Unsuccessful predation and learning of predator cues by crayfish.

The effect of latent inhibition on learning about cues related to increased predation risk was studied in a native crayfish, Orconectes virilis, and in an invasive species, Orconectes rusticus. Individuals of both species either were exposed or not exposed to the conditioned stimulus (potential ‘‘predator’’ odor 5 goldfish odor) prior to simultaneous exposure to conditioned (potential predator odor) and unconditioned (crushed conspecific 5 alarm odor) stimuli. Crayfish were then tested one day and one week later for inhibition of feeding responses following introduction of goldfish odor. Both species were clearly inhibited in their formation of an association between the goldfish odor and a predator risk stimulus after a training period during which they were exposed only to the goldfish odor. Thus, the effect of latent inhibition was demonstrated in both species. The implications for the learning of cues associated with predation risk are discussed.