As for the rats, how come they aren't used more? Is it just that their use is taking time to grow, for people to hear about it and then get some trained? Is it only these type of rat or could all types of rats be trained?
Now if we could train rats to detect drugs then set them loose on festivals to find all drugs and fetch them back. That would be nothing short of hilarious.
They use bees trained to detect target odours combined with sucrose to create a proboscis extension reflex (PER).
Then a high magnification camera is used to detect how many bees PER, thus indicating the presence of X target odour.