Retention of a Conditioned Avoidance Response after Metamorphosis in Mealworms

Abstract

METAMORPHOSIS of holometabolous insects involves extensive reorganization of their nervous systems^1,2. In spite of such changes, behavioural modifications can be demonstrated at the adult level after manipulations in the larval stage^3–5. For example, the adult reactions of Nemeritis and Drosophila to chemical cues have been altered by exposure to these cues during the larval stage^3,4. One limitation of these experiments, as Thorpe points out, is that the behavioural modification cannot be assessed directly in the larval stage. Using a more formal conditioning procedure, Borrell du Vernay⁵ found that Tenebrio trained to discriminate between surfaces and thus avoid shock in the larval stage showed subsequent savings in relearning the discrimination as adults. Unfortunately, this study did not include controls for such variables as sensitization to shock and familiarization with the test situation.