scholarly journals Drivers of Spruce Bark Beetle (Ips typographus) Infestations on Downed Trees after Severe Windthrow

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1290
Author(s):  
Branislav Hroššo ◽  
Pavel Mezei ◽  
Mária Potterf ◽  
Andrej Majdák ◽  
Miroslav Blaženec ◽  
...  

Research Highlights: Bark beetles are important agents of disturbance regimes in temperate forests, and specifically in a connected wind-bark beetle disturbance system. Large-scale windthrows trigger population growth of the European spruce bark beetle (Ips typographus L.) from endemic to epidemic levels, thereby allowing the killing of Norway spruce trees over several consecutive years. Background and Objectives: There is a lack of evidence to differentiate how outbreaks are promoted by the effects of environmental variables versus beetle preferences of trees from endemic to outbreak. However, little is known about how individual downed-tree characteristics and local conditions such as tree orientation and solar radiation affect beetle colonization of downed trees. Materials and Methods: To answer this question, we investigated the infestation rates and determined tree death categories (uprooted, broken, and stump) in wind-damaged areas in Western Tatra Mts. in Carpathians (Slovakia) from 2014–2016, following a windthrow in May 2014. In total, we investigated 225 trees over eight transects. For every tree, we measured its morphological (tree height, crown characteristics), environmental (solar radiation, terrain conditions, trunk zenith), temporal (time since wind damage), and beetle infestation (presence, location of attack, bark desiccation) parameters. We applied Generalized Additive Mixed Models (GAMM) to unravel the main drivers of I. typographus infestations. Results: Over the first year, beetles preferred to attack broken trees and sun-exposed trunk sides over uprooted trees; the infestation on shaded sides started in the second year along with the infestation of uprooted trees with lower desiccation rates. We found that time since wind damage, stem length, and incident solar radiation increased the probability of beetle infestation, although both solar radiation and trunk zenith exhibited nonlinear variability. Our novel variable trunk zenith appeared to be an important predictor of bark beetle infestation probability. We conclude that trunk zenith as a simple measure defining the position of downed trees over the terrain can anticipate beetle infestation. Conclusions: Our findings contribute to understanding of the bark beetle’s preferences to colonize windthrown trees in the initial years after the primary wind damage. Further, our findings can help to identify trees that are most susceptible to beetle infestation and to prioritize management actions to control beetle population while maintaining biodiversity.

2021 ◽  
Author(s):  
Daniel Powell ◽  
Ewald Grosse-Wilde ◽  
Paal Krokene ◽  
Amit Roy ◽  
Amrita Chakraborty ◽  
...  

Abstract Conifer-feeding bark beetles are important herbivores and decomposers in forest ecosystems. These species have evolved specializations to complete their life cycle in nutritionally poor wooden substrates and some can overwhelm tree defences and kill enormous numbers of trees during population outbreaks. The Eurasian spruce bark beetle (Ips typographus) is one tree-killing species; during a recent epidemic it destroyed >100 million m3 of spruce in a single year. We report a 236 Mb, highly contiguous I. typographus genome assembly using PacBio long-read sequencing. The final phased assembly had a contig N50 of 6.65 Mb in 272 contigs and was predicted to contain 23,923 protein-coding genes. Comparative genomic analysis including 11 additional coleopterans revealed expanded gene families associated with plant cell wall degradation, including pectinases, aspartyl proteases, and glycosyl hydrolases. This first whole-genome sequence from the genus Ips provides timely resources to address important questions about the evolutionary biology of the true weevils (Curculionidae), one of the most species-rich animal families. This resource will also allow for improved studies of functional genomics of both fundamental and applied value. In forests of today, increasingly stressed by global warming, this draft genome may ultimately assist in developing novel pest control strategies to mitigate outbreaks.


