The Beekeeper’s Companion Since 1861
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For the Love of Bees and Beekeeping

The Defense Cascade

- August 1, 2017 - Keith Delaplane - (excerpt)

In the life of every beginning beekeeper there is a moment of truth when he or she makes peace with the prospect of bee stings. Stings are, I believe, the biggest deterrent, the biggest moment of hesitation, the biggest obstacle to overcome. However, I also find that among newbies, talk of bee stings, worry about bee stings, dressing for bee stings, and jokes about bee stings are among the first things to go. There is simply so much else to command one’s attention that stings get relegated to background – like water to a swimmer. When I was teaching an undergraduate course on beekeeping, one of my biggest problems was all the time it took students to get suited up at the beginning of the semester. Nothing would do but the whole suit of armor – suits, veils, gloves, cuffs stuffed down boots. By the end of the semester I had the opposite problem. The bees had worked their charm, and students were now wearing too little in the bee yard. Shorts, flip-flops, baggy t-shirts, no veils. Some compromise between familiarity and respect, I argued, was what we’re aiming for.

Beekeepers become skilled at reading the signs of a defensive colony and handling bees in a way that minimizes stings. It boils down to little things like brushing away bees with a flick of one’s fingers before picking up a frame, reaching in from the edges of a super instead of reaching across the super – the latter perceived by bees as a threatening silhouette against the sky, recognizing the difference between a forager landing on your arm, confused and disoriented, versus a buzzing soldier ready to sting, and knowing when to give a judicious puff of smoke – when the inmates are lined up between frames looking up at you, bad intentions written on every face – to remind everyone that there’s nothing to get worked up about.

It’s also worth pausing to think about the marvel of being able to go through a bee hive like I just described. There is no reason for them to tolerate us. A giant mammal, armed with smoke and tools for breaking-and-entering, constitutes nothing less than the biggest disaster possible in their evolutionary universe – yet tolerate us they do. Most of us reading these pages are acquainted with the joys of watching bees go about their business while we hold a frame in our hands – the queen laying eggs in broad daylight, the court forming about her, a waggle dance in this section of the comb, nurse bees feeding larvae in this one. Experiences like this, I believe, are evidence of the evolutionary effects we humans have had on Apis mellifera. The ancient sympatry, or shared natural ranges, between humans Homo sapiens and honey bees Apis mellifera spans the entire existence of our species. We are the newcomer, first showing up in Africa a mere 140,000 years ago and emigrating into Europe 61,000-44,000 years ago.1 For Apis mellifera, on the other hand, there is evidence for its presence throughout Africa and Europe by the very latest 333,000 years ago3, even though its place of origin is argued variously as Africa2, the Middle East3, or Asia.4 In the beginning, it is certain that the relationship between the two was adversarial, that of predator and prey. But we have cultural evidence that by 7,000 years ago humans were harvesting honey and wax5; the relationship was beginning to transition from predation to management. Given that this transition likely pre-dates our material evidence for it, it seems reasonable to me that humans have been “managing” Apis mellifera for at least 10,000 years, all the while applying artificial, even unintentional, selection for productivity and gentleness, allowing us in the 21st century the pleasure of handling a quiet frame of bees.

I will talk more about the evolution of social nest defense in the next installment, but for now I want to focus on the behavior itself. In spite of widespread cultural presumption otherwise, stinging is the last thing a bee wants to do. Nest defense, like an immune response, is a costly undertaking, especially for the individual worker bee who dies after she stings. This is the extreme example of altruism we talked about back in the March 2015 installment of this series – how social evolution can favor self-sacrificing individuals. That is an interesting discussion in its own right that I tried to answer back then, but for now let’s return to why it is lethal.

The loss of the sting – so-called “sting autonomy6” – is an adaptation against vertebrate predators. It’s no good against other insects or invertebrates who have sclerotized cuticles that resist penetration. The sting’s barbed tip allows it to lodge in the flesh of a vertebrate assailant like a harpoon (indeed, it looks like a harpoon under magnification), and as the bee pulls away the stinger remains along with its closely-associated poison sac. The next time you’re stung, grit your teeth and watch it for a few moments and you’ll see the poison sac pumping like a tiny heart. Its independent involuntary muscles are contracting to inject venom. Meanwhile, there is a sudden pronounced behavior change in the bee that just stung you. She becomes recklessly aggressive, beating against your veil, circling your face, buzzing in your hair – all behaviors adapted to intimidate the intruder. In other words, she has doubled her defensive output; while her sting is autonomously doing its job, she is free to engage in additional defensive behaviors. Magnify this by tens or scores or hundreds of assailants, and you have a very effective colonial defense response. But the down side is the irreparable damage caused to individual stinging bee who dies a few hours later.

However, I am guilty of putting the cart before the horse. What I have just described is the final step in a cascade of earlier behaviors, each a step of increasing engagement as the …