The emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a dangerous invasive pest of ashes, Fraxinus spp. Based on the results of a survey conducted in July 2025, the first record of A. planipennis in the Karachay-Cherkess Republic is reported, new foci were detected in Stavropol Territory (Mineralnye Vody region), and the locations of foci were clarified in Krasnodar Territory, including the first record of the pest in urban plantings in the city of Krasnodar. No A. planipennis presence was revealed in the Kabardino-Balkaria or Adygea republics. Of the total number of detected foci, 70 % were located in shelterbelts and roadside plantings, two foci were recorded in city parks, and one in a botanical garden. The results of the study are important for predicting the further spread of the pest in the North Caucasus.

Pest management strategies for invasive species like the emerald ash borer (EAB) must combine chemical control with biological control agents to protect vulnerable hosts. When used in tandem with biological control agents, however, systemic insecticides may impact the fitness of biological control agents, thus reducing their effectiveness. Systemic insecticides are used for EAB management in urban forests across North America, while classical biocontrol with introduced natural enemies has been an important tactic for managing EAB in natural forests in North America. We tested the non-target effects of azadirachtin on Tetrastichus planipennisi Yang, a larval parasitoid of EAB introduced to North America. A novel bioassay protocol was developed whereby EAB larvae were initially reared on host material in the laboratory and then temporarily transferred to an artificial EAB diet containing azadirachtin followed by exposure to parasitism by T. planipennisi. Exposure to azadirachtin at concentrations causing 30% and 50% mortality in EAB larvae reduced EAB larval parasitism by T. planipennisi. Exposure to azadirachtin also reduced T. planipennisi's sex ratio, adult emergence, female body size, potential fecundity, and adult longevity. These results suggest there are negative interactions between systemic insecticides and EAB biological control agents, which present challenges for the integration of tactics for long-term EAB management.

The emerald ash borer (EAB), Agrilus planipennis, is a destructive invasive insect of North American ash (Fraxinus). While microorganisms associated with the beetle may contribute to tree decline and death, the microbial community succession during an EAB attack is unknown. We repeatedly sampled the bottom two meters of green ash (Fraxinus pennsylvanica) and black ash (Fraxinus nigra) in seven stands across an infestation gradient over four years. Amplicon libraries were sequenced from control phloem tissue of trees showing no symptoms of infestation, uninfested phloem of trees with EAB, infested phloem (galleries), frass, and larvae to determine if there are shifts in the fungal and bacterial communities as trees succumb to EAB attack. We found that the control phloem communities significantly differed from the beetle-infested phloem in both tree species. Furthermore, as EAB progressed in its attack from the top limbs to the tree’s base, the microbial communities in uninfested phloem outside the galleries shifted away from communities in phloem of control trees. In infested phloem, more than 80% of the detected taxa were absent from control trees (i.e., most taxa were non-latent). However, the relative abundance of latent taxa in infested phloem was higher than the relative abundance of the non-latent taxa, especially for potential canker-causing fungi, which increased 21-fold and 32-fold in black ash and green ash trees, respectively. These findings provide valuable insight into how a woodboring beetle shapes the microbial environment within trees over time, influencing the overall microbial diversity, such as canker-causing and wood decay taxa.

Acoustic detection technology has emerged as a promising, non-destructive and continuous monitoring method for pest early detection at the single tree level. However, field application still encounters problems, especially under complex infestation scenarios, i.e., co-infestations by multiple pest species. This study aims to develop a novel acoustic-based recognition model for detecting forest wood-boring pests, specially designed to enhance monitoring accuracy under complex infestation scenarios. We collected feeding vibration signals from four wood-boring pests: Semanotus bifasciatus, Phloeosinus aubei, Agrilus planipennis, and Streltzoviella insularis. Three infestation scenarios were designed: single-species, co-infestation without mixed signals, and co-infestation with mixed signals. Three machine learning (ML) models (Random Forest, Support Vector Machine, and Artificial Neural Network) based on seven acoustic feature variables, and three deep learning (DL) models (AlexNet, ResNet, and VGG) using spectrograms were employed to classify the signals. Results showed that ML models achieved perfect accuracy (OA: 100%, Kappa: 1) in single-species scenarios but declined significantly under co-infestation scenarios with mixed signals. In contrast, DL models, particularly ResNet, maintained high accuracy (OA: 85.0-88.75%) and effectively discriminated mixed signals. In conclusion, this study demonstrates the superiority of spectrogram-based DL models for acoustic detection under complex infestation scenarios and provides a foundation for developing a general, real-time detection model for integrated pest management in forest ecosystems.

