ORGANISATION 

      EUROPEAN AND        

EUROPEENNE ET  

MEDITERRANEAN

MEDITERRANEENNE

PLANT PROTECTION

POUR LA PROTECTION 

ORGANIZATION DES PLANTES 

Newsletter 

of the EPPO Network of experts working  on surveillance, monitoring, and control  of the Emerald ash borer, Agrilus planipennis

The webpage of the Network:

https://www.eppo.int/RESOURCES/special_projects/agrilus_planipennis_network

Photo of Agrilus planipennis above: Courtesy of Dr. Eduard Jendek.

21 Bld Richard Lenoir  Tel: +33 1 84 79 07 57  Web: www.eppo.int 75011 Paris, France E-mail: dm@eppo.int   GD: gd.eppo.int

1. Introduction

Welcome to the 3rd issue of the Newsletter of the EPPO Network of experts working on surveillance, monitoring, and control of the Emerald ash borer, Agrilus planipennis. This Network was established by the European and Mediterranean Plant Protection Organization (EPPO) following the decision made in October 2022 by its Panel on Quarantine Pests for Forestry. The Network was established in association with an EPPO-EU project.

Following the release of the 2nd issue of the Newsletter, the Network coordinator received an official response from the NPPO of Ukraine (see Section 3), information about new publications about A. planipennis, etc. This information made it possible to prepare the 3rd issue. Once again, the EPPO Secretariat would like to encourage participants to send all relevant information to the Network coordinator (Dmitrii Musolin, dm@eppo.int). 

2. The Network is growing

As of December 2023, the Network has more than 220 members (subscribers) from more than 40 countries. The EPPO Secretariat welcome you all. These numbers indicate a strong interest in the subject. Please encourage your colleagues to join the Network via the link https://forms.office.com/e/7GxvJkS0YT (registered email addresses will not be disclosed).

3. Agrilus planipennis in Kyiv, Ukraine is officially confirmed by NPPO

In the 2nd issue of the Newsletter we informed readers that on 30 May 2023, a new record of distribution of A. planipennis had been added to the pest’s profile in iNaturalist (https://www.inaturalist.org/observations/164638313). The EPPO Secretariat contacted the NPPO of Ukraine with a request to clarify the situation of A. planipennis in Kyiv and received a response. The NPPO of Ukraine explained that the state phytosanitary inspectors conducted a survey using pheromone traps in Kyiv, in the Bohdan Stupka Park in accordance with the geolocation indicated in the iNaturalist record. According to the results of the survey, A. planipennis was not present in that location. 

Five new records of the pest were published on the iNaturalist platform in June 2023 (https://www.inaturalist.org/taxa/70057-Agrilus-planipennis; see below) and two conference papers were published (Strygun et al., 2022, 2023 − see Section 12) claiming that A. planipennis is present in Kyiv. On 16 November 2023, the EPPO Secretariat again contacted the NPPO of Ukraine with a request to update information about A. planipennis in Kyiv. On 17 November 2023, the NPPO of Ukraine responded with an official letter (signed by the Deputy Head of the NPPO − the Chief Phytosanitary Inspector of Ukraine Mr. Vadym Chaikovskyi) which informed EPPO that during a regular inspection and monitoring of green spaces in the territory of Kyiv city by state phytosanitary inspectors an outbreak of A. planipennis was found on ash trees. Following a request from the NPPO, on the 27.12-ha landscape park on Solomianska Street a quarantine regime was introduced in accordance with the order of the Kyiv City Military Administration dated 10 October 2023 No. 790. It was further stated that as of 15 November 2023, on the territory of Ukraine a quarantine regime was introduced in the districts of Luhansk and Kharkiv regions and in Kyiv city. In addition, a 100-km zone bordering the quarantine zones of Luhansk and Kharkiv regions and Kyiv city was established. Currently, the monitoring of green spaces on the territory of Kyiv city continues.

The official      statement is   available   online:      https://dpss.gov.ua/news/v-kyievizaprovadzheno-karantynnyi-rezhym-smarahdova-iaseneva-vulkozlatka

Records of Agrilus planipennis on the iNaturalist platform (six red symbols; https://www.inaturalist.org/taxa/70057-Agrilus-planipennis; accessed on 12 December 2023).

