Damage Function Analysis for the Rice Stink Bug (Hemiptera: Pentatomidae)

Abstract

The effect of the rice stink bug, Oebalus pugnax (F.), on rough rice yield, head yield, and peck was investigated during 3 yr of experiments at Beaumont and Eagle Lake in the Texas Rice Belt. Natural infestations of rice stink bugs were manipulated by varying planting date and applying control measures at selected rice grain maturation stages. Data were subjected to linear, quadratic, and square root functions to obtain best-fit relationships. Damage functions were characterized as nested or nonnested models to facilitate statistical test selection. Nested models were statistically evaluated using the Schwarz criterion; nonnested models were subjected to the Cox test. In the case of peck, damage that manifests itself as discolored spots on the rice kernel and thus reduces quality, we detected no statistical differences in explanatory power between a model including both nymphs and adult rice stink bugs and a model with only adult rice stink bugs. Head yield (the percentage of whole grains after milling) was not affected by nymphal populations. Linear models best fit the damage relationships between adult rice stink bug densities at various grain maturation stages. Peck varied across grain maturation stages, with a low of 0.019% in milk to a high of 0.033% in hard dough per observed adult rice stink bug. Data also suggest that a significant level of peck was unaccounted for by rice stink bug populations in the milk and later grain maturation stages, indicating monitoring of rice stink bug populations should begin during panicle exsertion. Rough rice yield was not affected by nymphal or adult rice stink bug populations encountered in the experiments.