Survey and mass trapping of ambrosia beetles (Coleoptera: Scolytidae) in timber processing areas on Vancouver Island

Abstract

The spatial distribution and population estimates of overwintering Trypodendronlineatum (Olivier) were determined by sampling beetles in the duff at four dryland log sorts. The temporal and spatial distributions of flying T. lineatum, Gnathotrichussulcatus (LeConte), and G. retusus (LeConte) over 3 years were determined by catches by pheromone-baited traps in three dryland sorts. At one dryland sort the distribution data from survey trapping and overwintering sampling were used to establish optimal trap placement for the subsequent year's trapping. At this dryland sort the trapping effort was expanded from a survey into a mass trapping program, using a barrier strategy. The total catches of all three species in 1979, 1980, and 1981 were 120 000, 690 000, and 2 800 000, respectively. Approximately 66 and 79% of the captured beetles in 1980 and 1981, respectively, were T. lineatum. When compared with high and low population estimates of overwintering T. lineatum the catches of this species represented 1–3, 12–21, and 44–77% of the total overwintering population for the respective years. For each year, the following winter's population remained constant relative to previous years. A mass trapping program, utilizing synthetic pheromones, multiple funnel traps, and sticky vane traps, was recommended in conjunction with improved log inventory management.