Sniffer bees

Anyone entering New Zealand via the International arrivals terminal at Auckland may well have been welcomed by one of MAF Biosecurity’s sniffer dogs. These lovely animals are specially trained to search baggage, mail and cargo to locate undeclared or forgotten agricultural products.

But one day you may be greeted by bees too.

Honeybees can be trained to recognise particular smells and associate that smell with a food reward. When the bees detect the smell, they extend their tongue or proboscis (the Proboscis Extension Reflex or PER) in expectation of food. Honeybees make excellent detectors because they are cheap, quick to train and have extremely low limits of detection.

Inscentinel Ltd. is a biotech company specialising in harnessing this reflex. They have developed a system for temporarily housing bees in thumb-size cartridges within a machine that resembles a handheld vacuum cleaner. When the bees extend their tongues in response to a stimulus, this trips an optical sensor which is detected by the machine.

One potential application of the sniffer bees could be in the diagnosis of tuberculosis (TB). TB is a lung infection caused by the bacterium Mycobacterium tuberculosis. Breathing in as few as 5 bacteria is all it takes to become infected. It is estimated that one third of the world’s population (that’s 2 billion people) unknowingly have M. tuberculosis in their lungs. These people are ticking TB time bombs; 1 in 10 of them (200 million people) will fall ill with TB at some stage during their life. TB kills almost 2 million people every year, that’s over 4500 people every day.

Current diagnosis methods for TB are labour intensive, involving examination of sputum samples for the tubercle bacterium. What is really needed is a cheap, quick and reliable method that could be easily used in developing countries, which often have little money and few resources. Scientists from New Zealand recently reported that honeybees could be trained to detect some of the volatile compounds released by laboratory grown M. tuberculosis. It remains to be seen whether these volatile compounds are also released during disease. But if it turns out they are present in detectable concentrations in the breath of TB patients, then this could be a game-changer in our battle against this truly terrifying superbug.

Reference: Suckling DM, Sagar RL. (2011). Honeybees Apis mellifera can detect the scent of Mycobacterium tuberculosis. Tuberculosis (Edinb), 91(4):327-8.