A. Steven Munson

Trap Lure Blend of Pine Volatiles and Bark Beetle Pheromones for Monochamus spp. (Coleoptera: Cerambycidae) in Pine Forests of Canada and the United States

ABSTRACT n In 2007–2008, we examined the flight responses of Monochamus titillator (F.) complex [M. titillator, Monochamus carolinensis (Olivier), and any possible hybrids], Monochamus scutellatus (Say), Monochamus clamator (LeConte), Monochamus obtusus Casey, and Monochamus mutator LeConte (Coleoptera: Cerambycidae) to multiple-funnel traps baited with and without host volatiles and bark beetle pheromones. Experiments were conducted in mature pine (Pinus) stands in Alberta (Canada), and Arkansas, Arizona, California, Florida, Idaho, Michigan, Montana, New Hampshire, North Carolina, Ohio, Oregon, Tennessee, Utah, and Wisconsin (United States). At each location, traps were deployed in 10 replicate blocks of four traps per block. The trap treatments were: 1 ) blank control; 2) ipsenol and ipsdienol; 3) ethanol and &agr;-pinene; and 4) a quaternary blend of ipsenol, ipsdienol, ethanol, and &agr;-pinene. All five species or species complex of Monochamus preferred traps baited with the quaternary blend over all other treatments. The consistency of these results across such a large geographic area suggests that similar selection pressures may be acting on Monochamus spp. in pine forests, regardless of variation in stand composition and climatic conditions. Our results suggest that multiple-funnel traps baited with the quaternary blend of ipsenol, ipsdienol, ethanol, and &agr;-pinene may be highly effective for monitoring various Monochamus spp. in pine forests of North America, and may have utility in trapping and detection programs in North America and overseas.

Spray Deposition from Ground-based Applications of Carbaryl to Protect Individual Trees from Bark Beetle Attack

Bark beetles (Coleoptera: Curculionidae, Scolytinae) are recognized as the most important tree mortality agent in western coniferous forests. A common method of protecting trees from bark beetle attack is to saturate the tree bole with carbaryl (1-naphthyl methylcarbamate) using a hydraulic sprayer. In this study, we evaluate the amount of carbaryl drift (ground deposition) occurring at four distances from the tree bole (7.6, 15.2, 22.9, and 38.1 m) during conventional spray applications for protecting individual lodgepole pine (Pinus contorta Dougl. ex Loud.) from mountain pine beetle (Dendroctonus ponderosae Hopkins) attack and Engelmann spruce (Picea engelmannii Parry ex Engelm.) from spruce beetle (D. rufipennis [Kirby]) attack. Mean deposition (carbaryl + alpha-naphthol) did not differ significantly among treatments (nozzle orifices) at any distance from the tree bole. Values ranged from 0.04 +/- 0.02 mg carbaryl m(-2) at 38.1 m to 13.30 +/- 2.54 mg carbaryl m(-2) at 7.6 m. Overall, distance from the tree bole significantly affected the amount of deposition. Deposition was greatest 7.6 m from the tree bole and quickly declined as distance from the tree bole increased. Approximately 97% of total spray deposition occurred within 15.2 m of the tree bole. Application efficiency (i.e., percentage of insecticide applied that is retained on trees) ranged from 80.9 to 87.2%. Based on review of the literature, this amount of drift poses little threat to adjacent aquatic environments. No-spray buffers of 7.6 m should be sufficient to protect freshwater fish, amphibians, crustaceans, bivalves, and most aquatic insects. Buffers >22.9 m appear sufficient to protect the most sensitive aquatic insects (Plecoptera).

Evaluations of emamectin benzoate and propiconazole for protecting individual Pinus contorta from mortality attributed to colonization by Dendroctonus ponderosae and associated fungi

BACKGROUNDnProtection of conifers from bark beetle colonization typically involves applications of liquid formulations of contact insecticides to the tree bole. An evaluation was made of the efficacy of bole injections of emamectin benzoate alone and combined with the fungicide propiconazole for protecting individual lodgepole pine, Pinus contorta Dougl. ex Loud., from mortality attributed to colonization by mountain pine beetle, Dendroctonus ponderosae Hopkins, and progression of associated blue stain fungi.nnnRESULTSnInjections of emamectin benzoate applied in mid-June did not provide adequate levels of tree protection; however, injections of emamectin benzoateu2009+u2009propiconazole applied at the same time were effective for two field seasons. Injections of emamectin benzoate and emamectin benzoateu2009+u2009propiconazole in mid-September provided tree protection the following field season, but unfortunately efficacy could not be determined during a second field season owing to insufficient levels of tree mortality observed in the untreated control, indicative of low D. ponderosae populations.nnnCONCLUSIONnPrevious evaluations of emamectin benzoate for protecting P. contorta from mortality attributed to D. ponderosae have failed to demonstrate efficacy, which was later attributed to inadequate distribution of emamectin benzoate following injections applied several weeks before D. ponderosae colonization. The present data indicate that injections of emamectin benzoate applied in late summer or early fall will provide adequate levels of tree protection the following summer, and that, when emamectin benzoate is combined with propiconazole, tree protection is afforded the year that injections are implemented.

