Optimal Cross-Sectional Sampling Strategy for Red Oak Borer (Coleoptera: Cerambycidae) Scars within Northern Red Oaks

We used dendrochronological techniques to develop an optimal sampling strategy for the purpose of investigating the history of red oak borer (Enaphalodes rufulus [Haldeman]) population patterns within northern red oaks (Quercus rubra L.). We cut the entire length of three northern red oak tree boles into cross-sections, sanded top and bottom surfaces of each cross-section, and dated all scars within each bole. Our goal was to devise a strategy to reduce the amount of bole sampled without compromising the data necessary to accurately estimate historical population patterns of red oak borer. When we tested four possible sampling strategies and compared them with the entire-tree data sets from which they originated, we found no statistical differences in the distribution of scar counts by year. We also assessed processing time and found that compared with sampling an entire host bole, sampling strategies that include the lower 20% or 30% of boles would reduce labor efforts by 55–63%. We suggest that development of similar sampling methods for other bark or wood-boring species may be possible if the relationship between insect life history and annual tree-ring formation, as well as the general spatial and temporal distribution of insect evidence within trees, is known.