ABSTRACT
In general, woodlice show in vapor-unsaturated air a higher water loss than most insects. With regard to the water balance, the absorption of water vapor and the transpiration through the cuticula are important since they characterize the cuticular permeability, which is, apart from behavioral adaptation, the most important factor in the animal’s ability to withstand terrestrial conditions. In woodlice, a possible site of water vapor absorption outside the excluded mouth and rectal region might be the pleoventral chamber, the space between the pleoventral body wall and the exopodites of the pleopods. The effect of different air humidities on the cuticular permeability of woodlice cannot be investigated by following the weight change alone, since transpiration and absorption of water vapor occur simultaneously. The effects of a variable drying power of the air can then be eliminated by dividing the transpiration or weight change through the corresponding vapor saturation deficit.
