Distribuição espacial e amostragem sequencial de percevejos e desempenho agronômico em soja (Glycine max L.) Bt e não Bt

Abstract

The knowledge of the arrangements of dispersion of insect pests in soybean cultivars is needed to improve the monitoring and control. The objective of this study was to evaluate the spatial distribution of adults and nymphs of Euschistus heros in Bt and non-Bt soybean into two regions, under field conditions. The experimental area located in Dourados and Douradina, Mato Grosso do Sul. For the evaluations we used the method of cloth-to- beat, where we collected one sample per plot randomly from each experimental area. Evaluations were performed at 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98 days after emergence (DAE). For data analysis, the rates of dispersion (variance/average Morisita index and exponent k Negative Binomial Distribution) and theoretical frequency distributions (Poisson, Binomial and Negative Binomial Positive) were estimated at 1-5 % probability. Adults of E. heros are arranged differently for Bt and non-Bt soybean and between regions, since in both cultivars and locations, individuals of the populations evaluated in probabilistic set arrangements negative binomial distribution (aggregate), Poisson (random) and positive binomial distribution (uniform), as the days after soybean emergence. The nymphs of E. heros showed aggregated spatial arrangement, being distributed similarly for Bt and non-Bt soybean and regions, setting a negative binomial distribution model.