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Although there are benefits to being a generalist, the majority of herbivorous insects are diet specialists. This raises the question whether the ability to reproduce on various host plants hides an unknown ecological optimum. Our study investigated the existence of such an ecological optimum in the fungus‐farming ambrosia beetle, Xyleborinus saxesenii Ratzeburg (Coleoptera: Curculionidae).We hypothesised that X. saxesenii may exhibit higher fitness in specific hosts that are particularly abundant in their respective regions. To test this hypothesis, we bred X. saxesenii from a broadleaved forest population in semi‐artificial media mimicking either a coniferous or a broadleaved host‐tree species. As trade‐offs between different traits can occur, we examined various aspects of the life history, social behaviour and fungal symbionts of X. saxesenii.We found that dispersing females did not exhibit any preference, and that the host tree did not have any impact on life history parameters or larval and adult behaviours. The fungal community associated with the species was made up of identical fungal species, albeit with different relative abundances between host trees. Our findings indicate that X. saxesenii does not exhibit a specific adaptation to the most abundant host trees in its native habitat. However, we identified significant effects of laboratory breeding on life history traits, social behaviour and adult dispersal.This generalism in host use in combination with inbreeding mating system may be the main drivers of the invasion success of the Eurasian X. saxesenii, which is currently among the most prevalent and widely distributed ambrosia beetle species worldwide. [ABSTRACT FROM AUTHOR]

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are small wood-boring insects that live in an obligate symbiosis with fungi, which serve as their primary food source. Beetles residing in the genus Euwallacea have evolved a unique association with a clade of Fusarium that falls within the aptly named Ambrosia Fusarium Clade (AFC). The discovery of the invasive polyphagous shot hole borer, E. fornicatus, in South Africa, has heightened awareness of ambrosia beetles and their symbionts in the country. In this study, we investigated the Fusarium symbionts of three species of Euwallacea in South Africa, with a specific focus on those associated with E. xanthopus. Isolations of Fusarium strains from both living and dissected beetles yielded nearly 100 isolates. Using multigene phylogenetic analyses, these isolates were identified as six different Fusarium species. Fusarium hypothenemi and F. euwallaceae have previously been reported from South Africa. Fusarium pseudensiforme and Fusarium AF-6 are new records for the country. The remaining two species are new to science and are described here as F. rufum sp. nov. and F. floriferum sp. nov. Targeted fungal isolation from specific beetle body parts revealed that the AFC species collected were typically associated with the dissected beetle heads and helped us identify the likely nutritional symbiont of E. xanthopus. This study highlights the understudied diversity of fungal associates of ambrosia beetles present in South Africa. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Simple Summary: Xyleborus beetles are tiny insects that impact forests and agriculture. These beetles burrow into trees and crops, causing damage that affects both the environment and the economy. This review aims to provide a clear understanding of the biology and behavior of Xyleborus beetles, including their life cycle, habitat, and feeding habits. We also discuss the various methods currently used to manage and control these pests, such as chemical treatments, biological controls, and integrated pest management strategies. By highlighting recent scientific advancements and identifying future research needs, this review offers insights for researchers, farmers, and policymakers. Understanding and effectively managing Xyleborus beetles is crucial for protecting our forests and agricultural resources, ultimately benefiting society by reducing economic losses and preserving ecological balance. Xyleborus beetles, a diverse group of ambrosia beetles, present challenges to forestry and agriculture due to their damaging burrowing behavior and symbiotic relationships with fungi. This review synthesizes current knowledge on the biology, ecology, and management of Xyleborus. We explore the beetles' life cycle, reproductive strategies, habitat preferences, and feeding habits, emphasizing their ecological and economic impacts. Control and management strategies, including preventive measures, chemical and biological control, and integrated pest management (IPM), are critically evaluated. Recent advances in molecular genetics and behavioral studies offer insights into genetic diversity, population structure, and host selection mechanisms. Despite progress, managing Xyleborus effectively remains challenging. This review identifies future research needs and highlights innovative control methods, such as biopesticides and pheromone-based trapping systems. [ABSTRACT FROM AUTHOR]

The polyphagous shot hole borer (PSHB) beetle, Euwallacea fornicatus (Eichhoff) (Coleoptera: Curculionidae, Scolytinae), and its phytopathogenic fungal symbiont (Fusarium euwallaceae Freeman et al.) threaten commercial and urban tree species worldwide. This pest–fungus complex has been newly discovered in the commercial deciduous fruit industry (Western Cape, South Africa), where its effect is still unknown. This study explored the impact of PSHB infestation on fruit quality and plant water‐use efficiency (WUE) – as indicated by carbon and nitrogen stable isotope ratios – of commercially cultivated Packham's Triumph pear trees within the first year of invasion, as well as changes in phenotypic plasticity (trait expression range). The impact of PSHB infestation is currently most evident in fruit quality traits, with a clear distinction between the control and most densely attacked tree categories. Fruit and leaf traits showed high variation and a significant change in phenotypic plasticity. Increased PSHB attack density was associated with smaller, duller‐toned, sweeter fruit at the time of harvest and data tended towards reduced plant WUE. Producers can expect significant variation in fruit quality and plant WUE even in hosts without branch dieback, visible plant stress or extensive beetle breeding, especially in orchards where infestations persist beyond the first year. These findings necessitate additional research to describe the long‐term impact, examine the threat to other deciduous fruit crops and cultivars and assess the need for adapted management or harvesting methods. [ABSTRACT FROM AUTHOR]

Background: Chemoreception is crucial for insect fitness, underlying for instance food-, host-, and mate finding. Chemicals in the environment are detected by receptors from three divergent gene families: odorant receptors (ORs), gustatory receptors (GRs), and ionotropic receptors (IRs). However, how the chemoreceptor gene families evolve in parallel with ecological specializations remains poorly understood, especially in the order Coleoptera. Hence, we sequenced the genome and annotated the chemoreceptor genes of the specialised ambrosia beetle Trypodendron lineatum (Coleoptera, Curculionidae, Scolytinae) and compared its chemoreceptor gene repertoires with those of other scolytines with different ecological adaptations, as well as a polyphagous cerambycid species. Results: We identified 67 ORs, 38 GRs, and 44 IRs in T. lineatum ('Tlin'). Across gene families, T. lineatum has fewer chemoreceptors compared to related scolytines, the coffee berry borer Hypothenemus hampei and the mountain pine beetle Dendroctonus ponderosae, and clearly fewer receptors than the polyphagous cerambycid Anoplophora glabripennis. The comparatively low number of chemoreceptors is largely explained by the scarcity of large receptor lineage radiations, especially among the bitter taste GRs and the 'divergent' IRs, and the absence of alternatively spliced GR genes. Only one non-fructose sugar receptor was found, suggesting several sugar receptors have been lost. Also, we found no orthologue in the 'GR215 clade', which is widely conserved across Coleoptera. Two TlinORs are orthologous to ORs that are functionally conserved across curculionids, responding to 2-phenylethanol (2-PE) and green leaf volatiles (GLVs), respectively. Conclusions: Trypodendron lineatum reproduces inside the xylem of decaying conifers where it feeds on its obligate fungal mutualist Phialophoropsis ferruginea. Like previous studies, our results suggest that stenophagy correlates with small chemoreceptor numbers in wood-boring beetles; indeed, the few GRs may be due to its restricted fungal diet. The presence of TlinORs orthologous to those detecting 2-PE and GLVs in other species suggests these compounds are important for T. lineatum. Future functional studies should test this prediction, and chemoreceptor annotations should be conducted on additional ambrosia beetle species to investigate whether few chemoreceptors is a general trait in this specialized group of beetles. [ABSTRACT FROM AUTHOR]

