Ips confusus

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Claus Tittiger - One of the best experts on this subject based on the ideXlab platform.

  • RNA-Seq used to identify Ipsdienone reductase (IDONER): A novel monoterpene carbon-carbon double bond reductase central to Ips confusus pheromone production
    Insect biochemistry and molecular biology, 2021
    Co-Authors: Katherine E. Fisher, Gary J. Blomquist, Claus Tittiger, Richard L. Tillett, Misha Fotoohi, Cody Caldwell, Juli Petereit, Karen Schlauch, Marina Maclean
    Abstract:

    Abstract The pinyon Ips beetle, Ips confusus (LeConte) is a highly destructive pest in pine forests in western North America. When colonizing a new host tree, I. confusus beetles coordinate a mass attack to overcome the tree's defenses using aggregation pheromones. Ips confusus, as with other Ips spp. beetles, biosynthesize Ipsdienol and Ipsenol in a specific enantiomeric blend and ratio as aggregation pheromones. While several of the initial steps in the pheromone biosynthetic pathway have been well defined, the final steps were unknown. We used comparative RNA-Seq analysis between fed and unfed male I. confusus midgut tissue to identify candidate genes involved in pheromone biosynthesis. The 12,995 potentially unique transcripts showed a clear separation based on feeding state. Differential expression analysis identified gene groups that were tightly connected. This analysis identified all known pheromone biosynthetic genes and suggested a novel monoterpene double bond reductase, Ipsdienone reductase (IDONER), with pheromone biosynthetic gene expression patterns. IDONER cDNA was cloned, expressed, and functionally characterized. The coding DNA sequence has an ORF of 1101 nt with a predicted translation product of 336 amino acids. The enzyme has a molecular weight of 36.7 kDa with conserved motifs of the medium chain dehydrogenases/reductase (MDR) superfamily in the leukotriene B4 dehydrogenases/reductases (LTB4R) family. Tagged recombinant protein was expressed and purified. Enzyme assays and GC/MS analysis showed IDONER catalyzed the reduction of Ipsdienone to form Ipsenone. This study shows that IDONER is a monoterpene double bond reductase involved in I. confusus pheromone biosynthesis.

  • Two Regulatory Mechanisms of Monoterpenoid Pheromone Production in Ips spp. Of Bark Beetles
    Journal of Chemical Ecology, 2009
    Co-Authors: Jeremy C Bearfield, Gary J. Blomquist, Claus Tittiger, Anastasia G. Henry, Matthew D. Ginzel
    Abstract:

    Bark beetles use aggregation pheromones to coordinate host colonization and mating. These monoterpenoid chemical signals are produced de novo in midgut cells via the mevalonate pathway, and pheromone production is induced when an adult beetle feeds on phloem of a host tree. In Ips pini , juvenile hormone (JH) III influences key regulatory enzymes along the mevalonate pathway that leads to pheromone production. In fact, topically applied JH III is sufficient to stimulate pheromone production in unfed males. In this study, we explore the influence of feeding and JH III treatment on pheromone production in male Ips confusus, the pinyon Ips. We also characterize the influence of feeding and JH III treatment on transcript levels and activity of three key enzymes involved in pheromone biosynthesis: 3-hydroxy-3-methylglutaryl-CoA (HMG) synthase (HMGS), HMG-CoA reductase (HMGR) and geranyl diphosphate synthase (GPPS). We also extend the current understanding of the regulation of pheromone biosynthesis in I. pini, by measuring the influence of feeding and JHIII treatment on enzymatic activity of HMGS and GPPS. Feeding on host phloem alone strongly induces pheromone production in male I. confusus , while JH III treatment has no effect. However, feeding and JH III both significantly up-regulate mRNA levels of key mevalonate pathway genes. Feeding up-regulates these genes to a maximum at 32 h, whereas with JH III-treatment, they are up-regulated at 4, 8, and 16 h, but return near to non-treatment levels at 32 h. Feeding, but not JH III treatment, also increases the activity of all three enzymes in I. confusus, while both feeding or treatment with JH III increase HMGS and GPPS activity in I. pini. Our data suggest that pheromone production in Ips is not uniformly controlled by JH III and feeding may stimulate the release of some other regulatory factor, perhaps a brain hormone, required for pheromone production.

