Toxicity of two Engelmann spruce (Pinaceae) monoterpene chemotypes from the southern Rocky Mountains to North American spruce beetle (Coleoptera: Scolytidae)

AbstractEngelmann spruce, Picea engelmannii Parry ex Engelm. (Pinaceae), in the southern Rocky Mountains is composed of two distinct phloem monoterpene chemotypes that differ in relative abundances of multiple monoterpenes, particularly α-pinene and Δ3-carene (hereafter, the “α-pinene chemotype” and the “Δ3-carene chemotype”). Here, relative toxicity of these chemotypes is tested on spruce beetle (Dendroctonus rufipennis Kirby) (Coleoptera: Scolytinae), a phloeophagous herbivore that colonises trees of both types. Synthetic monoterpene blends representing each chemotype were tested across a range of concentrations (0, 10, 50, 100, 200, and 500 µg/L) in the lab, and probability of survival of adult beetles exposed to each blend was modelled using a logit function. Logit curves were solved to determine LC25, LC50, and LC75 of each monoterpene blend. On average, probability of beetle survival was lower when exposed to the Δ3-carene chemotype than when exposed to the α-pinene chemotype. However, both chemotypes were completely lethal to beetles at concentrations exceeding 100 µg/L. Adult body mass did not affect survival probability. It is concluded that spruce phloem chemotypes may differ in their toxicity to spruce beetles, with potential consequences for patterns of host-tree colonisation by spruce beetle.

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Advances in Semiochemical Repellents to Mitigate Host Mortality From the Spruce Beetle (Coleoptera: Curculionidae)

Journal of Economic Entomology ◽

10.1093/jee/toz172 ◽

2019 ◽

Vol 112 (5) ◽

pp. 2253-2261 ◽

Cited By ~ 3

Author(s):

E Matthew Hansen ◽

A Steven Munson ◽

David Wakarchuk ◽

Darren C Blackford ◽

Andrew D Graves ◽

...

Keyword(s):

Picea Engelmannii ◽

Individual Tree ◽

Dendroctonus Rufipennis ◽

Tree Diameter ◽

Degree Of Protection ◽

Southern Rocky Mountains ◽

Single Tree ◽

Engelmann Spruce ◽

Tree Protection ◽

Spruce Beetle

AbstractWe tested 3-methyl-2-cyclohexen-1-one (MCH) and novel semiochemicals as potential spruce beetle (Dendroctonus rufipennis Kirby) (Coleoptera: Curculionidae, Scolytinae) repellents over multiple years in Utah and Colorado trapping bioassays. MCH is a known spruce beetle repellent and our testing revealed Acer kairomone blend (AKB) and isophorone plus sulcatone as repellents. We subsequently tested these semiochemicals for area and single tree protection to prevent spruce beetle attacks at locations in Utah, Colorado, Wyoming, New Mexico, and Alaska. Individual tree protection trials found MCH–AKB provided significant protection against spruce beetle attacks in the southern Rocky Mountains but not in Alaska. Adding sulcatone or doubling MCH–AKB pouches did not further enhance protection. A degree of protection was extended to spruce at least 10 m distant from the repellents, including in Alaska. Tree diameter was not a significant covariate among treated trees but was positively correlated with the probability of infestation for surrounding spruce. In area protection trials, spruce in control plots were 2.4 times more likely to be in a higher severity attack class compared with spruce in plots treated with MCH–AKB pouches deployed at 30 sets per hectare. Tree diameter had a significant, positive relationship to the probability of infestation. We found MCH–AKB to offer a high degree of protection against beetle attack in Engelmann spruce (Picea engelmannii Parry ex Engelm.) (Pinales: Pinaceae) (Picea engelmannii Parry ex Engelm.) (Pinales: Pinaceae), especially for single tree protection (66% of control trees were strip- or mass-attacked compared with 6% of repellent-treated trees). AKB requires registration and labeling, however, before this economical and environmentally benign semiochemical can be used operationally.