In 2023, two bark beetle species were recorded in Russia for the first time based on findings in Sochi: the cypress bark beetle, Phloeosinus armatus, on Mediterranean cypress (Cupressus sempervirens) and the black twig borer, Xylosandrus compactus, on southern magnolia (Magnolia grandiflora), noble laurel (Laurus nobilis), and cherry laurel (Prunus laurocerasus). P. armatus is a Mediterranean pest attacking exclusively Cupressaceae. In Sochi, it was recorded on cypress trees in several locations, including on plants for planting imported from Italy. X. compactus is a highly polyphagous pest from East Asia. In Sochi, it has established populations in ornamental planted areas. The paper provides species descriptions with identification keys. One specimen of X. compactus from Sochi was DNA‐barcoded and compared with 31 specimens deposited in the BOLD and GenBank under the name of X. compactus. High genetic variability (>7%) was detected highlighting the difficulty of identifying 'true' X. compactus using DNA data. Genetically, the specimen of X. compactus from Sochi was identical to those from Italy, Spain and France. An accidental introduction with ornamental plants for planting from Italy is considered the most probable pathway of invasion of both bark beetle species into the Russian Black Sea coast of the Caucasus. [ABSTRACT FROM AUTHOR]

Delayed dispersal of sexually mature offspring is a fundamental component of cooperative breeding in fungus farming ambrosia beetles. These beetles dwell in logs of recently deceased trees, where female offspring postpone reproduction and invest in alloparental care before dispersing to found a new nest. The wood quality affects investment of adult offspring in alloparental care and hence the breeder's reproductive success.This raises the question of whether dispersing breeders choose habitats strategically to optimise breeding prospects and modulate their offspring's helping propensity. To answer this question, here we tested experimentally whether during dispersal, Xyleborinus saxesenii Ratzeburg (Coleoptera: Scolytinae) uses olfactory cues emitted by mutualistic or pathogenic fungi as an information source on prospective habitat quality.As the mutualistic relationship between the fungi and beetles is obligate, fungus scent should provide a reliable source of information on habitat quality, indicating prior successful colonisation by conspecifics.We found no evidence for direct pathogen avoidance. However, the beetles clearly responded to scent of their mutualistic fungi, dependent on dispersal state. At the onset of dispersal, females avoided the scent of fungus mutualists, whereas they were attracted to them after being exhausted by an experimentally prolonged dispersal time.The observed change of preference during dispersal suggests that beetles freshly emerging from their home gallery may choose pristine habitat by avoiding mutualist scent. This might help to avoid competition with conspecifics and potential pathogen and parasite cross contamination. Exhausted beetles, however, may accept these risks and choose successfully colonised habitat to avoid starvation.State‐dependent adjustment of habitat preferences may be exhibited also in other economically impactful bark and ambrosia beetles, which prompts further study of the olfactory cues used by these beetles during dispersal. [ABSTRACT FROM AUTHOR]

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are among the most devastating pests of orchards, nurseries, and forests. Improving trap design and ethanol lures for capturing ambrosia beetles is necessary to develop effective monitoring and management strategies. In this 2-year study, we assessed 4 trap designs and 3 commercially formulated ethanol lures to refine trapping methods tailored for orchard environments in the eastern United States. Our investigation included orchards in 2 regions, Georgia (pecan orchards) and New York (apple orchards), targeting major ambrosia beetle (Coleoptera: Curculionidae) pest species such as Xylosandrus crassiusculus (Motschulsky), X. compactus (Eichhoff), X. germanus (Blandford), and Anisandrus maiche (Stark). Among the trap designs evaluated, clear sticky cards were most effective for capturing ambrosia beetles across orchard locations. Notably, in Georgia, sticky cards paired with specific low-release ethanol lures demonstrated enhanced capture of X. crassiusculus and X. compactus , 2 key ambrosia beetle pests found infesting young pecan trees. Similarly, in New York, sticky cards baited with low-release ethanol lures captured the highest rates of X. germanus and A. maiche , thus indicating its suitability for diverse ambrosia beetle populations. Overall, our study provides practical implications for tailoring trapping protocols to optimize ambrosia beetle management strategies in orchard settings. [ABSTRACT FROM AUTHOR]

In 2009, we determined the effects of the enantiomeric composition of the kairomone, α-pinene, on trap catches of arboreal beetles (Coleoptera) in stands of eastern pine trees with resin dominated by (+)-α-pinene. We hypothesized that the responses of beetles would correlate with the predominant enantiomer of α-pinene found in host pines. Lures of (+)-, racemic (±), and (−)-α-pinene were added separately to ethanol-baited multiple-funnel traps. Species such as Monarthrum mali (Fitch), Dendroctonus terebrans (Olivier), Ips grandicollis (Eichhoff), and Pachylobius picivorus (Germar) (Coleoptera: Curculionidae) showed a preference for traps co-baited with (–)-α-pinene. α-Pinene enhanced attraction of Hylastes salebrosus Eichhoff, Hylastes porculus Erickson and Hylastes tenuis Eichhoff (Coleoptera: Curculionidae) to ethanol-baited traps with no effects from enantiomeric composition of α-pinene. The attraction of the ambrosia beetles, Xyleborinus saxesenii (Ratzeburg) and Dryoxylon onoharaense (Murayama) (Coleoptera: Curculionidae) to ethanol-baited traps was interrupted by the addition of α-pinene, regardless of enantiomeric composition. Species such as Xylosandrus germanus (Blandford), Cnestus mutilatus (Blandford) and Stenoscelis brevis (Boheman) (Coleoptera: Curculionidae) were unaffected by the presence of α-pinene. Trap catches of some species of longhorn beetles and bark beetle predators (Coleoptera: Cerambycidae, Cleridae, Elateridae, Histeridae, and Trogossitidae) were increased by the addition of α-pinene, although results varied by location. Platysoma spp. (Coleoptera: Histeridae) showed a marked preference for traps co-baited with (+)-α-pinene in Florida and Georgia. In summary, we found that the enantiomeric composition of α-pinene in hosts was not a good predictor of enantiomeric preferences by beetles. [ABSTRACT FROM AUTHOR]

Infestations of ambrosia beetles in the tribe Xyleborini (Coleoptera: Scolytinae) are associated with economic losses to horticultural trees due to branch die‐back and tree death. Ethanol is a key attractant used for monitoring flight activity.Trapping experiments were conducted in woodlots in Ohio, USA, and Veneto, Italy, to characterize the effect of ethanol release rate on captures of Anisandrus maiche, Xyleborinus saxesenii, Xylosandrus crassiusculus and Xylosandrus germanus. In Ohio (2019, 2020 and 2021) and Italy (2021), traps were baited with centrifuge tubes that were modified to achieve ethanol release rates of 0.1–13.2 g/day. In Ohio (2022), traps were baited with varying quantities of manufactured lures to achieve release rates of 0.02–1.4 g/day.There was no consistent relationship between ethanol release rate and trap captures for the modified centrifuge tubes. In nine of sixteen analyses, traps baited with the centrifuge tubes releasing ethanol at 1.1 g/day or higher collected more A. maiche, X. saxesenii, X. crassiusculus and X. germanus than traps baited with centrifuge tubes releasing 0.1 g/day. In contrast, the manufactured lures releasing 0.1–1.4 g/day attracted more A. maiche, X. saxesenii, X. crassiusculus and X. germanus than lures releasing 0.02–0.05 g/day.This comprehensive study provides important insights into monitoring tactics for ambrosia beetles along with implications for optimizing ethanol‐baited traps as part of a 'push‐pull' strategy whereby repellents are used to 'push' beetles away from vulnerable trees and attractants are used to 'pull' them into annihilative traps. [ABSTRACT FROM AUTHOR]

