Our first intended follow-up post to our brief report in March on the MBA conference was published months afterward. Now even more months have passed and with the year almost done we hurry to finally finish the second, about Steve Tilmann’s presentation on the Cape Bee, apis capensis1.
The map at left shows six floral kingdoms of the world, areas with broadly uniform composition of plant species. Five of the six are large continent-sweeping regions, as one might expect. The sixth is just the tip of Africa, isolated from the rest by mountains and subject to high winds from the three oceans.
The winds result in a high rate of virgin queens failing to return from the mating flight, having been blown to Madagascar. In response the Cape bees2 have developed a capacity for thelytoky, a kind of parthenogenesis. A female worker with the right genes can lay eggs which will develop, not into the expected drones, but into clones of herself. A colony without a queen will thus not decay into a frat house and die but carry on producing workers as well.
While it keeps the colony alive, this is a not a perfectly happy situation. Just as in a usual laying worker situation, there is not only one worker who tries to seize the throne but many, each cloning away. Also as usual, workers will give preferential treatment to brood that is more closely related to them, i.e. whose genes more resemble theirs. Such resemblance gets no closer than identical and preferential treatment here turns into actively destroying brood from other laying workers. As a result the colony will likely be split into several cohabiting and competing subcolonies. Such a colony at war with itself is not at all as productive as a queenright colony.
Unfortunately the Cape bees have somehow crossed the mountains and parasitized the hives of European bees. Compared to a cancer, the parasites rapidly outbreed the non-Cape bees, as offspring of laying workers become laying workers themselves, but are useless foragers away from their natural region. The colony eventually dwindles, leaving some surviving Cape bees to move on to infect another hive.
Regarded as a bigger problem than varroa, may they never reach our shores.
1 There is one caveat if you get a chance to see his talk. It was a hunting safari that brought him to South Africa and there are pictures of kills with some gore among the slides.
2They look like Carniolans.