Scientists comb DNA for secrets of the honey bee

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The Independent Online

She has a biological clock to tell the time of day, uses a sophisticated navigation system to locate food miles away and can produce the sweetest natural substance on earth simply by chewing up pollen grains.

The secret life of the honey bee is about to be revealed after an international consortium of scientists sequenced the full genetic code of the honey bee's genome, with the results published jointly in the journals Nature and Science.

An early analysis of the bee's genes has shown that its ancestors originated in Africa and migrated from that continent at least twice in the distant past to populate Asia and Europe.

The honey bee also has an unusually high number of genes devoted to smell, showing that she is better at detecting a wafting scent in the air than either fruit flies or mosquitoes.

Scientists hope that many more secrets of the honey bee will soon be explained with the help of the full DNA sequence of the only social insect to be partially domesticated by man.

A study of the bee's genome has already shown that the molecular machinery of its internal body clock more closely resembles that of a mammal than it does any other insect, much to the surprise of scientists.

Honey bees can learn to reach flowers at nine different times of the day with an accuracy of 20 minutes. The clock is essential for its navigation system - based on the movement of the sun - which can locate a food source up to six miles away.

Scientists also announced yesterday the discovery of the world's oldest bee, a 100 million-year-old specimen preserved in amber that had evolved from a wasp-like ancestor.

Honey bees co-evolved several million years later alongside flowering plants, explained Hugh Robertson, professor of entomology at the University of Illinois at Urbana-Champaign. Honey bees today pollinate billions of dollars worth of crops.

Scientists had hoped that the honey bee genome would also explain how it evolved into being a social insect with a caste of sterile female workers, male drones and a fertile queen, said Gro Amdam, of Arizona State University. Most honey bees in a colony are female worker bees.

"An early expectation of the sequencing project was that we would find many new genes responsible for social behaviour in the honey bee genome," Professor Amdam said. "However, we didn't find much diversification of such social genes and, in fact, the number of honey bee genes overall was smaller than in the genome of the fly." However, the scientists hope that by selectively silencing certain honey bee genes they will be able to work out which are involved in the genetic programming necessary for the evolution of castes within the hive.

By analysing genes of the male drones, scientists also hope to be able to find how they use their antennae to detect chemical pheromones released by queen bees.

"We have identified several honey bee odorant receptors that are abundantly expressed in male antennae. This moves us an important step closer to understanding the molecular details of how bees, and insects in general, smell," Professor Robertson said.

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