Simple Summary: In our study, we explored ways to effectively trap invasive ambrosia beetles, which pose significant threats to trees and forests. We focused on comparing two types of bait—pure ethanol and denatured ethanol—to attract these pests in different environments like tree nurseries and orchards. We found that traps using pure ethanol captured more Xylosandrus germanus beetles compared to those with denatured ethanol. Our findings suggest that using pure ethanol could be more effective for monitoring certain ambrosia beetle species. This research contributes to better pest management strategies, helping protect trees from invasive pests, ultimately benefiting society by safeguarding ecosystems and agricultural productivity. Ambrosia beetles, particularly invasive species within the tribe Xyleborini, such as Xylosandrus germanus (Blandford, 1894), pose significant threats to various ecosystems and managed habitats worldwide. Monitoring these invaders is vital for effective pest management, typically accomplished through ethanol-baited traps. We compared trap efficacy using denatured ethanol versus absolute ethanol in orchards, tree nurseries, and lumber yards in northeastern Ohio, USA, finding that absolute ethanol traps captured significantly more X. germanus. Analysis revealed acetone, ethanol, and methyl isobutyl ketone in the denatured ethanol, likely impacting trap efficacy. Our study underscores the importance of using pure denatured ethanol without acetone for effective monitoring, especially for X. germanus. Exotic xyleborines dominated trap captures across various habitats, emphasizing the need for tailored pest management strategies. Further research is warranted to explore the chemical ecology of ambrosia beetles and the influence of ethanol impurities on trap effectiveness. [ABSTRACT FROM AUTHOR]

Early detection of invasive species is critical for preventing ecological and economic damage and maintaining ecosystem health. In Hawaiʻi, a complex of generalist ambrosia beetle species in the tribe Xyleborini (Coleoptera: Scolytinae) are threatening the health and productivity of forests and crops due to their association with tree diseases such as rapid ʻōhiʻa death (ROD) and key agricultural commodities including coffee and macadamia.We conducted trapping experiments to determine the efficacy of semiochemicals to attract and repel Xyleborini ambrosia beetles within two ʻōhiʻa (Metrosideros polymorpha) forests on the Island of Hawaiʻi. We compared the attraction of beetles to 100% ethanol and a 1:1 mixture of ethanol: methanol at Waiākea Forest Reserve and ʻŌlaʻa Forest in Hawaiʻi Volcanoes National Park. In addition, we tested the extent to which verbenone and verbenone + methyl salicylate repellents (SPLAT® Verb and SPLAT® Beetle Guard, respectively) deterred beetles from baited traps at Waiākea Forest Reserve in two separate experiments.For all invasive ambrosia beetle species, including Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xyleborus perforans, Xylosandrus compactus, and Xylosandrus crassiusculus, more beetles were captured in traps baited with 100% ethanol than 1:1 ethanol: methanol. Across all species, both repellents were effective, with fewer beetles captured in traps equipped with repellents.Our research demonstrates the utility of semiochemicals for attracting and repelling invasive ambrosia beetle species in Hawaiʻi, and the potential use of these tools for early detection and management strategies. [ABSTRACT FROM AUTHOR]

Laurel wilt, a fungal disease (Harringtonia lauricola T.C. Harr., Fraedrich and Aghayeva) spread by the Asian redbay ambrosia beetle [Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae)], presents an imminent threat to North American members of the Lauraceae family, having caused extensive mortality in several species, especially redbay (Persea borbonia L. Spreng). Varying levels of disease resistance have been recorded in redbay under controlled conditions. To investigate if previously monitored putatively resistant field redbays have influenced the regeneration and survival of conspecifics within the surrounding 0.08 ha, a survey was conducted in 2018-19 and compared to similar data collected years prior (2008-09, 2013) along the coasts of Florida, Georgia, and South Carolina, United States. Plots were originally established at six disease-infested study sites around large redbay (>7.5-cm diameter at breast height (1.37 m) (DBH)) that had survived the initial laurel wilt disease epidemic that began in approximately 2007. In 2018-19, a subset of 61 plots within 16 m of the original "survivor" redbay were recorded and compared to previous surveys. Among the original redbay selected for resistance, 22 of 61 (36%) survivors across all sites were alive in 2018 with survival rates varying from 0 to 70% between survey periods (average mortality 3.6%/year). Trees that died in years since 2008-09 had their plots reclassified as susceptible or "suscepts". Changes in mean quadratic diameter at 1.37 m of redbay plots near survivors were significantly greater than those near suscepts, and in 2018-19, the average diameter of redbay near survivors was 7.62 cm vs. 4.90 cm for suscepts. The diameter distribution of dead and live redbay in the whole population showed a decrease in live individuals surviving past 8 cm DBH in 2018–2019, but 20 of 22 survivor candidate trees were larger than 8 cm DBH. Regeneration was occurring both clonally and sexually and tended to be greater near suscepts, but midstory resprouts per hectare and understory seedlings interacted significantly with the site and the latter differed between sites. These findings indicate that redbay is regenerating in these ecosystems, and disease resistance may allow for increased average tree size for some individuals, but an upper size threshold of around 8 cm DBH may still exist for much of the population. In addition, the importance of site variables in regeneration was apparent, making either local genetic or environmental effects an important topic for future research. Continuing to monitor these survivors while locating new candidates for disease screenings and breeding, preventing the introductions of new strains of H. lauricola, shedding light on the nature of resistance and its heritability, and initiating outplanting trials with resistant germplasm are instrumental steps in bringing redbay back to prominence in its historical range. [ABSTRACT FROM AUTHOR]

The polyphagous shot hole borer beetle (PSHB, Euwallacea fornicatus) is a pest of global significance. PSHB is an ambrosia beetle which, together with its mutualistic fungi (including Fusarium euwallaceae), can cause the death of more than 100 tree species in invaded ranges. Management of PSHB mostly relies on the removal of infested plant material. Chemical control options have been investigated only in the USA and Israel and only on a few tree species. This study evaluated four chemical treatments for the therapeutic control of PSHB on American sweetgum (Liquidambar styraciflua) in South Africa (1) bifenthrin + surfactant (alcohol ethoxylate), (2) cypermethrin + surfactant (vitamin E) + salicylic acid, (3) emamectin benzoate, and (4) propiconazole. Trees were inoculated with F. euwallaceae and mature PSHB females using a novel technique to document fungal lesion development and PSHB colony establishment success. The bifenthrin and cypermethrin treatments reduced additional PSHB colonisation attempts on treated trees by ca. 40%, while the other treatments had no effect. Colony establishment success was reduced in all treatments by between 20 and 40%. Fungal growth was inhibited only after the application of propiconazole by ca. 36%. Gallery length and the number of PSHB individuals in successful colonies were unaffected by any of the chemical treatments. These results indicate that chemical control of PSHB is only partially effective. Successful PSHB management will likely depend on a combination of chemical control options and other control strategies in an integrated pest management program. [ABSTRACT FROM AUTHOR]

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Abstract 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.

