Cyclic CO2 release and water loss in the western drywood termite (Isoptera: Kalotermitidae)

Abstract

CO2 release and water loss patterns of Incisitermes minor (Hagen) pseudergates were investigated using flow-through respirometry techniques. Four hours of real-time CO2 release and water loss data were recorded for pseudergates of 1. minor at 20-40°C. Cyclic release, but not traditional DGC, was the CO2 release pattern observed in these pseudergates. Variability of Vco2 expressed as coefficient of variability (CV) was used to estimate the level of cycling in each recording. CV decreased exponentially with temperature. Mean Vco2 values ranged from 0.24 = 0.07 mlCO2g-1 h-1 at 25°C to 0.89 = 0.16 ml CO2g-1 h-1 at 35°C. Vco2 increased significantly (P = 0.014) with temperature, but was not influenced (P = 0.063) by body mass. Q10 for Vco2 over the range of 20-40°C was 1.75 for 1. minor pseudergates. Water loss cycled coincidently with CO2 release. Water loss rates ranged from 5.22 = 1.97 mg H2O lost g-1 h-1 at 20°C to 17.96 = 2.55 mg H2O lost g-1 h-1 at 40°C. Q10 for water loss over the range of 20-40°C was 1.86 for 1. minor pseudergates. Daily respiratory water loss represented from 9.23% at 20°C to 4.72% at 25°C of total daily water loss. Cuticular water loss represented from 93.5% at 25°C to 89.1% at 30°C of total daily water loss.