Calcium transport from Malpighian tubules to puparial cuticle ofMusca autumnalis

Summary The transport of calcium from mineralized granules stored in the Malpighian tubules to the puparium of the face fly,Musca autumnalis De Geer, was studied. Calcium was transported directly from the tubules to the cuticle via the hemolymph. Little, if any, calcium entered the hindgut or other tissues during or prior to transport. A total of approximately 0.8 mg of calcium per larva was transported, beginning at the wandering stage; peak hemolymph concentrations occurred at anterior retraction. Hemolymph calcium levels subsequently decreased as puparial calcium increased. Puparial mineralization utilized most of the minerals stored during the larval stage, with lesser amounts of minerals being recovered in the adult or excreted. Deposition of mineral salts in the cuticle was accompanied by an increase in cuticular pH from 7.0 to 8.4. The house fly,Musca domestica L., which contains much lower concentrations of minerals in the puparial cuticle, exhibited no increase in cuticular pH during pupariation. Biomineralization of the face fly puparial cuticle appears to occur, in part, as a result of ionic equilibria involving calcium and magnesium phosphates and carbonates, which have relatively low solubility products at alkaline pH.Contribution No. 87-237-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas. Cooperative investigation between Agricultural Research Service, U.S. Department of Agriculture and the Kansas Agricultural Experiment Station. K.J.K. is a research chemist and adjunct professor at U.S. Grain Marketing Research Laboratory and Kansas State University, respectively. Mention of a proprietary product in this paper does not imply its approval by the USDA to the exclusion of other products that may also be suitable. Reprint requests to A.B. Broce