I read a lot of scientific articles, but I rarely jump out of my chair while reading them.  This morning was an exception.

This article in PLOS Genetics published on June 9th 2016 made me sit up strait.  In case you don't want to or don't have the time to read it yourself, I'll summarize: there are some colonies of Apis mellifera capensis in South Africa that have laying workers producing socially parasitic viable female offspring.  While this isn't news to anyone living in South Africa (the trait has been documented for a long time) it is very much news to me.  Apparently it was also news to the New York Times.  Pro tip: If you want to terrify beekeepers, talk about unstoppable laying workers.  If you don't want to read my entire post, let me quickly say that you don't have to worry about Apis mellifera capensis unless you live in South Africa.

Laying Worker Eggs. Souce: BeeBase, Crown Copyright

For those of you who are newer to beekeeping I should explain 'normal' laying workers.  Sometimes a healthy hive will go queenless.  This can occur for any number of reasons: the old queen might die, or newly hatched queens might kill each other, or a victorious princess on her mating flight might get eaten by a bird before she makes it home, or emergency queen cells might fail.  In any of these cases the hive usually tries to raise another queen, but that takes a lot of energy, and other things can happen in the meantime.  In a normal hive about 1% of worker bees have functional ovaries - but their laying behaviour is suppressed by the queen pheromones.  Worker bees ovaries don't contain fertilized eggs, and unfertilized eggs can only develop into drone brood.  Of course, if a colony is queenless, laying workers can and sometimes do take over - leading to lots of drone brood and ultimately the death of the colony.  The proliferation of drones ensures that at least the colony genetics are not lost, since the drones can mate with queens from other hives.  A vigilant beekeeper will know when a hive is queenless and attempt to rectify the situation before the hive dies.

Drone brood from a laying worker.

A laying worker producing self-fertilized eggs - like the ones in South Africa - produces worker bees that are indistinguishable from other workers.  But these workers are different: they are social parasites who seek out other colonies and start laying in those hives, even in the presence of a queen, eventually leading to the death of that queen and colony.  On the one hand, a laying worker that can produce viable female offspring means that even a queenless colony can raise a new queen using eggs from a worker.  On the other hand, the social parasitism means that they can decimate other nearby colonies.  This apparently happened in the early 1990s when beekeepers moved around 200 colonies of capensis north into commercial Apis mellifera scutellata territory. This was called the capensis calamity (they 'solved' the problem by eradicating all colonies with 3.5km of the affected hives).

If you're worried about this, don't be.  A.m. capensis is staying put in Fynbos where it provides the local beekeepers with honey and where it pollinates a very unique ecosystem.  At the risk of sounding trite, if A.m. capensis was going to take over the world they'd have started with Africa.  Instead, they are an at-risk, very small subspecies of honey bee that is locally adapted.  They are at-risk partly because of commercial beekeeping disease spread, since American Foulbrood is currently a major problem for commercial capensis beekeepers.  Crazy, socially parasitic laying workers are no threat to my bees down here in Australia, nor are they a threat to hives in America or Europe or Asia, or even most of Africa. 

Breath easy.




The Fynbos ecoregion where A.m. capensis lives.  Figure courtesy of Hugo Ahlenius, UNEP/GRID-Arendal