Lethal trap trees and semiochemical repellents as area host protection strategies for spruce beetle (Coleoptera: Curculionidae, Scolytinae) in Utah

Abstract We tested lethal trap trees and repellent semiochemicals as area treatments to protect host trees from spruce beetle (Dendroctonus rufipennis Kirby) attacks. Lethal trap tree treatments (“spray treatment”) combined a spruce beetle bait with carbaryl treatment of the baited spruce. Repellent treatments (“spray-repellent”) combined a baited lethal trap tree within a 16-m grid of MCH (3-methylcyclohex-2-en-1-one) and two novel spruce beetle repellents. After beetle flight, we surveyed all trees within 50 m of plot center, stratified by 10-m radius subplots, and compared attack rates to those from baited and unbaited control plots. Compared to the baited controls, spruce in the spray treatment had significantly reduced likelihood of a more severe attack classification (e.g., mass-attacked over strip-attacked or unsuccessful-attacked over unattacked). Because spruce in the spray treatment also had significantly heightened probability of more severe attack classification than those in the unbaited controls, however, we do not recommend lethal trap trees as a stand-alone beetle suppression strategy for epidemic beetle populations. Spruce in the spray-repellent treatment were slightly more likely to be classified as more severely attacked within 30 m of plot center compared to unbaited controls but, overall, had reduced probabilities of beetle attack over the entire 50-m radius plots. The semiochemical repellents deployed in this study were effective at reducing attacks on spruce within treated plots despite the presence of a centrally located spruce beetle bait. Further testing will be required to clarify operational protocols such as dose, elution rate, and release device spacing.

A Novel Semiochemical Tool for Protecting Pinus contorta From Mortality Attributed to Dendroctonus ponderosae (Coleoptera: Curculionidae)

ABSTRACT n Verbenone (4,6,6-trimethylbicyclo[3.1.1]hept-3-en-2-one) is an antiaggregant of the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), a notable forest insect capable of causing extensive levels of tree mortality in western North America. Several formulations of verbenone are registered for tree protection, but failures in efficacy are not uncommon, particularly when applied during large infestations. A formulation of (—)-verbenone was developed (Specialized Pheromone & Lure Application Technology [SPLAT] Verb, ISCA Technologies Inc., Riverside, CA) and evaluated for protecting individual lodgepole pine, Pinus contorta Douglas ex Loudon, and small stands of P. contorta from mortality attributed to D. ponderosae. SPLAT Verb applied to individual P. contorta resulted in complete tree protection, while 93.3% mortality occurred in the untreated controls. Significantly fewer P. contorta were killed by D. ponderosae within 0.041-ha circular plots surrounding P. contorta treated with SPLAT Verb compared with the untreated control. In a second study, a smaller percentage of P. contorta were colonized and killed on 0.4-ha square plots treated with SPLAT Verb compared with the untreated control. No significant differences in levels of tree mortality were observed between the untreated control and another formulation of verbenone (7-g pouch) or between the 7-g pouch and SPLAT Verb. In a trapping bioassay, no significant differences were observed among captures in multiple-funnel traps at 1, 2, or 4m from the point of release of SPLAT Verb. Significantly fewer D. ponderosae were collected at 1 and 2m compared with 8m. Significantly more D. ponderosae were captured at the farthest distance evaluated (16m) than at any other distance. Our data indicate that SPLAT Verb is effective for protecting individual P. contorta and small stands of P. contorta from mortality attributed to D. ponderosae at moderate doses. The high levels of tree protection observed are attributed to the ability of applying release points (dollops) at high densities, and a larger zone of inhibition than reported for other formulations of verbenone. SPLAT Verb was registered by the U.S. Environmental Protection Agency for use on pines, Pinus spp., in 2013.

Efficacy of Abamectin and Tebuconazole Injections to Protect Lodgepole Pine from Mortality Attributed to Mountain Pine Beetle (Coleoptera: Curculionidae) Attack and Progression of Blue Stain Fungi

Abstract Bark beetles (Coleoptera: Curculionidae, Scolytinae) are important tree mortality agents in western coniferous forests. Protection of individual trees from bark beetle attack has historically involved applications of liquid formulations of contact insecticides to the tree bole using hydraulic sprayers. More recently, researchers have examined the effectiveness of injecting small quantities of systemic insecticides directly into trees, but early efforts were largely unsuccessful. In this study, we determine the efficacy of fall (16 - 18 September) injections of abamectin (Abacide™ 2Hp; Mauget Inc., Arcadia, CA) alone and combined with tebuconazole (Tebuject™ 16, Mauget Inc.) for protecting individual lodgepole pine, Pinus contorta Dougl. ex Laws., from mortality attributed to mountain pine beetle, Dendroctonus ponderosae Hopkins. Both abamectin and abamectin + tebuconazole were efficacious for one field season, whereas results from a second field season were inconclusive due to insufficient beetle pressure. To our knowledge, this is the first demonstration of the successful application of a systemic insecticide for protecting P. contorta from mortality attributed to D. ponderosae.

