Abstract: Intraspecific and interspecific competition of Sitophilus zeamais and Rhizopertha dominica were studied at 28℃ and 33℃ according to the method of Giga in laboratory. The results showed that the reproductive curves of S.zeamais and R.dominica under single rearing condition were quadratic curves, and the competition types belonged to resource competition type. Hence the intensity of intraspecific competition was affected by initial density. Population numbers of S. zeamais and R. dominica under mixture rearing condition were less than those of single rearing condition, there was remarkable competition between the two species for limited resources, and the intensity of interspecific competition was affected by initial density and temperature. The S. zeamais with convex reproduction curve was stronger competitor and would be the dominant species for a long period at 28℃; the competition ability of R. dominica became stronger at 33℃ than that at 28℃, the reproduction curve changed from concave at 28℃ to convex at 33℃, it would be the dominant species, but the reproduction curve of S. zeamais was also convex at higher density, so that coexistence was possible finally．

Key words: intraspecific competition, interspecific competition, Sitophilus zeamais, Rhizopertha dominica