Effect of verbenone on response ofDendroctonus brevicomis toexo-Brevicomin, frontalin, and myrcene.

exo-Brevicomin (E), frontalin (F), and myrcene (M) were released at two rates 10-fold apart with verbenone at four rates 10-fold apart, and without verbenone in plots with one trap on a vertical cylinder at the pheromone source and one trap on each of four cylinders 5 m away. Catch of the western pine beetleDendroctonus brevicomis decreased with increasing levels of verbenone at both release rates of EFM, but not all differences in catch were statistically significant. Significantly more beetles were caught at the high rate of EFM than at the low rate, combining all rates of verbenone. The percent of total beetles caught at the center trap tended to decrease with increasing rates of verbenone, but the only statistically significant differences were at the low rate of EFM.