Galleries produced by Platypus mutatus Chapuis in Populus deltoides cv. Catfish-2 according to stem size and to diameter, height and exposition of the attacked stem section

Abstract

The objective of this work was to study the distribution of galleries of Platypus mutatus Chapuis according to plant size, height and diameter of the stem sections, and to the exposure of the attacked stem section, in trees from plantations of P. deltoides cv. Catfish-2. Trees from plantations heavily attacked by the insect were felled. All galleries produced by the insect were recorded and classified as active or inactive. Height on the stem, and diameter of the section at the gallery entrance were measured. Exposure of each gallery on the stem was also determined. The percentage of active galleries in relation to total galleries were not proportional to the size of the attacked stem section. The minimum diameters of the attacked sections were 11,5 and 12 cm. Height on the stem was not related to attack susceptibility, and the location of the highest gallery was dependent on plant size of attacked tree. Multiplicative, S-Curve and Exponential mathematical models relating stem sections with the number of galleries present from section to the tree top were satisfactorily fit. The entrance holes to the galleries were unevenly distributed around the stem circunference. Higher numbers of galleries were started from Northern and Eastern exposures.