Insect herbivory on C and C grasses.

This study tested the hypothesis that grasses with the C photosynthetic pathway are avoided as a food source by insect herbivores in natural communities. Insects were sampled from ten pairs of C-C grasses and their distributions analyzed by paired comparisons tests. Results showed no statistically significant differences in herbivore utilization of C-C species. However, there was a trend towards heavier utilization of C species when means for both plant groups were compared. In particular, Homoptera and Diptera showed heavier usage of C plants. Significant correlations between insect abundances and plant protein levels suggest that herbivores respond to the higher protein content of C grasses. δC values for six of the most common grasshopper species in the study area indicated that three species fed on C plants, two species fed on C plants, and one species consumed a mixture of C and C tissue.