Red turpentine beetle primary attraction increases linearly with (-)-β-pinene plus ethanol dose regardless of component ratios, and no change in response with addition of high-release frontalin

Lure efficacy for primary attraction of red turpentine beetle, Dendroctonus valens (Coleoptera: Curculionidae: Scolytinae) observed previously in US Pacific Northwest ponderosa pine forests is (-)-beta-pinene+ethanol > (+)-3-carene+ethanol > (+)-alpha-pinene+ethanol. Influence of (-)-beta-pinene+ethanol release rates was tested with nine lures representing all combinations of three release levels for each compound in a 3 x 3 factorial design field test in Oregon. Beetle catch had a positive, linear relationship with the combined (-)-beta-pinene+ethanol total release (or dose), resulting from higher release of either one or both compounds. Reversing component ratios, that is, 1 : 2 versus 2 : 1 with similar total doses, produced minimal changes in beetle response. Females produce frontalin with dual aggregation and sex-pheromone functions. In another test, high-release frontalin, defined as >1.0 mg/day release, was tested at 1.4 to 1.5 mg/day in combination with each monoterpene+ethanol lure above and their trap catch compared with (-)-beta-pinene+ethanol lures. Presence of high-release frontalin produced minimal changes in beetle responses.

Automated summary

Research shows that the lure efficacy of (-)-beta-pinene+ethanol is the strongest for the red turpentine beetle, and different release rates of the compounds in combination result in varying levels of attraction. Frontalin in females serves a dual function and high-release mode has minimal impact on beetle responses.