Short-term control of food intake by the terrestrial slugAriolimax

Summary

Advantage was taken of the ability to systematically manipulate consumption rate in the slugAriolimax to quantitatively characterize the factors affecting the short-term control of food intake.

• 1. The rate at whichAriolimax consumes an agar-based food was found to be inversely related to the food's hardness (Fig. 3) which is determined by its agar concentration (Fig. 2).

• 2. Under conditions in which food intake is restricted by feeding slugs hard agar-foods, meal duration and size were observed to be monotonically related to the chemostimulant intensity of the food (Fig. 5).

• 3. Agar-foods having similar chemostimulant concentrations but consumed at faster rates, were associated with a significant increase in meal size (Fig. 6A) and a concomitant reduction in meal duration (Fig. 6A). The reduction in meal duration was highly correlated (r=0.99) with the increase in meal size (Fig. 6B).

• 4. Bite frequency was not significantly effected by either food hardness or increased meal volumes (Fig. 7).

• 5. A “Feeding Equation” was derived from the empirical data. The equation was shown to be capable of predicting meal durations to a reasonable degree of accuracy over a range of chemostimulant concentrations and food hardness (Table 1, Fig. 8).

The accuracy of the Feeding Equation implies that two processes are necessary and sufficient to account for the short-term control of food intake inAriolimax. It is suggested that these two processes may be sensory adaptation and post-ingestional feedback. The significance of these findings for future neurobehavioral studies of taste-aversion learning in terrestrial slugs is discussed.