Antibiosis of Released Soybean Germplasm to Mexican Bean Beetle (Coleoptera: Coccinellidae)

Abstract

None of the soybean, Glycine max (Merrill), cultivars released as being insect resistant are grown over large areas in the U.S. partly due to reduced yields and lower than expected insect resistance levels. Recently, Ohio released two germplasm lines, HC95-15MB and HC95-24MB, with significant levels of insect resistance and yields approaching those of adapted cultivars. A study was conducted that compared their resistance levels to other advanced breeding lines. HC95-15MB and HC95-24MB were found to have moderate levels of resistance to Mexican bean beetle, Epilachna varivestis Mulsant, much higher compared with the other advanced lines. Additionally, resistance levels in HC95-15MB and HC95-24MB remained relatively constant during two different soybean growth stages, late vegetative and mid-reproductive, compared with the resistance levels in the other germplasm lines which tended to lower as the soybeans matured. The higher levels of resistance offered by these two lines make them very useful as sources of germplasm for breeders in their breeding programs.