New Approaches in Urban Forestry to Minimize Invasive Species Impacts: The Case of Xiongan New Area in China.

China is implementing an extensive urban forestry plan in Xiongan New Area (XNA), a new city in Hebei province. The city has been designated to serve Beijing's noncapital functions and promote the integration of the broader Beijing-Tianjin-Hebei city-region. As part of a green initiative to minimize environmental impacts and its carbon footprint, a massive urban forestry system has been planned on an unprecedented scale, expected to cover over 600 km by 2030.

Fighting and aggressive sound determines larger male to win male-male competition in a bark beetle.

Intrasexual selection occurs in male-male competition over access to females and usually results in the larger male winning. While much research has documented that size matters, little is known about how the larger male wins. Dendroctonus valens is an aggregating monogamous bark beetle in which males have large variation in body size and display intense competition over females.

Physical contact, volatiles, and acoustic signals contribute to monogamy in an invasive aggregating bark beetle.

The behavioral strategies and mechanisms by which some insects maintain monogamous mating systems are not well understood. We investigated the mating system of the bark beetle Dendroctonus valens, and identified several contributing mechanisms. Field and laboratory observations suggest the adults commonly form permanent bonds during host colonization.

Immune tolerance of vector beetle to its partner plant parasitic nematode modulated by its insect parasitic nematode.

Immune response of insect vectors to transmitted pathogens or insect hosts against parasites are well studied, whereas the mechanism of tripartite interactions remains elusive. In this study, we investigated the immune interactions of the vector beetle Monochamus alternatus ( Ma) to the devastating plant parasitic nematode Bursaphelenchus xylophilus ( Bx) and the insect parasitic nematode Howardula phyllotretae ( Hp). We report the unique immune mechanism by which the vector beetle tolerates many devastating Bx in its trachea, yet that immune tolerance is compromised by the parasitic nematode Hp.

Comparative analysis of the Monochamus alternatus immune system.

The pine sawyer beetle, Monochamus alternatus, is regarded as a notorious forest pest in Asia, vectoring an invasive pathogenic nematode, Bursaphelenchus xylophilus, which is known to cause pine wilt disease. However, little sequence information is available for this vector beetle. This hampered the research on its immune system.

Invasive bark beetle-associated microbes degrade a host defensive monoterpene.

Conifers respond to herbivore attack with defensive chemicals, which are toxic to both insects and their associated microorganisms. Microorganisms associated with insects have been widely reported to metabolize toxic chemicals, which may help both microorganisms and host insects overcome host conifer defense. Dendroctonus valens LeConte, an introduced exotic pest from North America to China, has killed millions of healthy pines.

Reproductive Isolation of Ips nitidus and I. shangrila in Mountain Forests of Western China: Responses to Chiral and Achiral Candidate Pheromone Components.

Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the species responsible nor the semiochemicals guiding these attacks are well understood. Two high-mountain Ips species on Qinghai spruce, Picea crassifolia, I.

Sentinel trees as a tool to forecast invasions of alien plant pathogens.

Recent disease outbreaks caused by alien invasive pathogens into European forests posed a serious threat to forest sustainability with relevant environmental and economic effects. Many of the alien tree pathogens recently introduced into Europe were not previously included on any quarantine lists, thus they were not subject to phytosanitary inspections. The identification and description of alien fungi potentially pathogenic to native European flora before their introduction in Europe, is a paramount need in order to limit the risk of invasion and the impact to forest ecosystems.

Yeast diversity associated with invasive Dendroctonus valens killing Pinus tabuliformis in China using culturing and molecular methods.

Bark beetle-associated yeasts are much less studied than filamentous fungi, yet they are also considered to play important roles in beetle nutrition, detoxification, and chemical communication. The red turpentine beetle, Dendroctonus valens, an invasive bark beetle introduced from North America, became one of the most destructive pests in China, having killed more than 10 million Pinus tabuliformis as well as other pine species. No investigation of yeasts associated with this bark beetle in its invaded ranges has been conducted so far.

Large shift in symbiont assemblage in the invasive red turpentine beetle.

Changes in symbiont assemblages can affect the success and impact of invasive species, and may provide knowledge regarding the invasion histories of their vectors. Bark beetle symbioses are ideal systems to study changes in symbiont assemblages resulting from invasions. The red turpentine beetle (Dendroctonus valens) is a bark beetle species that recently invaded China from its native range in North America.

Do novel genotypes drive the success of an invasive bark beetle-fungus complex? Implications for potential reinvasion.

Novel genotypes often arise during biological invasions, but their role in invasion success has rarely been elucidated. Here we examined the population genetics and behavior of the fungus, Leptographium procerum, vectored by a highly invasive bark beetle, Dendroctonus valens, to determine whether genetic changes in the fungus contributed to the invasive success of the beetle-fungal complex in China. The fungus was introduced by the beetle from the United States to China, where we identified several novel genotypes using microsatellite markers.

Immunocompetence of the red turpentine beetle, Dendroctonus valens LeConte (Coleoptera: Curculionidae, Scolytinae): variation between developmental stages and sexes in populations in China.