The emerald ash borer (EAB; Agrilus planipennis Fairmaire) is a deadly pest of ash trees (Fraxinus spp.) in North America. Chemical and biological control methods are already in use against EAB, but additional integrated pest management (IPM) strategies are needed to reduce EAB populations in remote, northerly forests on the edge of the infestation front, such as those in northern Minnesota, USA. One entomopathogenic fungus (EPF) isolate, Beauveria bassiana (Bals.-Criv) Vuill. CFL-A, deployed in autodissemination devices (ADDs) has previously shown promise in reducing EAB population growth. Additionally, EPF has been found to be associated with EAB in Minnesota. This study assessed the suitability of ten Minnesota-indigenous, and one commercial, EPF strains for potential use in ADDs targeting EAB adults. Fungal isolates spanned five genera, including Beauveria, Purpureocillium, Metarhizium, Clonostachys, and Samsoniella. Of those tested, Beauveria pseudobassiana S.A. Rehner and Humber EAB 16.8, Beauveria bassiana GHA, Metarhizium sp. Meta, and Purpureocillium sp. EAB 59-16-2 consistently reduced the mean survival time (MST) and probability of survival over time for EAB adults dropped into an EPF-containing ADD in the laboratory. Furthermore, these fungi were readily recovered from surface-sterilized EAB cadavers. Future ADD field trials using these isolates are warranted to validate their ability to reduce EAB population growth.

Survival and growth of underplanted replacement tree species in black ash wetlands threatened by emerald ash borer in Minnesota, USA

An emerald ash borer early monitoring method for low-noise environments based on spectral features extraction of boring vibration signals

The article examines the ecological and biological characteristics of the development and impact of several quarantine organisms, including the emerald ash borer (Agrilus planipennis Fairmaire), the Eastern fruit moth (Grapholita molesta Busck), the California red scale (Quadraspidiotus perniciosus Comstock), and the black pine sawyer beetle (Monochamus galloprovincialis Ol.). It identifies quarantine phytosanitary zones within the Volgograd region and presents a list of measures for localizing outbreaks of these quarantine organisms and/or eradicating quarantine organisms’ populations. Additionally, the article outlines the criteria for confirming the eradication of pest outbreaks and discusses the rationale for lifting quarantine phytosanitary zones and discontinuing the quarantine phytosanitary regime.

Emerald ash borer (Agrilus planipennis Fairmaire) is an invasive wood-boring beetle that has killed millions of ash trees (Fraxinus spp.) across North America. In 2014, emerald ash borer was discovered attacking white fringetrees (Chionanthus virginicus L.) in Ohio, indicating a host range expansion. Since then, emerald ash borer activity in white fringetree has been confirmed in additional states, posing a potential threat to this native tree in natural and managed ecosystems. Though emerald ash borer can complete a full life cycle in white fringetree, there has been little research into the comparative success with which emerald ash borer develops in this novel host versus ash, or how introduced biocontrol agents will respond. We conducted laboratory and field infestations of white fringetree and ash in Delaware to compare the timing of emerald ash borer larval development and the associated response of larval parasitoids. In lab-infested white fringetree bolts, emerald ash borer developed slowly, with no larvae reaching the mature J-shaped larval stage (JL) during the 14-wk lab study, compared with all surviving larvae developing to the J-shaped larval stage in ash. Field results showed delayed emerald ash borer development and reduced survival in white fringetree, with just 1 larva out of 158 reaching the JL stage over 2 growing seasons. There was no parasitism of emerald ash borer larvae in lab- or field-infested white fringetree, likely because few larvae in this host reached instars suitable for larval parasitism. Overall, this study suggests that emerald ash borer populations in white fringetree are not self-sustaining, though further studies should be conducted using larger fringetree material, as small sizes may negatively impact larval survival.

The performances of traps used for pest monitoring are not well understood. Variable trap sizes and shapes make cross-comparisons difficult. We tested with four Scolytinae species (Coleoptera, Curculionidae) a set of traps of the same model (fan-traps) in four sizes (310, 536, 832.5, 1,200 cm2), and a larger trap with another design (a four-vane trap, 4,500 cm2). A significantly linear relationship was observed between trap sizes and catches for Pityogenes chalcographus, but the catches of Ips typographus, Trypodendron lineatum and T. signatum tapered off. In the literature, comparable tapering-off effects were observed with Xyleborus glabratus (Scolytinae) and Agrilus planipennis (Coleoptera, Buprestidae), but a significant linear response with increasing trap size was observed with Trypodendron lineatum and T. rufitarsus. In another test, beetle landing behaviour was measured on a 1 m2 glued panel baited with lineatin (the Trypodendron spp. pheromone) and ethanol (a host kairomone). The landing densities of Trypodendron spp. did not increase with the distance to the attractants whilst Anisandrus dispar landed in very significantly higher densities far from the attractants. Species using pheromones to locate mate and host appear to land closer to the source of attractants than species responding to kairomones for locating a suitable host.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-16511-6.

