ovary development in workers, and, in the lab at least, can reduce “aversive learning” in young honeybees – i.e. the learning of a sting response to certain odours (1). And that looks like a clue. Especially if we remember that, even in the grumpiest colony, most of the bees don’t follow or sting at all, and those that do vary a lot in their aggressiveness. According to a 2010 paper (2) “there is substantial variation in worker attraction to QMP among individuals, and that this variation is linked with specific differences in physiology and brain gene expression patterns” – so not genes, exactly, but more the combinations of genes that are turned on and off at a given time, something varies from worker to worker, and can change through a worker’s life. All of which suggests aggressiveness isn’t necessarily instinctive or inherited, but something more subtle, and not entirely dependent on the queen. This doesn’t explain why re-queening works, but we know a queen gives out a bunch of different pheromones, and perhaps it’s less the new queen than the period of queenlessness (you need to remove the old queen a few days before introducing a new one) that ‘resets’ the behaviour of the workers, and makes them behave much better when the new queen is added.

In that case, grumpiness is as much to do with the way the workers have adapted to react to different things as it is to do with the queen herself. And, if that’s so, then might a shook swarm be as good a way of dealing with a newly aggressive colony as re-queening? Shook swarming, like swarming in general, does seem to force the bees to adopt different roles in the hive, with the foragers (notoriously grumpy) having to play at house bees again for a while, and that might be just what they need to ‘reset’ their aggressive response.

I’ve certainly heard of shook-swarmed colonies becoming nicer. That could just be a short-term effect while the colony has little to defend, but maybe, if you find your bees have turned grumpy and you’ve no spare queen to hand, and aren’t in a public space, a shook-swarm might be worth trying.  Especially if the only other advice is to destroy them.

(1)    Vergoz V¹, Schreurs HA, Mercer AR (2007) Queen pheromone blocks aversive learning in young worker bees. Science. 2007 Jul 20;317(5836):384-6.

(2)    Kocher SD, Ayroles JF, Stone EA, Grozinger CM (2010) Individual Variation in Pheromone Response Correlates with Reproductive Traits and Brain Gene Expression in Worker Honey Bees. PLoS ONE 5(2): e9116. doi:10.1371/journal.pone.0009116