Lithium Chlorine-Induced Food Aversions in the Toad (Bufo americanus)

This research established that a strong and persistent food aversion can be produced in the toad (Bufo americanus), using lithium chloride­ prey pairings. No previous study has reported taste-illness aversions in amphibians. The first of three experiments established this aversion learning and also suggested that prior "safe" exposures to a prey had little effect on subsequent aversive conditioning to that food (mealworm). No effect on general eating behavior as measured by response to another prey object (cricket) was observed in the initial study. The second experiment tested the effectiveness of five different dosages of a hypertonic LiCl solution (.5 M LiCl) in establishing a mealworm aversion. A 2.5 mEq (.5 M LiCl@ .5% BW) LiCl dose was found to condition the avoidance without any decrement in general eating behavior, while a 7.5 m q LiCl dosage was nearly always fatal. Once the mealworm avoidance was established the aversion was maintained without diminution over six weeks of extinction. The final study examined the ability of the toad to develop a long cue-consequence (CS-US) taste aversion. No difference between groups occurred when the CS-US delay was varied from 0 to 90 minutes. Additionally, six weeks of extinction found a persistent aversion with no differences between the five delay groups studied.