Distribution of Digestive Enzymes in the Alimentary Canal of Larvae of Flies of Medical and Veterinary Importance

Abstract

The distribution of a variety of digestive enzymes in the tissue of the different divisions of the digestive tract of last-stadium larvae of 3 spp. each of calliphorid and of sarcophagid flies was determined. The larvae of Apaulina avium, an obligate blood-sucking parasite, showed considerable reduction in the number and variety of enzymes, as compared to the other 2 calliphorid spp. of scavenger and facultative parasitic habits, respectively[long dash]Phaenicia sericata and Eucalliphora lilaea. The obligate parasite larvae of W. opaca showed an over-all striking similarity in kind, variety, and extent of activity of the several enzymes reported upon, in comparison with the other 2 sarcophagids, Sarcophaza exuberans and S. cooleyi, both facultative parasites. A positive lactase activity was found in the esophagus of A. avium larvae, and questionable lactase activity in the crop and mid-gut of Wohlfahrtia opaca larvae. Positive ethyl [image]-butyrase was found in the salivary glands of both these obligate parasites, but not in those of any other spp. studied. Possible significance of the observed enzyme distribution, of the application of physiological characters to support and supplement morphological characters in classification, and of the relation of physiological modifications to adaptive evolution is discussed.