OPTIMIZATION OF SAMPLING EFFORT FOR WITHIN-TREE POPULATIONS OF SOUTHERN PINE BEETLE AND ITS NATURAL ENEMIES

As a prerequisite to full-scale collection of southern pine beetle [Dendroctonus frontalis] population data, determination of optimum sample unit size and numbers were made. Optimum sample unit size was developed as a function of the variables to be measured (i.e., attack density, egg gallery length, total brood, parasite complex and predator complex). A series of permanent 2000 cm2 X-ray maps, depicting southern pine beetle life stages plus natural enemies occurring at varying heights in trees of different sizes, were made. These map data were stored, as addressable grid cell values in the computer. Programs were written for randomly selecting a series of defined experimental sample unit sizes. From thse observations, the relationship of sample number to sample unit size was determined, and a procedure was outlined for estimating density of the bark beetle and its natural enemy populations throughout an infested area.