2003 ◽  
Vol 154 (11) ◽  
pp. 437-441 ◽  
Author(s):  
Franz Meier ◽  
Rolf Gall ◽  
Beat Forster

In the past 20 years, several mass attacks by the eight-toothed spruce bark beetle (Ips typographus L.) occurred in Switzerland. Since 1984 data on compulsory fellings, numbers of infestation spots and numbers of beetles captured in pheromone traps have been collected in all Swiss forest districts. The annual data were published in short reports. This paper gives an overview of the progress of bark beetle epidemics from 1984 to 1999. On the national level, two periods with epidemics of the spruce bark beetle can be distinguished. The first epidemic started after windthrows and drought in the years 1982 and 1983. It reached its height in 1984/1985 and faded at the end of the decade. The second epidemic started after the storm Vivian (February 1990). It reached its height in 1992/1993 and ended in 1997. Storm damage that produced high quantities of suitable breeding material was not the only factor for the bark beetle gradation;weather conditions were also exceptional, such as hot and dry vegetation periods. Windthrows and exceptional weather conditions are mostly events on regional scales and do not affect the whole country with the same intensity. The gradation that appears to be an «epidemic of the spruce bark beetle in Switzerland after the storm Vivian» is in truth the accumulation of several local epidemics. This is shown by the number of compulsory fellings and infestation spots analysed at regional levels. Extreme weather conditions and storms not only directly influence the bark beetle population, they also stress standing trees, thus creating suitable breeding material for bark beetles. To analyse the influence of exceptional weather conditions on bark beetle epidemics,it is therefore necessary to evaluate regional data.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Daniel Powell ◽  
Ewald Groβe-Wilde ◽  
Paal Krokene ◽  
Amit Roy ◽  
Amrita Chakraborty ◽  
...  

AbstractConifer-feeding bark beetles are important herbivores and decomposers in forest ecosystems. These species complete their life cycle in nutritionally poor substrates and some can kill enormous numbers of trees during population outbreaks. The Eurasian spruce bark beetle (Ips typographus) can destroy >100 million m3 of spruce in a single year. We report a 236.8 Mb I. typographus genome assembly using PacBio long-read sequencing. The final phased assembly has a contig N50 of 6.65 Mb in 272 contigs and is predicted to contain 23,923 protein-coding genes. We reveal expanded gene families associated with plant cell wall degradation, including pectinases, aspartyl proteases, and glycosyl hydrolases. This genome sequence from the genus Ips provides timely resources to address questions about the evolutionary biology of the true weevils (Curculionidae), one of the most species-rich animal families. In forests of today, increasingly stressed by global warming, this draft genome may assist in developing pest control strategies to mitigate outbreaks.


2021 ◽  
Author(s):  
Erica Jaakkola ◽  
Anna Maria Jönsson ◽  
Per-Ola Olsson ◽  
Maj-Lena Linderson ◽  
Thomas Holst

