Excretion and Its Products in Some Stored-Grain-Infesting Beetles1

Abstract

Urine is excreted as a clear fluid through the malpighian tubules in adult Tribolium confusum Duv., Cryptolestes ferrugineus (Steph.), C. turcicus (Grouv.), and Sitophilus granarius (L.). A portion of the uric acid and urates remains stored in the fat body of S. granarius only. Heavy deposits of storage excretion (not uric acid or urates) in the form of dark brown granules are present in the cells of malpighian tubules of T. confusum, C. ferrugineus, and C. turcicus, but no such deposit occurs in S. granarius. Uric acid and urates enter through the wall of the anterior portion of the hindgut in S. granarius, whereas in the other three species the urine discharged through the malpighian tubules contains a solution of uric acid and its salts. Presence of a large quantity of uric acid seems responsible for lowering the hydrogen-ion concentration in the hindgut of all the four species.