Seasonal variation in the diet of Tetrix tenuicornis (Orthoptera: Tetrigidae)

Many animals change their diet during the season according to food availability. The current field study determined whether the groundhopper Tetrix tenuicornis (Orthoptera: Tetrigidae), which specializes on moss and detritus, changes its diet during the season under conditions in which food components are constantly available. Dietary differences of T. tenuicornis were studied through the season, from May to October, by alimentary tract analyses. Detritus and moss (phylloids) dominated the alimentary tract contents, and other components were found in only minor amounts. The diversity of moss species in the alimentary tract varied during the season, and more moss species were consumed in spring and summer than in autumn. Diet was affected by developmental stage, sex (females consumed more food than males), population and abiotic factors. The rate at which detritus was consumed was significantly affected by the ambient temperature but the rate at which moss was consumed was mainly affected by relative humidity. Later instars consumed greater amounts of detritus than younger instars, and this difference corresponded to body size.