Respiratory gas exchange in the tick Amblyomma hebraeum (Acari: Ixodidae).

Respiratory gas exchange was studied in unfed adult Amblyomma hebraeum Koch. Carbon dioxide emission was measured at 25 degrees C using flow-through respirometry to determine standard metabolic rate and the temporal pattern of gaseous emission. The standard CO2 production rate (sVCO2) of inactive ticks was 0.0135 +/- 0.0085 ml g-1 h-1, and the standard O2 consumption rate (sVO2) was 0.0158 +/- 0.0097 ml g-1 h-1. Ventilation was discontinuous and was characterized by periodic bursts of CO2 emissions at frequencies of 0.33 h-1-1.11 h-1. Low metabolic rate coupled with discontinuous ventilation may contribute to the ability of adult A. hebraeum to withstand prolonged periods of starvation and desiccation in the absence of a host.