Sniffer bees: New flying squad in war against terror

In remarkable field trials completed this week, scientists have harnessed the insect's powerful sense of smell to track down samples of TNT, Semtex, gunpowder and other explosives hidden in shipments passing through a busy cargo airport.

The project is the result of five years of government-funded research carried out by scientists from Rothamsted Research Centre in Hertfordshire.

The prototype under trial consisted of a shoebox-sized device nicknamed the "buzz box", containing three trained bees harnessed into a removable drawer. An electric fan draws air into the box, while a video camera records the bees' response, which can alert the handler to even the faintest trace of explosives.

According to the researchers, bees are able to detect the scent of explosives at concentrations as low as two parts per trillion. "It's the equivalent of finding a grain of sand in a swimming pool," said Rachael Carson, general manager of Inscentinel, the company behind the research.

"If you give them the smell, and then reward them with a sugar solution, they quickly make the association between the smell and the food," she said.

After training, bees will react to even the smallest trace of an explosive by extending their tongue-like proboscis in anticipation of food. "It's like Pavlov's dogs salivating at the sound of a bell," Ms Carson added.

Unlike dogs, however, bees are quick to learn, and relatively cheap to maintain. Furthermore, the insects do not need a dedicated handler and cannot be distracted from their task.

Inscentinel now hopes to produce a commercially available bee-powered bomb detector within two years. According to Ms Carson, the "buzz box" could also be used to search for drugs and contraband tobacco, but Inscentinel is also exploring various non-security-related applications.

The device could, for instance, be used to monitor food quality or even to detect changes in blood or urine caused by illness. A separate trial has been launched in conjunction with the London School of Tropical Medicine into the possibility of detecting signs of tuberculosis in a patient's breath, Ms Carson said.

Richard Jones, the director of the International Bee Research Association, said that although bees can be trained, the experience of being strapped into a box could well distort their reactions. "Any animal under stress will behave differently. I think you'd be better off with a spaniel," he said.

There is another potential sting in the tail, too: certain natural compounds would cause any bee to react, even if it had received counter-explosives training. "That could be a problem if someone was carrying lots of honey," said Inscentinel director Stephen James.