  • myrcene hydroxylases do not determine enantiomeric composition of pheromonal Ipsdienol in Ips spp
    Journal of Chemical Ecology, 2008
    Co-Authors: Pamela Sandstrom, Matthew D. Ginzel, Jeremy C Bearfield, William Welch, Gary J. Blomquist, Claus Tittiger
    Abstract:

    Myrcene (7-methyl-3-methylene-1,6-octadiene) hydroxylation is likely one of the final reactions involved in the production of the Ips spp. (Coleoptera: Scolytidae) aggregation pheromone components, Ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol) and Ipsenol (2-methyl-6-methylene-7-octen-4-ol). To gain insight into the evolution of pheromone production, we isolated a full-length cDNA from the pinyon Ips, Ips confusus (LeConte), that encodes a pheromone-biosynthetic cytochrome P450, I. confusus CYP9T1 (IcCYP9T1). The recovered cDNA is 1.70 kb, and the open reading frame encodes a 532 amino acid protein. IcCYP9T1 is 94% identical to the pine engraver, Ips pini (Say), CYP9T2 ortholog that hydroxylates myrcene. Quantitative real-time PCR experiments showed that IcCYP9T1, as does CYP9T2, has an expression pattern similar to other pheromone-biosynthetic genes in I. pini. Basal expression levels were higher in males than females, and expression was significantly induced in male, but not in female, anterior midguts by feeding on host phloem. Microsomes, prepared from Sf9 cells co-expressing baculoviral-mediated recombinant IcCYP9T1 and house fly (Musca domestica) NADPH-cytochrome P450 reductase, converted myrcene to ~85%-(R)-(−)-Ipsdienol. These results are consistent with IcCYP9T1 encoding a myrcene hydroxylase that functions near the end of the pheromone-biosynthetic pathway. Since the I. confusus pheromone blend contains >90%-(S)-(+)-Ipsdienol, these results confirm further that Ips spp. myrcene hydroxylases do not control the final Ipsdienol enantiomeric blend. Other enzymes are required following myrcene hydroxylation to achieve the critical quantity and enantiomeric composition of pheromonal Ipsenol and Ipsdienol used by different Ips spp.

Dave Turner - One of the best experts on this subject based on the ideXlab platform.

  • relationship of stand characteristics to drought induced mortality in three southwestern pinon juniper woodlands
    Ecological Applications, 2009
    Co-Authors: Lisa M Floyd, Michael Clifford, Neil S Cobb, Dustin Hanna, Robert Delph, Paulette L Ford, Dave Turner
    Abstract:

    Extreme drought conditions accompanied by rising temperatures have characterized the American Southwest during the past decade, causing widespread tree mortality in pinon-juniper woodlands. Pinon pine (Pinus edulis Engelm.) mortality is linked primarily to outbreaks of the pinyon Ips (Ips confusus (Leconte)) precipitated by drought conditions. Although we searched extensively, no biotic agent was identified as responsible for death in Juniperus L. spp. in this study; hence this mortality was due to direct drought stress. Here we examine the relationship between tree abundance and patterns of mortality in three size classes (seedling/sapling, pre-reproductive, reproductive) during the recent extended drought in three regions: southwest Colorado, northern New Mexico, and northern Arizona. Pinon mortality varied from 32% to 65%, and juniper mortality from 3% to 10% across the three sites. In all sites, the greatest pinon mortality was in the larger, presumably older, trees. Using logistic regression models, we examined the influence of tree density and basal area on bark beetle infestations (pinon) and direct drought impacts ( juniper). In contrast to research carried out early in the drought cycle by other researchers in Arizona, we did not find evidence for greater mortality of pinon and juniper trees in increasingly high density or basal area conditions. We conclude that the severity of this regional drought has masked density- dependent patterns visible in less severe drought conditions. With climate projections for the American Southwest suggesting increases in aridity and rising temperatures, it is critical that we expand our understanding of stress responses expected in widespread pinon-juniper woodlands.

