Illness-dependent conditioned prey avoidance in an amphibian

摘要

Conditioned taste avoidance (CTA) helps prevent consumption of dangerous foods. It results from the pairing of a novel food or taste with subsequent aversive consequences, such as illness. Previous studies of CTA in amphibians have produced conflicting results. Establishing the presence or absence of CTA in amphibians is needed to clarify the phylogeny of this phenomenon. This experiment evaluated the ability of the fire-bellied toad Bombina orientalis to avoid a novel food item previously paired with subsequent illness or unpalatable taste. Mealworms, a novel prey item for the subjects, were coated with a solution of either 2% HC1 or 3% CuSO_4 to make them unpalatable or nauseating, respectively. Lengthy and obvious signs of illness such as face wiping and retching followed the consumption of mealworms coated with CuSO_4, whereas consumption of mealworms coated with HC1 only resulted in distinct and short lived aversive reactions at the time of consumption. The results showed that consumption of mealworms tainted with CUSO_4, but not HC1, rapidly induced prey avoidance. This response was specific to mealworms; the usual food (crickets) was not avoided. The results suggest that CTA following illness is not restricted to amniote vertebrates.