Animal societies use nestmate recognition to protect against social cheaters and parasites. In most social insect societies, individuals recognize and exclude any non‐nestmates and the roles of cuticular hydrocarbons as recognition cues are well documented. Some ambrosia beetles live in cooperatively breeding societies with farmed fungus cultures that are challenging to establish, but of very high value once established. Hence, social cheaters that sneak into a nest without paying the costs of nest foundation may be selected. Therefore, nestmate recognition is also expected to exist in ambrosia beetles, but so far nobody has investigated this behavior and its underlying mechanisms. Here we studied the ability for nestmate recognition in the cooperatively breeding ambrosia beetle Xyleborinus saxesenii, combining behavioural observations and cuticular hydrocarbon analyses. Laboratory nests of X. saxesenii were exposed to foreign adult females from the same population, another population and another species. Survival as well as the behaviours of the foreign female were observed. The behaviours of the receiving individuals were also observed. We expected that increasing genetic distance would cause increasing distance in chemical profiles and increasing levels of behavioural exclusion and possibly mortality. Chemical profiles differed between populations and appeared as variable as in other highly social insects. However, we found only very little evidence for the behavioural exclusion of foreign individuals. Interpopulation donors left nests at a higher rate than control donors, but neither their behaviours nor the behaviours of receiver individuals within the nest showed any response to the foreign individual in either of the treatments. These results suggest that cuticular hydrocarbon profiles might be used for communication and nestmate recognition, but that behavioural exclusion of non‐nestmates is either absent in X. saxesenii or that agonistic encounters are so rare or subtle that they could not be detected by our method. Additional studies are needed to investigate this further. [ABSTRACT FROM AUTHOR]

The polyphagous shot hole borer (PSHB), Euwallacea fornicatus Eichhoff (Coleoptera: Curculionidae, Scolytinae), is a significant tree‐killing pest recently introduced into South Africa. Many native trees in urban settings are susceptible to infestation, but the presence of PSHB in natural ecosystems is unstudied. The presence and drivers of PSHB colonization in 1682 trees of 68 species were evaluated in 51 plots across a native Afrotemperate forest complex in South Africa. Breeding colonies of PSHB were found in six native species (breeding hosts). An additional 11 species did not contain PSHB colonies but hosted its mutualistic fungus Fusarium euwallaceae Freeman et al. (Hypocreales: Nectriaceae). Invasibility increased when plots were closer to the urban infestation border, further away from surface water, and when containing a larger number of breeding hosts. Invasibility decreased with an increase in tree species richness. Polyphagous shot hole borers were found in climax forest distant to urban areas at sites frequented by tourists. The severity of infestation of trees increased with an increase in host diameter, breeding host abundance, and infested tree abundance. Probability of infestation increased with an increase in the number of infested trees. Infested trees were not spatially clumped. Instead, PSHB preferentially selected eight of the 17 native host species. And the data suggest that larger trees of these species may be more susceptible to PSHB. Eight species were infested at random and two were infested seemingly accidentally. Infestations increased more rapidly on larger trees and on those surrounded by a high abundance of breeding hosts. This study confirms that Afrotemperate forests are highly susceptible to invasion by PSHB. Direct anthropogenic impact had no discernible effect on infestations, but humans aided spread of PSHB to distant sites. Halting movement of contaminated wood is important. Management of PSHB should focus on highly infested areas and trees as these increase the likelihood of further and more severe infestations. [ABSTRACT FROM AUTHOR]

Xylosandrus crassiusculus is an invasive ambrosia beetle comprising two differentiated genetic lineages, named cluster 1 and cluster 2. These lineages invaded different parts of the world at different periods of time. We tested whether they exhibited different climatic niches using Schoener's D and Hellinger's I indices and modeled their current potential geographical ranges using the Maxent algorithm. The resulting models were projected according to future and recent past climate datasets for Europe and the Mediterranean region. The future projections were performed for the periods 2041–2070 and 2071–2100 using 3 SSPs and 5 GCMs. The genetic lineages exhibited different climate niches. Parts of Europe, the Americas, Sub-Saharan Africa, Asia, and Oceania were evaluated as suitable for cluster 1. Parts of Europe, South America, Central and South Africa, Asia, and Oceania were considered as suitable for cluster 2. Models projection under future climate scenarios indicated a decrease in climate suitability in Southern Europe and an increase in North Eastern Europe in 2071–2100. Most of Southern and Western Europe was evaluated as already suitable for both clusters in the early twentieth century. Our results show that large climatically suitable regions still remain uncolonized and that climate change will affect the geographical distribution of climatically suitable areas. Climate conditions in Europe were favorable in the twentieth century, suggesting that the recent colonization of Europe is rather due to an increase in propagule pressure via international trade than to recent environmental changes. [ABSTRACT FROM AUTHOR]

A molecular tool has been set up for the unambiguous molecular identification of the ambrosia beetle, Xyleborinus saxesenii (Ratzeburg, 1837) (Coleoptera Curculionidae Scolytinae), the cosmopolitan fruit‐tree pinhole borer, widely distributed in temperate regions of the five continents, where it infests a wide range of hardwoods and softwoods. The test was based on real‐time PCR with TaqMan probe technology and was developed on whole insect bodies (adults) as well as on frass produced by the beetle. The test was shown to meet the criteria established by EPPO for the harmonization of molecular diagnostic methods. In particular, the test gave good results in terms of analytical specificity (inclusivity and exclusivity) and analytical sensitivity, and was fully repeatable and reproducible. Since X. saxesenii is one of the most commonly intercepted ambrosia beetles during phytosanitary controls worldwide, this practical diagnostic tool will be useful for its rapid identification of the beetle in biological material (frass, body fragments). The test can be useful in countries where X. saxesenii is a quarantine species, as well as in the EPPO region. [ABSTRACT FROM AUTHOR]

A new species of ambrosia beetle Indocryphalus chiyui Lin & Beaver (tribe Xyloterini LeConte, 1876) from Taiwan is described. The species is monogamous and xylomycetophagous, breeding in Castanopsis cuspidata var. carlesii (Hemsl.) Yamazaki (Fagaceae). Indocryphalus sordidus (Blandford) is recorded for the first time from Taiwan. Diagnostic characters, biological data and a key to species of Indocryphalus in Taiwan are provided. [ABSTRACT FROM AUTHOR]

The Microperus ambrosia beetle fauna of Taiwan is reviewed. Microperus alpha (Beeson, 1929), M. kadoyamaensis (Murayama, 1934), M. kirishimanus (Murayama, 1955), M. perparvus (Sampson, 1922), M. quercicola (Eggers, 1926) have all been previously recorded from Taiwan. Microperus bucolicus Sittichaya, Smith & Beaver, 2021 and M. latesalebrinus Smith, Beaver & Cognato, 2020 are new country records for Taiwan. Of which, the males of M. alpha, M. bucolicus, M. kadoyamaensis, M. latesalebrinus, M. perparvus, and M. quercicola are described for the first time. In this study, we document a likely occurrence of mycocleptism by M. bucolicus. Diagnostic characters, biological data and a key to species in Taiwan are provided. [ABSTRACT FROM AUTHOR]

