Synomones of two sympatric species deter attack by the pine engraver, Ips pini (Coleoptera: Scolytidae)
The capture of pine engravers, Ips pini (Say), in ipdienol-baited, multiple-funnel traps in British Columbia was significantly reduced when devices releasing ipsenol or verbenone were placed in the traps. These results suggest that ipsenol and verbenone are synomones release by Ips latidens (LeC.) and the mountain pine beetle, Dendroctonus ponderosae Hopk., respectively. When verbonone and ipsenol were released together from five stations 2 m apart on felled trees, at 50 and 1.5 mg per day per tree, respectively, there was a 66.7% reduction in the number of logs attacked and 98.8% reduction in attack density. The same treatment caused 74.1% reduction in attack density on standing trees surrounding by a 4 x 4 grid 16 release devices at 5-m centres. The antiaggregant composition of verbenone plus ipsenol has considerable operational potential for use in pre-commercial thinnings and in areas where standing pines are of high value; e.g., in rural subdivisions, shelterbelts, and recreational forests.