The teak bee‐hole borer (Xyleutes ceramica (Walker, 1865)) is widespread in northern Thailand and is considered the most serious pest of teak (Tectona grandis) in the country. The present study ...investigated the factors affecting the infestation of teak trees by this species in three plantations in northern Thailand at different spatial scales, including the tree, plot and stand levels. At each plantation, 48 plots evenly distributed in three different young stands (1–10 years), three medium‐aged stands (11–20 years) and six old stands (exceeding 20 years) were sampled. At the plots, the number of current entrance holes of X. ceramica per teak tree was counted, and the characteristics of the trees and stands were assessed. A total of 1952 teak trees were sampled, 22.7% of which were infested by X. ceramica. According to our results, infestation was much more strongly affected by stand characteristics than by the characteristics of individual trees. Above all, understorey cover exhibited substantial effect with the infestation level being strongly limited in stands with dense understories. Additionally, young and medium‐aged stands on better quality sites were found to be the most susceptible to infestation, and well‐growing and/or damaged trees were preferred by the pest species. In conclusion, major recommendations for suppressing damage caused by X. ceramica include (a) promoting and maintaining the understorey above 30% cover, (b) planting mixed stands of commercial forest trees and (c) intensively monitoring the pest in young and medium‐aged stands, especially those growing at good‐ and medium‐quality sites.
Research Highlights: The percentage of canopy closure was found to be the main factor associated with ambrosia beetle abundance and species richness. The latter two variables increased as canopy ...closure increased, probably because a high percentage of canopy closure provides a stable and humid environment suitable for the growth of ambrosia fungi. Objectives: Oak is a common host tree for ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), which have independently evolved a nutritional mutualism with fungi. We suspected that ambrosia beetles might have specific habitat preferences that are different from those of other saproxylic beetles and that reflect the specific habitat preferences of their food, i.e., ambrosia fungi. Methods: We assessed ambrosia beetle abundance with ethanol-lured traps in five old-growth oak dominated forests and five managed oak dominated forests (one trap per forest) during the vegetation period in 2020. We determined whether ambrosia beetle abundance and species richness depend on forest type (managed vs. unmanaged), degree of canopy closure, abundance of oak trees, abundance of coarse deadwood, and abundance of dead oak branches. Results: In total, 4137 individuals of six species of ambrosia beetles associated with oaks were captured. The native ambrosia beetle Anisandrus dispar represented the majority of trapped ambrosia bark beetles. A. dispar along with another ambrosia beetle, Xyleborinus saxesenii, represented 99% of all captured beetles. Conclusions: In addition to canopy closure, the abundance of oak trees and the abundance of dead oak branches were significantly associated with ambrosia beetle abundance and species richness. The abundance of A. dispar was mainly correlated with dead oak branch abundance and the degree of canopy closure, whereas the abundances of X. saxesenii and of the invasive species Xyleborinus attenuatus and Cyclorhipidion bodoanum were mainly correlated with the net area occupied by oak trees.
1 The community composition of early-arriving saproxylic beetles on 80 standing and recently deceased Scots pine trees (Pinus sylvestris L.) was examined. 2 In total, 34 species of saproxylic beetles ...were found, comprising at least four well-defined groups of species identified by correspondence analysis. 3 Bark thickness, trunk/branch diameter and height above ground significantly affected community composition, with bark thickness being the most important factor. 4 Overall, 13.7% of the variance in species composition was explained by section of the tree that was sampled, a variable that encompasses the three aforementioned parameters.
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.
Detailed knowledge of habitat requirements is an essential prerequisite for efficient conservation of any endangered species. Despite the grain support beetle
Aegosoma scabricorne
(Cerambycidae) ...being one of the largest European beetles, and an endangered, disappearing, species in Central Europe, its bionomics remain relatively poorly known.
A. scabricorne
is known as a polyphagous species on broadleaved trees; thus, to investigate its habitat preferences 174 broadleaved trees (87 occupied and 87 unoccupied by the species) were surveyed in the area of southern Moravia (Czech Republic) in 2015. The species was found to be strongly associated with declining or freshly dead trees that are, preferably, further damaged (breakage of stem or primary branch, hollows, etc.) and it particularly thrives on large trees (diameter >50 cm). Surprisingly, stem exposure to the sun was shown to be an unimportant characteristic for this species. However, in this study the number of exit holes was significantly smaller on the shaded north-facing quarter of the stem. Our results suggest concrete conservation measures to support the species. We also suggest that this species may be used as an umbrella species for saproxylic beetles of European lowland forests.
European mountain forests are unique ecosystems, and they harbour specific saproxylic beetle fauna, including relict species such as the longhorn beetle
Ropalopus ungaricus
(Herbst, 1784). This ...endangered species is endemic to European mountain forests and is considered to be monophagous on living sycamore trees (
Acer pseudoplatanus
L.). Insufficient knowledge of the species ecology limits its effective conservation. Hence, to investigate its habitat requirements, 175 sycamore trees (87 occupied and 88 unoccupied by the species) were surveyed in the Hrubý Jeseník Mts. and Moravskoslezské Beskydy Mts. in northern Moravia (Czech Republic) in 2016. The species strongly preferred trees with reduced vitality, including variously damaged trees. The species was also documented to be much more abundant on sun-exposed trees, and the parts of the trunk mantle (south- and east-facing quarters) with the warmest microclimates were preferred. Surprisingly, trunk diameter seems to be an unimportant characteristic for this species (the diameters of occupied trees varied between 5 and 72 cm). In conclusion,
R. ungaricus
is a specialised species whose survival depends upon a continuous supply of sun-exposed declining and damaged sycamores in mountain forests. Based on the results of the present study, we suggest concrete conservation measures to support the species, and these will benefit other saproxylic species associated with the same habitat.