Many insect taxa cultivate fungi for food. Compared to well-known fungus cultivation in social insects, our knowledge on fungus cultivation in nonsocial insects is still limited. Here, we studied the nutritional potentials of the fungal cultivar, Penicillium herquei, for the larvae of its nonsocial insect farmer, Euops chinensis, a specialist on Japanese knotweed Reynoutria japonica. Overall, fungal hyphae and leaf rolls contained significantly higher carbon (C), stable isotopes of C (d13C), and nitrogen (d15N) but significantly lower C/N ratios compared to unrolled leaves, whereas insect bodies contained significantly higher N contents but lower C and C/N ratios compared to other types of samples. The MixSIAR model indicated that fungal hyphae contributed a larger proportion (0.626-0.797) to the diet of E. chinensis larvae than leaf materials. The levels of ergosterol, six essential amino acids, seven nonessential amino acids, and three B vitamins tested in fungal hyphae and/or leaf rolls were significantly higher than in unrolled leaves and/or larvae. The P. herquei genome contains the complete set of genes required for the biosynthesis of ergosterol, the essential amino acids valine and threonine, nine nonessential amino acids, and vitamins B2 and B3, whereas some genes associated with five essential and one nonessential amino acid were lost in the P. herquei genome. These suggest that P. herquei is capable of providing the E. chinensis larvae food with ergosterol, amino acids, and B vitamins. P. herquei appears to be able to synthesize or concentrate these nutrients considering that they were specifically concentrated in fungal hyphae. IMPORTANCE The cultivation of fungi for food has occurred across divergent insect lineages such as social ants, termites, and ambrosia beetles, as well as some seldomreported solitary insects. Although the fungal cultivars of these insects have been studied for decades, the dietary potential of fungal cultivars for their hosts (especially for those nonsocial insects) is largely unknown. Our research on the mutualistic system Euops chinensis-Penicillium herquei represents an example of the diverse nutritional potentials of the fungal cultivar P. herquei in the diet of the larvae of its solitary host, E. chinensis. These results demonstrate that P. herquei has the potential to synthesize or concentrate ergosterol, amino acids, and B vitamins and benefits the larvae of E. chinensis. Our findings would shed light on poorly understood fungal cultivation mutualisms in nonsocial insects and underscore the nutritional importance of fungal cultivars in fungal cultivation mutualisms. [ABSTRACT FROM AUTHOR]

Clarifying the influence of disturbances by biotic and abiotic agents on long‐term changes in forest structure and demographic rates is an important task of forest ecology. Here, we investigated changes in forest structure and demographic rates and the effects of biotic and abiotic factors (sika deer, ambrosia beetle, neighborhood trees, and indices of strong wind and wetness) in a 4‐ha long‐term ecological study plot in a lowland warm temperate rain forest on Yakushima Island, Japan, from 1996 to 2019 for three regeneration groups related to gap dynamics (gap demander: GD, light shade tolerant: LS, and strong shade tolerant: SS). GD had relatively lower recruitment and survival than LS and/or SS. Changes in demographic rates were not significantly correlated with those in the index of strong wind in any regeneration group. The effects of sika deer on demographic rates did not differ among groups. Stems of Fagaceae species belonging to LS attacked by ambrosia beetles recorded in 2013 did not significantly differ in RGR and survival rates. Our results indicate that despite the relatively long monitoring period of 23 years, we did not detect significant effects of strong winds on demographic rates among regeneration groups, and shade‐tolerant species (LS and SS) showed better demographic performance than light‐demanding species (GD) and an increase in total basal area over time. We need longer monitoring of forest dynamics to understand forest responses to disturbances considering several factors, including the time lag of demographic responses to disturbances and the long‐term effects of disturbances. [ABSTRACT FROM AUTHOR]

This article provides information on the distribution and abundance of the invasive ambrosia beetle Xyleborinus attenuatus Blandford in the Czech Republic. The beetle, originally from East Asia, is believed to be widespread in the country and mainly found in soft deciduous trees. While it has not caused economic damage, it is a carrier of ambrosia fungi and should be monitored. The article also discusses the beetle's flight activity, overwintering habits, and preferred tree species. Additionally, the document is a compilation of references from various scientific articles and theses that explore the behavior of ambrosia beetles in different forest ecosystems, covering topics such as trapping methods, bacterial involvement, distribution, and the impact of bark beetle outbreaks. The references are written in multiple languages. [Extracted from the article]

The ambrosia beetle Platypus quercivorus is a vector of a pathogenic fungus that causes Japanese oak wilt. Its host is Fagaceae trees; however, these beetles also erroneously bore into unsuitable, non‐host tree species, which can be affected by neighbouring host tree species and the size of the non‐host.We attached sticky sheets to the host and non‐host tree species of P. quercivorus and counted the number of beetles that landed weekly, in a season of beetle dispersal. We quantified the density of the host canopy above, the basal area of surrounding hosts and the diameter at breast height (DBH) of each non‐host tree.The host canopy density affected the probability of beetles landing on non‐hosts, and the host basal area and non‐host DBH affected the number of beetles landing on non‐hosts. Thus, P. quercivorus is probably initially attracted to a dense host canopy, secondly attracted to the high density of the host and thereafter aggregate onto thick trees, including non‐host species.The number of beetles landing on the surrounding host also affected beetle landing on the non‐hosts, suggesting that landing on non‐hosts is an error that occurs in high frequency during the seasons when many beetles land on the hosts. [ABSTRACT FROM AUTHOR]

The east Asian ambrosia beetle Xylosandrus germanus (Blanford) was first detected in the United States in 1932. It now occurs across much of eastern North America and parts of the Pacific Northwest. It attacks a broad range of stressed, woody hosts including ornamental and orchard species. The foundress tunnels into the sapwood of hosts where it cultures a symbiotic fungus as food for its offspring. A few other ambrosia beetles have been shown to possess a facultatively eusocial structure among gallery members, but this has not been described for Xylosandrus spp. Using a novel artificial diet arena, we quantified the behaviors of X. germanus larvae and adults (foundress and mature offspring) over 10 wk inside their galleries. Foundresses were responsible for constructing the gallery. They also initially tended the fungal garden and brood but eventually spent most of their time blocking the gallery entrance. Larvae were mainly observed to feed, crawl, or be inactive within the gallery, regardless of the absence or presence of adult siblings. Adult female offspring were primarily inactive, likely due to dormancy. Adult male offspring actively crawled and attempted to mate with their sisters before eventually dispersing out of the gallery. Cooperative hygienic behaviors (removal of frass, cannibalism of dead nest mates, grooming siblings) were observed but a division of labor among offspring was not clear. Rather, foundress behaviors were mostly distinct from offspring behaviors, particularly as the gallery aged. Because no overlap in generations occurred, X. germanus displays a quasisocial structure. [ABSTRACT FROM AUTHOR]

Anisandrus maiche Stark (Coleoptera: Curculionidae: Scolytinae) is a non-native ambrosia beetle from central Asia that has been spreading throughout the eastern United States since 2005. Preferred hosts of A. maiche are not well characterized within its currently invaded range, but it is established in managed and natural forests throughout Indiana. Current monitoring and detection efforts for this beetle rely on ethanol-baited traps, but fungal volatiles may alter the attraction of A. maiche to ethanol. In this study, we conducted trapping experiments in Indiana to determine the extent to which a suite of common fungal alcohols influences the response of A. maiche to ethanol-baited traps. We then evaluated isoamyl and isobutyl alcohol as potential attractants for A. maiche and their ability to enhance attraction to ethanol. Lastly, we used SPME-GC-MS to identify volatiles from Ambrosiella cleistominuta (Mayers & Harr.), the fungal symbiont of A. maiche , grown for 7 and 14 days on malt extract agar. Benzyl alcohol, isobutyl alcohol, hexanol, methyl phenylacetate, phenethyl alcohol, and piperitone reduced the attraction of A. maiche to ethanol-baited traps in the field. Moreover, adding methyl benzoate and isoamyl alcohol individually to ethanol-baited traps did not further increase A. maiche capture. When paired with ethanol, isoamyl alcohol repelled beetles in the early flight period but did not significantly increase trap capture during the fall flight. These results represent a first step in understanding the role of fungal volatiles in the colonization behavior of A. maiche and may ultimately inform management strategies for this species. [ABSTRACT FROM AUTHOR]

