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DNA triggers beehive air-con

Bee fanning wings

Bees with different fathers start fanning their wings to keep the hive cool at different temperatures (Image: University of Sydney)

Honey bees have a sophisticated way of air-conditioning their hives that depends on genetic diversity, say Australian scientists.

Biologist Julia Jones, of the University of Sydney, and colleagues report their study online today ahead of print publication in the journal Science.

Genetic diversity in beehives, which results from the queen bee mating with numerous drones, plays a role in allocating tasks such as nectar collecting and pollen foraging, Jones told ABC Science Online.

For example, worker bees with different genotypes will only collect nectar once it reaches a certain threshold concentration.

But, Jones said, so far nothing has been known about the role of genetic diversity in the extraordinary ability of honey bees to keep the temperature of their hives relatively constant, especially in spring and summer when they have a brood.

"When they have a brood the temperature is strictly controlled between 32° and 36°C," Jones said.

Bees use a range of methods to deal with a hot or cold hive.

They fan their wings to drive out hot air, put drops of water in the hive for evaporative cooling, and evacuate when it's too hot.

When it gets cold they can cluster around the brood in a sphere, press their thorax against the top of the brood cells and even generate metabolic heat by engaging their flight muscles but not moving their wings.

But Jones said the ability to keep the temperature of the hive stable means bees must have developed a sophisticated system of temperature control so they don't all start cooling or heating the hive at the same time.

"It's like stove top," said Jones. "You can't simmer some water in a saucepan with just two settings of 'on' and 'off'. You need to have a graded response."

Jones and team monitored the temperature of eight colonies of bees over a week. Four of the hives had a queen that mated normally with a number of drones and thus had a genetically diverse colony. The other four hives had a queen that had been artificially inseminated and thus had a genetically uniform population of bees.

The researchers found that the multiple-mated genetically diverse colony kept temperatures more stable than the genetically uniform colony. She then heated some of the hives up to 40°C and found similar results.

In a third experiment, Jones set out to study which bees fanned their wings, and when, in the multiple-mated hives. She started with the theory that bees with different fathers had different thermostats and would start fanning the hive at different temperatures.

She heated the hives and at each temperature sampled the bees that were fanning their wings at the hive entrance, then analysed their genetic make-up.

She found that different genotypes of bees were more common at the hive entrance at different temperatures.

"We think this is because the different genotypes have different temperature thresholds," she said.

Tags: environment, biology, cloning-and-dna