The emergence, or eclosion, of large moths from the confines of the pupal case has been shown to be initiated by a blood-borne factor, the eclosion hormone (Truman and Riddiford 1970; Truman 1971). The release of this neurohormone into the blood is a vital link in a chain of events that leads from a circadian clock, located in the brain (Truman 1972), to the performance of a stereotyped sequence of behaviors that effect the moth’s escape from the old cuticle (Truman 1971). Thus, the brain clock (which in turn is entrained by environmental variables) is able to determine the time at which eclosion occurs by controlling the release of the eclosion hormone. Once the hormone appears in the blood, eclosion inevitably follows. In the Saturniid silkmoths, the interval between eclosion hormone release and the performance of eclosion behavior is relatively invariant (Truman 1971; 1973a); in Manduca sexta (a Sphingid), on the other hand, the actual initiation of eclosion behavior once eclosion hormone has been released is somewhat subject to the influence of environmental variables (Reynolds et al, 1979).
KeywordsCircadian Clock Test Wing Ammonium Acetate Solution Pupal Case Eclosion Hormone
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- Charlet M, Schaller F (1976) Blocage de l’exuviation chez la larve d’Aeshna cyanea (Insecte, Odonate) après électrocoagulation d’un centre neurosécréteur du protocérébron antérieur. CR Acad Sci Paris D 283:1539–1541.Google Scholar
- Miller PL, Mills PS (1976) Some aspects of the development of breathing in the locust. In: Spencer Davies P (ed) Perspectives in experimental biology, Vol. 1, Pergamon, Oxford.Google Scholar
- Pittendrigh CS (1965) On the mechanism of entrainment of a circadian rhythm by light cycles. In: Aschoff J (ed) Circadian clocks. North-Holland, Amsterdam.Google Scholar
- Reynolds SE (1977) Control of cuticle extensibility in the wings of adult Man-duca at the time of eclosion: effects of eclosion hormone and bursicon. J Exp Biol 70:27–39.Google Scholar
- Reynolds SE (1980) Cuticle plasticizing factors. In: Miller TA (ed) Neurohor-monal Techniques in Insects, Springer Series in Experimental Entomology. Springer-Verlag, New York.Google Scholar
- Reynolds SE, Taghert PH, Truman JW (1979) Eclosion hormone and bursicon titres and the onset of hormonal responsiveness during the last day of adult development in Manduca sexta (L). J Exp Biol 78:77–86.Google Scholar
- Saunders DS (1975) Insect clocks. Pergamon, Oxford.Google Scholar
- Truman JW (1971) Physiology of insect ecdysis. I. The eclosion behaviour of sa-turniid moths and its hormonal release. J Exp Biol 54:805–814.Google Scholar
- Truman JW(1973b) How moths “turn on”: A study of the action of hormones on the nervous system. Am Sci 61:700–706.Google Scholar
- Truman JW (1973c) Physiology of insect ecdysis. III. Relationship between the hormonal control of eclosion and of tanning in the tobacco hornworm, Manduca sexta. J Exp Biol 58:821–829.Google Scholar
- Truman JW (1978) Hormonal release of stereotyped motor programmes from the isolated nervous system of the cecropia silkmoth. J Exp Biol 74:151–174.Google Scholar