Water vapour intake and body water (3HOH) clearance in the housemite Glycyphagus domesticus
1980 - Volume: 21 Issue: 3-4 pages: 442-450
The dynamics of body water in Glycyphagus domesticus (Deg.) are of interest because this species is one of the few arthropods having no tracheal system even in the adult stage, although it can absorb water from vapour when kept at a relative humidity rate of 75% or slightly less. In starved adults, which were investigated in the laboratory in Berlin by means of water labelled with radioactive tritium, the body-water dynamics were that of a single compartment from which water was cleared by zero-order and first-order processes while water was supplied at a rate constant from day to day. The clearance rate was not affected by air turbulence nor regulated according to the remaining body-water reserve. Clearance rates increased with increasing temperature. At 15 deg C, the first-order clearance increased with increasing relative humidity from 2%/h at 70% RH or lower to 5.4% in a saturated atmosphere, while the zero-order clearance was at least 0.06 andmu; g/h; water vapour diffused into the body at the rate of up to 0.23 andmu; g/h in proportion both to the rate constant of first-order clearance and to the relative humidity, and water was physiologically absorbed from air at mean rates from 0.14 andmu; g/h at 80% RH to 0.06 andmu; g/h in a saturated atmosphere while maintaining a steady-state mass. The zero-order clearance is the only feature in G. domesticus that differs markedly from the body-water dynamics reported from mites that have a tracheal system.
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