Bees trained to provide low-cost virus smell test

The fight against the coronavirus pandemic has scientists tapping an unlikely resource: the finely tuned olfactory senses of bees.

Dutch researchers say they have trained honeybees to stick out their tongues when presented with the virus’s unique scent, acting as a kind of rapid test.

Although a less conventional method than laboratory tests, the scientists say teaching bees to diagnose the coronavirus could help to fill a gap in low-income countries with limited access to more sophisticated technology, like materials for polymerase chain reaction (PCR) tests.

The scientists trained roughly 150 bees with a Pavlovian conditioning method in which they gave the insects sugar water each time they were exposed to the smell of the coronavirus. When the bees were presented with a sample that was negative for the virus, they received no reward.

The bees eventually learned to stick out their tongues for a positive sample, even with no reward offered. Within hours, the insects had been trained to identify the virus a few seconds after encountering it, the researchers said.

Wim van der Poel, a professor at Wageningen University, which led the research, said the scientists believed they could achieve about a 95 per cent accuracy rate if they used multiple insects to sniff each sample. Their results have not yet been published or peerreviewed.

The idea for the research sprang from the founders of Dutch insect technology startup InsectSense, who have used bees to detect mineral-rich ores and land mines.

The bees smelled samples from both minks and humans, and were similarly good at identifying the virus in both situations, van der Poel said.

InsectSense said it was working on a machine that could train multiple bees simultaneously to make the diagnoses, as well as a biochip that would use genes from the cells that bees smell with to detect the virus.

Researchers are also examining whether dogs could be used to detect the coronavirus. A study published by the University of Pennsylvania last month suggested that dogs can detect the virus with 96 per cent accuracy.