Douglas-fir beetle (Coleoptera: Curculionidae) response to single-point-source 3-methylcyclohex-2-en-1-one (MCH) releasers

The Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) (Coleoptera: Curculionidae) antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), has been used since 2000 to protect high-value trees and stands throughout western North America. Operational treatments involve placing individual releasers on a 12 m × 12 m grid throughout the area to be protected. In this study, six widely spaced trap lines were established with aggregation attractant–baited traps located 1, 3, 9, 27, and 81 m from a location where an operational MCH release device was alternately either present or absent, and changes in catches caused by the MCH device were assessed at all distances. Trap catches were suppressed by about 70% at one and three metres, by 50% at nine metres, by 30% at 27 m, and not at all at 81 m. Inhibition by the MCH device varied with distance (m) from the source according to the function 0.79 − 0.092x0.51 (R 2 = 0.986). Decline of attractant inhibition with distance from the MCH device was much less steep than would have been expected if catch inhibition had varied directly with the average airborne concentration of MCH.

3-Methylcyclohex-2-en-1-one and the Douglas-fir beetle (Coleoptera: Curculionidae): history of successful bark beetle pheromone treatments

This paper reviews the literature on the identification of 3-methylcyclohex-2-en-1-one (MCH) as the antiaggregation pheromone of the Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) (Coleoptera: Curculionidae) and the development of successful management applications using the pheromone. Previously unpublished data from two studies on novel uses of MCH are included. The successful development of antiaggregation pheromone-based treatments for the Douglas-fir beetle is discussed in relation to efforts to develop similar treatments for other bark beetle species, and opportunities for future research on MCH and the Douglas-fir beetle are suggested.

A Biodegradable Formulation of MCH (3-Methylcyclohex-2-en-1-one) for Protecting Pseudotsuga menziesii from Dendroctonus pseudotsugae (Coleoptera: Curculionidae) Colonization

Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, trees and stands can be protected from Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins (DFB)-caused mortality by application of synthetic formulations of the beetle’s antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH). A biodegradable formulation of MCH, SPLAT MCH, was developed and evaluated for protecting individual Douglas-fir trees and small stands from colonization and mortality by DFB. In an individual-tree experiment in Idaho, both MCH bubble capsules and SPLAT MCH significantly reduced the proportion of treated trees colonized and killed by DFB compared to untreated controls. SPLAT MCH was as effective as MCH bubble capsules for protecting individual trees. Both MCH bubble capsules and SPLAT MCH significantly reduced the proportion of trees colonized and killed by DFB within 0.04-ha circular plots surrounding each treated tree compared to untreated controls. In 0.41 ha stands in New Mexico, both MCH bubble capsules and SPLAT MCH significantly reduced the proportion of trees colonized and killed by DFB compared to untreated controls, again with no differences observed between MCH treatments. In a similar stand level trial in Idaho, neither MCH treatment significantly reduced the proportion of trees colonized by DFB, and only MCH bubble capsules significantly reduced levels of tree mortality compared to untreated controls, but no significant difference was observed between SPLAT MCH and MCH bubble capsules. Overall, the results indicate that SPLAT MCH is as effective as MCH bubble capsules for protecting individual trees and small stands of Douglas-fir from DFB-caused mortality.

Operational Success of Verbenone Against the Mountain Pine Beetle in a Rural Community

Pouches releasing verbenone, the antiaggregation pheromone of the mountain pine beetle, were stapled to 1191 lodgepole pines throughout 95 residential properties in four subdivisions at Lac le Jeune, British Columbia, in July 2005. Postflight assessment in October in three of the subdivisions, where almost all infested trees had been removed before beetle flight, revealed new mass attacks on 3.6% of 3857 available trees 17.5 cm or greater (7 in) dbh. In a fourth subdivision where no infested trees were removed, 19.6% of 634 available trees were mass-attacked. In contrast, 17.4% of 1145 available trees were mass-attacked within 25 m (27.5 yd) wide, verbenone-treated buffer strips on public forest land adjacent to the residential properties, and 48.3% of 4975 available trees were mass-attacked on untreated control areas beyond the buffer strips. We conclude that treatment with verbenone pouches at roughly 15 m (16.5 yd) centers is a useful tool for protecting trees from attack by the mountain pine beetle provided that verbenone is used as part of a multiyear integrated pest management program that also includes disposal of all infested trees on the area to be protected before beetle flight in midsummer.

Antennae of Cryptorhynchus lapathi (Coleoptera: Curculionidae) detect two pheromone components of coniferophagous bark beetles in the stems of Salix sitchensis and Salix scouleriana (Salicaceae)

Several scolytid beetles (Coleoptera: Scolytidae) produce conophthorin, (E)-7-methyl-1,6-dioxaspiro[4.5]decane, and use it as an aggregation or antiaggregation pheromone or competition-mediating synomone (Francke et al. 1979; Kohnle et al. 1992; Birgersson et al. 1995; Pierce et al. 1995; de Groot et al. 1998; Dallara et al. 2000; Rappaport et al. 2000). Predators or associates of these beetles may use conophthorin as a host- or habitat-finding kairomone (Kohnle et al. 1992). Other conifer-infesting scolytid and predator species use chalcogran, 2-ethyl-1,6-dioxaspiro[4.4]nonane, a semiochemical with functions similar to those of conophthorin (Francke et al. 1977; Heuer and Vité 1984; Baader 1989; Byers 1993; Byers et al. 1989, 2000).

Using Aggregation and Antiaggregation Pheromones of the Douglas-Fir Beetle to Produce Snags for Wildlife Habitat

Pheromone baits for the Douglas-fir beetle were applied alone and in combination with the antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), to test potential treatments for creating snags to improve wildlife habitat. All baited trees were attacked by beetles following both treatments. However, more unbaited trees were attacked on plots without MCH than on plots with MCH. One year after treatment, more of the attacked trees were dead on plots without MCH than on plots with MCH. Bark beetle pheromones can be used effectively to create snags for improving wildlife habitat, but to achieve specific objectives treatments must be prescribed based on knowledge of the expected beetle population densities. West. J. Appl. For. 12(2):00-00.