Ion and water balance in the feeding lone star tick

Abstract

1. The water content % in the lone star tick, Amblyomma americanum (L.), increased to 69·0 at the beginning of the bloodmeal, then decreased to 63·3 with the onset of rapid engorgement and decreased further to 57·5 prior to and just after completion of engorgement. 2. The concentration of sodium in host blood was higher than in the tick's gut fluid, but lower than in the tick's haemolymph; the reverse held true for potassium. 3. The sodium concentration in tick oral secretion (saliva) was about 10% higher than in its haemolymph, but the potassium concentrations in the haemolymph and saliva were not significantly different. 4. The distribution of chloride was very similar to that of sodium in the different compartments. 5. The results suggest that a relatively large proportion of ingested potassium is retained within the gut lumen of the tick. The osmolarities of the haemolymph and collected roal secretion (saliva) throughout feeding were not significantly different.