Abnormal Metamorphosis in Saturniid Moths infected by a Microsporidian

Abstract

DEVIATIONS from the normal course of metamorphosis in insects may be caused by parasitic infections^1,2. In studies on a microsporidian of the genus Nosema, found in Hyalophora (Platysamia) cecropia and afterwards sub-cultured in Antheraea polyphemus and A. pernyi ³, seventeen of the many infected animals failed to metamorphose normally. The most severely affected were adults of H. cecropia. They retained a number of pupal structures. The tip of the abdomen and the genitalia were pupal in form.; the cuticle of the rest of the abdomen and of the thorax was a mosaic of pupal and adult types and at the base of each eye was an unpigmented band. Such abnormalities can be produced experimentally by introducing active corpora allata or juvenile hormone (neotenin) into the developing adult during the period when its own corpora allata are inactive^4,5. Lesser effects were seen in two A. pernyi pupæ that had been formed from infected larvæ. Each had white, larval-type setæ scattered over the abdomen, and crotchets in the position of the larval prolegs. Finally, there were adults of both species of Antheraea which had patches of pupal type cuticle.