  • Relationship of stand characteristics to drought-induced mortality in three Southwestern piñon–juniper woodlands
    Ecological applications : a publication of the Ecological Society of America, 2009
    Co-Authors: M. Lisa Floyd, Michael Clifford, Neil S Cobb, Dustin Hanna, Robert Delph, Paulette L Ford, Dave Turner
    Abstract:

    Extreme drought conditions accompanied by rising temperatures have characterized the American Southwest during the past decade, causing widespread tree mortality in pinon-juniper woodlands. Pinon pine (Pinus edulis Engelm.) mortality is linked primarily to outbreaks of the pinyon Ips (Ips confusus (Leconte)) precipitated by drought conditions. Although we searched extensively, no biotic agent was identified as responsible for death in Juniperus L. spp. in this study; hence this mortality was due to direct drought stress. Here we examine the relationship between tree abundance and patterns of mortality in three size classes (seedling/sapling, pre-reproductive, reproductive) during the recent extended drought in three regions: southwest Colorado, northern New Mexico, and northern Arizona. Pinon mortality varied from 32% to 65%, and juniper mortality from 3% to 10% across the three sites. In all sites, the greatest pinon mortality was in the larger, presumably older, trees. Using logistic regression models, we examined the influence of tree density and basal area on bark beetle infestations (pinon) and direct drought impacts ( juniper). In contrast to research carried out early in the drought cycle by other researchers in Arizona, we did not find evidence for greater mortality of pinon and juniper trees in increasingly high density or basal area conditions. We conclude that the severity of this regional drought has masked density- dependent patterns visible in less severe drought conditions. With climate projections for the American Southwest suggesting increases in aridity and rising temperatures, it is critical that we expand our understanding of stress responses expected in widespread pinon-juniper woodlands.

Dustin Hanna - One of the best experts on this subject based on the ideXlab platform.

  • Structural and regenerative changes in old-growth piñon–juniper woodlands following drought-induced mortality
    Forest Ecology and Management, 2015
    Co-Authors: M. Lisa Floyd, Dustin Hanna, William H. Romme, Monique E. Rocca, David D. Hanna
    Abstract:

    Abstract Two decades of drought and rising temperatures have triggered bark beetle outbreaks and extensive mortality of Colorado pinon (Pinus edulis) and Utah juniper (Juniperus osteosperma) across the southwest US. For example from 2002 to 2005, over one-third of the pinons in Mesa Verde National Park’s old-growth woodlands were killed by the bark beetle Ips confusus and other drought-related factors. Extensive wildfires have also burned through the Park over the last two decades, reducing the extent of old-growth woodlands by nearly one-half. We compared historical (1970–1990s) and recent (2005–2011) data to gauge the effects of the 2002–2005 mortality event on canopy structure, woody surface fuels, and tree recruitment. Large, mature pinons were the most susceptible to mortality; we measured significant reductions in pinon cover and diameter. Due to the loss of large trees, woodlands that were subjected to substantial mortality had reduced structural complexity relative to nearby unaffected stands. In a longitudinal fuels comparison, 2010–2011 fuels were compared to historical 1993 values in the same plots; we could not detect a change in woody fuel load. However when the 2010–2011 fuels are compared across mortality severity classes, there was a trend toward slightly greater 1–100 h, greater 1000 h fuel loads, and more litter in stands with higher levels of tree mortality. However, modeled surface fire behavior did not differ across mortality severity classes. Modeled crown fires needed higher wind speeds to spread from tree to tree in stands without tree mortality, but this is likely due to the inherently more open canopy structure in stands that resisted mortality rather than due to tree mortality per se. Post-mortality pinon reproduction and recruitment were recorded from 2005 to 2011 and compared with NPS monitoring data from 1975 to 1995. Cone production in 2005 was comparable to historical trends, but recent seedling and sapling densities were significantly below historical values. Yearly seedling and sapling density in 1975–2011 was positively correlated with precipitation during the sampling year and two years prior. The largest proportion of seedlings and saplings occurred under pinon or juniper canopies, and a smaller proportion under native shrubs. Given the loss of a substantial component of the adult trees, reduced stand structural complexity, and demonstrated need for moist conditions and nurse plants for effective recruitment, these old-growth woodlands may be vulnerable to decline under future warm and dry climate projections. Management strategies focusing on maintaining structural features of both the overstory and understory could help provide conditions for sustainable recruitment and contribute to the goal of conservation of rare old-growth pinon–juniper woodlands.

