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 haemolymph of over 25% but little change in osmotic pressure. When dehydrated insects imbibe distilled water in the absence of food, the volume of the haemolymph 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 amifto acids and gain of soluble protein in the haemolymph 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 haemolymph, it is possible that they interchange with soluble protein and playa limited role in maintaining osmotic pressure, especially during rapid increases in volume of the haemolymph in the absence of dietary salts.