| The energy dynamics and feeding ecology of populations of Aeropedellus clavatus (Thomas) and Melanoplus femurrubrum (De Geer) (Orthoptera:Acrididae) were investigated in a north temperate grassland ecosystem, over a three-year period.; Estimates of population density and biomass were made by weekly sampling using the Smith Trap method. Both populations were relatively small in this habitat; the low density was attributed to the cool wet weather conditions during the summers of 1968 and 1969, and to limited areas suitable for oviposition caused by accumulation of old grass on the study site.; The total nymphal mortality was estimated to be about 92% for A. clavatus and 95% for M. femurrubrum. The predominant mortality causing factor for the population of A. clavatus appeared to be predation by birds. For M. femurrubrum weather limited abundance of preferred food plants and predation appeared to play important roles in keeping numbers low.; Measured energy parameters included biomass, production, O2 consumption rates, defecation rates and caloric equivalents of all life stages. The egg production rates of the two species were also determined. The number of eggs in the egg pods of M. femurrubrum was 4 times as great as that of A. clavatus.; A total of 1.9 and 1.7 K cal/m2 of the net primary production was ingested by populations of A. clavatus and M. femurrubrum, respectively. The manner of feeding of grasshoppers is such that an additional amount of about 9.1 and 8.2 K cal/m of the primary production was assumed to be cut and dropped by the two populations, and was made available to the decomposers in the ecosystem. The material cut, dropped and eaten by each of the two grasshopper populations represented about 1% of the above ground primary production available to them. Mean annual energy flow (assimilation) was 699.2 cal/m2 for A. clavatus and 560.9 cal/m2 for M. femurrubrum.; Secondary production was considered to be the sum of production due to growth, exuviae and eggs and was estimated to be 316.2 cal/m2 for A. clavatus and 270.0 cal/m2 for M. femurrubrum. The contribution to total production by exuviae and eggs was found to be far from insignificant. (Abstract shortened by UMI.)... |
