The small cypress bark beetle Phloeosinus aubei is considered an invasive pest in several central European countries, and we have determined its current distribution on common juniper trees (Juniperus communis) in the Czech Republic. The results indicated that P. aubei is widely distributed in the country but is more common in the east than in the west. The beetle was mainly detected on older, damaged trees and on stems with diameters > 3 cm. The apparently widespread and abundant populations of P. aubei could explain infestations of the beetle on Thuja spp. and Juniperus spp. in gardens (three confirmed cases during the last 10 years). We consider P. aubei to be a potential pest on older, naturally occurring J. communis in protected areas where its population density could increase on weakened and damaged trees. We suggest that P. aubei can be monitored via simple inspection of dying and dead J. communis trees in the field.

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.

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Invasive organisms represent great threats to ecosystems and great challenges to forest management. In Europe, the black timber bark beetle (Xylosandrus germanus) is an invasive secondary pest that mostly attacks the logs of felled trees. We showed the invasion history for Europe and using many local surveys, we summarize the current distribution and other available information on X. germanus in the Czech Republic. We report that this species is distributed from the lowlands to the mountains in the Czech Republic; it is widespread in the eastern half of the country, where it is more abundant in the warmer south and southeast areas than in the cooler areas. Most (78%) of the known localities are at elevation below 400 m a.s.l. Although an ice storm greatly increased X. germanus abundance near the border with Austria, its high abundance did not result in damage to standing trees. Presence of X. germanus in the Czech Republic for over 10 years has not led to heavy tree infestation.

Ambrosia beetles are among the most damaging forest pests. They are frequently moved intercontinentally and are therefore subject to quarantines. The objective of the current research was to determine whether two commercially produced lures for Trypodendron species also attract central European ambrosia beetles. In 2018, Theysohn^® traps were deployed in an oak forest that also contained hornbeam and linden trees. Five pair of traps was baited with the standard synthetic pheromone lures, Trypowit^® or Lineatin Kombi^®. The 201 adults of ambrosia bark beetles that were trapped were identified to eight species, which represents almost the entire spectrum of oak ambrosia scolytids in the region. Trypodendron domesticum, Xyleborinus saxesenii, and Xyleborus monographus were the most abundant species and exhibited a slight preference for the lure with a higher content of alcohols (Lineatin Kombi^®). Both lures attracted T. lineatum because both contain lineatin. The number of beetles trapped was low probably because food sources (damaged or wilting oaks) were rare and because the forest was surrounded by agricultural land and therefore isolated from other oak forests.

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Cryphalus asperatus (Coleoptera: Curculionidae, Scolytinae) is described as an exceptional but important secondary pest of Norway spruce seedlings. Of the 10 000 seedlings transported to one location in the Ore Mountains, Central Europe in 2020, in total 1 500 seedlings were killed by C. asperatus. The infestation and death of seedlings probably resulted in part from the substantial local increase in the local abundance of C. asperatus after the sanitation felling of many Ips typographus-infested and otherwise damaged trees; the felled trees provided many branches suitable for C. asperatus feeding. In addition, the seedlings were probably stressed by the multi-hour transportation (probably drought) from the forest nursery.

In this report, we describe a local outbreak of small bark beetles on 4-year-old seedlings of Picea abies in a forest nursery in Central Europe in 2021. In March 2022, 10–50% of the seedlings were “dry” (i.e., with dry and easily broken twigs and with easily peeled bark) in each 4-row bed in the nursery. Half of the dry plants were completely covered by galleries of bark beetles and another 35% of the seedlings were with one or two bark beetle galleries. Almost 90% of the beetles found on the affected seedlings were Pityogenes chalcographus, and only 10% were Pityophthorus pityographus (we studied 100 seedlings in the second bed). The chipping of Picea pungens in previous years had left many felled trunks, branches, and other logging residues in the area. These residues are covered by galleries of both bark beetles. We suggest that, after multiplying on the logging residues, the beetles could not find suitable material for reproduction and were lured to the nursery seedlings, which had been weakened by location (a location that provided inadequate shade and no wind protection) and by repeated replanting.