BEES HAVE THERMOSTATS, CAN REGULATE TEMPERATURE IN HIVES

by Whit Gibbons

October 1, 2017

Honeybees are intriguing. Worker bees, who perform all the hive-keeping chores, are female. Males, also known as drones, have only one function: to mate with the queen.

A study in Australia, where European honeybees have been introduced (as they have here), indicates that how hive temperature is controlled depends on whether the queen mates with only one male or with several.

Being social insects, honeybees are considered a super-organism, with each individual operating in the best interest of the hive. Self-interest does not exist in a bee colony. Members of the colony operate in unison to keep the temperature in the hive as close to 95 degrees as possible. To cool the hive in hot weather, they wave their wings, creating a misting effect with water they bring into the hive.

In cold weather, they warm the hive by generating heat from body muscles. As environmental temperatures may rise or fall rapidly, depending on local weather conditions, honeybees must be in a constant state of readiness to act in unison to raise or lower hive temperature. Honeybees thermoregulate not for their own comfort but for the developing brood that are highly sensitive to fluctuating temperatures.

Scientists at the University of Sydney conducted a study that was an impressive mix of behavioral observations and DNA analyses. They demonstrated that a queen’s normal choice – to mate with not just one drone but several – is in the best interest of the hive. Experiments were conducted on pairs of hives having the same number of bees but differing genetically. One hive consisted of worker bees that were the offspring of a single queen and a single drone. The behavior of this hive, with uniform genetic parentage, was compared to that of a normal hive in which the queen has had multiple mates so that the workers are of mixed genetic heritage.

The researchers found that in both colonies worker bees maintained the hive at the preferred temperature. However, the temperature over time in the mixed genetic hive remained relatively invariable compared to the other hive. The uniformly genetic individuals eventually got the hive to the proper temperature, but their response time lagged behind that of the genetically diverse hive.

The explanation for the differing responses is fascinating. Bees vary from individual to individual in their internal thermostats – just like people. We see this frequently in offices, theaters, classrooms – any place where people congregate. Some will think the room is too cold; others will think it’s too hot; some lucky souls will think it’s just right. Bees are apparently the same way. Some bees will find the hive too hot, some too cold, and so on, and they will act to regulate the temperature. Not for their own comfort but for the welfare of the hive.

When honeybees are genetically similar, they are more likely to respond to a need to begin “regulating the thermostat of the hive” at the same temperature. This means they all begin to operate at about the same time. In the genetically diverse hive, individuals respond at different temperature levels. Some begin the cooling process of fanning the hive on a hot day at slightly lower temperatures than other individuals that pick up the call to duty a little later. The temperature of a genetically diverse hive is kept at a more uniform level because individual bees are responding across a wider gradient of temperatures.

To confirm the relationship between genetics and behavior, the researchers did DNA tests in a mixed genetic hive. They removed some workers that began fanning at one temperature and some that began fanning at other temperatures. Sure enough, individuals that began fanning at a given temperature were more likely to have the same father than those fanning at other temperatures.

The honeybee findings are as captivating as the insects themselves, and when you consider the scientific complexity involved in conducting such a study, the scientists are as impressive as the bees.

If you have an environmental question or comment, email

(Back to Ecoviews)

 

 
SREL HomeUGA Home