The high titre of free amino acids in the larval haemolymph of the moth, Spodoptera mauritia boisduval

Abstract The pattern and magnitude of the changes in the titre of free amino acids in the larval haemolymph/fat body of Spodoptera mauritia showed marked differences between unit and total volume/weight during development. The free amino acid content of the fat body was about one-tenth of that found in the haemolymph. The changes in the total content of free amino acids in the total tissue (haemolymph and fat body) showed a bell-shaped pattern of variation during the development of the larva. The increase in the total amount of free amino acids was proportional to the growth of the larva and the decrease indicates that there is a positive balance in protein storage. It has been postulated that the characteristic organization of insect cuticle and its lability during the life cycle necessitate a ready supply of a large amount of free amino acids and that the direct relationship between the titre of free amino acids and the evolutionary status of insects lies in the frequency of the remodelling of the integumentary structures.