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Evaluations of Bole Injections for Protecting Engelmann Spruce from Mortality Attributed to Spruce Beetle (Coleoptera: Curculionidae) in the Intermountain West

Journal of Entomological Science ◽

10.18474/0749-8004-55.3.301 ◽

2020 ◽

Vol 55 (3) ◽

pp. 301-309

Author(s):

Christopher J. Fettig ◽

A. Steven Munson ◽

Donald M. Grosman ◽

Darren C. Blackford

Keyword(s):

Bark Beetles ◽

Tree Mortality ◽

Crop Protection ◽

Tree Age ◽

Picea Engelmannii ◽

Future Research ◽

Emamectin Benzoate ◽

Dendroctonus Rufipennis ◽

Engelmann Spruce ◽

Spruce Beetle

Abstract Bark beetles are important disturbance agents in coniferous forests, and spruce beetle, Dendroctonus rufipennis (Kirby) (Coleoptera: Curculionidae), is one of the more notable species causing landscape-level tree mortality in western North America. We evaluated the efficacy of bole injections of emamectin benzoate (TREE-äge®; Arborjet Inc., Woburn, MA) alone and combined with propiconazole (Alamo®; Syngenta Crop Protection Inc., Wilmington, DE) for protecting Engelmann spruce, Picea engelmannii Parry ex Engelmann (Pinales: Pinaceae), from mortality attributed to colonization by D. rufipennis. Two injection periods in 2013 (the spring and fall of the year prior to trees first being challenged by D. rufipennis in 2014) and distributions of injection points (7.6- and 15.2-cm spacings) were evaluated. Tree mortality was monitored over a 3-yr period (2014–2017). Emamectin benzoate injected in spring at a narrow spacing (7.6 cm) was the only effective treatment. Two (but not three) field seasons of protection can be expected with a single injection of this treatment. We discuss the implications of these and other results regarding the use of emamectin benzoate and propiconazole for protecting western conifers from mortality attributed to bark beetles, and provide suggestions for future research. A table summarizing the appropriate timing of treatments in different bark beetle/host systems is provided.

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Drought-driven disturbance history characterizes a southern Rocky Mountain subalpine forest

Canadian Journal of Forest Research ◽

10.1139/x2012-102 ◽

2012 ◽

Vol 42 (9) ◽

pp. 1649-1660 ◽

Cited By ~ 27

Author(s):

R. Justin DeRose ◽

James N. Long

Keyword(s):

Vegetation Dynamics ◽

Rocky Mountain ◽

Subalpine Forest ◽

Dendroctonus Rufipennis ◽

Southern Rocky Mountains ◽

Engelmann Spruce ◽

Spruce Beetle ◽

Drought Conditions ◽

Recent Outbreak ◽

Species Specific

The view that subalpine forest vegetation dynamics in western North America are “driven” by a particular disturbance type (i.e., fire) has shaped our understanding of their disturbance regimes. In the wake of a recent (1990s) landscape-extent spruce beetle ( Dendroctonus rufipennis Kirby) outbreak in the southern Rocky Mountains, we re-examined the temporal continuity in disturbance types and interactions and the possible role of drought on their occurrence by reconstructing antecedent disturbances for 11 sites across the Markagunt Plateau, southern Utah, USA. Multiple consistent lines of evidence suggested that historic fires were the primary antecedent disturbance, while relatively minor, stand-specific spruce beetle activity occurred later in stand development but prior to the recent outbreak. Unlike the recent outbreak, antecedent fires were spatially and temporally asynchronous over the period examined (~1600–2000). Reconstructed fire events primarily occurred during periods of prolonged drought. Similarly, historic spruce beetle activity, indicated by species-specific tree-ring release, and timing of Engelmann spruce ( Picea engelmannii Parry ex Engelm.) death dates from the recent outbreak were related to drought conditions. Vegetation dynamics on this landscape were strongly driven by historic fires and the recent spruce beetle outbreak, and drought conditions likely influenced the occurrence of both disturbance types.

