Search Results (7)

Windthrow and other calamities pose major challenges for forestry companies. In addition to difficult processing, solutions for the medium- and long-term storage of logs without the loss of quality are required in order to counteract the oversupply and falling prices of raw wood. The application of foil piles is a comparatively young and only regionally established procedure, which is of particular interest when wet storage is not possible. As part of a case study, a total of 32 piles of Norway spruce (Picea abies) wood were monitored under foil in the forest district of Dassel (Lower Saxony State Forests, Germany), and the conditions for wood-destroying fungi and the resulting wood quality were evaluated. A considerable depreciation in the stored wood was directly related to the atmosphere inside the pile and could be attributed to various types of damage to the foil. It became evident that quality losses can only be avoided by working quickly, being careful when sealing the piles and providing intensive support in the form of monitoring and rapid repairs. Full article

Norway spruce, economically and ecologically one of the most important European forest tree species, rapidly declines due to massive bark beetle outbreaks across many countries. As a prerequisite of ecosystem stability facing climate changes of uncertain predictions, the reforestation management promoting locally adapted resources of broad genetic diversity should be prioritized, especially in nature conservation areas. In our case study carried out in the national park, Krkonoše Mountains (the Giant Mountains, the Czech Republic), we demonstrated a tree breeding strategy aiming at maximizing genetic diversity. More than four hundred unique Norway spruce accessions were genotyped on 15 microsatellite loci (N_e = 5.764, I = 1.713 and H_e = 0.685). Two core collection selection approaches were proposed to establish a new deployment population providing local gene sources of high genetic diversity. Namely, the Core Hunter selection algorithm, with average entry-to-nearest-entry distance (EN) optimization, was applied to identify the most diverse core collection set with the highest genetic diversity parameters obtained for 57 selected individuals (N_e = 6.507, I = 1.807, and H_e = 0.731). The latter core collection method proposed is innovative, based on choosing appropriate genotypes from a clustered heatmap. For simplicity, we demonstrated the principle of selection strategy on a reduced dataset. It is vital to promote panmixia of a newly established production population from a core collection to complete the conservation breeding effort. Thus, we demonstrated the utilization of the Optimum Neighborhood Algorithm (ONA) deployment that outperformed other deployment algorithms, especially in the case of balanced clone representation and uneven shapes of planting plots. We believe that the case study presented can be generalized and considered as a guideline for analogical tree breeding intentions. Full article

Increased frequencies and windspeeds of storms may cause disproportionately high increases in windthrow damage. Storm-felled trees provide a surplus of breeding material for bark beetles, often resulting in calamities in the subsequent years. Thus, the timely removal of fallen trees is regarded as a good management practice that requires strategic planning of salvage harvesting. Precise information on the number of stems and their location and orientation are needed for the efficient planning of strip roads and/or cable yarding lines. An accurate assessment of these data using conventional field-based methods is very difficult and time-consuming; remote sensing techniques may be a cost-efficient alternative. In this research, a methodology for the automatic detection of fallen stems from aerial RGB images is presented. The presented methodology was based on a line segment detection algorithm and proved to be robust regarding image quality. It was shown that the method can detect frequency, position, spatial distribution and orientation of fallen stems with high accuracy, while stem lengths were systematically underestimated. The methodology can be used for the optimized planning of salvage harvesting in the future and may thus help to reduce consequential bark beetle calamities after storm events. Full article

Many forms of polygyny are observed across different animal groups. In some species, groups of females may remain with a single male for breeding, often referred to as “harem polygyny”. The environment and the amount of habitat available for feeding, mating and oviposition may have an effect on the formation of harems. We aimed to determine how the surrounding environment (a harvested or unharvested pine plantation) and availability of local substrate affect the harems of the bark beetle, Ips grandicollis (Coleoptera: Curculionidae: Scolytinae). In a harvested pine plantation with large amounts of available habitat, the population density of these beetles is much higher than in unharvested plantations. We found the number of females per male to be significantly greater in the harvested plantation than the unharvested one. Additionally, the amount of substrate available in the immediate local vicinity (the number of logs in replicate piles) also influences the number of beetles attracted to a log and size of individual harems. We also examined how females were distributing themselves in their galleries around the males’ nuptial chamber, as previous work has demonstrated the potential for competition between neighbouring females and their offspring. Females do not perform clumping, suggesting some avoidance when females make their galleries, but they also do not distribute themselves evenly. Female distribution around the male’s nuptial chamber appears to be random, and not influenced by other females or external conditions. Full article

