There really is no end to the number of animals that can be trained to respond to cues using positive reinforcement. The list really runs the whole gamut of mammals, reptiles, amphibians, bird, and fish be conditioned. Even planaria (flatworms) and C. elegans (roundworm) are amenable to training. Success or failure really depends on the science, art and skill of the trainer. And with the proper imagination, animals are capable of incredible things.
Researchers in New Zealand have trained bees to stick out their tongues when exposed to a particular chemical profile associated with M. tuberculosis.
The method used will be familiar to anyone familiar with positive reinforcement:
they puffed TB volatiles at the bee, using a Pasteur pipette containing filter paper infused with one of three characteristic components of the smell of M. tuberculosis. Every time the bee correctly stuck out its proboscis in response, it was rewarded with food.
The power of reinforcement as seen in a bee.