The first full host plant dataset of Curculionidae Scolytinae of the world: tribe Xyleborini LeConte, 1876

Host plant selection and performance of ambrosia beetles in flood-stressed versus ethanol-injected trees provide implications for management strategies

Ambrosia beetles (Curculionidae: Scolytinae and Platypodinae) are fungus-farming woodborers that can cause damage to the trees they colonize. Some of these beetles target stressed plants that emit ethanol, and management strategies have proposed using ethanol-injected trees as trap trees to monitor or divert dispersing adult females away from valuable crops. In this study, we used container-grown trees from 8 species to compare the effect of ethanol injection versus flooding on ambrosia beetle host selection and colonization success. Our aims were to understand whether ethanol injection is a suitable technique for different ambrosia beetle species and whether its effectiveness varies depending on the tree species used. In addition, we quantified the amount of ethanol in tree tissues to understand whether ethanol concentration could reflect observed differences among treatments and tree species. Our findings demonstrated that ethanol-injected trees were significantly more selected by both Xyleborinus saxesenii and Xylosandrus spp. and that significantly more adult beetles of both taxa emerged from ethanol-injected than flood-stressed trees. In addition, we showed that ethanol injection can trigger attacks by X. saxesenii and Xylosandrus spp. on a variety of deciduous tree species, nullifying the effects of the species-specific characteristics observed on flood-stressed trees, which can only partially be attributed to the amount of ethanol within the plant. This supported the idea that practitioners can potentially select any species of deciduous trees in management programs for ambrosia beetles based on ethanol-injected trees.

The first host plant dataset of Curculionidae Scolytinae of the world: miscellaneous tribes (Part 2)

Scolytinae (Coleoptera: Curculionidae) are one of the most successful groups of invasive species. They are generally moved among continents transported within live plants, timber and wood-packaging materials. The damages caused by these insects, of economic and ecological relevance, can be caused both by the direct action of burrowing within host plant tissues and by the pathogens carried by some species. In order to prevent the introduction of new and potentially harmful species by planning effective monitoring strategies, the knowledge of recorded host plants is essential. This third contribution provides a complete list of host plants, with economic categorization, for 2,193 scolytine species, belonging to 16 tribes: Amphiscolytini, Bothrosternini, Carphodicticini, Chaetophloeini, Crypturgini, Diamerini, Dryocoetini, Hexacolini, Hylesinini, Hyorrhynchini, Hypoborini, Micracidini, Phloeotribini, Phrixosomatini, Scolytini, and Scolytoplatypodini.

Chromosome Structural Rearrangements in Invasive Haplodiploid Ambrosia Beetles Revealed by the Genomes of Euwallacea fornicatus (Eichhoff) and Euwallacea similis (Ferrari) (Coleoptera, Curculionidae, Scolytinae)

Bark and ambrosia beetles are among the most ecologically and economically damaging introduced plant pests worldwide. Life history traits including polyphagy, haplodiploidy, inbreeding polygyny, and symbiosis with fungi contribute to their dispersal and impact. Species vary in their interactions with host trees, with many attacking stressed or recently dead trees, such as the globally distributed Euwallacea similis (Ferrari). Other species, like the Polyphagous Shot Hole Borer Euwallacea fornicatus (Eichhoff), can attack over 680 host plants and is causing considerable economic damage in several countries. Despite their notoriety, publicly accessible genomic resources for Euwallacea Hopkins species are scarce, hampering our understanding of their invasive capabilities as well as modern control measures, surveillance, and management. Using a combination of long and short read sequencing platforms, we assembled and annotated high quality (BUSCO > 98% complete) pseudo-chromosome-level genomes for these species. Comparative macrosynteny analysis identified an increased number of pseudo-chromosome scaffolds in the haplodiploid inbreeding species of Euwallacea compared to diploid outbred species, due to fission events. This suggests that life history traits can impact chromosome structure. Further, the genome of E. fornicatus had a higher relative proportion of repetitive elements, up to 17% more, than E. similis. Metagenomic assembly pipelines identified microbiota associated with both species including Fusarium fungal symbionts and a novel Wolbachia strain. These novel genomes of haplodiploid inbreeding species will contribute to the understanding of how life history traits are related to their evolution and to the management of these invasive pests.