A total of480 Scots pine (Pinus sylvestris L.) trees felled during pre-commercial thinning in a single stand in the Drahanska Highlands in the Czech Republic were examined for the occurrence of bark- ...and wood-boring beetles. Thinning was performed on different dates during 2006 and 2007 (February, May, August and November). Half of the felled trees were cut into 1 m-long sections, and the rest were left whole. The fauna inhabiting the logging residues were investigated by peeling off the bark ofthe felled trees during the first six months of the vegetative period following felling. The studied logging residues hosted species-rich assemblages of bark- and wood-boring beetles (28 species identified), including numerous populations of several pest species (Pityogenes chalcographus, Tomicus minor and Tomicus piniperda). The occurrence of species was significantly affected mainly by the part of the tree and its diameter and bark thickness and by the felling date and post-felling cutting of the trees.
Invasive, alien trees threaten native biodiversity, but detailed information about the patterns and mechanisms of diversity loss remain unknown. We explored the impact of an invasive tree on vascular ...plants and saproxylic beetles. We compared their species richness, community composition, and selected biological characteristics between stands of invasive black locust (Robinia pseudoacacia), a nitrogen-fixing clonal tree, and native oak-dominated, broadleaf forests in the SE Czech Republic and W Slovakia.
Compared to native forests, R. pseudoacia stands were characterised by low canopy cover, high light and soil nutrient availability, and similar deadwood volumes. R. pseudoacacia had species-poor, dense understorey vegetation composed of tall, nitrophilous herbs. Saproxylic beetles, on the other hand, were similarly diverse and abundant in both R. pseudoacacia stands and native forests. Their communities were mainly shaped by forest structure, as overall beetle diversity and guilds exploiting more decayed wood benefited from the open canopies and high deadwood volumes. Richness and abundance of threatened plants and beetles requiring fresh wood, together with total richness of threatened beetles were, however, substantially lower in R. pseudoacacia stands.
The adverse impacts of R. pseudoacacia on plants partly contrasted with its much less pronounced effects on saproxylic beetles. In intensively exploited landscapes, R. pseudoacacia stands can offer refuge to saproxylic beetles. However their lower diversity and lower incidence of threatened species show that R. pseudoacacia contributes to homogenization and impoverishment of plant and insect assemblages. Robinia stands thus should be eliminated from protected areas and minimalised wherever biodiversity conservation is of concern.
To reduce the risk of bark- and wood-boring beetle pests, the extensive removal of logging residues is conducted in forests; however, this practice can lead to a loss of saproxylic insect diversity. ...Thus, finding a better pest management strategy is needed and requires additional information on the actual effects of various, differently treated logging residues for pest multiplication. In the present study, a total of 2,160 fragments of Scots pine (Pinus sylvestris L.) logging residues generated during final felling in a single stand in the Drahanská Highlands in the Czech Republic were examined for bark- and wood-boring beetles. The felling occurred on four dates in 2006 (in February, May, August and November). The logging residues from each felling were left scattered on the clear-cut area or were gathered into piles. The fauna inhabiting the logging residues were investigated by peeling off the bark during the first six months of the vegetative period following the felling. The logging residues hosted species-rich assemblages of bark- and wood-boring beetles (25 species were identified). Beetle occurrence was significantly affected by felling date, logging residue type (trunk fragment or branch and branch thinner or thicker than 1 cm), diameter and the manner in which the logging residues were deposited (freely scattered, top pile layer, or bottom pile layer). The Scots pine logging residues were a substrate for the significant multiplication of several potentially significant pests (particularly, Pityogenes chalcographus Linnaeus, Ips acuminatus Gyllenhal and Pityophthorus pityographus Ratzeburg). The results indicated that the risk of pest reproduction can be minimised by felling the trees in August (and probably also September and October). For I. acuminatus and P. pityographus, the risk can be minimised by gathering the logging residues into piles.
1 Logging residues form a substantial portion of the dead wood in managed forests, and logging residues can facilitate bark beetle multiplication and outbreaks. For these reasons, it is highly ...advisable to find a way of reducing the risk of bark beetle outbreaks without extensive removal of logging residues, which is inconsistent with nature conservation. 2 The coverage of Pityogenes chalcographus (L.) galleries and the presence of other bark beetle species on 3520 fragments of logging residues of the Scots pine (Pinus sylvestris L.) that originated over different months from 2004 to 2008 were examined in 135 stands in four study areas of the Czech Republic. 3 Pityogenes chalcographus was the most abundant species. 4 The month of felling had a significant effect on the coverage of P. chalcographus galleries on logging residues. 5 Concentrating felling in August and September (and possibly October) can minimize the risk of P. chalcographus multiplication and outbreaks.
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