Aggregation Pheromone for Manipulation of the Douglas-Fir Beetle12

Abstract

The possibility of attracting Dendroctonus pseudotsugae Hopkins, by baiting host trees with frontalin (1,5-dimethyl 6,8-dioxabicyclo[3.2.1]octane), camphene and alpha pinene was tested in southern Idaho during 1970. Mature Douglas-fir, Pseudotsuga menziesii (Mirb) Franco, on 8 scattered plots ranging in area from 11 to 34 acres were baited with Douglure (2 parts frontalin: 0.7 parts camphene, and 0.3 parts alpha pinene) contained in polyethylene caps. Trees averaging over 18 inches in diameter were selected at 132-foot intervals on a grid pattern and were alternately treated with attractant or empty caps. Three months after placing the caps, 100% of the J57 baited trees and 8% of the 154 unbaited trees had 6 or more attacks per square foot bark surface at, a height of 12 feet Beetle attacks eventually spread 10 trees adjacent to those baited, killing 58.5% of those which had a DBH of 4 inches or larger and were within 33 feet of a baited tree. A trend was detected in this attack pattern which suggested that as distance from the bait increased from 14 to 33 feet a preference was shown for larger diameter classes. Under 14 feet, all trees 24 inches and greater were attacked and killed. Utilization of chemical messengers, frontalin and host terpenes, in the management of the Douglas-fir beetle by the trap-tree harvest, method is a distinct possibility. The biological effectiveness of these compounds and the simplicity of their deployment should encourage further studies toward adoption of the technique as a routine practice in Douglas-fir management.