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As walnut trees (Juglans spp.) are of high economic importance, considerable attention has been given to invasive pests of these trees in Europe. In 2016, Dryocoetes himalayensis Strohmeyer, 1908, an alien bark beetle originating from the Himalayas region of India, already present in several European countries, was confirmed to have attacked walnut trees in the Czech Republic. Within the present study, we (i) surveyed the current distribution of D. himalayensis in the Czech Republic, (ii) examined D. himalayensis phenology by rearing it in trap logs, and (iii) investigated tree level habitat preferences of the species in two study stands with 180 black walnut (Juglans nigra L.) trees and 66 common walnut (Juglans regia L.) trees sampled. The present study documented the species to be relatively widespread in some warmer lowland regions of the Czech Republic (42 localities found) and to reach high abundance locally. Almost 15 thousand D. himalayensis individuals reared from the trap logs showed the species emerging throughout the whole vegetation period with a distinctive peak in June. Even though the species is able to develop in thin stems (diameter <5 cm), it is most numerous in thicker trunk bases and also preferably attacks trees of higher diameters. The species preferred common walnut trees (its native host) with decreased vitality. In contrast, black walnut trees (North American species) were attacked regardless of their vitality, but the vitality of occupied trees successively decreased. Based on our results, D. himalayensis should be assumed as a considerable pest of walnut trees (particularly black walnuts), which might become of significant importance in its European invasive range in the future, and thus substantial attention should be given to it., info:eu-repo/semantics/openAccess

As walnut trees (Juglans spp.) are of high economic importance, considerable attention has been given to invasive pests of these trees in Europe. In 2016, Dryocoetes himalayensis Strohmeyer, 1908, an alien bark beetle originating from the Himalayas region of India, already present in several European countries, was confirmed to have attacked walnut trees in the Czech Republic. Within the present study, we (i) surveyed the current distribution of D. himalayensis in the Czech Republic, (ii) examined D. himalayensis phenology by rearing it in trap logs, and (iii) investigated tree level habitat preferences of the species in two study stands with 180 black walnut (Juglans nigra L.) trees and 66 common walnut (Juglans regia L.) trees sampled. The present study documented the species to be relatively widespread in some warmer lowland regions of the Czech Republic (42 localities found) and to reach high abundance locally. Almost 15 thousand D. himalayensis individuals reared from the trap logs showed the species emerging throughout the whole vegetation period with a distinctive peak in June. Even though the species is able to develop in thin stems (diameter <5 cm), it is most numerous in thicker trunk bases and also preferably attacks trees of higher diameters. The species preferred common walnut trees (its native host) with decreased vitality. In contrast, black walnut trees (North American species) were attacked regardless of their vitality, but the vitality of occupied trees successively decreased. Based on our results, D. himalayensis should be assumed as a considerable pest of walnut trees (particularly black walnuts), which might become of significant importance in its European invasive range in the future, and thus substantial attention should be given to it., info:eu-repo/semantics/openAccess

The spatial distribution of saproxylic beetles landing and climbing stems of 12 grown and healthy Scots pine trees (Pinus sylvestris L.) was examined in detail during a 3-year trial. The beetles were sampled using sticky traps attached to the tree trunk at three tree parts (i.e., the trunk base, middle part of the trunk, and trunk in crown). Each tree part was sampled using two sticky traps facing opposite cardinal directions (north and south). In total, 4063 individuals representing 169 taxa of saproxylic beetles were yielded in the 1405 obtained samples. Remarkable interstrata diversification of saproxylic beetle assemblages reflecting distribution of breeding substrates in the forest stand was observed. Overall, species richness decreased considerably from the trunk base to the crown, with intermediate values for the middle part of the trunk. However, the abundance of mycetophages and saproxylophages decreased from the trunk base to the crown, with xylophages being the most abundant in the tree crown. The cardinal direction exhibited overall weak effects on abundance, species richness, and composition, but the occurrence of a few particular species was significantly associated with the south (13 species) or north (3 species) facing part of the trunk. Our results suggest that primary attraction and random landing strategies are combined during the substrate selection by many species. High variability in the importance of the studied explanatory variables was observed among taxa, which shows how the species composition recorded in any study might alter its general outcomes., info:eu-repo/semantics/openAccess

As walnut trees (Juglans spp.) are of high economic importance, considerable attention has been given to invasive pests of these trees in Europe. In 2016, Dryocoetes himalayensis Strohmeyer, 1908, an alien bark beetle originating from the Himalayas region of India, already present in several European countries, was confirmed to have attacked walnut trees in the Czech Republic. Within the present study, we (i) surveyed the current distribution of D. himalayensis in the Czech Republic, (ii) examined D. himalayensis phenology by rearing it in trap logs, and (iii) investigated tree level habitat preferences of the species in two study stands with 180 black walnut (Juglans nigra L.) trees and 66 common walnut (Juglans regia L.) trees sampled. The present study documented the species to be relatively widespread in some warmer lowland regions of the Czech Republic (42 localities found) and to reach high abundance locally. Almost 15 thousand D. himalayensis individuals reared from the trap logs showed the species emerging throughout the whole vegetation period with a distinctive peak in June. Even though the species is able to develop in thin stems (diameter <5 cm), it is most numerous in thicker trunk bases and also preferably attacks trees of higher diameters. The species preferred common walnut trees (its native host) with decreased vitality. In contrast, black walnut trees (North American species) were attacked regardless of their vitality, but the vitality of occupied trees successively decreased. Based on our results, D. himalayensis should be assumed as a considerable pest of walnut trees (particularly black walnuts), which might become of significant importance in its European invasive range in the future, and thus substantial attention should be given to it., info:eu-repo/semantics/openAccess

