Print version ISSN 0006-8705
DINARDO-MIRANDA, Leila Luci; FRACASSO, Juliano Vilela and PERECIN, Dilermando. Spatial variability of Diatraea saccharalis populations in sugarcane fields and suggestion of sampling method. Bragantia [online]. 2011, vol.70, n.3, pp.577-585. Epub Sep 30, 2011. ISSN 0006-8705. http://dx.doi.org/10.1590/S0006-87052011005000008.
The sugarcane borer Diatraea saccharalis Fabr. (Lepidoptera: Crambidae) is one of the most important pests of sugarcane in Brazil. The management of infested area is based on biological control with Cotesia flavipes, whose releases are made according to the pest population in field. Therefore, the evaluation of D. saccharalis population is important for the success of management program. The objective of this work was to study the spatial variability of D. saccharalis in sugarcane and suggesting a sampling method that allows an adequate evaluation of the population in the field. Six fields with areas of 1 ha were sampled, within a grid measuring about 10 × 10 m, with islands. Each sample point was represented by collecting biological forms of the pest in the stalks, considering 2 m of furrow. In most areas, D. saccaralis has aggregated spatial distribution and the values of range in semivariogram varied from 18 to 80 m. Based on average range, it was estimated in six the number of samples per hectare to evaluate the population in a given area. This number was smaller than that estimated using classical statistical parameters. According to the results, to obtain a reliable evaluation of the population of D. saccharalis immature forms in sugarcane fields, samples should be collected 40 m apart, meaning about 6 sampling points per hectare. This method allows independent samplings, with coefficients of variation less than 50% in most areas.
Keywords : sugarcane borer; sugarcane; management.