Xylosandrus germanus (Blandford) is an invasive species of ambrosia beetle known to attack apple trees in North America. Xylosandrus germanus are attracted to ethanol produced by stressed and injured trees and can be a serious problem when grafting a new cultivar onto established fruit trees (topworking). The objective of this study was to evaluate the efficacy of 2 insecticides (emamectin benzoate and azadirachtin) and injection timing (fall and spring) on their ability to control X. germanus colonization in apple trees with simulated topworking. Our study shows evidence that both emamectin benzoate and azadirachtin injections can reduce X. germanus infestations; however, our results were inconsistent. The timing of injections influenced X. germanus, with spring injected azadirachtin being more effective than fall injections. Residue analyses of emamectin benzoate and azadirachtin showed the presence of residues in woody tissue comparable to those found in leaves. [ABSTRACT FROM AUTHOR]

The redbay ambrosia Xyleborus glabratus beetle has emerged as a significant pest of Laurel trees, Persea spp. [Laurales: Lauraceae], in the southeastern USA due to its symbiotic association with the pathogenic fungus Harringtonia lauricola, the causal agent of the laurel wilt disease. We evaluated the interaction of different species of ambrosia beetles with redbay trees Persea barbonia infected by H. lauricola. We measured the landing and emergence rates of different ambrosia beetle species throughout the wilting process at different heights. We assessed landing height passively in two redbay stands by placing staggered, unbaited white sticky traps at three height levels (low: 0–1 m; middle: 1–1.5 m; high: 1.5–2 m). We collected nine other Scolytinae species including Xyleborus volvulus, Xyleborinus saxesenii, Euplatypus compositus, Xyleborus bispinatus, and Xyleborus affinis. In the three experiments and both locations, the primary vector of H. lauricola, X. glabratus, was the most frequently collected species both in the landing captures and in the emergence rate, independently of the wilting status of the host. However, the numbers and diversity of ambrosia beetles landing on trees and emerging from logs increased when trees were in an advanced stage of wilting. Our results indicate that other ambrosia beetles benefit marginally from laurel wilt and that the contribution of secondary ambrosia beetle vectors in the spread of H. lauricola through lateral infection in the redbay system is most likely minimal as compared to the contribution of X. glabratus. [ABSTRACT FROM AUTHOR]

The redbay ambrosia beetle, harmless in its native Asia, has become a formidable pest since its introduction to the United States in 2002. The beetle spreads the fungus Harringtonia lauricola, a lethal pathogen of North American Lauraceae trees, including avocados. The fungus infection triggers a rapid onset of laurel wilt disease, which has nearly eliminated laurel trees across the southeastern United States within a few years. The beetle has spread across nearly 300 counties in the Southeast, facilitated by trade in wood products. Effective control in natural environments remains an unresolved challenge; in avocado groves, infected trees must be removed and destroyed. Introduction of X. glabratus into Mexico, California, Central America, or South America, regions with substantial avocado industries and diverse native Lauraceae species, would be disastrous. International cooperation is necessary to address this threat.

The granulate ambrosia beetle Xylosandrus crassiusculus (Motschulsky) has been reported to bore into the fuel pipe of petrol vehicles, leading to petrol leakage and fire accidents. Blending of ethanol in petrol due to the National Policy on Biofuels is implicated in X. crassiusculus getting attracted to the fuel pipe of petrol vehicles leading to burning of vehicles and loss of life. [ABSTRACT FROM AUTHOR]

Xyleborus beetles, a diverse group of ambrosia beetles, present challenges to forestry and agriculture due to their damaging burrowing behavior and symbiotic relationships with fungi. This review synthesizes current knowledge on the biology, ecology, and management of Xyleborus. We explore the beetles’ life cycle, reproductive strategies, habitat preferences, and feeding habits, emphasizing their ecological and economic impacts. Control and management strategies, including preventive measures, chemical and biological control, and integrated pest management (IPM), are critically evaluated. Recent advances in molecular genetics and behavioral studies offer insights into genetic diversity, population structure, and host selection mechanisms. Despite progress, managing Xyleborus effectively remains challenging. This review identifies future research needs and highlights innovative control methods, such as biopesticides and pheromone-based trapping systems.

We present the first report of Fusarium euwallaceae and its ambrosia beetle vector Euwallacea fornicatus in deciduous fruit tree orchards in South Africa. Fusarium euwallaceae, is shown to be pathogenic to pear (Pyrus communis) and the beetle can establish viable colonies in this host. [ABSTRACT FROM AUTHOR]

The range of interactions between Cladosporium, a ubiquitous fungal genus, and insects, a class including about 60% of the animal species, is extremely diverse. The broad case history of antagonism and mutualism connecting Cladosporium and insects is reviewed in this paper based on the examination of the available literature. Certain strains establish direct interactions with pests or beneficial insects or indirectly influence them through their endophytic development in plants. Entomopathogenicity is often connected to the production of toxic secondary metabolites, although there is a case where these compounds have been reported to favor pollinator attraction, suggesting an important role in angiosperm reproduction. Other relationships include mycophagy, which, on the other hand, may reflect an ecological advantage for these extremely adaptable fungi using insects as carriers for spreading in the environment. Several Cladosporium species colonize insect structures, such as galleries of ambrosia beetles, leaf rolls of attelabid weevils and galls formed by cecidomyid midges, playing a still uncertain symbiotic role. Finally, the occurrence of Cladosporium in the gut of several insect species has intriguing implications for pest management, also considering that some strains have proven to be able to degrade insecticides. These interactions especially deserve further investigation to understand the impact of these fungi on pest control measures and strategies to preserve beneficial insects. [ABSTRACT FROM AUTHOR]

Laurel wilt disease, caused by the fungus Harringtonia lauricola and transmitted by the ambrosia beetle Xyleborus glabratus, poses a significant ecological and economic threat to various species of the Lauraceae family, particularly avocado. The disease is characterized by the formation of tyloses blocking xylem vessels, hindering water conductance, and decreasing leaf gas exchange. The relationship between the fungus and the beetle is complex and not fully understood, which can be described, in general, as ambrosial symbiosis depending on the habitat. The secretome of the pathogen includes hydrolytic enzymes that aid in colonization and resistance of host defence. This paper reviews the current understanding of the causes, impacts, and management strategies for laurel wilt disease. Also, it provides an overview of the complex relationship between the fungal pathogen and its beetle vector and explores the various virulence factors and secretome of H. lauricola that contribute to the aggressive nature of the disease. Moreover, this review states the ecological and economic impacts of laurel wilt, particularly on ecologically and economically valuable plants such as avocado. Current management strategies for controlling the disease, including the use of insecticides, fungicides, and biological control methods, are reviewed. Finally, we highlight some critical key points in ambrosia symbiosis biology that are of importance for disease control. [ABSTRACT FROM AUTHOR]