Ash survival and growth in response to emerald ash borer invasion in Massachusetts riparian forests: Impacts of biological control

Exploration of winter diapause stages of the emerald ash borer based on morphological and biochemical parameters.

Agrilus planipennis is an invasive species that inflicts substantial harm on ash trees (Fraxinus spp.) globally. Elucidating its olfactory mechanisms is essential for devising effective pest management approaches. In this research, we identified chemosensory protein 4 (AplaCSP4) in A. planipennis, which is highly expressed in the antennae of both male and female individuals. Notably, the mRNA expression level of AplaCSP4 in females is 1.9 times higher than that in males. Fluorescence competition binding assays revealed that recombinant AplaCSP4 has a broad binding spectrum, capable of interacting with 11 compounds from various chemical classes such as esters, alkanes, terpenes, terpenoids, and terpenols. The dissociation constants (KD) for these binding affinities range from 0.25 to 11.47 µM. AplaCSP4 shows binding affinity for volatiles from Fraxinus species, including dodecane, myrcene, ocimene, farnesene, (+)-limonene, and nerolidol, with the highest affinity observed for farnesene (KD = 0.25 µM). Molecular docking and dynamics simulation were employed to elucidate the binding mode of farnesene, which exhibited the strongest binding affinity with AplaCSP4. The results indicated that farnesene binds within the hydrophobic pocket of AplaCSP4, with a binding energy of −31.830 ± 2.015 kcal/mol and −32.585 ± 2.011 kcal/mol in dual-replicate molecular dynamics simulations, and primarily driven by van der Waals interactions. Importantly, during the two molecular dynamics simulations, the centroid distances between farnesene and the key residues in the binding pocket of AplaCSP4 were maintained relatively stable. The combined results from in vitro experiments and computational modeling suggest that AplaCSP4 is critically involved in plant volatile detection. This study offers insights into the molecular basis of olfactory perception in A. planipennis and may provide a foundation for developing novel olfactory-based pest control strategies targeting chemosensory proteins.

Societal Impact StatementThe world‐wide diversity of ash trees includes genetic information encoding resistance to the ash dieback fungus and the emerald ash borer beetle, which are currently devastating ash populations in Europe and North America. In order to mobilise this genetic diversity in conventional breeding programmes, we need to be able to accurately identify ash species from around the world and cross them with one another. Here, we present a preliminary genetic barcoding system for ash, and a series of hybridisation experiments between European ash and other species. Two of the hybrids show early promise against ash dieback.Summary Native ash tree species in Europe and North America are being devastated by ash dieback and the emerald ash borer, respectively. As worldwide ash species differ in their level of susceptibility to these threats, hybrid breeding may allow resistance to be transferred among species. However, we do not know the extent to which distantly related ash species can be crossed, and many ash species are difficult to identify from morphology alone leading to some mislabelling in living collections. Here, we initiate development of a genetic barcode system for the identification of Fraxinus species based on low‐copy‐number protein coding genes. We also conduct experimental crosses among ash species in different sections. Three genes are effective in identifying ash samples to sectional level but only in some cases to species level. They highlight that Fraxinus mandshurica, Fraxinus platypoda and Fraxinus chiisanensis may be frequently mistaken for one another in living collections. We succeeded in generating 10 wide hybrid plants: two of section Melioides (species: Fraxinus pennsylvanica) × section Fraxinus (species: Fraxinus excelsior) and eight of section Ornus (species unclear) × section Fraxinus (species: F. excelsior). One hybrid from each of our crosses has survived natural infection with the ash dieback pathogen in Ireland. We also discovered a hybrid between section Melioides (species: F. latifolia) × section Fraxinus (species: F. excelsior) formed spontaneously in the ash collection at Kew. Our findings facilitate the utilisation of global ash species diversity in response to novel threats and highlight the difficulty of designing a barcoding system capable of distinguishing all species of a genus.

The emerald ash borer, Agrilus planipennis Fairmire (Coleoptera: Buprestidae), is a notorious invasive pest that can devastate ash trees, Fraxinus spp. L., and embedded communities. While emerald ash borer is established in eastern North America, it was recently detected in Forest Grove, Oregon and in Vancouver, British Columbia, raising concerns that it may spread across the Pacific Northwest riparian ecosystems dominated by ash. A quarantine zone has been established in Oregon, but future mitigation depends on assessing the spread to new regions. Here, we used habitat suitability models and dispersal simulations to predict the potential spread of emerald ash borer. Specifically, we compared climate spaces occupied by Oregon and British Columbia populations with other native and introduced populations, and then used habitat suitability models and dispersal simulations to predict future distributions. We show that the newly established Oregon and British Columbia populations currently occupy relatively narrow climate niche, and many suitable niche spaces are unoccupied in the Pacific Northwest, indicating potential for range expansion. We also show there are vast areas of suitable habitat that extend south of the present quarantine zone throughout inland western Oregon and north into Washington. In Vancouver, the most suitable habitat was found along the Fraser River, where emerald ash borer could disperse inland. Dispersal models suggest that, without intervention, emerald ash borer could disperse into Washington within 2 yr, throughout western Oregon in 15 yr, and reach California in 20 yr. Our work supports intensive quarantine efforts for emerald ash borer and identifies areas where monitoring and management efforts should focus.