Immune defense imposes fitness costs as well as benefits, so organisms should optimize, not maximize, their immune function through their life cycle. We investigated this issue in the red turpentine beetle, Dendroctonus valens LeConte (Coleoptera: Curculionidae, Scolytinae), which is a pine-killing invasive beetle in China, though it is usually considered as a secondary pest in its native range of North America. We hypothesized that pathogen pressure may affect these beetles differently throughout their life history.

Complex interactions among host pines and fungi vectored by an invasive bark beetle.

*Recent studies have investigated the relationships between pairs or groups of exotic species to illustrate invasive mechanisms, but most have focused on interactions at a single trophic level. *Here, we conducted pathogenicity tests, analyses of host volatiles and fungal growth tests to elucidate an intricate network of interactions between the host tree, the invasive red turpentine beetle and its fungal associates. *Seedlings inoculated with two strains of Leptographium procerum isolated from Dendroctonus valens in China had significantly longer lesions and higher mortality rates than seedlings inoculated with other fungal isolates.

Aggregation pheromone of the Qinghai spruce bark beetle, Ips nitidus eggers.

Volatiles from hindgut extracts of males of the Qinghai spruce bark beetle, Ips nitidus, from different attack phases (phase 1: unpaired males and phases 2-4: males joined with one to three females) and hindgut extracts of mated females were analyzed by gas chromatography-mass spectrometry (GC-MS)/flame ionization detection (FID) with both polar and enantioselective columns. The GC-MS/FID analyses demonstrated that unpaired males from attack phase 1 (nuptial chamber constructed) produced 2-methyl-3-buten-2-ol, approx. 74%-(-)-ipsdienol, and (-)-cis-verbenol as major hindgut components, and (-)-trans-verbenol, (-)-ipsenol, (-)-verbenone, myrtenol, and 2-phenylethanol as minor or trace components.

Host specificity of Argopistes tsekooni (Coleoptera: Chrysomelidae), a potential biological control agent of Chinese privet.

Chinese privet, Ligustrum sinense Lour., is a perennial semi-evergreen shrub that is a serious invasive weed in the United States. Classical biological control offers the best hope for controlling it in an economic, effective, and persistent way.

Biology and preliminary host range assessment of two potential kudzu biological control agents.

Two insect species from China, Gonioctena tredecimmaculata (Jacoby) (Coleoptera: Chrysomelidae) and Ornatalcides (Mesalcidodes) trifidus (Pascoe) (Coleoptera: Curculionidae), were studied in quarantine in the United States as potential biological control agents for kudzu, Pueraria montana variety lobata (Willd.) Maesen and S. Almeida.

Cross-attraction between an exotic and a native pine bark beetle: a novel invasion mechanism?

Background: Aside from the ecological impacts, invasive species fascinate ecologists because of the unique opportunities that invasives offer in the study of community ecology. Some hypotheses have been proposed to illustrate the mechanisms that allow exotics to become invasive. However, positive interactions between exotic and native insects are rarely utilized to explain invasiveness of pests.

DNA based cladograms augment the discovery of a new Ips species from China (Coleoptera: Curculionidae: Scolytinae).

The implementation of DNA in taxonomic study is in its infancy because the association of the amount and type of nucleotide change with species boundaries has not been fully examined for most taxa. Mitochondrial cytochrome c oxidase I (COI) nucleotide data is currently the most popular molecular marker for delimiting species boundaries and a standard pair-wise nucleotide divergence between groups of individuals has been suggested for the recognition of new species. It is unlikely that such a standard would be applicable across animal species, but the association of the amount and type of nucleotide change with species boundaries could help with the establishment of a taxon-specific DNA taxonomy.

Chemotaxis of the pinewood nematode, Bursaphelenchus xylophilus, to volatiles associated with host pine, Pinus massoniana, and its vector Monochamus alternatus.

The pinewood nematode (PWN), Bursaphelenchus xylophilus, the most important invasive species in pine forests of Asia, is transported to new pine hosts by beetles of the genus Monochamus. Third-stage dispersal juveniles (J(III)) aggregate in pupal chambers around the vector as it matures. We demonstrated that the ratio of three terpenes (alpha-pinene, beta-pinene, and longifolene at 1:2.

Sex pheromone components of the sandthorn carpenterworm, Holcocerus hippophaecolus.

Extracts of female sex pheromone gland of the carpenterworm moth, Holcocerus hippophaecolus Hua, a pest of sandthorn, Hippophae rhamnoides L. were found to contain (E)-3-tetradecenyl acetate (E3-14:Ac), (Z)-3-tetradecenyl acetate (Z3-14:Ac), (Z)-7-tetradecenyl acetate (Z7-14:Ac), the corresponding alcohols, E3-14:OH, Z3-14:OH, Z7-14:OH, and (E)-9-tetradecenyl acetate (E9-14:Ac). Electroantennographic (EAG) analysis of these chemicals and their analogs demonstrated that Z7-14:Ac elicited the largest male EAG response, followed by E3-14:Ac.