Phloeosinus aubei is invasive in Central Europe, spreading northward from the Mediterranean region because of climate change. P. aubei has the potential to become a pest of mature, naturally occurring juniper trees (Juniperus communis) in protected areas, as well as junipers, thujas and cypresses in nurseries and urban environments. In 2020 and 2021, we conducted two experiments to compare various lures for trapping P. aubei. In the first experiment, we compared four lures: α‐pinene; turpentine; a mixture of cade oil, juniper berry oil and ethanol; and a juniper branch (8–10 cm long, 3–5 cm wide) deployed with ethanol. In the second experiment, we compared Hostowit® with a juniper branch (8–10 cm long, 3–5 cm wide) deployed with ethanol. In both experiments, juniper branches deployed with ethanol attracted a greater number of P. aubei beetles compared to the other lures. In total, we captured 1056 individuals belonging to 36 species of Scolytinae. Among the most abundant species, Xyleborinus saxesenii, Xyleborus monographus and Anisandrus dispar were lured by ethanol in combination with other substances or deployed with juniper branches. Xyleborus dryographus showed a positive association with turpentine. Ips typographus was positively associated with α‐pinene, while Orthotomicus laricis, Hylastes attenuatus and Gnathotrichus materiarius were positively associated with Hostowit® lure. [ABSTRACT FROM AUTHOR]

Simple Summary: Symbiotic bacteria play an essential role in the digestion, detoxification, and nutrient supply of bark and ambrosia beetles. They may even promote the invasiveness and adaptability of invasive beetles. However, as a newly invasive pest in China, the diversity and community structure of bacteria associated with Hylurgus ligniperda is still unclear. This hinders our ability to comprehend their invasion mechanism and ecological adaptability. Therefore, this study revealed the differences in the diversity and community composition of associated bacteria in the beetle's elytra, prothorax, and gut. Our findings revealed that the microbial population of the elytra was distinct from that of the prothorax and gut. Additionally, gender disparities existed throughout the bacterial population of elytra. The distribution of associated bacteria in different organs of males and females may indicate that they undertake different ecological functions. This study will help to understand the bacterial communities that may play important roles in Hylurgus ligniperda. Hylurgus ligniperda (Fabricius) (Curculionidae: Scolytinae) is a new invasive pest beetle in China, which colonized the Shandong province, causing devastating damage. Originating in Europe, it has spread to Oceania, Asia, North and South America. Bacterial associates have been frequently reported to play a vital role in strengthening the ecological adaptations of bark and ambrosia beetles. The environmental adaptability of H. ligniperda may be supported by their associated bacteria. Bacterial communities colonizing different body parts of insects may have different functions. However, little is known about the bacteria associated with H. ligniperda and their potential involvement in facilitating the adaptation and invasion of the beetles into new environments. In this study, we employed high-throughput sequencing technology to analyze the bacterial communities associated with male and female adults of H. ligniperda by comparing those colonizing the elytra, prothorax, and gut. Results showed that the bacterial communities of male and female adults were similar, and the elytra samples had the highest bacterial diversity and richness, followed by the gut, while the prothorax had the lowest. The dominant phyla were Proteobacteria, Firmicutes, and Actinobacteriota, while the dominant genera were Serratia, Lactococcus, Rhodococcus, unclassified Enterobacteriaceae, and Gordonia. Among these, Rhodococcus and Gordonia were the specific genera of endobacteria and ectobacteria, respectively. Differences in the distribution of associated bacteria may suggest that they have different ecological functions for H. ligniperda. The results of functional prediction showed that bacteria were enriched in terpenoid backbone biosynthesis, degradation of aromatic compounds, limonene and pinene degradation, neomycin, kanamycin and gentamicin biosynthesis, indicating that they may assist their beetles in synthesizing pheromones, degrading toxic secondary metabolites of host trees, and antagonizing pathogenic fungi. These results help us understand the interaction between H. ligniperda and bacteria and highlight possible contributions to the invasion process. [ABSTRACT FROM AUTHOR]

This study identifies fungi associated with Euwallacea fornicatus and determines whether these fungal species play the role of primary symbiont. E. fornicatus adults that emerged from the branches of infested trees in Okinawa main island, Japan, were collected and used to isolate fungi. Fusarium kuroshium and Penicillium citrinum were the most dominant fungal associates of females and males, respectively. F. kuroshium was much more frequently isolated from the head, including mycangia (fungus-carrying organs), of females than any other body parts. We inoculated healthy mango saplings with F. kuroshium or F. decemcellulare, both of which were symbionts of E. fornicatus females infesting mango trees. F. kuroshium decreased leaf stomatal conductance and rate of xylem sap-conduction area and increased length and area of xylem discoloration of the saplings, thereby weakening and killing some. These results suggest that F. kuroshium, a mycangial fungus of E. fornicatus, inhibits water flow in mango trees. This study is the first to report that F. kuroshium causes wilt disease in mango trees and that it is a primary fungal symbiont of E. fornicatus. [ABSTRACT FROM AUTHOR]

Bark and ambrosia beetles (Coleoptera: Curculionidae) are receiving increasing scientific interest because of the economic losses that they can cause in invaded areas. Nonetheless, there are a number of emerging pest species, belonging to different tribes, for which invasions have likely been overlooked in the past due to their inconspicuousness, taxonomic confusion and/or misidentification. In the summer of 2022, severe infestations by a bark beetle species belonging to the tribe Cryphalini were observed on mango (Mangifera indica L.) in Eastern Sicily (Italy). No information about bark beetle attacks on mango trees in Europe was available previously. However, the occurrence of a cryphaline bark beetle species causing rapid common fig tree (Ficus carica L.) dieback was reported for the same investigated area in 2014 and 2015. We aimed to identify the bark beetle species attacking mango and common figs, and to describe the fungal pathogens vectored by this beetle species. Our results revealed that the bark beetle species attacking mango and fig trees in the studied area is Cryphalus dilutus Eichhoff and that different fungal pathogens, i.e., species of Botryosphaeriaceae, Ceratocystis ficicola and Neocosmospora spp., are vectored by this beetle species. [ABSTRACT FROM AUTHOR]

Little is known concerning terpenoids produced by members of the fungal order Ophiostomales, with the member Harringtonia lauricola having the unique lifestyle of being a beetle symbiont but potentially devastating tree pathogen. Nine known terpenoids, including six labdane diterpenoids (1–6) and three hopane triterpenes (7–9), were isolated from H. lauricola ethyl acetate (EtOAc) extracts for the first time. All compounds were tested for various in vitro bioactivities. Six compounds, 2, 4, 5, 6, 7, and 9, are described functionally. Compounds 2, 4, 5, and 9 expressed potent antiproliferative activity against the MCF-7, HepG2 and A549 cancer cell lines, with half-maximal inhibitory concentrations (IC50s) ~12.54–26.06 μM. Antimicrobial activity bioassays revealed that compounds 4, 5, and 9 exhibited substantial effects against Gram-negative bacteria (Escherichia coli and Ralstonia solanacearum) with minimum inhibitory concentration (MIC) values between 3.13 and 12.50 μg/mL. Little activity was seen towards Gram-positive bacteria for any of the compounds, whereas compounds 2, 4, 7, and 9 expressed antifungal activities (Fusarium oxysporum) with MIC values ranging from 6.25 to 25.00 μg/mL. Compounds 4, 5, and 9 also displayed free radical scavenging abilities towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide (O2−), with IC50 values of compounds 2, 4, and 6 ~3.45–14.04 μg/mL and 22.87–53.31 μg/mL towards DPPH and O2−, respectively. These data provide an insight into the biopharmaceutical potential of terpenoids from this group of fungal insect symbionts and plant pathogens. [ABSTRACT FROM AUTHOR]