The spatial distribution of saproxylic beetles landing and climbing stems of 12 grown and healthy Scots pine trees (Pinus sylvestris L.) was examined in detail during a 3-year trial. The beetles were sampled using sticky traps attached to the tree trunk at three tree parts (i.e., the trunk base, middle part of the trunk, and trunk in crown). Each tree part was sampled using two sticky traps facing opposite cardinal directions (north and south). In total, 4063 individuals representing 169 taxa of saproxylic beetles were yielded in the 1405 obtained samples. Remarkable interstrata diversification of saproxylic beetle assemblages reflecting distribution of breeding substrates in the forest stand was observed. Overall, species richness decreased considerably from the trunk base to the crown, with intermediate values for the middle part of the trunk. However, the abundance of mycetophages and saproxylophages decreased from the trunk base to the crown, with xylophages being the most abundant in the tree crown. The cardinal direction exhibited overall weak effects on abundance, species richness, and composition, but the occurrence of a few particular species was significantly associated with the south (13 species) or north (3 species) facing part of the trunk. Our results suggest that primary attraction and random landing strategies are combined during the substrate selection by many species. High variability in the importance of the studied explanatory variables was observed among taxa, which shows how the species composition recorded in any study might alter its general outcomes., info:eu-repo/semantics/openAccess

The spatial distribution of saproxylic beetles landing and climbing stems of 12 grown and healthy Scots pine trees (Pinus sylvestris L.) was examined in detail during a 3-year trial. The beetles were sampled using sticky traps attached to the tree trunk at three tree parts (i.e., the trunk base, middle part of the trunk, and trunk in crown). Each tree part was sampled using two sticky traps facing opposite cardinal directions (north and south). In total, 4063 individuals representing 169 taxa of saproxylic beetles were yielded in the 1405 obtained samples. Remarkable interstrata diversification of saproxylic beetle assemblages reflecting distribution of breeding substrates in the forest stand was observed. Overall, species richness decreased considerably from the trunk base to the crown, with intermediate values for the middle part of the trunk. However, the abundance of mycetophages and saproxylophages decreased from the trunk base to the crown, with xylophages being the most abundant in the tree crown. The cardinal direction exhibited overall weak effects on abundance, species richness, and composition, but the occurrence of a few particular species was significantly associated with the south (13 species) or north (3 species) facing part of the trunk. Our results suggest that primary attraction and random landing strategies are combined during the substrate selection by many species. High variability in the importance of the studied explanatory variables was observed among taxa, which shows how the species composition recorded in any study might alter its general outcomes.

As walnut trees (Juglans spp.) are of high economic importance, considerable attention has been given to invasive pests of these trees in Europe. In 2016, Dryocoetes himalayensis Strohmeyer, 1908, an alien bark beetle originating from the Himalayas region of India, already present in several European countries, was confirmed to have attacked walnut trees in the Czech Republic. Within the present study, we (i) surveyed the current distribution of D. himalayensis in the Czech Republic, (ii) examined D. himalayensis phenology by rearing it in trap logs, and (iii) investigated tree level habitat preferences of the species in two study stands with 180 black walnut (Juglans nigra L.) trees and 66 common walnut (Juglans regia L.) trees sampled. The present study documented the species to be relatively widespread in some warmer lowland regions of the Czech Republic (42 localities found) and to reach high abundance locally. Almost 15 thousand D. himalayensis individuals reared from the trap logs showed the species emerging throughout the whole vegetation period with a distinctive peak in June. Even though the species is able to develop in thin stems (diameter <5 cm), it is most numerous in thicker trunk bases and also preferably attacks trees of higher diameters. The species preferred common walnut trees (its native host) with decreased vitality. In contrast, black walnut trees (North American species) were attacked regardless of their vitality, but the vitality of occupied trees successively decreased. Based on our results, D. himalayensis should be assumed as a considerable pest of walnut trees (particularly black walnuts), which might become of significant importance in its European invasive range in the future, and thus substantial attention should be given to it.

Two populations of the species Diastolaimus grossus have been obtained from bark of trees in Bosnia and Herzegovina and the Czech Republic. The species is described and characterized in detail using morphological techniques (light and electron scanning microscopy) and morphometrical (Gower General Similarity coefficient of morphological characters) and molecular analyses, including phylogenetic analysis of all related and already sequenced species of the family Chambersiellidae. Morphological and molecular analyses, based on 18S and 28S ribosomal DNA sequences, show that the family Chambersiellidae is polyphyletic, being the subfamily Chambersiellinae related with Cephalobomorpha and Tylenchomorpha, and the subfamily Macrolaiminae is located into Panagrolaimomorpha. The genus Diastolaimus, previously belonging to Macrolaiminae, is transferred to Chambersiellinae. Diastolaimus mexicanus is proposed as a junior synonym of D. grossus., info:eu-repo/semantics/openAccess

Two populations of the species Diastolaimus grossus have been obtained from bark of trees in Bosnia and Herzegovina and the Czech Republic. The species is described and characterized in detail using morphological techniques (light and electron scanning microscopy) and morphometrical (Gower General Similarity coefficient of morphological characters) and molecular analyses, including phylogenetic analysis of all related and already sequenced species of the family Chambersiellidae. Morphological and molecular analyses, based on 18S and 28S ribosomal DNA sequences, show that the family Chambersiellidae is polyphyletic, being the subfamily Chambersiellinae related with Cephalobomorpha and Tylenchomorpha, and the subfamily Macrolaiminae is located into Panagrolaimomorpha. The genus Diastolaimus, previously belonging to Macrolaiminae, is transferred to Chambersiellinae. Diastolaimus mexicanus is proposed as a junior synonym of D. grossus.