Survival of olfactory memory through metamorphosis in the fly Musca domestica.

Metamorphosis in the fly (Musca domestica) involves extensive lysis, neurogenesis and reorganization of neural tissue. Despite this, two experiments are reported which show aspects of larval memory persist into the adult form. Experimental larvae were reared in sawdust scented with aversive odours (mint or geraniol). Control larvae were reared on plain sawdust. In blind post-metamorphosis testing using a Y maze, adult flies showed a preference for the specific odour to which the larvae had been exposed. Control flies found both test odours aversive. A second experiment explores the possible role of cell survival through metamorphosis as a mechanism of the persistence of memory. Cells from trained donor flies when grafted into untrained recipients produced specific changes in recipient odour preference reflecting the donor larvae training.