Development of respiratory function in the American locust Schistocerca americana: I. Across-instar effects

Kendra J. Greenlee, Jon Harrison

Research output: Contribution to journalArticlepeer-review

88 Scopus citations

Abstract

We tested the hypothesis that oxygen delivery from the atmosphere to the tissues becomes more difficult as grasshoppers increase in body size throughout development due to increases in tracheal length. If this is true, then older, larger grasshoppers should have smaller safety margins [higher critical oxygen partial pressures (PO2s)] for oxygen delivery than younger, smaller grasshoppers. We exposed grasshoppers of first, third and fifth instars and adults to decreasing levels of atmospheric O2 and measured their ventilatory responses. Contrary to our prediction, we found that larger grasshoppers had critical PO2s eight times lower than juveniles due in part to their threefold lower mass-specific metabolic rates and their ability to quadruple convective gas exchange. Adults more than doubled abdominal pumping frequency and increased tidal volume by 25% as PO2 decreased fourfold, whereas the youngest juveniles showed no such responses. This study indicates that juveniles may be more susceptible to hypoxia in natural situations, such as exposure to high altitude or restricted burrows. Also, larger size is not necessarily correlated with a smaller safety margin for oxygen delivery in insects.

Original languageEnglish (US)
Pages (from-to)497-508
Number of pages12
JournalJournal of Experimental Biology
Volume207
Issue number3
DOIs
StatePublished - Jan 1 2004

Keywords

  • Gas exchange
  • Grasshopper
  • Hypoxia
  • Insect
  • Ontogeny
  • Schistocerca americana
  • Ventilation

ASJC Scopus subject areas

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

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