Levantamento populacional de Bemisia tabaci (Gennadius 1989) biótipo B e ocorrência natural de Encarsia spp. na cultura da soja

Abstract

The whitefly Bemisia tabaci (Gennadius) biotype B (Hemiptera: Aleyrodidae) cause many direct and indirect damage to the soybean crop. Due to lack of knowledge of the nymphal stages and natural enemies of B. tabaci, the aim of this paper is to present the whitefly survey and parasitism of Encarsia spp. in soybean. The evaluations were performed every two weeks in an experimental field of 120 ha for three months. In each evaluation, were analyzed ten points at the center and ten points at the borders. To quantify whitefly adults population, each one of the ten evaluated pants in a straight line transect had its higher trefoil analised. Three leaflets of the third lower part of the plant were collected at each point, to subsequently nymphs count. The borders of the crop had the highest population of whitefly nymphs compared to the center. The parasitism was observed during the reproductive period of culture at a 57,43 % rate. The parasitoid of the genus Eretmocerus was found in evaluations at lower levels than Encarsia spp. which was the dominant parasitoid.