INVESTIGATION ON THE LOCUS OF ACTION OF DDT IN FLIES (DROSOPHILA)

Abstract

Injn. of a 1% DDT emulsion into the abdominal cavity causes muscular spasms and eventual death of adult and larval flies. Emulsion without DDT has no effect. Symptoms appear within a few seconds after injn. and may last many hrs. There are differences between adult and larval Drosophila, and between different regions of the neuromus-cular system of an individual animal, in the response to DDT. Abdominal parts of adults and larvae respond to DDT injns. even after isolation from the central nervous system. Isolated fragments of the body wall also respond to DDT. DDT causes muscular convulsions in adults and larvae by affecting the peripheral nervous system. An effect on the central nervous system is not excluded. Phenobarbital affects the peripheral nervous system of larvae but does not paralyze the muscles directly. Phenobarbital abolishes DDT convulsions in larval preparations and antagonizes DDT convulsions in adult flies. Imaginal discs from DDT-treated donors grow and differentiate normally when ex-planted into untreated hosts.