Equivocality of Survival of Learning acquired at the Larval Stage

Abstract

USING larvae of the beetle Tenebrio molitor, Borsellino, Pierantoni, and Schieti-Cavazza¹ tested whether learning could survive through metamorphosis. Their apparatus was a maze consisting of a circular starting chamber, a short stem leading to a choice point and two alternative paths leading to a circular goal chamber. They describe training procedures in which “all animals passed through the maze once a day” and in which animals in the learning groups were punished for a wrong choice while larval controls were not. Punishment procedures exploited the strong negative phototaxis exhibited by both larvae and adults and consisted of a bright light introduced when subjects from a learning group entered the wrong path. After metamorphosis, adults of both the larval learning and control groups were passed daily, but without punishment, through similar mazes. The results indicated that controls performed at chance levels while learning subjects significantly chose the side they were trained to enter earlier as larva. If their conclusion “that learning survives through metamorphosis” were justified, if their results were convincing, and if their procedures were acceptable, this study would indeed be very exciting.