New species and new records of Xylosandrus Reitter, 1913 (Coleoptera: Curculionidae: Scolytinae: Xyleborini) from China

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.

Cryptoxyleborus brevicauda, a new species of xyleborine ambrosia beetle from Thailand (Coleoptera: Curculionidae: Scolytinae: Xyleborini)

A new species, Cryptoxyleborus brevicauda Sittichaya & Beaver sp. nov., is described from the South of Thailand. A list of Cryptoxyleborus species found in Thailand with their provincial distributions and habitat types, and a key to Thai species are provided.

Pest categorisation of non-EU Scolytinae on non-coniferous hosts

The EFSA Panel on Plant Health performed a group pest categorisation for the EU territory of non-EU Scolytinae (Coleoptera: Curculionidae) on non-coniferous hosts, which total 6495 known species. Most species attack apparently healthy, weakened or dead trees, either feeding on the phloem ('bark beetles' subgroup) or on fungi inoculated into the sapwood ('ambrosia beetles' subgroup). Smaller subgroups feed and reproduce in seeds and fruits, or in herbaceous plants. Some species are polygynous, the males initiate a gallery or a chamber on or in a new host and attract females. Others are monogamous, and the females initiate the new galleries. Many species respond to primary volatile attractants emitted by the hosts, and some produce aggregation pheromones that attract conspecifics of both sexes. The species attacking living hosts are often associated with fungi that contribute to weakening the host defences and provide nutrients to the insects. Some are inbreeding; the males in the offspring mate with their sisters and rarely leave their natal tree. The larvae of all species develop and pupate within their hosts. Based on catalogues and other published data, a database was constructed providing information on hosts, feeding and reproductive habits, geographic distribution and the Köppen-Geiger climate types in countries where species occur. The Scolytinae were screened to exclude species in the following categories: (i) 708 species attacking conifers; (ii) 127 species present in at least four EU Member States and (iii) 440 species occurring in areas with climatic conditions not occurring in the EU. Among the remaining 5220 species, 88 species known for their mobility, occupying at least two landmasses separated by geographical barriers and some of which had impact levels documented in literature, were extracted. They were grouped into four subcategories: (i) 12 species with high impact on plant health; (ii) 16 species with low or doubtful impact; (iii) 48 species with no impact; (iv) 12 species with no impact and which had never been recorded as 'introduced' in the consulted catalogues but occurring on at least two landmasses. All 88 species could enter the EU with wood or wood products, or with plants for planting, and could establish because host plants are available, and climate is suitable in parts of the EU. Control measures to inhibit introduction are available. There is considerable uncertainty regarding the potential impact of many species. Methods for the reliable identification of many species are lacking. For some species of non-EU Scolytinae on non-coniferous hosts, all criteria assessed by EFSA for consideration as potential quarantine pest are met. Nevertheless, the Panel was not able to develop a method to discriminate confidently between species that clearly meet the criteria for potential quarantine pest status and those that do not.

Four new species of Arixyleborus Hopkins, 1915, ambrosia beetles from Thailand (Coleoptera: Curculionidae: Scolytinae: Xyleborini)

Four new species, Arixyleborus halabala Sittichaya, Beaver & Smith sp. nov., Arixyleborus longicauda Sittichaya, Beaver & Smith sp. nov., Arixyleborus vellus Sittichaya, Beaver & Smith sp. nov. are described from Thailand, and Arixyleborus liratus Sittichaya, Beaver & Smith sp. nov. from Thailand and East Malaysia (Sabah). With the inclusion of the species described here, the diversity of Arixyleborus is increased to 46 species, of which 20 occur in Thailand. A synoptic list with distributions and habitat types is provided.

