Last month we talked about one of the many examples of self organization in the honey bee superorganism – comb construction and the dynamics that govern how and when bees engage in it. At this moment, self organization is a theme in our evolutionary history of the honey bee, and it follows the principle that global order (such as comb construction) can emerge from a complex field of actors (worker bees), each responding independently to her own local conditions. As an example of how biology can be parsed into layers of systems, this month we delve deeper into comb construction and ask how cells get formed, cells of course being the units that collectively make up combs, and look at some properties of combs that emerge as natural outcomes of physics and prior conditions.
It seems to me that cell construction is an outcome of two interacting biological phenomena: (1) emergent properties as we’ve discussed before – the order that emerges from individual actions, along with (2) instinctive behavior of individuals.
First, a word about instinct, a common enough word that still needs definition. A behavior is traditionally considered instinctive if it is genetically “hardwired,” universal to a species, and not learned1. It is sometimes called innate behavior, and the sequence of events in an instinctive response is sometimes called a fixed action pattern. Examples include the movement of newly-hatched sea turtles from the beach toward the surf, language acquisition in humans2, and the suckling urge of new-born mammals. The instinctive behavior of bees we’re concerned about in this article is the propensity to build individualized cells. Readers may recall from my April 2015 article that the earliest ancestors of the honey bee nested in simple tunnels which over time were elaborated into individualized cells for holding food or rearing young, in many cases the cells being lined with water-resistant glandular secretions – the evolutionary precursors to what became wax glands and beeswax in the honey bee lineages. The individualization of cells is both ancient and persistent across all bee families; hence we can assume that it was strongly selected for as a means to protect food from spoilage and the young from pathogens, predators, and trampling by nestmates. I am considering it an instinctive behavior, not learned, and even though the social life of colonial bees offers many opportunities for learning such a behavior, the antiquity and ubiquity of individualized cell making argue against it being a more modern innovation.
From last month’s discussion we know that building the comb is priority #1 for a swarm newly-settled into a cavity. The initiation of comb construction is always associated with sheets of bees hanging together in a posture called festooning (Fig. 1). Inside these festoons are found wax-bearing workers and cell builders. In a natural cavity there can be many of these festoons – a behavior obscured in the more structured Langstroth hive with its interspersing frames – and the physical location of these festoons doubtless imparts a sort of template onto the ultimate outcome. In a new cavity there will numerous independent starts of comb construction, each festooned work crew working without regard to an overarching design. Comb initiation inside these festoons has been difficult to observe without disruption in spite of centuries’ worth of effort, owing naturally enough to the dark cavities and density of the festoons themselves. For this reason, our best observations come from the open-nesting Asian honey bee Apis florea as described by Hepburn at al.3 As with their western cousin A. mellifera, the initiation of comb construction is immediate upon setting onto a nest site – in A. florea’s case the underside of a limb. Within hours a first row …