Training Bees for Science

Science is always looking for inexpensive and innovative ways to diagnose disease states. For those who have been tested for COVID 19, you know how unpleasant it can be to have a Q-tip inserted three feet up your nose. And I’m sure you’d welcome alternative approaches.

Thinking along similar lines, scientists in the Netherlands have come up with a truly novel method for detecting COVID-positive patients: they utilized over 150 trained bees, making use of their excellent sense of smell. Metabolic changes from a coronavirus infection makes a person’s bodily fluids smell slightly different than those of a non-infected person. Bees are well suited to notice such differences, since they can detect new volatile substances with a sensitivity of parts per trillion. Amazingly, they are able to detect a flower several kilometers away.

This is the first time these small insects have been used for such a purpose. The research team used a refrigerator to cool down and relax the bees. After this, they were put in small harnesses in order to keep them immobilized in front of the samples before them. The bees were trained by giving them a treat--a sugar-water solution--every time they were exposed to the scent of a mink infected with COVID-19. And they would extend their proboscis to consume the sugar water. On the other hand, when bees were exposed to a negative control (disease-free mink), they were given no such treat. This is known as Pavlovian conditioning, named after the scientist who trained dogs to salivate just by the sound of a bell, because during their training, the bell was rung each time they were fed. Dogs have also been used for sensing body odor changes associated with cancers and other diseases, but unlike dogs, who require many hours of training before they become proficient in differential smell detection, bees require only a few minutes of training.

After repetitive training, the bees learned to associate a COVID-positive mink with a drink of sugar water, so when exposed to an infected sample, they reflexively began to stick out their tongues (like clockwork) within a few seconds in anticipation of the treat. Moreover, they continued to perform this task even when they were not awarded with sugar solution.

It can take hours or days to get a COVID-19 test result, but the response from the bees is immediate. The method is also cheap, potentially making it useful for countries where tests and resources are scarce.