SPATIAL AND TEMPORAL PATTERNS OF WITHIN-TREE COLONIZATION BY DENDROCTONUS FRONTALIS (COLEOPTERA: SCOLYTIDAE)

Abstract

Within-tree colonization by Dendroctonus frontalis infesting loblolly pine, Pinus taeda L., was investigated. Two components of the colonization process were studied: the establishment of attacking adults (ATK) and the ensuing construction of egg galleries (GL). Data on the two variables were taken from standing trees beginning at the time of initial attack and continuing for 14 consecutive days.The spatial and temporal sequence of ATK was described for 1.5 m intervals along the infested bole for the duration of the process. A three parameter nonlinear function was used to describe the data. The pattern of attack was also described as an average process for the entire tree using the same model. A frequency histogram encompassing the range in variation for peak ATK from 134 trees was prepared to provide starting values for simulation purposes.The spatial and temporal sequence of GL construction was described using essentially the same approach as employed for ATK. The modeling process was complicated by loss or obscuring of GL from the radiograph by omission errors and foraging by Monochamus spp. and other associates. GL construction was also described as an average function for the entire tree and the rate of GL construction was defined. A frequency histogram of peak GL was prepared from data on 54 trees for use in selecting starting values for simulation purposes.Numerical relationships between ATK and GL were defined by combining the data on ATK and cumulative expected GL.