Energy balance of food in a detrito-bryophagous groundhopper (Orthoptera: Tetrigidae).

Detritus (decaying organic matter) and phyllodes of mosses are two main components in the diet of groundhoppers (Orthoptera: Tetrigidae). We studied the energy balance of consumed food under laboratory conditions in the detrito-bryophagous groundhopper, Tetrix subulata (Linnaeus, 1758). The results indicated that the energy food budget of this detrito-bryophagous groundhopper was comparable to those of small herbivorous grasshoppers (Acrididae: Gomphocerinae, Melanoplinae), which have a similar energy food budget of approximately 800-1,100 J/g. T. subulata consumed four times more detritus than mosses, although both components provided similar amounts of energy (ca. 15-16 kJ/g). However, in contrast with detritus, moss fragments passed through the digestive tract without a distinct change in their mass or a loss in their energy value. We assume that moss may cause the longer retention of semifluid mass of partly digested food in the alimentary tract; hence, the digestion and efficiency of nutrient absorption from detritus could be more effective.

Synonymy of Discotettix adenanii Mahmood, Idris & Salmah, 2007 with D. belzebuth (Serville, 1838) (Orthoptera: Tetrigidae).

According to a study of type specimens of Discotettix adenanii Mahmood, Idris & Salmah, 2007 and copious specimens of D. belzebuth (Serville, 1838) collected in different parts of Borneo, we found that all species-specific morphological characters of D. adenanii, according to its original description, fall into the morphological variability of D. belzebuth. Thus, we synonymize D. adenanii with D. belzebuth. The sequence of a segment of the mitochondrial 16S ribosomal RNA of D. belzebuth was also evaluated and added to GenBank as a DNA barcode.

Age-related mandible abrasion in the groundhopper Tetrix tenuicornis (Tetrigidae, Orthoptera).

A study was conducted to determine whether the mandibles of the detrito-/bryophagous groundhopper Tetrix tenuicornis are subject to mechanical wear as a result of feeding, as is the case for grasshoppers that feed on silica-rich grasses. Abrasion was evaluated by measuring the length and width of the 3rd incisor and length of the 4th incisor in adults of different ages collected under natural conditions during one season. Although T. tenuicornis and other groundhoppers avoid feeding on grasses, we found that mandible abrasion increased with T. tenuicornis age. Age-related abrasion of the incisors of left and right mandibles was statistically significant in both sexes but the degree of abrasion was greater for females than males, apparently reflecting differences in the frequency and magnitude of feeding. Degree of abrasion also differed between right and left mandibles, probably because of differences in how each mandible is used during food processing. Abrasion of cuticular mandible structures may reduce the effectiveness of food processing late in the season.