Consumption of sugars, hemicellulose, starch, pectin and cellulose by the grasshopper Arcris flavolineata

Adults (0.61 g, fresh-weight) of Abracris flavolineata De Geer (Orthoptera: Acrididae) feeding on Brassica oleracea acephala leaves ingest 21 mg dry-weight/day with an approximate digestibility of 42%. Chemical determinations performed on the leaves ingested and on the feces expelled led to the determination of the approximate digestibilities (%) of the major carbohydrates of leaves as follows: soluble carbohydrates, 91; pectin, 32.1; hemicellulose, 0; starch, 66; cellulose, 15. The results are not sufficient to disregard the possibility that digestible hemicellulose polymers contaminate the pectin and the cellulose fraction. Thus, it is possible that the digestibility of hemicellulose is different from zero, and that the digestibility of pectin and cellulose are somewhat lower than reported. The data are used to propose physiological roles of the enzyme activities previously found in the A. flavolineata midgut.