Changes in the Relative Amounts of Soluble Protein and Amino Acid in the Haemolymph of the Locust, Chortoicetes Terminifera Walker (Orthoptera : Acrididae), in Relation to Dehydration and Subsequent Hydration

Abstract

Starvation and dehydration of fifth-instar female larvae of C. terminifera over concentrated sulphuric acid for 24 hr. causes a loss in volume of the hemolymph of over 29% but little change in osmotic pressure. When dehydrated insects imbibe distilled water in the absence of food, the volume of the hemolymph shows an increase after 7 hr. which is lost over the succeeding 17 hr. Compared with controls, the decreases in volume are associated with a loss of free amino acids and gain of soluble protein in the hemolymph as a whole; and the increase with a loss of soluble protein and gain of amino acids. Although amino acids contribute no more than 15% of the osmotically active constituents of the hemolymph, it is possible that they interchange with soluble protein and play a limited role in maintaining osmotic pressure, especially during rapid increases In volume of the hemolymph in the absence of dietary salts.