Dendroctonus-bark beetles are natural agents contributing to vital processes in coniferous forests, such as regeneration, succession, and material recycling, as they colonize and kill damaged, stressed, or old pine trees. These beetles spend most of their life cycle under stem and roots bark where they breed, develop, and feed on phloem. This tissue is rich in essential nutrients and complex molecules such as starch, cellulose, hemicellulose, and lignin, which apparently are not available for these beetles. We evaluated the digestive capacity of Dendroctonus rhizophagus to hydrolyze starch. Our aim was to identify α-amylases and characterize them both molecularly and biochemically. The findings showed that D. rhizophagus has an α-amylase gene (AmyDr) with a single isoform, and ORF of 1452 bp encoding a 483-amino acid protein (53.15 kDa) with a predicted signal peptide of 16 amino acids. AmyDr has a mutation in the chlorine-binding site, present in other phytophagous insects and in a marine bacterium. Docking analysis showed that AmyDr presents a higher binding affinity to amylopectin compared to amylose, and an affinity binding equally stable to calcium, chlorine, and nitrate ions. AmyDr native protein showed amylolytic activity in the head-pronotum and gut, and its recombinant protein, a polypeptide of ~53 kDa, showed conformational stability, and its activity is maintained both in the presence and absence of chlorine and nitrate ions. The AmyDr gene showed a differential expression significantly higher in the gut than the head-pronotum, indicating that starch hydrolysis occurs mainly in the midgut. An overview of the AmyDr gene expression suggests that the amylolytic activity is regulated through the developmental stages of this bark beetle and associated with starch availability in the host tree. Full article