Ambrosia beetles are fungal-growing insects excavating galleries deep inside the wood. Their success as invaders increased scientific interest towards them. However, most studies on their microbiota targeted their fungal associates whereas the role of bacterial associates is understudied. To explore the role of abundant microbial associates, we isolated bacteria from active galleries of two widespread ambrosia beetles, Xylosandrus crassiusculus and X. germanus. These isolates were classified within the Erwiniaceae family and through a phylogenetic analysis including isolates from other insects we showed that they clustered with isolates obtained from ambrosia and bark beetles, including Erwinia typographi. The whole genome analysis of the isolate from active galleries of X. crassiusculus suggested that this bacterium plays both a nutritional role, by providing essential amino acids and enzymes for the hydrolysis of plant biomass, and a defensive role, by producing antibiotics. This defensive role was also tested in vitro against fungi, including mutualists, common associates, and parasites. The bacteria inhibited the growth of some of the common associates and parasites but did not affect mutualists. Our study supported the hypothesis of a mutualist role of Erwiniaceae bacteria in ambrosia beetles and highlighed the importance of bacteria in maintaining the symbiosis of their host with nutritional fungi. [ABSTRACT FROM AUTHOR]

The ambrosia beetle Xylosandrus compactus (Eichhoff, 1875) is a serious pest of economically important plants including Mitragyna speciosa, but its body structure and cellular composition remain uncharacterized. In this study, we described whole-body histological characteristics of female X. compactus. Our observation found two district regions in the nervous system: frontal ganglion and ventral nerve cord. The frontal ganglion contained two layers: outer cortex and inner medullae, and the outer cortex was lined with three major types of cells including neurosecretory cells, neuroglia, and neurons. The integumentary system contained three different layers: epicuticle, exocuticle, and endocuticle in the head, thoracic, abdomen, and leg regions. Apparently, only skeletal muscles possessed muscle fibers in the muscular system. The main organ of the urinary system was the Malpighian tubule, the epithelium of which was lined with the simple cuboidal layer. The digestive system consisted of several distinct parts including foregut (for example esophagus, crop, and proventriculus), midgut, and hindgut (or rectum). Three different cell types were identified in the epithelial midgut. The respiratory organ was visible among the adipose tissue close to the integument system. Although this organ was not easily identified, it was covered by a simple squamous epithelium. The female reproductive system of this insect was a telotrophic meroistic ovary. The distribution of nurse cells was restricted to the anterior tropharium, connected to oocytes. All the above results provide the first histological description of X. compactus, which might be useful for advancing research in the related fields. [ABSTRACT FROM AUTHOR]

Laurel wilt disease (LWD) is a lethal vascular wilt caused by an exotic ambrosia beetle–fungal complex, the redbay ambrosia beetle, Xyleborus glabratus Eichhoff, and its nutritional symbiont, Harringtonia lauricola (Harr., Fraedrich & Aghayeva) de Beer & Procter. LWD is responsible for the widespread mortality of redbay, Persea borbonia (L.) Spreng., devastating coastal forests in the southeast United States. More recently, LWD is causing mortality of understory sassafras, Sassafras albidum (Nutt.) Nees, in deciduous forests in Kentucky, USA; the biology, epidemiology, and long-term impacts of LWD in deciduous forests are unclear. All North American lauraceous species evaluated have shown susceptibility, and numerous additional ambrosia beetles have demonstrated vector potential, but no studies to date have assessed the presence of H. lauricola in other insects associated with LWD-infected sassafras. We sampled infected sassafras from the leading edge of the LWD range and collected insect associates to evaluate phoretic and internal presence of H. lauricola. We recorded 118 individuals of 38 morphospecies emerging; most were Coleoptera. Of the 48 specimens evaluated for H. lauricola, none tested positive for phoretic presence, but internal presence was evident in the granulate ambrosia beetle, Xylosandrus crassiusculus Motschulsky, and in a hidden snout weevil, Apteromechus ferratus Say. This is the first report of H. lauricola associated with a non-ambrosia beetle and expands our understanding of the vector potential of additional insect species while confirming the role of the granulate ambrosia beetle. These findings contribute to our understanding of LWD epidemiology in sassafras hosts from more northerly latitudes. [ABSTRACT FROM AUTHOR]

Mutualistic interactions between organisms often mediate the innovation of traits essential to maintain the relationship. Yet our understanding of these interactions has been stymied due to various hurdles in studying the genetics of non-model animals. To understand the genetic mechanisms by which such traits develop, we examined the function of genes breathless (btl), trachealess (trh), and doublesex in the development of a novel fungus-carrying organ (mycangium) that facilitates an obligate relationship between fungus-farming ambrosia beetles and specific fungal partners. Gene knockdown by RNA interference and subsequent micro-computed tomography visualization suggest btl and trh are required for initiation of mycangia and that tubulogenesis may have been co-opted for early mycangial development. [ABSTRACT FROM AUTHOR]

The article discusses the issue of bark beetles and ambrosia beetles in Israel, focusing on the black twig borer (BTB), Xylosandrus compactus, which has become an invasive species in the Galilee region. The article highlights the challenges posed by invasive woodborers and presents research and development plans to find solutions. It also mentions other native and invasive woodborers in Israel and the need for monitoring, early detection, and environmentally friendly preparations to manage these pests. The article discusses the impact of the black twig borer on carob trees and the potential economic consequences for the carob industry. It also mentions the use of trunk injections and entomopathogenic agents for controlling wood borers, as well as the challenges posed by invasive insects to urban trees in Israel. [Extracted from the article]

A new species, Tricosa sokanovskiisp. n. (Coleoptera, Curculionidae: Scolytinae), is described from the south of the Russian Far East based on the material from the neighbourhood of Vladivostok. [ABSTRACT FROM AUTHOR]

The main pathogens affecting the carob (Ceratonia siliqua) tree in the Mediterranean basin are described in this overview. The most widespread diseases periodically occurring in carob orchards are powdery mildew (Pseudoidium ceratoniae) and cercospora leaf spot (Pseudocercospora ceratoniae). The causal agents of "black leaf spots" (e.g., Pestalotiopsis, Phyllosticta and Septoria spp.) are responsible for symptoms similar to those previously mentioned for foliar diseases, but are reported in carob orchards at a negligible frequency. Likewise, canker and branch diebacks caused by fungal species belonging to Botryosphaeriaceae are almost never recorded. Among the rots of wood tissues that may compromise old carob specimens, "brown cubical rot" caused by Laetiporus sulphureus is the most widespread and recurrent issue; this pathogen is also well-known for producing edible fruit bodies that are appreciated for pharmaceutical and industrial purposes. On the other hand, "white rots" caused by Fomes and Ganoderma species are less common and reported for the first time in this review. Gall-like protuberances on twigs of uncertain aetiology or tumors on branches associated with Rhizobium radiobacter are described, although these symptoms are seldom detected, as they are also observed for necrotic leaf spots caused by Pseudomonas syringae pv. ciccaronei. A worldwide list of pathogens not yet recorded but at high risk of potential introduction in Italian carob-producing areas is also provided. Finally, concerns related to new phytopathogenic fungi vectored by the invasive Xylosandrus compactus ambrosia beetle are addressed. All the described pathogens could become limiting factors for carob production in the near future, because they could be favored by high-density orchards, the increasing global network of trade exchanges, and the high frequency at which extreme events related to climate change occur globally. Thus, symptoms and signs, causal agents, epidemiology, and, whenever applicable, recommendations for disease prevention and management are provided in this review. [ABSTRACT FROM AUTHOR]