Gas exchange characteristics, metabolic rate and water loss of the Heelwalker, Karoophasma biedouwensis (Mantophasmatodea: Austrophasmatidae)

This study presents the first physiological information for a member of the wingless Mantophasmatodea, or Heelwalkers. This species shows cyclic gas exchange with no evidence of a Flutter period (more typical of discontinuous gas exchange in insects) and no indication that the spiracles are fully occluded during quiescent metabolism. Standard metabolic rate at 20 °C was 21.32±2.73 μl CO₂ h^-1 (mean±S.E.), with a Q₁₀ (10-25 °C) of 1.7. Increases in V^{{radical dot}}CO₂ associated with variation in mass and with trial temperature were modulated by an increase in burst period volume and a decline in cycle frequency. Total water loss rate, determined by infrared gas analysis, was 0.876±0.08 mg H₂O h^-1 (range 0.602-1.577, n = 1 1) whilst cuticular water loss rate, estimated by linear regression of total water loss rate and metabolic rate, was 0.618±0.09 mg H₂O h^-1 (range 0.341-1.363, n = 1 1). Respiratory water loss rate was therefore no more than 29% of the total rate of water loss. Both total water loss rate and estimated cuticular water loss rate were significantly repeatable, with intraclass correlation coefficients of 0.745 and 0.553, respectively.