title: Ontogenetic effects on aerobic and anaerobic metabolism during jumping in the American locust, Schistocerca americana.
abstract: Developing vertebrates increase both their locomotory power output and endurance due to ontogenetic improvements in anaerobic and aerobic metabolic capacities. Do similar patterns hold for insect locomotion, or do longer tracheal lengths create problems for oxygen delivery in older animals? We forced developing American locust grasshoppers (Schistocerca americana) to jump repeatedly and examined the effect of development on power output, endurance, lactate concentration, oxygen consumption and the oxygen sensitivity of jump performance. As previously shown, power outputs, relative leg lengths and leg cuticular content increased with age. A key finding of this study is that both lactate concentration and aerobic metabolic rate of the jumping muscle increase with age, explaining how the increased leg cuticular stiffness can result in increased power output. After two minutes of jumping, grasshoppers rely completely on aerobic ATP production. The rise in mass-specific, active aerobic metabolic rates with age indicates that problems with longer tracheae can be overcome; however, the reduced endurance, higher lactate concentrations and increased oxygen sensitivity of locomotory performance in older animals indicate that larger/older grasshoppers have smaller safety margins for oxygen delivery during hopping.
authors.affiliation: Section of Organismal, Integrative, and Systems Biology, School of Life Sciences, Arizona State University, PO Box 874601, Tempe, AZ 85287-4501, USA. skirkton@ucsd.edu
authors.forename: Scott D
authors.initials: SD
authors.lastname: Kirkton
authors.forename: Jared A
authors.initials: JA
authors.lastname: Niska
authors.forename: Jon F
authors.initials: JF
authors.lastname: Harrison
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D015308:Anaerobic Threshold / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001837:Body Weights and Measures; D002245:Carbon Dioxide / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005121:Extremities / Q000033:anatomy & histology / Q000502:physiology; D006110:Grasshoppers / Q000254:growth & development* / Q000502:physiology*; D019344:Lactic Acid / Q000378:metabolism; D008124:Locomotion / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid; D000255:Adenosine Triphosphate