How Much Does Size Matter for Honeybee Colonies?

When people think of bees, they oftentimes think of huge, potentially terrifying, swarms of bees. They think of a hive, coated in bees, that is a roiling mass of bees that works as a unit. These swarms are usually the work of honeybees. But what many people don’t realize is that there are many other species of bees, some of which live in small colonies but most of which are actually solitary. Thus, it is clear that these small colonies or even solitary species can survive just fine in many different environments. So, why do honeybees have such large colonies of up to 60,000 bees in captivity?

One aspect of honeybees that is unique relative to other species of bees is the complexity of their communication system. Honeybees use an amazing waggle dance communication system that allows them to relay the spatial location and quality of resources around the hive. Thus a natural question is: is the size of honeybee colonies connected to the waggle dance? In other words, is the benefit of communication greater for larger honeybee colonies than in smaller colonies? If this were the case, it would mean that larger colonies would be able to forage more efficiently and thus collect more nectar per forager.

This was the question I set out to answer in my senior thesis project this past year. A previous simulation study had shown that colony size did not affect the benefit of communication, but a subsequent empirical study revealed that in the particular environments tested, communication was actually more beneficial for larger colonies than smaller colonies. Thus, I designed a simulation in NetLogo that was identical to this original simulation, except that resources in the environment had different qualities, which modeled differences in the sugar concentration of flower nectar. In my simulation I had little yellow bee figures roaming around on my computer screen looking for little green resource dots.

Development of this model was a long and arduous process, but ultimately a very rewarding one. It gave me a great appreciation for GitHub and its revert feature which allowed me to go back to a previous version of my code. I needed to measure the foraging success of honeybees under many different conditions, and thus a set of simulation runs took around two whole days to run. Luckily, this gave me lots of time to work on my final thesis report so I wasn’t working on it the hour before it was due (hah-if only). However, eventually I worked through all of the technical bugs, so then the real bugs could do their thing.

Now in the above figure, we have the main results of my project, and I will get into a bit more of the technical jargon with terms and what the results actually mean. On the y-axis we have the amount of energy that was collected per forager, while on the x-axis we have a variety of different environments. An R value (resource distribution) close to 1.0 means that the resources are evenly distributed, while as the R value decreases, the resources get clumpier and closer together. ‘Comm’ defines whether communication was used by the colony, and ‘Pop’ is the size of the colony.

Using fixed-effects linear models and ANOVA tests, we found larger colonies collected significantly less energy per bee than smaller colonies, while colonies that used communication collected significantly more energy per bee than colonies that did not communicate. However, we also found that colony size did not significantly change how communication affected the log of the energy collected per bee, and there was no three-way interaction effect between colony size, communication, and environment. Thus, the benefit of communication was not greater for larger colonies than smaller colonies.

These results suggest that this simulation, like the previous simulation, did not capture the environmental factor or factors that cause communication to be more valuable for larger colonies in certain environments. While this was definitely disappointing, I’m very excited about the progress made in this model, and potential future uses. A hypothetical future thesis student could make small modifications to this model, run the same simulations, and then analyze the results to see if the benefit of communication changed with colony size. If it did, then it would mean that they had found an environment in which communication was more beneficial for larger colonies, and they could do further tests to determine what specific aspects of the environment made communication more beneficial for larger colonies. One potential environmental factor, which I didn’t have time to incorporate in this model, is ephemerality. If resources disappear quickly, then larger colonies might be able to quickly focus on a profitable resource before it disappeared. Understanding which environmental factors affect the benefit communication for honeybee colonies is crucial to understanding the evolutionary history of honeybees, and thus a worthy and important piece of knowledge to pursue.

Media Credit:

Honeybee image, photo by Matina Donaldson-Matasci:

https://www.flickr.com/photos/matina_c/26426462750/in/album-72157665354218234/

Further Reading:
Donaldson-Matasci MC, DeGrandi-Hoffman G, Dornhaus A (2013)
Bigger is better: honeybee colonies as distributed information-gathering systems.
Anim Behav 85: 585–592.
http://dx.doi.org/10.1016/j.anbehav.2012.12.020
(Nature Research Highlight)

Dornhaus A, Klugl F, Oechslein C, Puppe F, Chittka L (2006)
Benefits of recruitment in honey bees: effects of ecology and colony size in an individual-based model.
Behav Ecol 17: 336–344.
http://beheco.oxfordjournals.org/cgi/content/abstract/17/3/336