Comparisons of Two Trapping Methods for Hylobius pales (Coleoptera: Curculionidae) in Virginia

Abstract

The pales weevil, Hylobius pales (Herbst), is a major regeneration pest of Christmas tree plantations in the eastern United States, where traditional control measures include the use of highly toxic insecticides. The development of an effective, easily implemented sampling strategy to detect when serious infestations are imminent is highly desirable for reducing these preventative insecticide applications. Methods were evaluated for trapping walking H. pales under 3 vegetation management treatments in Christmas tree plantations and for their potential to forecast seedling damage. Standard pit traps baited with natural host material and synthetic volatiles caught significantly more H. pales than polyvinyl chloride (PVC) pitfall traps baited with synthetic volatiles alone. No gender differences were observed in response to the trap treatments. No differences in catch were observed between stationary traps and traps rotated biweekly to different locations within each plot. Vegetation management had no significant effect on trap catch. However, H. pales fed on a significantly higher proportion of eastern white pine seedlings, Pinus strobus L., in plots not managed for competing vegetation than in herbicide-treated plots. The data suggested a strong linear relationship between catch and seedling damage; these variables were significantly correlated in 1995, but not in 1994. However, one must be cautious because this regression was based solely on 4 data points. The seasonal occurrence of H. pales in Virginia Christmas tree plantations is reviewed in detail. Our results suggest we must rely on the use of pit traps for monitoring weevil populations in Virginia until an appropriate system for implementing the PVC pitfall trap is developed.