It’s no wonder that we call ants, wasps, termites, and honey bees social insects. It’s as plain as can be. What beekeeper has not marveled at the teeming thousands of colony members toiling away at their respective tasks – all for the common good. It has every appearance of a society, including specialization, cooperation, and order. Some of the workers are guarding the entrance, some fanning, some toting away the dead; some are feeding larvae, some feeding each other, some capping cells, some attending the queen. It’s all so coordinated, it’s no wonder authors of antiquity imagined it running off a top-down command structure while they filled their beekeeping books with words like “queens” and “kings” with all the hierarchical imagery of the monarchies and fiefdoms of their day.
But by now, equipped with 21st century biology, readers of this column should know that the idea of a honey bee “society” has become a little fuzzy. The word implies an assemblage of individuals, and in Darwin’s natural world an individual means one who is reproductively competent – a unit of selection – a concept so important I spent three months talking about it (July, Sept, and Oct 2015). Reproductive competence does not apply to any one member of the honey bee colony in isolation. The queen, and by extension her drones which constitute her “sperm,” is dependent upon the labors of the workers; and the workers, for reasons explained in my June column, have forsaken reproduction in favor of helping their mother produce siblings. To get rid of the fuzziness, an observer has to step back until it’s the whole colony that comes into focus. And that’s what happens with the superorganism concept – and it is just that, a concept and not a formal theory – it posits the whole colony as analogous to an organism, or a unit of selection. To put it another way – a superorganism does the kinds of things that only organisms do.
Last month I gave an example of this kind of organismal behavior in the honey bee colony – homeothermic temperature regulation. This month I’m presenting another – comb building, which in the metaphorical sense of a superorganism can be thought of as growth and development of the infrastructure, the skeleton if you will. As we see over and over, the material entity of the comb is so integral to the colony’s life that it almost acts as a colony member itself. The comb is the substrate upon which everything happens – brood rearing, food storage, pheromone deposition, dance recruitment, transmission of vibration signals. Nothing can happen without it, and building it is priority #1 for a new swarm occupying a new cavity. And being a metabolic product of consumed honey, it is expensive. As far back as 1965, Weiss1 calculated that it costs a colony 13.8 pounds of honey to produce 2.2 pounds of comb. Using data by Tom Seeley2 from New York, we can extrapolate from Weiss that a normal colony consumes 16.5 pounds of honey, roughly 12.5% of its annual honey income, just to build its comb. It is for this reason that a new swarm gains a significant advantage if it has the good fortune to find a cavity with pre-existing combs. Such colonies can end up collecting twice as much honey as new colonies founded without combs.3
To put the cost : benefit ratio into sharper relief, let us consider the time of year when all this is happening – for temperate-evolved honey bees that means late winter / early spring. In other words, these comb building campaigns are underwritten on stored honey – and in the case of a new swarm, that “stored” honey goes no further than the honey in the honey stomachs of individual bees. This is why swarms always occur on days with good nectar flows; bees immediately need the new honey to supplement the honey in their crops. If the flow shuts off, the swarm is toast. This is one reason why the 12-month survival rate of new swarms is only 24%.2
But the cost / benefit calculation applies as well to mature colonies, albeit with lower stakes. Consider: a colony benefits if it has plenty of empty comb on hand the minute a strong nectar flow begins. Foragers can immediately unload their nectar to “receiver” bees who in turn immediately deposit it into empty cells, the combined effect of which encourages more foraging and more honey storage. If, on the other hand, the colony builds “too” much comb “too” early then it runs the risk of exhausting its precious honey stores. If the colony / superorganism really does constitute a Darwinian unit of selection, then we should be able to make scientific predictions about how it behaves to optimize its survival chances between these two extremes.
There are certain conditions necessary for the initiation of comb construction: (1) bees prefer to initiate comb construction in the dark4, (2) building ceases in the absence of a queen5, and (3) workers must have adequate protein nutrients early in adult life if they are to activate their wax glands and serve as comb builders.6 These three conditions are …