A Test of High-Dose Verbenone for Stand-Level Protection of Lodgepole and Whitebark Pine from Mountain Pine Beetle (Coleoptera: Curculionidae: Scolytinae) Attacks

Abstract

The efficacy of verbenone as a stand-level protectant against mountain pine beetle, Dendroctonus ponderosae Hopkins, attacks was tested in lodgepole and whitebark pine stands at five geographically separated sites, including three consecutive years at one site. Forty and 20 high-dose pouches, with a verbenone emission rate up to 50 mg/d per pouch, were spaced in a grid pattern throughout 0.40-ha plots, replicated up to six times at each site. Although the verbenone treatment did not prevent beetles from dispersing through treated stands, attacking large-diameter trees most frequently, the overall number of trees attacked was, on average, reduced significantly compared with nontreated stands. In a few blocks each year, verbenone-treated plots had more attacked trees than controls. These blocks tended to have a large emerging beetle population, exceeding 140 previously attacked trees within the hectare including and surrounding the treated area. Additional research is needed on the behavioral role of verbenone in mountain pine beetle population dynamics and quantification of the infestation level above which treatment efficacy tends to be reduced.

Aerially applied verbenone-releasing laminated flakes protect Pinus contorta stands from attack by Dendroctonus ponderosae in California and Idaho

“…By the end of that study, however, stand basal area was dramatically reduced by beetle activity in both the control and untreated stands surrounding the small treated plots, rendering the comparison problematic. Bentz et al (2005) found that deployment of verbenone pouches in lodgepole and whitebark pine stands significantly reduced rate of attack by mountain pine beetle for up to 3 consecutive years, but they reported that some treated plots, particularly those with large emerging beetle populations, showed higher attack rates than controls. In these cases, higher levels of verbenone (Miller et al, 2006) or use of a combined ''push-pull'' strategy employing baited traps (e.g.…”

“…Forest managers have therefore sought methods to mitigate the effects of this pest. Several D. ponderosae management techniques have been tested, including silvicultural treatments to reduce stand density and/or basal area (Wood et al, 1985;Amman and Logan, 1998;Fettig et al, 2006a), sanitation (McMullen et al, 1986), insecticides (Haverty et al, 1998;Naumann and Rankin, 1999;Fettig et al, 2006b), and pheromone-based strategies including aggregation pheromones deployed in trap-out, trap tree, or concentration approaches (Gray and Borden, 1989;Gibson and Weber, 2004;Borden et al, 2006) and antiaggregants to interrupt colonization of hosts (Wilson et al, 1996;Huber and Borden, 2001;Borden et al, 2003Borden et al, , 2004Borden et al, , 2006Kegley et al, 2003;Gibson and Kegley, 2004;Progar, 2005;Bentz et al, 2005;Gillette et al, 2006). As suggested above, reducing stand basal area may be the single most effective treatment (Johnstone, 2002;Safranyik et al, 2004;Whitehead and Russo, 2005;Zausen et al, 2005), but forest management objectives, particularly on public lands, often require preservation of large old-growth trees for wildlife habitat (Andrews et al, 2005).…”

“…Earlier work with verbenone targeting the southern pine beetle, Dendroctonus frontalis Zimmerman, indicated promise for such pheromone-based approaches, and operational treatments were subsequently developed for D. frontalis (Payne and Billings, 1989;Payne et al, 1992;Salom et al, 1995;Borden, 1997;Clarke et al, 1999). More recently, a variety of approaches have been tested with verbenone targeting D. ponderosae (Lindgren and Miller, 2002;Kegley et al, 2003;Progar, 2003;Gibson and Kegley, 2004;Kegley and Gibson, 2004;Bentz et al, 2005;Progar, 2005;Gillette et al, 2006). Lister et al (1990) found that a verbenone bubblecapsule (''bubblecap'') formulation was ineffective for single tree protection, but the bubblecap release devices used in their study may not have had sufficiently high release rates.…”

Protection of spruce from colonization by the bark beetle, Ips perturbatus, in Alaska

“…Semiochemical-based tree protection from bark and ambrosia beetles, either at the single tree or stand level, has been attempted for nearly 20 years by applying verbenone to trees in bubblecap or pouch release devices (Amman et al, 1989;Lindgren et al, 1989;Shore et al, 1992;Progar, 2005); in a grid pattern on trees or stakes in pouches (Bentz et al, 2005); or broadcast in beads (Shea et al, 1992); or in flakes (Gillette et al, 2006). Some of these studies (i.e., Bentz et al, 2005;Progar, 2005) tested verbenone over multiple years, but results showed that the efficacy was not reliable over time.…”

“…Some of these studies (i.e., Bentz et al, 2005;Progar, 2005) tested verbenone over multiple years, but results showed that the efficacy was not reliable over time. With the discovery of other bark beetle repellent semiochemicals such as (E)-2-and (Z)-3-hexen-1-ol (Wilson et al, 1996), 1-hexanol, benzaldehyde, benzyl alcohol, and nonanal (Borden et al, 1998), and guaiacol, hexanal, (E)-2-hexanal, salicylaldehyde, and conophthorin (Borden et al, 2003) from various non-hosts, land managers have had a larger toolkit of potential interruptants with which to manage bark beetles.…”