title: Relative nutritional quality of C3and C4grasses for a graminivorous lepidopteran, Paratrytone melane (Hesperiidae).
abstract: We tested the hypothesis that C4grasses are inferior to C3grasses as host plants for herbivorous insects by measuring the relative performance of larvae of a graminivorous lepidopteran, Paratrytone melane (Hesperiidae), fed C3and C4grasses. Relative growth rates and final weights were higher in larvae fed a C3grass in Experiment I. However, in two additional experiments, relative growth rates and final weights were not significantly different in larvae fed C3and C4grasses. We examined two factors which are believed to cause C4grasses to be of lower nutritional value than C3grasses: foliar nutrient levels and nutrient digestibility. In general, foliar nutrient levels were higher in C3grasses. In Experiment I, protein and soluble carbohydrates were digested from a C3and a C4grass with equivalent efficiencies. Therefore, differences in larval performance are best explained by higher nutrient levels in the C3grass in this experiment. In Experiment II, soluble carbohydrates were digested with similar efficiencies from C3and C4grasses but protein was digested with greater efficiency from the C3grasses. We conclude (1) that the bundle sheath anatomy of C4grasses is not a barrier to soluble carbohydrate digestion and does not have a nutritionally significant effect on protein digestion and (2) that P. melane may consume C4grasses at compensatory rates.
authors.affiliation: Department of Entomological Sciences, University of California, 94720, Berkeley, CA, USA.
authors.forename: Raymond V
authors.initials: RV
authors.lastname: Barbehenn
authors.affiliation: Department of Entomological Sciences, University of California, 94720, Berkeley, CA, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Bernays
keywords: C3 and C4 grasses; Hesperiidae; Lepidoptera; Nutrients; Paratrytone melane