Distribuição espacial de Rhynchophorus palmarus (L.) (Coleoptera: Curculionidae) e Metamasius hemipterus (L.) (Coleoptera: Curculionidae) em palma de óleo no sul do Estado de Roraima

Abstract

The Oil Palm (Elaeis guineensis Jacq.) is a palm tree of African origin, typical of tropical regions, and, in Brazil, the largest areas of palm cultivation are found in Amazonia. The objective of the present work is was to evaluate the pattern of spatial distribution of the Rhynchophorus palmarum and Metamasius hemipterus on palm plantations in the South of the State of Roraima. The experimental area is located in the municipality of São João da Baliza, RR, where 24 samples were done in the period from September 2013 to August 2014. The perimeter of the area was demarcated with GPS, and the sample grids were 45x45m in dimension. The spatial distribution was determined by putting a bucket type trap with alimentary attraction (sugarcane), in each sample point. The analysis of spatial variability and of spatial dependence were done by incorporating geostatistical procedures based on spatial modeling techniques by semivariograms. The kriging maps were generated from adult R. palmarum and M. hemipterus counted. The sample grids appeared appropriate for the characterization of spatial distribution of the R. palmarum and M. hemipterus in the field. It was observed that the infestation of M. hemipterus was noted in the centre, as well as the fringes of the plantation where it is encountered in greater density and frequency. The spatial distribution of the R. palmarum and M. hemipterus in the area of study occurred in an aggregated form, with spatial dependency described by the spherical model, forming cluster of 100 to 210 m and 78 to 199m of rays, respectively. The index of moderated spatial dependency prevailed, occurring in 23 evaluations, and only on the dependency is strong for the R. palmarum. For the M. hemipterus spatial dependency occurred in 20 evaluations, and only two the dependency is strong. For the palmarum the maximum reach encountered was 210 metres with an area of influence of 13.9 ha and a minimum of 100 with an area of influence of 3.1 ha. For M. hemipterus the maximum reach encountered was of 199 metres with area of influence of 12.4 ha and a minimum of 78 with an area of influence of 1.9 ha.