Population dynamics and distribution of Sitophilus zeamais in peach and apple orchards

Abstract

The objective of this work was to evaluate the population dynamics of Sitophilus zeamais (Coleoptera: Curculionidae) and to determine the distribution of this pest in plants of peach and apple orchards, in the region of Pelotas, state of Rio Grande do Sul, Brazil. Population dynamics was evaluated in the 2009/2010 and 2010/2011 growing seasons by weekly monitoring the orchards with traps for approximately five months. Ten “Pet‑milho”‑type traps were used per hectare, positioned 1.7 m above the ground, distributed equidistantly in the borders and in the center of the orchards. Insect distribution in plants was evaluated in fruits from the top, middle, and bottom portions of the plants, in the apple cultivar Eva and in the peach cultivars Sensação (early cycle), Eldorado (late cycle), and Eragil (late cycle). In apple, S. zeamais attack occurred for five to seven weeks, and in peach, for three to four weeks. A greater number of S. zeamais males was observed at the beginning of the orchard infestation, mainly in fruits from the top portion of the plants. In the following weeks, the highest infestation of fruits occurred in the middle portion. Sitophilus zeamais attack occurs both in early and late cultivars of peach, with a peak attack at the harvesting stage.