A blog post highlighting the article written by M.L. Smith, M.M. Otswald & T.D. Seeley in Insectes Sociaux

Written by Michael L. Smith

I think Walter Tschinkel (1991) said it best when he wrote: “The list [of sociometric data] is not exhaustive, though collecting the data could be exhausting.” My research into honey bee sociometry is a case study in how right he was.

But let’s start at the beginning: what is sociometry? Sociometry is the description and analysis of the physical and numerical attributes of social insect colonies over their lifetimes (Tschinkel 1991). Sociometric data, therefore, is just about anything that you could measure in a social insect colony throughout its life, such as: the size of the nest, the number of workers, the size of the workers, the size of the food stores, the number of sexuals, etc.

Unfortunately, sociometric data are often not collected, and if they are, they’re rarely reported. It’s probably because collecting these data (plus the analyzing and writing) is tedious work. But it’s rewarding, it’s important information that forms the foundation of future research.

My primary interest is reproductive investment in honey bee colonies. In particular, I wanted to know when workers begin to build the large cells of beeswax comb that they use for rearing reproductive males or “drones.” With this question in mind, I set out to conduct a sociometric study, but not just of drone comb, I’d track the whole colony’s growth and development from birth until death. Surprisingly, this had never been done. Many studies had looked at one or two colony parameters throughout a single season, but only a couple had tracked multiple parameters in concert (Lee & Winston 1985; Pratt 1999). The study that tracked the most parameters simultaneously only did so for the first year (Rangel & Seeley 2012), and so missed out on the production of sexuals that occurs in the second year. It seemed like it was time to conduct a broad sociometric study on honeybee colonies throughout their entire life cycles.

To do this, I built and set up four large observation hives, each one about 1m x 1m. These are larger than standard observation hives, and I chose them because I needed sufficient volume (ca. 40L) for the colony to grow to its full size (Seeley & Morse 1976). I then installed into each observation hive an artificial swarm, and monitored the colonies weekly until they died.

Through the glass of the observation hives, I could observe the colonies without disturbing them. I could monitor the number of inhabitants, the growth of the comb, and the contents of the comb, all traced upon a sheet of plastic placed atop the glass of the observation hive. Together with a keen undergraduate, Maddie Ostwald, we tracked honey bee colonies from birth until death while recording worker population, drone population, comb area, comb use (cells holding brood, pollen, honey, or nothing), swarming and secondary swarming events, and time of death. This began in July 2012 and continued until January 2014, and that doesn’t count the time it took to transcribe the comb areas from the plastic sheets!

What do we get at the end of it all? Well, first and foremost, I think it’s a great way to get extremely familiar with your study organism. I grew fond of my colonies, each one with its own personality. One hive was in my office, so I’d hear them buzzing along throughout the day- the perfect office mate. Second, I’m now able to frame my experimental work within the context of these observational descriptions. For example, I now know that although all four colonies built drone comb in their first year, none of them used the drone comb for rearing drones until the second year. Despite having only four colonies, we observed a diversity of life-history strategies, including one colony that attempted to reproduce by producing queen-laid drones in worker cells (the drones were two-thirds smaller than those produced by the other colonies). We also found that drones tend to stay at home when a swarm departs, presumably because they have higher reproductive success at home, but the workers will quickly cull the drones if food stores are low. These highlights, of course, are biased by my interest in drones, so please check out the paper if you’d like to know more (Smith et al. 2016). Lastly, sociometric data are a valuable resource for all social insect biologists, and we cannot conduct comparative analyses without good descriptions of the natural growth and development of many social insect colonies.

I encourage you to think of your favorite social insect species. Is there a paper out there that describes, in painstaking detail, everything that you could possibly count, measure, and describe, from colony founding to colony death? If not, then maybe this is your chance to make it happen!

 

References

Lee, P.C. & Winston, M.L., 1985. The effect of swarm size and date of issue on comb construction in newly founded colonies of honeybees (Apis mellifera L.). Canadian Journal of Zoology, 63(3), pp.524–527.

Pratt, S.C., 1999. Optimal timing of comb construction by honeybee (Apis mellifera) colonies: a dynamic programming model and experimental tests. Behavioral Ecology and Sociobiology, 46(1), pp.30–42.

Rangel, J. & Seeley, T.D., 2012. Colony fissioning in honey bees: size and significance of the swarm fraction. Insectes Sociaux, 59(4), pp.453–462.

Seeley, T.D. & Morse, R.A., 1976. The nest of the honey bee (Apis mellifera L.). Insectes Sociaux, 23(4), pp.495–512.

Smith, M.L., Ostwald, M.M. & Seeley, T.D. 2016. Honey bee sociometry: tracking honey bee colonies and their nest contents from colony founding until death. Insectes Sociaux.

Tschinkel, W.R., 1991. Insect sociometry, a field in search of data. Insectes Sociaux, 38(1), pp.77–82.