ENERGY DYNAMICS OF MELANOPLUS BIVITTATUS AND M. FEMURRUBRUM (ORTHOPTERA: ACRIDIDAE) IN A GRASSLAND ECOSYSTEM,

Abstract

AbstractBioenergetic studies on populations of the two-striped grasshopper, Melanoplus bivittatus (Say), and the red-legged grasshopper, M. femurrubrum (De Geer), at a natural grassland site in Ottawa in 1971 and 1972 indicated that the former species ingested 0.42% and the latter 0.44% of the green shoot primary production (3057 kcal/m2). An additional 1.22 and 1.30% of this production were cut and dropped by the grasshoppers, so that a total of 1.64 and 1.74% of the green vegetation was removed by M. bivittatus and M. femurrubrum, respectively. These two species assimilated 41 and 35% of the ingested food, the remainder being voided as faeces. Respiration accounted for 62% of the energy assimilated by M. bivittatus and for 63% of that assimilated by M. femurrubrum. Approximately 0.06% of the energy of primary production was converted by each species into body and was available to higher trophic levels. However, 94% of the potential energy of the green vegetation removed by the grasshoppers was returned to the "decomposer compartment" of the ecosystem, with only 6% removed or lost from the system.