Effects of harvest treatments anticipating emerald ash borer invasion on northern hardwood forests in New England, USA

Abstract Rising global temperatures are significantly affecting species distributions worldwide. Properly assessing the threat of invasive species in the context of global warming is crucial. In this study, we quantitatively assessed the potential threat of emerald ash borer (EAB) against global ash tree species (Fraxinus) under multiple future climate scenarios based on the premise of niche conservatism. Through a multidimensional comparison of overlapping distribution areas and niches forecasted by species distribution modeling, we observed that rising temperatures lead to significant shifts in the habitat ranges of both EABs and Fraxinus species, often resulting in increased overlap of both their suitable habitats and niches. These results indicate that global warming, across most climate scenarios, exacerbates the threat of biological invasions by EABs in all main distribution regions. This study highlights the critical importance of considering both invasive species and their potential hosts in predictive modeling. Additionally, our results establish a well theoretical foundation for future research and management strategies aimed at protecting vulnerable ecosystems form the expanding of invasive species.

Abstract. The emerald ash borer is an invasive pest causing widespread mortality of ash trees (Fraxinus spp.) across the USA. Broad-scale models can help identify management strategies to maintain lowland ash ecosystems. Simulating lowland forest dynamics in landscape models has been problematic because lowland hydrology is extremely complex, making most hydrology algorithms intractable at the landscape scale. A succession extension (PnET-Succession) of the LANDIS-II forest landscape model was recently updated to include simple algorithms to approximate lowland hydrology, but estimating parameters of tree species' waterlogging tolerance is difficult. We describe empirical experiments conducted to generate such estimates and illustrate their behavior in single-cell and landscape simulations. Simulated water stress mimicked two critical characteristics of the empirical experiment: (1) there was little difference in simulated stress variables between the well-drained and intermediate flooding treatments, and (2) simulated water stress of species aligned with empirical waterlogging tolerance. We used the landscape model to scale the empirical experiment to landscape scales of space and time. When the simulation experiment was extended to 90 years, species productivity plateaued or peaked at a level that could be supported by the precipitation inputs and rooting zone depth. In a virtual experiment testing the competition outcomes between two species, the more-waterlogging-tolerant species did much better under the flooding treatment, but also tended to do better under the drained treatment because it never produced droughty conditions. When the updated waterlogging parameters were applied at landscape scale under future climate change and assisted migration (AM) scenarios, the mean biomass density of native species declined, and the introduced AM species increased as the climate gradually changed and introduced cohorts thrived. Species that are waterlogging tolerant were able to persist under all assisted migration–climate change scenarios and to a limited extent were able to colonize (and ephemerally dominate) upland sites. Well-parameterized landscape models provide a powerful tool to conduct simulation experiments involving novel situations such as climate change, invasive (or intentionally migrated) tree species, invasive insects or diseases, and proposed management strategies.

Abstract Phytophagous insects select for oviposition sites that improve offspring survival outcomes. Many woodboring insects, such as the invasive emerald ash borer (EAB), Agrilus planipennis, select for oviposition sites underneath bark crevices of host trees. Although the preference for rougher bark has been demonstrated, the limits of EAB oviposition site selection are unknown. Here we determined the effective bark crevice size that EAB females oviposit under through trials with coffee filter paper covered with mesh screening in a no-choice experiment. We then conducted a choice experiment where we wrapped an ash log with polypropylene ribbons at different tightness treatments as oviposition stimulants. We found that EAB females oviposited onto coffee filter paper through mesh pores ranging from 0.6 × 0.6 mm (0.36 mm2) to 1.4 × 1.4 mm (1.96 mm2), but not 0.2 × 0.2 mm (0.04 mm2). The width of ovipositors on a sample of 30 EAB females ranged from 0.270 to 0.689 mm, suggesting the smallest pores prevented ovipositor insertion. Females also oviposited more on logs wrapped with ribbon at a moderate gap width (0.5 mm) than on logs with loose gaps (1 mm) or logs with tight gaps (0.06 mm), which was smaller than our measured ovipositor widths. Our findings suggest that female EAB prefer gap sizes that are relatively tight so long as they are large enough to allow insertion of the ovipositor. These results have implications for larval host selection in field settings as the attribute of bark crevices limiting EAB oviposition may vary drastically with host plant.

Homogenization of a temperate old-growth forest remnant in central Illinois following the introduction of Dutch elm disease (Ophiostoma novo-ulmi) and emerald ash borer (Agrilus planipennis)