Activity of carbohydrases in the gut of Bibionidae (Diptera) larvae
2002
Sustr, V. ((Academy of Sciences of the Czech Republic, Ceske Budejovice (République Tchèque). Institute of Soil Biology)) | Frouz, J.
Dipteran larvae play an important role in the soil of some deciduous forests. They can consume a considerable part of the annual litter fall and produce a large amount of faecal pellets, which are forming an important part of the fermentation horizon of forest soils. The pH changes were measured and the activities and pH optima of saccharolytic enzymes were assayed in the digestive tracts of the larvae of Bibio pomonae and Penthetria holosericea (Bibionidae). The pH of the litter offered as a food was about 5. The gut content became highly alkaline (pH about 10) in the anterior part of the midgut and the pH decreased posteriorly and in the hindgut. Excrements were neutral or had slightly alkaline pH (7.5-8.0) in both species. The alkaline pH optima of amylase (9.5-10.0) and maltase (8.0), trehalase and cellobiase (7.0) were the same in both species. Saccharolytic activity showed an optimum at pH 7 in B. pomonae and at pH 8 in P. holosericea. Though there are previously published reports of high assimilation efficiency of bibionid larvae fed in litter (46-76 per cent in B. pomonae), activities of both exo and endocellulases were below the detection limit of saccharolytic and chromolytic assays along a wide pH range (5-10). Possible explanations are discussed
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