Abstract
In recent decades, Brazil has been standing out as one of the major world producers of pulp and paper. The industrial sector defined as pulp and paper currently consists of approximately 222 companies with activities in 539 municipalities, which are distributed throughout the national territory. The pulp and paper industry is divided in the forest and industrial sectors. In the forest sector a major problem in the production process is the control of pests that occur in the culture, reducing the productive capacity of the forest which directly affects the industrial sector. Noteworthy are the defoliating insects such as leaf-cutter ants, Lepidoptera and beetles, which cause great damage. Studies assessing defoliation caused by these insects are important tools that can aid programs of integrated pest management to increase productivity and reduce production costs. This work aimed to evaluate the effect of different levels of simulated defoliation on the growth of Eucalyptus grandis trees, with six months of age. The experiment was conducted in a randomized block design with five replications and six treatments, totaling 3,000 trees. Defoliation levels of 100 %; 50 % and 75 % of the upper canopy were analysed, as well as 50 % and 75 % of the basal part of the crown, and the top 25 % of the trees. The control was 0 % defoliation. The results showed that only total defoliation can cause a reduction in diameter and height growth. These trees lost10.88 mm and 0.72 m in their diameter and height, respectively. At 240 days after injury, in spite of total defoliation, the trees already, presented height identical to those of trees which had undergone 50 to 75 % defoliation. The volume loss in this period, for the totally defoliated trees was 35 %. This loss will be reduced to 13 % when extrapolated for a rotation of 7 years. The results may be used in the monitoring program of leaf-cutting ants to reduce to the cost of chemical control of these insects on Eucalyptus in Brazil, and consequently improve the environmental quality of planted forests, raising their productivity and quality.