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Late summer temperature variability for the Southern Rocky Mountains (USA) since 1735 CE: applying blue light intensity to low-latitude Picea engelmannii Parry ex Engelm

Climatic Change ◽

10.1007/s10584-020-02772-9 ◽

2020 ◽

Vol 162 (2) ◽

pp. 965-988

Author(s):

Karen J. Heeter ◽

Grant L. Harley ◽

Justin T. Maxwell ◽

James H. McGee ◽

Trevis J. Matheus

Keyword(s):

Light Intensity ◽

Blue Light ◽

Rocky Mountains ◽

Late Summer ◽

Summer Temperature ◽

Temperature Variability ◽

Picea Engelmannii ◽

Low Latitude ◽

Southern Rocky Mountains

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The effect of fires on susceptibility of subalpine forests to a 19th century spruce beetle outbreak in western Colorado

Canadian Journal of Forest Research ◽

10.1139/x06-182 ◽

2006 ◽

Vol 36 (11) ◽

pp. 2974-2982 ◽

Cited By ~ 27

Author(s):

Dominik Kulakowski ◽

Thomas T Veblen

Keyword(s):

19Th Century ◽

Fire History ◽

Abies Lasiocarpa ◽

Subalpine Forests ◽

Dendroctonus Rufipennis ◽

The Past ◽

Engelmann Spruce ◽

Spruce Beetle ◽

History Of ◽

Colorado Rocky Mountains

In the subalpine forests of the Colorado Rocky Mountains, research on disturbances that have occurred over the past several decades has shown that prior occurrence of disturbances can alter the extent and severity of subsequent disturbances. In the current study, we consider how fire history affected stand susceptibility to a mid-19th century spruce beetle (Dendroctonus rufipennis Kirby 1837) outbreak. Twenty-one sites were randomly located in an Engelmann spruce – subalpine fir (Picea engelmannii Parry ex Engelm. – Abies lasiocarpa (Hook.) Nutt.) forest across ~2000 km2 of the Grand Mesa area, Colorado. At each site, dendrochronological methods were used to reconstruct the history of severe fires and beetle outbreak. Stand-origin dates were estimated by collecting increment cores from 20–27 of the largest trees at each sample site. The beetle outbreak was reconstructed based on coincident releases among nonhost trees that survived the outbreak. Forest stands originated following severe fires in ca. 1790, ca. 1740, and ca. 1700. The 1840's outbreak affected 67% of these stands. Stands that initiated following the ca. 1790 fire were less susceptible to the outbreak than older stands. These findings indicate that stand-replacing fires have mitigated susceptibility to outbreaks of spruce beetles not only during recent outbreaks, but also over the past centuries.

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Taxonomy and origin of present-day morphometric variation in Picea glauca (×engelmannii) seed-cone scales in North America

Canadian Journal of Botany ◽

10.1139/b06-071 ◽

2006 ◽

Vol 84 (7) ◽

pp. 1129-1141 ◽

Cited By ~ 15

Author(s):

W.L Strong ◽

L.V. Hills

Keyword(s):

Rocky Mountains ◽

Picea Glauca ◽

White Spruce ◽

Black Hills ◽

Picea Engelmannii ◽

Morphometric Variation ◽

Engelmann Spruce ◽

Seed Cone ◽

Northern United States ◽

Cone Scale

White spruce ( Picea glauca (Moench) Voss) and Engelmann spruce ( Picea engelmannii Parry ex Engelm.) seed-cones from 676 sites in Canada and the northern United States were analyzed to determine the degree and spatial extent of interspecific hybridization. Fifteen cone-scale variables were analyzed, with percent free-scale and scale shape considered best for differentiating these taxa. The results show that putative Engelmann spruce and their hybrids occur mostly in the vicinity of the Rocky Mountains. Putative white spruce occurs across Canada east of the Rocky Mountains, whereas white × Engelmann hybrids occur eastward to Manitoba and northward to 68° latitude in northwest Canada. To explain the occurrence of the latter taxon hundreds of kilometres from an Engelmann spruce pollen source, it is hypothesized that palaeohybridization occurred during the Wisconsinan glacial period, probably in the southern Montana – Wyoming – Black Hills (South Dakota) region, with the resulting hybrids spreading north and northeastward into interior Canada following the retreat of the Laurentide glacier. White and Engelmann spruce have morphologically distinct cone-scales, whereas their hybrids have intermediate characteristics. An emended species ( Picea albertiana ) and two subspecies (P. albertiana subsp. albertiana and P. albertiana subsp. ogilviei) are proposed to account for morphological intermediates between the parent species.

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

Journal of Economic Entomology ◽

10.1093/jee/tox208 ◽

2017 ◽

Vol 110 (5) ◽

pp. 2140-2148 ◽

Cited By ~ 4

Author(s):

E Matthew Hansen ◽

A Steven Munson ◽

Darren C Blackford ◽

Andrew D Graves ◽

Tom W Coleman ◽

...

