Intricate but tight coupling of spiracular activity and abdominal ventilation during locust discontinuous gas exchange cycles

Stav Talal, Eran Gefen, Amir Ayali

Research output: Contribution to journalArticlepeer-review


Discontinuous gas exchange (DGE) is the best studied among insect gas exchange patterns. DGE cycles comprise three phases, which are defined by their spiracular state: Closed, flutter and open. However, spiracle status has rarely been monitored directly; rather, it is often assumed based on CO2 emission traces. In this study, we directly recorded electromyogram (EMG) signals from the closer muscle of the second thoracic spiracle and from abdominal ventilation muscles in a fully intact locust during DGE. Muscular activity was monitored simultaneously with CO2 emission, under normoxia and under various experimental oxic conditions. Our findings indicate that locust DGE does not correspond well with the commonly described three-phase cycle.We describe unique DGE-related ventilation motor patterns, coupled to spiracular activity. During the open phase, when CO2 emission rate is highest, the thoracic spiracles do not remain open; rather, they open and close rapidly. This fast spiracle activity coincides with in-phase abdominal ventilation, while alternating with the abdominal spiracle and thus facilitating a unidirectional air flow along the main trachea. A change in the frequency of rhythmic ventilation during the open phase suggests modulation by intratracheal CO2 levels. A second, slow ventilatory movement pattern probably serves to facilitate gas diffusion during spiracle closure. Two flutter-like patterns are described in association with the different types of ventilatory activity.We offer a modified mechanistic model for DGE in actively ventilating insects, incorporating ventilatory behavior and changes in spiracle state.

Original languageEnglish
Article numberjeb.174722
JournalJournal of Experimental Biology
Issue number6
StatePublished - Mar 2018

Bibliographical note

Funding Information:
This study was supported by an Israel Science Foundation award no. 792/12.

Publisher Copyright:
© 2018. Published by The Company of Biologists Ltd | Journal of Experimental Biology.


  • Active ventilation
  • Central pattern generator
  • Electromyogram
  • Insects
  • Spiracles
  • Tracheal system

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science


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