FLIGHT-MUSCLE DEVELOPMENT IN JUVENILE AND ADULT FORMS OF THE DESERT LOCUST, SCHISTOCERCA-GREGARIA

Hormonal control of flight muscle development was studied in the deser t locust, Schistocerca gregaria through quantitative analysis of elect ron micrographs from normal adults, precocious adults (obtained after ethoxy-precocene treatment), as well as supernumerary nymphs (obtained by methoprene treatment) and azadirachtin-induced overaged nymphs. Du ring the first 2 weeks after imaginal ecdysis, flight muscle of normal adults as well as its constituent mitochondria and myofibrils increas ed in size. The mitochondrial portion of the tissue enlarged from 17 t o 30%. Similar growth of all components was observed in precocious adu lts, obtained after treatment of 3rd-instar nymphs with ethoxy-precoce ne. Overaged nymphs as well as 6th-instar, supernumerary nymphs did no t exhibit growth of myofibrillar components; size and distribution of mitochondria however was similar to adult insects. The results indicat e that metamorphosis is required for complete muscle differentiation a nd development. Mitochondrial growth, however, is largely independent of endocrine influences. The results are discussed in light of publish ed biochemical findings.