I can’t remember why I opened the natural-selection chapter in Why Evolution is True (chapter 5: “The Engine of Evolution”) with the story of the Asian giant hornet (Vespa mandarina) and of the counterdefense of its prey of native honeybees. (The European honeybee, more recently introduced into Asia, has not evolved such a bizarre and amazing defense.) The giant hornet is much to be feared by both honeybees and humans: it’s as big as your thumb, and several humans (and millions of bees) die from its attacks every year.
Since you all should have a copy of WEIT (as Hitch would say, “Available at fine bookstores everywhere”), I won’t recount the story of the native honeybees’ defense, but it involve luring the voracious hornet scout into the bee nest and the cooking it to death: surrounding it with a ball of vibrating bee bodies that raises the ball’s internal temperature to 117 degrees F (47°C): a temperature that kills the wasp but not the bees.
I suppose I put that story in because it’s a stunning example of the power of natural selection to shape behavior (in both wasp and bee), and not many people knew about it. Now I hear that a lot of readers especially liked that story. It is a true one, and in this segment from BBC Earth, you can see the nefarious hornet scout discovering a hive of native honeybees.
The scout marks the hive with pheromones and usually flies back to recruit a swarm of fellow hornets to return to the nest to destroy it: a process that can take only a short while as the wasps nest in minutes, decapitate adult bees and steal their honey and and bee grubs. But, as I relate in the book, sometimes, as here, the hornet scout never gets back to its own nest because of the counterdefense. The native bees lure it inside and cover it with vibrating bees that kill it.
This video is, of course, far more vivid that what I could say in words, so I want to show it here. But imagine the sequence of evolutionary steps that produced this defense!
If you want to see how these hornets slaughter the non-native European honeybees, watch this gruesome attack (each wasp can kill 40 bees per minute!). I’m sure I’ve shown this video somewhere in the distant past.
Now if you’ll excuse me, i’ll go home to rest.