<p>Tree killing by spruce bark beetles (<em>Ips typographus</em>) is one of the main disturbances to Norway spruce (<em>Picea abies</em>) forests in Europe and the risk of outbreaks is amplified by climate change with effects such as increased risk of storm felling, tree drought stress and an additional generation of spruce bark beetles per year<sup>[1]</sup>. The warm and dry summer of 2018 triggered large outbreaks in Sweden, the increased outbreaks are still ongoing and affected about 8 million m<sup>3</sup> forest in 2020<sup>[2]</sup>. This is the so far highest record of trees killed by the spruce bark beetle in a single year in Sweden<sup>[2]</sup>. In 1990-2010, the spruce bark beetle killed on average 150 000 m<sup>3</sup> forest per year in southern Sweden<sup>[3]</sup>. Bark beetles normally seek and attack Norway spruces with lowered defense, i.e. trees that are wind-felled or experience prolonged drought stress<sup>[4]</sup>. However, as the number of bark beetle outbreaks increase, the risk of attacks on healthy trees also increase<sup>[5]</sup>. This causes a higher threat to forest industry, and lowers the possibilities to mitigate climate change in terms of potential decreases in carbon uptake if the forests die<sup>[4,5]</sup>. Norway spruce trees normally defend themselves by drenching the beetles in resin<sup>[6]</sup>. The resin in turn contains different biogenic volatile organic compounds (BVOCs), which can vary if the spruce is attacked by bark beetles or not<sup> [4,6]</sup>. The most abundant group of terpenoids (isoprene, monoterpenes and sesquiterpenes), is most commonly emitted from conifers, such as Norway spruce<sup>[7,8]</sup>. The aim of this study was to enable a better understanding of the direct defense mechanisms of spruce trees by quantifying BVOC emissions and its composition from individual trees under attack</p><p>To analyze the bark beetles’ impact on Norway spruce trees a method was developed using tree trunk chambers and adsorbent tubes. This enables direct measurements of the production of BVOCs from individual trees. Three different sites in Sweden, with different environmental conditions were used for the study and samples were collected throughout the growing season of 2019. After sampling, the tubes were analyzed in a lab using automated thermal desorption coupled to a gas chromatograph and a mass spectrometer to identify BVOC species and their quantity.</p><p>The preliminary results show a strong increase in BVOC emissions from a healthy tree that became infested during the data collection. The finalized results expect to enable better understanding of how spruce trees are affected by insect stress from bark beetles, and if bark beetle infestation will potentially result in increased carbon emission in the form of BVOCs.</p><p><strong>References</strong></p><p>[1] Jönsson et al. (2012). Agricultural and Forest Meteorology 166: 188–200<br>[2] Skogsstyrelsen, (2020). https://via.tt.se/pressmeddelande/miljontals-granar-dodades-av-granbarkborren-2020?publisherId=415163&releaseId=3288473<br>[3] Marini et al. (2017). Ecography, 40(12), 1426–1435.<br>[4] Raffa (1991). Photochemical induction by herbivores. pp. 245-276<strong><br></strong>[5] Seidl, et al. (2014). Nature Climate Change, 4(9), 806-810. <br>[6] Ghimire, et al. (2016). Atmospheric Environment, 126, 145-152.<br>[7] Niinemets, U. and Monson, R. (2013). ISBN 978-94-007-6606-8<br>[8] Kesselmeier, J. and Staudt, M. (1999). Journal of Atmospheric Chemistry, 33(1), pp.23-88</p>


Author(s):  
Peter H. W. Biedermann ◽  
Jean-Claude Grégoire ◽  
Axel Gruppe ◽  
Jonas Hagge ◽  
Almuth Hammerbacher ◽  
...  

Tree-killing bark beetles are the most economically important insects in conifer forests worldwide. Yet  despite >200 years of research, the drivers of population eruptions or crashes are still not fully understood, precluding reliable predictions of the effects of global change on beetle population dynamics and impacts on ecosystems and humans.  We critically analyze potential biotic and abiotic drivers of population dynamics of the European spruce bark beetle (Ips typographus) and present a novel ecological framework that integrates the multiple drivers governing this bark beetle system. We call for large-scale collaborative research efforts to improve our understanding of the population dynamics of this important pest; an approach that might serve as a blueprint for other eruptive forest insects.


1992 ◽  
Vol 124 (1) ◽  
pp. 1-5 ◽  
Author(s):  
W.W. Bowers ◽  
J.H. Borden

AbstractThe cylindrical bark beetle, Lasconotus intricatus Kraus., is attracted to multiple-funnel traps baited either with black spruce logs infested with male four-eyed spruce bark beetles, Polygraphus rufipennis (Kirby), or the male-produced aggregation pheromone, 3-methyl-3-buten-1-ol. The addition of the host terpenes, bornyl acetate and β-pinene, to 3-methyl-3-buten-1-ol reduced the attraction of L. intricatus. 3-Carene, myrcene, and α-pinene appeared to have a partial inhibitory effect. Catches in spring and summer disclosed a high degree of temporal coincidence between the two species. We hypothesize that L. intricatus utilizes the aggregation pheromone of P. rufipennis as a host-finding kairomone.


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