Bees can detect volatiles with a sensitivity of parts per trillion. For example, they find a flower a few kilometres away. Bees, like dogs, can learn to detect volatiles and odors, but with just a few minutes of training.

Sugar water reward

The bees were trained to detect SARS-CoV-2 infected samples in a Pavlovian conditioning method. Each time the bees were exposed to the scent from an infected sample, they received a sugar water solution reward. The bees extended their tongues to collect the sugar water solution. By repeating this action several times, the bees associated the sugar reward with the scent as the stimulus. With this repeated conditioning, soon enough bees started extending their tongues out for the scent alone, with no reward offered as a follow-up. A trained bee can detect an infected sample within a few seconds.

This research was conducted with more than 150 bees at the Biosafety laboratory of Wageningen Bioveterinary Research with different training setups to determine the most optimum training protocol. The samples used in the first experiments were collected from healthy and SARS-CoV-2 infected minks. In the experiments with the mink-samples, several bees indicated very good results and were able to distinguish the infected samples and those from healthy animals with very low numbers of false positives and false negatives. Similar great results were also achieved in later experiments with human samples as well.