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Hormonal Control of Pupal Ecdysis in the Tobacco Hornworm, Manduca Sexta

  • James W. Truman
  • Paul H. Taghert

Abstract

Molting in insects is a complex process that begins with apolysis, extends through the production of a new cuticle, and ends with ecdysis and the expansion and hardening of the new skin. This process is controlled by an interplay between at least 5 hormones (see Riddiford and Truman, 1978, for a review), three of which are involved in the initiation and direction of the molt. The prothoracicotropic hormone (PTTH) from the brain exerts a tropic influence on the prothoracic glands, driving them to release aecdysone. This steroid is then converted by peripheral tissues to the active form, 20-hydroxyecdysone, which causes apolysis and the beginning of secretion of a new cuticle by the epidermis. The type of cuticle that is secreted is regulated by the titer of the third hormone, juvenile hormone. The final phases of the molt are controlled by 2 additional hormones: the eclosion hormone triggers the behavior involved in the shedding of the old cuticle, and bursicon stimulates the postecdysial tanning of the new cuticle.

Keywords

Juvenile Hormone Ventral Nerve Cord Tobacco Hornworm Adult Eclosion Prothoracic Gland 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1981

Authors and Affiliations

  • James W. Truman
    • 1
  • Paul H. Taghert
    • 1
  1. 1.Department of ZoologyUniversity of WashingtonSeattleUSA

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