• Rocky Mountain Research Station
• 240 West Prospect
• Fort Collins, CO 80526
• (970) 498-1100

Verbenone for Reducing Mountain Pine Beetle Attacks in the Black Hills

Bark beetles regulate the attack process on its host (the tree) to avoid overcrowding the host through a very complex chemical communication system that includes the use of pheromones. Verbenone has been identified as a chemical with anti-aggregation or repellent properties that arrests additional mountain pine beetle attacks on a tree. This anti-aggregation compound is insect-produced and is most likely released when the resource (the tree) is fully utilized by the insects already present. The use of synthetically-produced verbenone has been experimentally tested for reducing the number of mountain pine beetle attacked trees in various studies, but the results have been mixed. This study was conducted to examine potential reduction of mountain pine beetle attackes with two different release techniques.

In 2000 and 2002, Verbenone, a compound with anti-aggregation properties for mountain pine beetle was tested for reducing attacks by the insect in Ponderosa pine forests in the Black Hills of South Dakota. The verbenone was released to the environment with the use of a permeable membrane, two different mechanisms were tested. Mountain pine beetle attractants were placed on three trees at plot center to ensure insect population pressure. In neither experiment were there any observed differences in (1) number of mountain pine beetle-killed trees, (2) the number of partial attackes (strip attacks), (3) the number of unsuccessful attacks (pitchouts), (4) the diameter at breast height of infested trees, (5) the attack height of infested trees, (6) the mean distances of infested trees to verbenone releasers, or (7), the attractants located a plot center. Stand environment was identified as a possible explantation for lack of effectiveness. Further studieson this topic should be conducted as treatment technology is developed further or the appropriate release amount and timing is better understood.

At this point, based on this and prior studies, the operational use of vebenone for reducing mountain pine beetle attacked trees in ponderosa pine forest is not advisable. This study and others did not detect significant reductions in the number of trees attacked when verbenone was used.

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