The first host plant dataset of Curculionidae Scolytinae of the world: miscellaneous Tribes

Tribes Coriacephilini, Corthylini, Cryphalini, Ernoporini, Trypophloeini, Xyloctonini, and Xyloterini (Coleoptera: Curculionidae; Scolytinae) include spermophagous, phloeophagous, and xylomycetophagous species. Besides direct damage caused by burrowing into host plant tissues, some species are vectors of aggressive pathogens causing plant dieback and death, with consequent economic and ecological relevance. The international trade in plants and wood products is one of the main pathways for the introduction of non-native species worldwide. In this context, data availability on host plants and their economic uses is essential in pest risk assessment and for planning effective detection and monitoring strategies against invasive species. This paper provides a complete and updated list of host plants, with economic categorization, for 2139 scolytine species.

New records of non-native Coleoptera in Italy

Background

In the last decades, climate change and globalisation have been exacerbating the introduction of non-native beetles worldwide. Due toits peculiar territory, climate and geographical position in the middle of the Mediterranean Basin, Italy is one of the European countries with the highest number of intercepted, adventive and established non-native beetles, some of which are invasive. In this perspective, producing new faunistic records and continuously updating reliable and easily accessible distributional data is a fundamental step in investigating and potentially preventing further species introduction.

New information

The aim of this contribution is to report and discuss new faunistic records of non-native Coleoptera in Italy. For some species, new records enlarge the previously-known distribution (e.g. the ambrosia beetles Anisandrusmaiche (Kurentzov, 1941) and Cnestusmutilatus (Blandford, 1894) or the click beetle Monocrepidiusposticus (Eschscholtz, 1829)), while for others (e.g. the scarab beetle Archophileurusspinosus Dechambre, 2006), data confirm their establishment and highlight a possible expansion phase. The false powderpost beetles Ptilineurusmarmoratus (Reitter, 1877) and the longhorn beetle Xylotrechuschinensis (Chevrolat, 1852) are two new additions to the Italian fauna, while the establishment of the monotomid beetle Monotomaamericana Aubé 1837 is confirmed.

First record of the genus Immanus Hulcr & Cognato (Coleoptera: Curculionidae: Scolytinae: Xyleborini) from China, with description of a new species

Immanus Hulcr & Cognato, 2013 is reported from China for the first time, with the description and illustration of a new species, Immanus songi sp. nov., based on an adult female collected with a flight intercept trap from Yunnan province, China. A key to all known species of Immanus is given.

Uncharted Territories: First report of Euwallacea fornicatus (Eichhoff) in South America with new reproductive hosts records

We report the presence of the invasive ambrosia beetle, Euwallacea fornicatus (Eichhoff, 1868), for the first time in South America. The identity is established by morphological and molecular methods, although the sequences suggest that it represents a separate haplotype from the populations that have caused significant damage in South Africa, Israel, and California, and is most phylogenetically similar to specimens from Asia and greenhouses in Europe. This pest is one of the most successful invaders, causing high economic and ecological impacts in the regions where it is introduced. Our records are from the city of Buenos Aires, Argentina, one of the most populated and largest port cities in South America, where attacks by this beetle are present on a wide range of living street trees. The large number of trees attacked and the new records of reproductive host species suggest that the beetle is already established and widespread in the citys urban forest. This context implies that the beetle may pose a threat to the urban and natural environment, as well as to the forests and fruit production of the region. Informamos la presencia del escarabajo invasor de ambrosa, Euwallacea fornicatus (Eichhoff, 1868), por primera vez en Sudamrica. La identificacin se estableci mediante mtodos morfolgicos y moleculares, si bien las secuencias sugieren que representa un haplotipo distinto de las poblaciones que han causado daos significativos en Sudfrica, Israel y California, resulta filogenticamente ms similar a especmenes de Asia e invernaderos de Europa. Esta plaga es una de las especies invasoras ms exitosas, causando altos impactos econmicos y ecolgicos en las regiones donde es introducida. Nuestros registros provienen de la ciudad de Buenos Aires, Argentina, una de las ciudades portuarias ms pobladas y grandes de Sudamrica, donde los ataques de este coleptero estn presentes en una amplia diversidad de especies pertenecientes al arbolado urbano. El gran nmero de rboles atacados y los nuevos registros de especies hospedadoras reproductoras sugieren que el coleptero ya est establecido y extendido en el bosque urbano de la ciudad. Este contexto implica que el coleptero puede suponer una amenaza para el medio urbano y natural, as como para los bosques y la produccin frutcola de la regin.