Respiratory physiology and water relations of three species of Pogonomyrmex harvester ants (Hymenoptera: Formicidae)

• Published in: Physiological entomology Vol. 24; no. 4; pp. 293 - 302
• Main Authors: Quinlan, Michael C., Lighton, JohN. R. B.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.12.1999; Wiley Subscription Services, Inc
• Subjects: Discontinuous gas exchange; Formicidae; harvester ants; Pogonomyrmex; Pogonomyrmex californicus; Pogonomyrmex occidentalis; Pogonomyrmex rugosus; water relations
• ISSN: 0307-6962; 1365-3032
• DOI: 10.1046/j.1365-3032.1999.00140.x

The respiratory physiology and water relations of three harvester ant species (Pogonomyrmex rugosus Emery, P. occidentalis[Cresson] and P. californicus[Buckley]) were examined at three temperatures (15, 25 and 35°C) using a flow‐through respirometry system. As intact ants tended to be active during testing, we performed a parallel set of experiments on individuals rendered motionless by decapitation. Both intact and decapitated ants exhibited discontinuous ventilation. Decapitation caused metabolic rate (V˙CO2) and burst frequency to decrease in all three species. Burst volume either remained constant or increased after removal of the head, though mass‐specific V˙CO2 was unaffected except in P. rugosus. Mass‐specific V˙CO2s of headless harvesters were comparable with published values derived from motionless specimens of other ant species. The mean Q10 for intact ants of all three species was 2.37; for decapitated insects the mean was 2.32. Respiratory water constituted a small (< 5%) fraction of total loss, and we believe that discontinuous ventilation does not act to conserve water in these organisms, although it may serve other functions.