Estudo do comportamento espacial de Tibraca limbativentris Stal, 1860 (Hemiptera: pentatomidae) na cultura do arroz irrigado por inundação no planalto da campanha do Rio Grande do Sul

Abstract

The objective of this study was investigated spatial behavior of Tibraca limbativentris Stal, 1860 (Hemiptera: Pentatomidae) in flooded rice field in Planalto da Campanha region of the State of Rio Grande do Sul, Brazil. The experiment was conducted under field commercial rice in the municipality of Itaqui, RS, in the growing seasons of 2009/10, 2010/11 and 2011/12 in areas of 13,5, 7,67 and 3,75 ha, respectively. Through fortnightly samples, the survey covered the entire phenological cycle of culture and was conducted following an established regular grid for GPS navigation. In the season 2009/10 totaled 81 points grid sampling spaced 50 m. Already harvests in 2010/11 and 2011/12 the grids totaled 693 e 352 points spaced 10m, respectively. For carrying out the sampling at each sampling point was released a framework of metal of 0.25 m², where counts were performed in nymphs and adults of rice stem bug. The spatial distribution of the pest was determined by the variance/mean (I), Morisita index (Iδ) and adjustment to theoretical distributions of variable frequency. The data were also subjected to geostatistical analysis as a tool for mapping the population of rice stem bug. The spatial distribution pattern of Tibraca limbativentris type is aggregate. When observed, the spatial dependence among stink bugs, most of the sampling occasions, classified as strong and variability generated by the spatial structure is high. The collection of population data grids from 10 m to 85 m between points enables the generation of maps forecasting the number of stem bug, giving subsidies for location management of the pest.