Drones odorant receptor that detects queen honeybees identified

University of Illinois entomologists have identified an odorant receptor on the antennae of male drones that allows them to detect a queen honeybee even 60 metres away during a mating flight.

Washington, Aug 31 : University of Illinois entomologists have identified an odorant receptor on the antennae of male drones that allows them to detect a queen honeybee even 60 metres away during a mating flight.

Hugh Robertson, a professor of entomology at the university, said, this is the first time an odorant receptor has been linked to a specific pheromone in honeybees.

The "queen substance," or "queen retinue pheromone," was first identified decades ago, but scientists have only recently begun to understand its structure and role in the hive.

The pheromone - the primary source of the queen's authority - is made up of eight components, one of which, 9-oxo-2-decenoic acid (9-ODA), attracts the drones during mating flights. It also draws workers to the queen and retards their reproductive growth.

In an earlier study, Prof Robertson's team had identified 170 odorant receptors in honeybees. This time, they used a functional genomics approach to determine which odorant receptors were more dominant in males than females.

Entomology postdoctoral researcher Kevin Wanner found four receptors that were expressed in much higher quantities in males than females.

Tests revealed that only one of the four receptors responded to the 9-ODA. When it bound 9-ODA, the protein receptor's conformation changed, setting off a measurable shift in the membrane potential.

"These proteins are expressed in the membranes of the olfactory neurons way up in the tips of these little sensilla in the antennae of these males. A neuron goes all the way from there to the brain. Now the brain gets a signal that says, 'I've smelled this chemical.' If the chemical is 9-ODA, for the drone that means one thing and one thing only: 'There's a queen somewhere! Go get her!'" said Prof. Robertson.

The findings appear in the Proceedings of the National Academy of Sciences.

ANI