Effects of Tibraca limbativentris Stal (Heteroptera: Pentatomidae) infestations on rice (Oryza sativa L.) yield components

Rice stink bugs are the primarily pests of rice in South America. Tibraca limbativentris is the major pest that feed on rice stem. Field experiments were conducted during the growing seasons of 2006 to 2008 and 2013 in Goiânia, GO, Brazil, to determine yield-loss relationships for T. limbativentris on rice (Oryza sativa L.) and the effect of feeding on yield components. The experimental design was in randomized complete blocks with four replications. Treatments consisted of six stink bug population levels (0, 1, 2, 3, 4 e 5 couples per m²). Each plot consisted of 1 m², was covered with a cage to prevent dispersion of the insects after infestation. Evaluations were performed before each procedure (infestation, spraying and harvesting) measuring the following variables: dead hearts, total of tillers with and without panicle, surviving insects, mass of spikelets and milling yield. The impact of T. linbativentris was greater when infestations occurred at maximum tillering and with lower significance when the infestation was at full booting. The difference between the two phases can be explained by the longer exposure of plants to pest attack. Yield data were submitted to regression analysis in function of number of insects/m² to estimate the reduction rates of productivity per insect. This study indicated that rice is most vulnerable to T. limbativentris infestations during maximum tillering and that the effects of stink bug feeding change with the duration of their feeding.