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New Delhi, Oct. 26: Scientists have sequenced the genome of the honeybee, a major step towards deciphering the biology of a social insect that has evolved a caste system and uses a dance language despite a tiny brain.

A research team spread across five continents has determined the complete sequence of genetic alphabets in honeybee DNA, a feat that provides fresh insights into how honeybees differ from other insects and how their genes might play a role in their social hierarchy.

The sequence study, published today in the journal Nature, shows that honeybees have more genes for smell than other insects and new genes for nectar and pollen utilisation, consistent with their ecology and their social organisation in beehives.

The study also suggests that the honeybee, Apis mellifera, originated in Africa and migrated over time to other continents, just as humans did. The honeybee is the third insect to have its genome sequenced after the fruit fly and the mosquito.

“Already, some tantalising findings have emerged to help us better understand the honeybee,” said Gene Robinson, professor of biology at the University of Illinois at Urbana-Champaign in the US and a project leader with the Honeybee Genome Sequencing Consortium.

The sequence has helped scientists detect novel genetic material that appears to have caste-specific expression and thus plays a role in the social diversification among honeybees.

In a typical honeybee colony, a single queen produces young ones, while worker bees numbering into thousands collect and process food, care for the young, build nests and defend colonies. These workers communicate their discovery of food through a sophisticated “dance language”.

Researchers have also identified genes that encode major proteins in royal jelly, a substance rich in proteins, fats and vitamins that worker-bees perpetually feed a young bee that they have chosen to be their next queen.

The new studies have also shown that queens and workers have different gene expression patterns — some genes are more actively expressed in queens than in workers while others are better expressed in workers than in queens.

“This DNA sequence is a major step towards answering a basic question of social evolution: at the genomic level what does it take to engineer an advanced colonial insect?” Harvard University biologist Edward . Wilson said in Nature.

In related papers in the journals Science and Genome Research this week, scientists have reported the discovery of genes and peptides active in the honeybee brain that may contribute to behaviour and presented genetic studies that the Apis mellifera honeybee originated in Africa.

“Neuropeptides undoubtedly play a role in the bees’ shift from working in the hive to foraging, displaying and interpreting dance language and in defending the hive,” said Jonathan Sweedler, a consortium team member at the University of Illinois.