Keyword(s):

Rocky Mountains ◽

Individual Tree ◽

Southern Rocky Mountains ◽

Tree Protection ◽

Spruce Beetle

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Suppression of Spruce Beetle Attacks by MCH Released from Bubble Caps

Western Journal of Applied Forestry ◽

10.1093/wjaf/4.2.49 ◽

1989 ◽

Vol 4 (2) ◽

pp. 49-52 ◽

Cited By ~ 12

Author(s):

B. Staffan Lindgren ◽

Mark D. McGregor ◽

Robert D. Oakes ◽

Hubert E. Meyer

Keyword(s):

Early Stage ◽

Mass Trapping ◽

Brood Production ◽

Dendroctonus Rufipennis ◽

Suppression Effect ◽

Engelmann Spruce ◽

Stage Of Development ◽

Baited Traps ◽

Spruce Beetle ◽

Release Devices

Abstract The attack density of the spruce beetle, Dendroctonus rufipennis (Kirby), was reduced to 10-25% of that on untreated felled Engelmann spruce (Picea engelmannii) trees, when the trees were treated with 9-15 bubble cap release devices, each releasing the aggregation inhibitor MCH at 1-3 mg/24 h at 20°C. In the first experiment, deterioration of many release devices reduced the suppression effect. In the second experiment, MCH reduced attacks by 85%, and total brood production by 79-88%. The attacks on the MCH treated trees occurred late, as evidenced by the early stage of development of galleries and brood on these trees. Semiochemical-baited traps at untreated, or MCH-treated, felled trees caught few beetles, and had no effect on the attack density. The results show that manually applied MCH can be used operationally to reduce attacks by the spruce beetle on small groups of wind thrown trees. Mass trapping of spruce beetles is not feasible with currently known semiochemicals. West. J. Appl. For. 4(2):49-52, April 1989.

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Improved Identification and New Records of Dendroctonus Bark Beetles Attacking Pinus contorta in the Subalpine Forest of the Southern Rocky Mountains

Forests ◽

10.3390/f11060656 ◽

2020 ◽

Vol 11 (6) ◽

pp. 656

Author(s):

Javier E. Mercado

Keyword(s):

Rocky Mountains ◽

Bark Beetles ◽

Pinus Contorta ◽

Subalpine Forest ◽

Attack Behavior ◽

Dendroctonus Rufipennis ◽

Southern Rocky Mountains ◽

Attack Pattern ◽

Detection And Identification ◽

The Impact

Research Highlights: Atypical and poorly understood attacks by Dendroctonus rufipennis (Kirby) to Pinus contorta Doug. ex Loudon were detected in the southern Rocky Mountains (SRM). The phenomenon is confirmed across all examined area. Its reproduction is described for the first time as well as the first attacks of D. adjunctus Blandf. in that host. Improved detection and diagnostics of D. rufipennis will allow a simpler, and efficient identification of the species. It will improve the detection capacity by pest detection specialists and entomologists, which will increase our understanding of the phenomena within and beyond the known range. Background and Objectives: In addition to D. ponderosae Hopk. other Dendroctonus species, sometimes together, attacked P. contorta that grew intermixed with Picea engelmannii in the SRM’ subalpine forest. The identification of these beetles was difficult. The goal was to improve the detection and identification of the species from similar Dendroctonus spp. attacking that host and to uncover biological facts about the phenomena. Materials and Methods: Dendroctonus attacking P. contorta were collected along the entire SRM, their attack signs and behavior were recorded. These characteristics were revised from those in the literature and new characters were introduced and tested. Results: The identification of Dendroctonus bark beetles attacking P. contorta in the SRM was improved using revised and new characters including attack signs, attack behavior, and adult beetle characters. An improved identification key couplet is presented to effectively distinguish D. murrayanae from D. rufipennis. Conclusions: Simplified insect identifications that are both accessible to users with different levels of expertise and are based on insect characters, their attack pattern, and signs, like the present, improve detection of insects of interest. Efficient insect detections allow a better understanding of the capabilities they have and the impact they cause to the woodland ecosystems we study, protect, and manage around the globe.

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