Containment and Concentration of Mountain Pine Beetle (Coleoptera, Scolytidae) Infestations with Semiochemicals. Validation by Sampling of Baited and Surrounding Zones

1989

S. 1399-1405

3 Abb., 3 Tab., 18 Lit. Ang.

Unselbständiges Werk

200091733

Attack intensification within mountain pine beetle, Dendroctonus ponderosae Hopkins, infestations in five stands of lodgepole pine, Pinus contorta var. latifolia Englemann, was compared within a central zone (A) and two concentric, surrounding zones (B and C) that were 50 and 100 m wide, respectively. When trees in Zone A were baited at 50-m centers with semiochemicals (trans-verbenol, exo-brevicomin, and myrcene), ratios of newly attacked (green) trees to previously attacked (red) trees were greater in Zone A than the outer zones in two of three stands, indicating successful containment and concentration of these infestations. In two control stands in which Zone A was unbaited, the green/red ratios were higher in Zone B than in the other two zones, indicating an outward spread of the infestation. Baiting of trees caused an increase in attack density in Zone A. Attack density and diameter were positively correlated for all sites. Incorporating attack density and tree diameter into a weighted green/red ratio or an attack intensification ratio amplified the results obtained by calculating unweighted green/red ratios, and indicated containment and concentration in the third experimental stand. These results confirm that tree baiting is an effective method of containing and concentrating mountain pine beetle infestations.