Efficacy of Fipronil for Protecting Individual Pines from Mortality Attributed to Attack by Western Pine Beetle and Mountain Pine Beetle (Coleoptera: Curculionidae, Scolytinae)

Bark beetles (Coleoptera: Curculionidae, Scolytinae) are commonly recognized as important tree mortality agents in coniferous forests of the western U.S. Most species feed on the phloem and cambium, or xylem tissue of woody plants; and a few are recognized as the most destructive of all forest insect pests. The last decade has seen elevated levels of bark beetle caused tree mortality in spruce, Picea spp., forests of south-central Alaska and the Rocky Mountains; lodgepole pine, Pinus contorta Dougl. ex Loud., forests of the Rocky Mountains; pinyon-juniper, Pinus-Juniperus spp., woodlands of the Southwest; and ponderosa pine, P. ponderosa Dougl. ex Laws., forests of Arizona, California, Colorado and South Dakota (Cain and Hayes 2009, U.S. Dept. of Agric. For. Serv. Gen. Tech. Rep. PNW-GTR-784). Today, about 8% of forests in the U.S. are classified at high risk (defined as >25% of stand density will die in the next 15 years) to insect and disease outbreaks (Krist et al. 2007, U.S. Dept. of Agric. For. Serv. FHTET Report 2007 06). Mountain pine beetle, Dendroctonus ponderosae Hopkins, is ranked most damaging of all mortality agents considered and colonizes several pine species, most notably P. contorta, P. ponderosa, sugar pine, P. lambertiana Dougl., whitebark pine, P. albicaulis Engelm., limber pine, P. flexilis James, and western white pine, P. monticola Dougl. ex D. Don. (Furniss and Carolin 1977, U.S. Dept. of Agric. For. Serv. Misc. Publ. 1339). The western pine beetle, D. brevicomis LeConte, is also a major cause of P. ponderosa mortality in much of the western U.S., specifically in California (Furniss and Carolin 1977). Together, these 2 bark beetle species are

3-Methylcyclohex-2-en-1-one for area and individual tree protection against spruce beetle (Coleoptera: Curculionidae: Scolytinae) attack in the southern Rocky Mountains

Abstract We tested 3-methylcyclohex-2-en-1-one (MCH) and an Acer kairomone blend (AKB) as repellent semiochemicals for area and single tree protection to prevent spruce beetle (Dendroctonus rufipennis Kirby) attacks at locations in Utah and New Mexico. In the area protection study, we compared host infestation rates of MCH applications at three densities (20, 40, and 80 g MCH ha–1) against a control treatment over 0.64 ha plots centered within ∼1.25 ha treatment blocks. All treatments included two baited funnel traps within the plot to assure spruce beetle pressure. Following beetle attack, plots were surveyed for new spruce beetle attacks and to quantify stand characteristics. The probability of more severe spruce beetle attacks was significantly reduced, by ∼50%, in each of the MCH area treatments compared with the control treatment but there was no significant treatment difference among the MCH deployment densities. For the single tree protection study, we compared attack rates of MCH, Acer kairomone blend (AKB), and MCH plus AKB on spruce beetle-baited trees against bait-only trees. Each treatment was applied over a range of host diameters to test for host size effects. Seventy-five percent of control trees were mass-attacked, about one-third of MCH- and AKB-alone spruce was mass-attacked, and no MCH plus AKB spruce were mass-attacked. These results suggest that MCH alone is a marginal area and single tree protectant against spruce beetle but that deployment with other repellents can significantly increase treatment efficacy.

Efficacy of Spring and Fall Treatments of Carbaryl for Protecting Ponderosa Pine From Mortality Attributed to Mountain Pine Beetle (Coleoptera: Curculionidae)

High-value trees, such as those growing in residential, recreational, or administrative sites, are often susceptible to colonization by bark beetles (Coleoptera: Curculionidae: Scolytinae) as a result of increased amounts of stress associated with off-site plantings, drought, soil compaction, and/or mechanical injury. The value of these trees, cost of removing dead trees, and loss of aesthetics often justify the use of insecticides to protect trees from mortality attributed to bark beetles. Carbaryl (1-naphthyl methylcarbamate) is among the most effective, economically-viable, and ecologically-compatible insecticides available for protecting conifers from several species of bark beetles in the western United States. Treatments are usually applied in spring prior to initiation of flight of the target species. We evaluated the efficacy of spring and fall applications of carbaryl for protecting individual ponderosa pine, Pinus ponderosa Dougl. ex Laws. (Pinales: Pinaceae), from mortality attributed to mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), in Idaho. Both spring and fall treatments of 2.0% a.i. carbaryl (maximum label rate; Sevin SL, Bayer Environmental Science, Montvale, NJ 07645) provided one field season of protection, and thus should be applied annually if tree protection is desired for multiple years. Our research also provides some insight on the efficacy of carbaryl treatments after wildfire. We found no evidence that a mixed-severity wildfire negatively affected the efficacy of carbaryl treatments.