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

19 April 2007

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 degrees C was 21.32 +/- 2.73 mu l CO2 h(-1) (mean +/- S.E.), with a Q(10) (10-25 degrees C) of 1.7. Increases in (VCO2)-C-center dot 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 = 11) 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 = 11). 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. (c) D 2006 Elsevier Ltd. All rights reserved.