Abstract
Intrinsic rates of the natural increase of four cereal aphid species, Melanaphis sacchari (Zehntner), Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (L.), and Schizaphis graminum (Rondani) reared on sorghum or barley were compared in order to evaluate their usefulness as alternative hosts for a banker plant system using predators such as an aphidophagous gall midge, Aphidoletes aphidimyza (Rondani), especially for the use in the hot season. Survivorship curves, total survival period, and fecundity of each aphid species on the leaf fragments of the two host plants were examined at four constant temperatures. Based on these data, intrinsic rates of the natural increase of all aphid species were calculated. On the leaf fragments of sorghum, M. sacchari had the highest intrinsic rate of a natural increase among four aphid species at all temperatures. On leaf fragments of barley at 20°C, 25°C and 30°C, S. graminum showed the highest intrinsic rates. These results suggest that the combination of sorghum as banker plants, and M. sacchari as alternative hosts, could be suitable for use in the hot season. Based on the results, the usefulness of these banker plants and alternative hosts in commercial greenhouses was discussed.