  • relationship of stand characteristics to drought induced mortality in three southwestern pinon juniper woodlands
    Ecological Applications, 2009
    Co-Authors: Lisa M Floyd, Michael Clifford, Neil S Cobb, Dustin Hanna, Robert Delph, Paulette L Ford, Dave Turner
    Abstract:

    Extreme drought conditions accompanied by rising temperatures have characterized the American Southwest during the past decade, causing widespread tree mortality in pinon-juniper woodlands. Pinon pine (Pinus edulis Engelm.) mortality is linked primarily to outbreaks of the pinyon Ips (Ips confusus (Leconte)) precipitated by drought conditions. Although we searched extensively, no biotic agent was identified as responsible for death in Juniperus L. spp. in this study; hence this mortality was due to direct drought stress. Here we examine the relationship between tree abundance and patterns of mortality in three size classes (seedling/sapling, pre-reproductive, reproductive) during the recent extended drought in three regions: southwest Colorado, northern New Mexico, and northern Arizona. Pinon mortality varied from 32% to 65%, and juniper mortality from 3% to 10% across the three sites. In all sites, the greatest pinon mortality was in the larger, presumably older, trees. Using logistic regression models, we examined the influence of tree density and basal area on bark beetle infestations (pinon) and direct drought impacts ( juniper). In contrast to research carried out early in the drought cycle by other researchers in Arizona, we did not find evidence for greater mortality of pinon and juniper trees in increasingly high density or basal area conditions. We conclude that the severity of this regional drought has masked density- dependent patterns visible in less severe drought conditions. With climate projections for the American Southwest suggesting increases in aridity and rising temperatures, it is critical that we expand our understanding of stress responses expected in widespread pinon-juniper woodlands.

  • Relationship of stand characteristics to drought-induced mortality in three Southwestern piñon–juniper woodlands
    Ecological applications : a publication of the Ecological Society of America, 2009
    Co-Authors: M. Lisa Floyd, Michael Clifford, Neil S Cobb, Dustin Hanna, Robert Delph, Paulette L Ford, Dave Turner
    Abstract:

    Extreme drought conditions accompanied by rising temperatures have characterized the American Southwest during the past decade, causing widespread tree mortality in pinon-juniper woodlands. Pinon pine (Pinus edulis Engelm.) mortality is linked primarily to outbreaks of the pinyon Ips (Ips confusus (Leconte)) precipitated by drought conditions. Although we searched extensively, no biotic agent was identified as responsible for death in Juniperus L. spp. in this study; hence this mortality was due to direct drought stress. Here we examine the relationship between tree abundance and patterns of mortality in three size classes (seedling/sapling, pre-reproductive, reproductive) during the recent extended drought in three regions: southwest Colorado, northern New Mexico, and northern Arizona. Pinon mortality varied from 32% to 65%, and juniper mortality from 3% to 10% across the three sites. In all sites, the greatest pinon mortality was in the larger, presumably older, trees. Using logistic regression models, we examined the influence of tree density and basal area on bark beetle infestations (pinon) and direct drought impacts ( juniper). In contrast to research carried out early in the drought cycle by other researchers in Arizona, we did not find evidence for greater mortality of pinon and juniper trees in increasingly high density or basal area conditions. We conclude that the severity of this regional drought has masked density- dependent patterns visible in less severe drought conditions. With climate projections for the American Southwest suggesting increases in aridity and rising temperatures, it is critical that we expand our understanding of stress responses expected in widespread pinon-juniper woodlands.

