Role of neurosecretory cells in the photoperiodic induction of pupal diapause of the tobacco hornworm Manduca sexta

Sakiko Shiga, Norman T. Davis, John G. Hildebrand

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

In the tobacco hornworm, Manduca sexta, pupal diapause can be induced by exposure of fifth-instar larvae to a short-day photoperiod. We studied the effect of surgical ablation of tissues containing the neurosecretory cells of the brain of fifth-instar larvae on the photoperiodic induction of pupal diapause. At the end of the experiments, we immunostained the neurosecretory cells to determine the success of the ablations. Under long-day conditions (LD 16:8 at 22°C), all intact larvae, most of the sham-operated larvae, and control-operated larvae developed into nondiapausing pupae. Under short-day conditions (LD 10:14 at 22°C), most intact, sham-operated, and control-operated larvae developed into diapausing pupae. Removal of type-II cells did not interfere with the photoperiodic response. Under long-day conditions, elimination of type-Ia1 cells did not affect the incidence of nondiapausing pupae. When type-Ia1 cells were removed under short-day conditions, however, the incidence of nondiapausing pupae was higher (51%, n = 41) than that of the intact (16%, n = 75), sham-operated (24%, n = 88), control-operated larvae (5%, n = 40), and larvae with type-II cells removed (11%, n = 27). Thus, removal of type-Ia1 cells can impede induction of diapause. These results indicate that the type-Ia1 neurosecretory cells have an important role in the induction of pupal diapause.

Original languageEnglish (US)
Pages (from-to)275-285
Number of pages11
JournalJournal of Comparative Neurology
Volume462
Issue number3
DOIs
StatePublished - Jul 28 2003

Keywords

  • Corazonin
  • PTTH
  • Photoperiodic response

ASJC Scopus subject areas

  • Neuroscience(all)

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