The digestive enzymes of larvae of the black fly, Prosimulium fuscum (Diptera, Simuliidae)

1. 1. The digestive system of larvae of the black fly, Prosimulium fuscum, resembles those of other aquatic dipteran detritivores, such as mosquito and crane fly larvae. 2. 2. Midgut proteolytic activity is very high, due to the presence of high levels of alkaline proteinases. 3. 3. The only polysaccharides toward which significant enzymatic activity is evident in midgut extracts are α-1,4- and β-1,3-glucans. 4. 4. There is negligible activity toward cellulose, carboxymethylcellulose, xylan, locust bean gum, pectin, chitin, Micrococcus lysodeikticus cells, and phenolphthalein mono-β-glucuronate. 5. 5. The larvae are better adapted to exploit the polysaccharides of fungi and algae than those of vascular plants.