Susceptibility of cedar to pest attack in seasonally deciduous forest

Abstract

The objective of this work was to evaluate the characteristics of cedar plants (Cedrela fissilis) attacked by pests, the resultant damages, and the conditions in which the damage was more pronounced. A census of cedar individuals was conducted by going through a total area of 5.55 hectares of native forest in the municipality of Silveira Martins, in the state of Rio Grande do Sul, Brazil. Cedars with total height greater than 15 cm and collar diameter less than 12 cm were measured, and their pest status was evaluated. Frequency histograms of the collar diameter were made, and the hypsometric relationship of attacked and healthy trees was evaluated by analysis of covariance. For the spatial analysis of individuals, maps of cedar density and maps for risk assessment of sawyer beetle and moth were made. Trees with the greatest probability of being attacked were those with collar diameter between 2 and 6 cm. The clearings and areas with low total density of trees were the most susceptible ones to attacks of the Hypsipyla grandella caterpillar, and locations with high density of individuals whose collar diameter is between 8 and 12 cm are the most susceptible ones to the attacks of Oncideres sp. larvae.