Ion and Water Balance in the Ixodid Tick Dermacentor Andersoni

Abstract

1. Of the total meal imbibed by female Dermacentor andersoni during the normal adult feeding cycle, about 80% is excreted. Of the total water excreted by the tick, 75% is removed by salivation, less than 3% is evaporated from the integument and spiracles, and the remainder is lost via the anus. 2. Of the total excreted sodium and potassium, 4 and 82% respectively are lost via the anus. The remainder in each case is presumed excreted via the salivary glands. 3. The ionic and osmotic concentrations of the haemolymph and saliva stabilize at constant values by the third or fourth day of feeding. The volume of extracellular fluid is constantly maintained at 23% of the body weight, even though the total body weight increases 75 times over the unfed weight, and the volume of excreted fluid passing through the haemolymph is about ten times the haemolymph volume at repletion.