Exotic diseases and pests of trees have caused continental-scale disturbances in forest ecosystems and industries, and their invasions are considered largely unpredictable. We tested the concept of preinvasion assessment of not yet invasive organisms, which enables empirical risk assessment of potential invasion and impact. Our example assesses fungi associated with Old World bark and ambrosia beetles and their potential to impact North American trees. We selected 55 Asian and European scolytine beetle species using host use, economic, and regulatory criteria. We isolated 111 of their most consistent fungal associates and tested their effect on four important southeastern American pine and oak species. Our test dataset found no highly virulent pathogens that should be classified as an imminent threat. Twenty-two fungal species were minor pathogens, which may require context-dependent response for their vectors at North American borders, while most of the tested fungi displayed no significant impact. Our results are significant in three ways; they ease the concerns over multiple overseas fungus vectors suspected of heightened potential risk, they provide a basis for the focus on the prevention of introduction and establishment of species that may be of consequence, and they demonstrate that preinvasion assessment, if scaled up, can support practical risk assessment of exotic pathogens.

American sweetgum Liquidambar styraciflua (Altingiaceae) was first introduced to China over 60 years ago. It is an important tree species for increasing landscape value and promoting afforestation in urbanized areas of eastern China in the past 20 years. Sweetgum inscriber Acanthotomicus suncei (Coleoptera: Curculionidae) is a local bark beetle pest and lethal to the introduced American sweetgum. To provide preliminary estimates of the potential economic losses caused by the sweetgum inscriber, a field investigation was conducted to survey the beetles’ natural distribution in China. Based on field collections, potential distribution was predicted using Maxent. All nurseries stocking American sweetgum were in the high and very high suitability area of sweetgum inscriber. Additionally, we employed a model of direct loss incorporating tree and removal cost. A questionnaire was sent to maintenance companies, growers, and gardener associations for tree removal prices. We estimated the removal cost of each tree. In addition, the market price and inventory were also gained from telephone interview. Our economic analysis indicates that if sweetgum inscriber were to become established in the main American sweetgum business, the potential losses of nursery stock and urban area could range from USD 12.81 to 14.41 million.

Two new species of ambrosia beetles Xylosandrus Reitter, 1913 (Scolytinae: Xyleborini), Xylosandrus luokengensis Lin & Gao sp. nov. and Xylosandrus nanlingensis Lin & Gao sp. nov., from Guangdong Province, South China are described. Xylosandrus trunculus Park & Smith, 2020 is reported from China for the first time, and provincial records of all known Xylosandrus are provided.

The pine shoot beetles Tomicus minor and Tomicus yunnanensis are important stem borers of Pinus yunnanensis in southwestern China. To determine strategies for cold resistance and changes in major cold-resistant substances in adults of two Tomicus species during two critical transferring periods, “shoot-to-trunk” and “trunk-to-shoot”, the insects’ supercooling point (SCP), freezing point (FP), and antifreeze protective substances were determined. The SCP and FP did not differ between female and male adults in the shoot-to-trunk phase, but were significantly lower in females in the trunk-to-shoot period. Although there was no difference in the SCP and FP between the two Tomicus species adults, both indexes were significantly lower in the shoot-to-trunk period than in the trunk-to-shoot period. The trehalose content in females of two Tomicus species was significantly lower than that in males in the trunk-to-shoot period, and the protein, glycerol, glycogen, fat, and sorbitol contents were different between the species in the same period. The protein and water content in adults of both species were significantly lower in the shoot-to-trunk period than in the trunk-to-shoot period, but the content of glycerol, trehalose, water, sorbitol, glycogen, and fat content were significantly higher in the shoot-to-trunk. Different types of cold-resistant substances regulating sex, species, and developmental stages were found, and the most abundant were cold-resistant substances regulating developmental stages.