The rate of establishment of non-native bark beetle species is accelerating in many parts of the world and is considered a serious threat to forests and forest crops. Distributional data for exotic bark beetles are urgently needed, but they must be based on sound taxonomy. Using primary literature and original records, I review for the first time the invasive bark beetle (Scolytinae) species in Chile and Argentina, and I give a short risk assessment for each. I also provide the best sources for identifying these species. The invasive pine bark beetle commonly referred to in Chilean research as Orthotomicus erosus (Wollaston) is not that species: evidence suggests that the only Orthotomicus that is or has been in Chile is O. laricis (Fabricius), which is also the Orthotomicus species reported in the most recent research from Argentina. I add new information on the distributions of two other abundant pine-breeding invasive species, Hylurgus ligniperda (F.) and Hylastes ater (Paykull), and I report that populations of Hylastes linearis Erichson have been found in Chile. This is the first known occurrence of the species in South America. Phloeotribus willei Schedl, a tiny bark beetle collected from domestic fig trees in Chile and Peru, has been considered native heretofore. I argue that it must be an introduced Neotropical species, and I present new localities for Chile. I present the first Chilean records of the Myrtaceae specialist ambrosia beetle Amasa truncata (Erichson), an Australian species recently found in southern Brazil and northeastern Uruguay, and new Argentinian records that seem to be the earliest finds of Xylosandrus crassiusculus (Motschulsky) in South America. The Canary Island palm seed specialist Dactylotrypes longicollis (Wollaston) is reported for the first time from South America, from Chile. The presence in Chile of another spermatophage, Coccotrypes dactyliperda (F.), is confirmed. New Chilean regions and new host records are given for Pagiocerus frontalis (F.), a species that breeds in Lauraceae seeds but also in stored maize. Other exotic species treated briefly include Hylastinus obscurus (Marsham), Hylesinus taranio (Danthione), Scolytus multistriatus (Marsham), S. rugulosus (Müller), Coccotrypes cyperi (Beeson), and Xyleborinus saxeseni (Ratzeburg). Finally, reports of several species from Chile or Argentina are considered unsupported by evidence: Scolytus kirschii Skalitzky, Pityokteines curvidens (Germar), Coccotrypes robustus Eichhoff, and Hypothenemus hampei (Ferrari).
La velocidad de establecimiento de especies de coleópteros descortezadores no nativos se está acelerando en muchas partes del mundo y se considera una amenaza seria a bosques y cultivos forestales. Se requiere datos distribucionales urgentemente, pero estos tienen que basarse en taxonomía sólida. Utilizando literatura primaria y registros originales, reviso por primera vez la fauna invasora de especies de descortezadores (Scolytinae) en Chile y Argentina, y ofrezco una evaluación breve del riesgo de cada una. También proporciono los mejores referencias para identificar estas especies. La especie descortezador invasora de pinos comunmente citado en investigaciones chilenas como Orthotomicus erosus (Wollaston) no es esa: la evidencia sugiere que la única especie de Orthotomicus actualmente o históricamente presente en Chile es O. laricis (Fabricius), la cual es la especie de Orthotomicus reportado en las investigaciones mas recientes de Argentina. Agrego información nueva sobre las distribuciones de otros dos especies abundantes invasoras que se reproducen en pinos, Hylurgus ligniperda (F.) y Hylastes ater (Paykull) y comunico que poblaciones de Hylastes linearis Erichson se han encontrado en Chile, siendo esta el primer hallazgo de la especie en Sudamérica. Phloeotribus willei Schedl, una especie minúscula colectado de higueras cultivadas en Chile y Peru, se ha considerado nativa hasta ahora: presento argumentos que debe de ser una especie neotropical introducida y presento nuevas localidades para Chile. Presento los primeros registros chilenos de Amasa truncata (Erichson) coleóptero ambrosial, especialista en Myrtaceae, especie australiana recientemente encontrada en el sur de Brasil y nordeste de Uruguay, y nuevos registros argentinos que parecen ser los primeros hallazgos de Xylosandrus crassiusculus (Motschulsky) en Sudamérica. Se registra la especialista en semillas de palma, Dactylotrypes longicollis (Wollaston), originario de las Islas Canárias pro primera vez de Sudamérica; se confirma la presencia en Chile de otra espermatófago, Coccotrypes dactyliperda (F.). Se presentan nuevos registros regionales de Chile y de hospederas por Pagiocerus frontalis (F.), especie que se reproduce en semillas de Lauraceae pero también en maíz almacenado. Otras especies exóticas tratadas brevemente incluyen Hylastinus obscurus (Marsham), Hylesinus taranio (Danthione), Scolytus multistriatus (Marsham), S. rugulosus (Müller), Coccotrypes cyperi (Beeson), y Xyleborinus saxeseni (Ratzeburg). Finalmente, registros de varias especies de Chile o de Argentina se consideran sin apoyo de evidencia: Scolytus kirschii Skalitzky, Pityokteines curvidens (Germar), Coccotrypes robustus Eichhoff, y Hypothenemus hampei (Ferrari). Full article

Since its first identification in Poland in 2006, the ascomycete Hymenoscyphus fraxineus has caused massive dieback of Fraxinus excelsior in the countries of eastern, northern and central Europe. This work shows the development, expansion, and severity of the disease in south-eastern Germany for a period of four years, starting in 2010. Differences between habitats, as well as age classes have been captured. The presence and the amount of potentially resistant trees were proven over the years, to determine how high the resistance level might be. Typical disease symptoms are the wilting of leaves, necrotic lesions in the bark and reddish discolorations of branches and stems. In addition, stem necroses also appear by infection with species of Armillaria. Therefore, special attention has been given to Armillaria species in affected ash stands but also to other secondary pathogens, like ash bark beetles. It is shown that breeding galleries of Hylesinus fraxini are only found in trees that have recently died and thus Hylesinus fraxini is still acting as a secondary opportunistic pathogen. In contrast, Armillaria spp. can be considered as serious pathogens of weakened ash trees. In different ash stands, typical symptoms of infection can be found. A relationship between stem base necrotic lesions and vitality was examined. It is shown that necrotic lesions severely contribute to accelerating the mortality of ash trees. In addition to the high infection pressure by H. fraxineus, the high inoculum of Armillaria in the soil facilitates further infections and, thus, likewise endangers the survival of potentially resistant trees. In the following years, forest conversion and seed harvest in affected ash stands will have to be urgently considered to avoid tree gaps on a large scale. Furthermore, infection assays of potentially resistant trees with ensuing breeding programmes should be initially started for the conservation of this ecologically and economically important tree species. Full article