Influência do arranjo espacial do mogno (Swietenia macrophylla king) com o nim (Azadirachta indica A. Juss) como barreira natural ao ataque da Hypsipyla grandella Zeller

Abstract

This work aimed evaluates the efficiency of the nim, as natural barrier to control the attack of the H. grandella Zeller in the mahogany, as well as the influence of this attack in the growth and survival of the mahogany. The experimental area was located in in Vigia, Pará State (00º 51 ' 12 " S and 48º 08 ' 41 " W). The experiment design was carried out in a randomized complete block, in split plot, with five replicates. The form of planting of the mahogany (homogeneous stand and associated with nim) it was considered the principal factor and the time the secondary factor. Each plot was constituted by 66 plants, however just the 36 central plants were evaluated. Four forms of plantings were tested: 1)homogeneous stand of mahogany, containing 66 mahogany plants (P1); 2) mixed planting containing 33 mahogany plants and 33 nim plants (P2); 3) mixed planting containing 21 mahogany plants and 45 nim plants (P3); 4) mixed planting containing 15 mahogany plants and 51 nim plants (P4). The results obtained in this study evidenced that the natural barrier formed by Azadirachta indica didn't avoid the attack of Hypsipyla grandella, however it delayed the attack of this insect in these plantings. The homogeneous stand of mahogany contributed to the intensification of the attack of Hypsipyla grandella, not being, therefore, recommended for the cultivation of that Meliaceae in commercial scale. The attack of Hypsipyla grandella affected the growth in height and diameter, and it favored the bifurcation occurrence and of mortality of the mahogany plants in homogeneous stands and in mixed plantings with nim. In these last ones the damages were smaller. The nim, in general, benefitted the growth in height and in diameter of the mahogany, however the best performance of the mahogany was observed in the mixed plantings (P4 and P3), both containing smaller density of mahogany plants for area. For the largest control of the attack of H grandella in the mahogany stand, it is recommended that this meliácea is assigned in the time and she should not be planted simultaneously with the nim, but one year later after the planting of the nim, when he presents more than three meters of height forming natural barrier to control the attack of this insect. The species A. indica is resistance to the attack of the H. grandella, and it presents better development in height and diameter in relation to the mahogany, being indicated for the reforestation of degraded area s in the Pará State.