T. G. Whitham - One of the best experts on this subject based on the ideXlab platform.

  • Predictors of Ips confusus Outbreaks During a Record Drought in Southwestern USA: Implications for Monitoring and Management
    2013
    Co-Authors: M. J. Santos, T. G. Whitham
    Abstract:

    Abstract In many ecosystems the effects of disturbance can be cryptic and disturbance may vary in subtle spatiotemporal ways. For instance, we know that bark beetle outbreaks are more frequent in temperate forests during droughts; however, we have little idea about why they occur in some locations and not others. Understanding biotic and abiotic factors promoting bark beetle outbreaks can be critical to predicting and responding to pest outbreaks. Here we address the environmental factors which are associated with Ips confusus outbreaks during the 2002 widespread drought within the distribution range of pinyon pine woodlands in Arizona. We used univariate statistics to test if whether tree characteristics, other herbivores, stand properties, soil type, wind, and topography were associated with I. confusus outbreak, and logistic regression to create a predictive model for the outbreaks. We found that I. confusus attacks occur in low elevation stands on steeper slopes, where favorable winds for I. confusus dispersion occur. I. confusus select larger trees, in high density stands with understory shrubs that exhibit phenotypic traits characteristic of resistance to stem-boring moths. The mode

  • Predictors of Ips confusus Outbreaks During a Record Drought in Southwestern USA: Implications for Monitoring and Management
    Environmental Management, 2010
    Co-Authors: M. J. Santos, T. G. Whitham
    Abstract:

    In many ecosystems the effects of disturbance can be cryptic and disturbance may vary in subtle spatiotemporal ways. For instance, we know that bark beetle outbreaks are more frequent in temperate forests during droughts; however, we have little idea about why they occur in some locations and not others. Understanding biotic and abiotic factors promoting bark beetle outbreaks can be critical to predicting and responding to pest outbreaks. Here we address the environmental factors which are associated with Ips confusus outbreaks during the 2002 widespread drought within the distribution range of pinyon pine woodlands in Arizona. We used univariate statistics to test if whether tree characteristics, other herbivores, stand properties, soil type, wind, and topography were associated with I. confusus outbreak, and logistic regression to create a predictive model for the outbreaks. We found that I. confusus attacks occur in low elevation stands on steeper slopes, where favorable winds for I. confusus dispersion occur. I. confusus select larger trees, in high density stands with understory shrubs that exhibit phenotypic traits characteristic of resistance to stem-boring moths. The model was highly accurate, and explained 95% of the variability in occurrence (98% of the absences and 95% of the presences). Accurate prediction of the impacts of disturbance allow us to anticipate, minimize or mitigate for and eventually counteract its effects, especially those affecting diversity and ecosystem function. Identification of outbreak risk areas can guide regional and national management towards the reduction of infestation risk and enhancing conservation of pinyon-juniper woodlands.

Gerald J. Gottfried - One of the best experts on this subject based on the ideXlab platform.

  • Microbial and nitrogen pool response to fuel treatments in Pinyon-Juniper woodlands of the southwestern USA
    Forest Ecology and Management, 2017
    Co-Authors: Steven T. Overby, Gerald J. Gottfried
    Abstract:

    Abstract Wildfire mitigation in Pinyon-Juniper woodlands in the Colorado Plateau region is a management priority. Two wildfire mitigation treatments, mastication and thin-pile-burn, are often chosen based on costs and availability of equipment, yet there are ecological concerns with either treatment. Ecological outcomes from additions of low quality organic residues following mastication can potentially alter microbially mediated soil nitrogen availability, therefore we wished to evaluate the effects of the additions of low quality woody residues to the soil surface compared to thin-pile-burn treatments at three Ips confusus affected woodland sites in the Colorado Plateau region. Thin-pile-burn treatments consisted of thinning between 40% and 60% of the canopy cover, while mastication treatments entailed shredding dead trees and 50% of shrub canopy while retaining live pinyon trees and designated snags. Both fuels treatments achieved wildfire mitigation goals, yet twice as much basal area and three times as much volume were removed by thinning relative to mastication. Surface additions of woody residues favored bacteria, while fungal populations that typically colonize and decompose woody organic residues did not increase in the upper mineral horizon. Neither fuel treatment affected mineral soils at the plot level, but the carbon to nitrogen (C:N) ratio of the organic horizon was significantly greater with mastication compared to the control. Nitrogen availability was reduced by almost half during the non-growing season, yet fuel treatments did not significantly influence nitrogen availability compared to control. Fuel treatment as performed in our study following the large mortality event demonstrated that microbial populations and their effects on nitrogen availability are resistant to disturbances produced by wildfire mitigations treatments.