Examination of factors affecting the efficacy of intercept traps for the capture of Monochamus beetles

When monitoring bark and woodboring beetle populations in forests, Lindgren funnel (hereafter funnel) traps and cross-vane panel (hereafter panel) traps are the two most used trap types. The literature indicates a discrepancy in the performance of these two trap types, with panel traps typically capturing more beetles than funnel traps. To assess where the discrepancy in beetle attraction exists, we conducted observational studies wherein we recorded the number of Monochamus beetles approaching panel and funnel traps from downwind and coming within 5, 3, and 1 meter of the trap, the number of beetles contacting the trap’s surface, and the number captured. Results from this experiment suggest the difference in attraction between these two trap types occurs in the near field (< 1 m). We also assessed the importance of visual stimulus in trap performance in a trapping experiment comparing open- and closed-canopy deployments of black, white, and clear panel traps with black funnel traps. Results from this experiment suggest that traps deployed in open-canopy conditions capture more beetles than those in closed canopy conditions. In terms of colour, black panel traps caught the most beetles, followed by clear and white panel traps, and funnel traps caught the fewest number of beetles. Field trials in 2022 will further assess the effects of trap colour and visual apparency on trap catch.