Factors influencing the growth of multiple-tree infestations by the southern pine beetle, Dendroctonus frontalis Zimmermann

Abstract

Many factors influence the ability of an infestation of the southern pine beetle, Dendroctonus frontalis Zimmermann to enlarge. These factors may relate to the characteristics of the host trees in the stand, the population dynamics of the insect, and weather conditions. This study was undertaken to determine the importance of the last two factors. There were four specific objectives: to monitor the population dynamics of D. frontalis within individual infestations; to provide a record of the host and insect data collected for each tree; to provide summaries of all data at both the infestation and pooled infestation levels; and to correlate the measured and estimated variables to the different final sizes achieved in the spots examined. Two basic subsets of the data were defined: one subset was comprised of descriptions of host tree characteristics, estimates of total insect life stage estimates, and various supposed indices of infestation trend; the second data subset consisted of estimates of daily abundances of the different insect life stages and records of daily weather conditions. For each data subset two types of analyses were conducted: stepwise regression analysis and a series of mean value comparisons using Duncan's multiple range test. The objective of these analyses was to identify those variables most indicative of the final size attained in the individual infestations.