Rice injury and ecology of the rice stink bug, Oebalus pugnax (F.) in the Delta Region of Mississippi

The rice stink bug, Oebalus pugnax(F.), is an important late season pest of rice that is noted for causing grain yield and quality reductions in the United States. This study investigated rice injury using field cages in two rice cultivars ('Cocodrie' and 'Wells') at bloom, milk, and soft dough stages and O. pugnax ecology in the Delta Region of Mississippi. Specific objectives were: 1) to determine the impact of adult O. pugnax infestation on rice yield and grain quality at bloom, milk, and soft dough stages of rice development; 2) to determine the impact of adult O. pugnax gender and infestation duration on rice yield and grain quality at the milk stage of panicle development; 3) to identify and examine the seasonal abundance and phenology of O. pugnaxon non-cultivated host grasses; and 4) to evaluate feeding preference and development of O. pugnax on host grasses. Rice injury increased as O. pugnax density increased. The bloom and milk stages were the most vulnerable to blank and discolored kernels, respectively. O. pugnax feeding injury was significant after 3 d of infestation duration during the milk stage of panicle development. Female O. pugnax caused a greater percentage of blank kernels compared to males. A survey of O. pugnax hosts indicated that Italian ryegrass, Lolium perenne L. ssp. multiflorum and winter wheat, Triticum aestivum L., were important hosts during spring and early summer. Junglerice, Echinochloa colona (L.) Link; crabgrass spp., Digitaria spp. Haller; southwestern cupgrass, Eriochloa acuminata (J. Presl) Kunth; and praire cupgrass, Eriochloa contracta (Hitchc.), were important hosts for O. pugnax during early to mid-summer. Browntop millet, Urochloa ramosa, and broadleaf signalgrass, Urochloa platyphylla, supported adult O. pugnax prior to overwintering. In a choice test of wild host grasses, junglerice was the most preferred over 10 other host grasses. In the no-choice test, mean development time was shorter and survival was greater for O. pugnax nymphs reared on rice, Oryza sativa L., compared to dallisgrass, Paspalum dilatatum Poir and junglerice. These results provide biological and ecological information on which new O. pugnax integrated pest management practices can be developed