Action of Juvenile Hormone on Imaginal Discs of the Indian Meal Moth

Abstract

The action of the corpora allata, which secrete juvenile hormone (JH), on the development of imaginal discs has received limited attention during the three decades that followed Vogt’s pioneering work with Diptera. Vogt (1943) reported that removal of the medial cells (corpora allata) of the ring gland in larvae resulted in accelerated development of the eye discs. Precocious development of imaginal discs was also obtained by transplanting imaginal discs into a JH-free milieu. In these experiments Williams (1961) transplanted wing discs from Cynthia into chilled pupae. The discs metamorphosed with the host into pupal, pupal-adult, or directly into adult structures. Not only could the imaginal discs be induced to metamorphose prematurely by reducing their exposure to JH, but they could also be maintained in an undifferentiated state by extending the JH period. These early studies demonstrated that the corpora allata prevented the differentiation of imaginal discs in both dipteran (Vogt, 1946; Possompes, 1953) and lepidopteran larvae (Sehnal, 1968). Other investigations have shown that imaginal discs are targets of the ecdysones (Oberlander, 1972).