4. A dynamic map of distribution of Agrilus planipennis in Ukraine

In the previous issues of the Newsletter the members of the Network were informed that the Ukrainian State Specialized Forest Protection Enterprise DSLP "Kharkivlisozakhist" had developed and published on its webpage a dynamic map showing the change of the range of A. planipennis in Ukraine in 2019–2023 (https://lisozahyst.at.ua/index/agrilusplanipennis/0-17).

Recently, the map was updated and now shows not only districts where the presence of the pest is confirmed by the NPPO, but also districts with local reports that are not yet confirmed by the NPPO.

The dynamics of the invasive range of A. planipennis in Ukraine in 2019−2023 (Courtesy: The Ukrainian State Specialized Forest Protection Enterprise DSLP "Kharkivlisozakhist"; units: administrative districts; https://lisozahyst.at.ua/index/agrilus-planipennis/0-17; accessed on 12 December 2023).

5. Exchange of reference specimens of Agrilus planipennis

In the previous issues of the Newsletter, members of the Network were invited to share spare reference specimens of A. planipennis with colleagues from NPPOs and/or national reference collections of the countries where this pest is not present. Since then, Network members from Ukraine and the United Kingdom helped colleagues from Sweden to obtain sample adults and larvae. A few more specimens are available which can be shared with NPPOs and/or national reference collections that need them for their work. 

The EPPO Secretariat is willing to continue to facilitate the process of exchange of reference specimens. Please write to the Network coordinator if you or your colleagues have spare reference specimens which you would be able to send to colleagues in other countries or if you need specimens for your national reference collection. Contact email: Dmitrii Musolin (dm@eppo.int)

6. A new EU Commission Implementing Regulation on measures to prevent

the establishment and spread of Agrilus planipennis within the Union territory

The European Commission prepared a draft of the Commission Implementing Regulation (EU) on measures to prevent the establishment and spread of Agrilus planipennis Fairmaire within the Union territory (https://ec.europa.eu/info/law/better-regulation/have-yoursay/initiatives/14026-Plant-health-measures-to-eradicate-prevent-the-spread-of-theemerald-ash-borer-Agrilus-planipennis-_en). This document, after adoption, will regulate how to carry out risk-based surveys to detect A. planipennis, establish demarcated areas, perform annual surveys in demarcated areas, prepare and apply eradication measures, prepare contingency plans and annual reporting. The draft considers Chionanthus virginicus L. and Fraxinus L. (other than fruits, seeds, pollen and plants in tissue culture) as specified plants (hosts). The feedback period lasted from 10 November 2023 to 08 December 2023. It is sent for the Commission adoption. 

7. A review: Emerald ash borer management and research

A comprehensive review paper will be published in the upcoming issue of Annual Review of Entomology: 

Sun J, Koski T-M, Wickham JD, Baranchikov YN, Bushley KE (2024) Emerald ash borer management and research: Decades of damage and still expanding. Annual Review of Entomology 69, 239-258 (https://doi.org/10.1146/annurev-ento-012323-032231)

Abstract: Since the discovery of the ash tree (Fraxinus spp.) killer emerald ash borer (EAB; Agrilus planipennis) in the United States in 2002 and Moscow, Russia in 2003, substantial detection and management efforts have been applied to contain and monitor its spread and mitigate impacts. Despite these efforts, the pest continues to spread within North America. It has spread to European Russia and Ukraine and is causing sporadic outbreaks in its native range in China. The dynamics of EAB's range expansion events appear to be linked to the lack of resistant ash trees in invaded ranges, facilitated by the abundance of native or planted North American susceptible ash species. We review recently gained knowledge of the range expansion of EAB; its ecological, economic, and social impacts; and past management efforts with their successes and limitations. We also highlight advances in biological control, mechanisms of ash resistance, and new detection and management approaches under development, with the aim of guiding more effective management.

Structure of the review:

1.  Introduction: global expansion of the emerald ash borer

1.1.  Outbreaks in the native range in China

1.2.  Introduction and expansion within North America

1.3.  Introduction and expansion to Europe

2.  Ash resistance

3.  Emeral ash borer impacts

3.1.  Ecological impacts

3.2.  Emerald ash borer damage: economic, health, and social impact

4.  Current detection and management practices

4.1.  Prevention and early detection

4.2.  Chemical control

4.3.  Biological control

4.4.  Integrated pest management and other management efforts

5.  Advances in Emerald ash borer management

5.1.  Resistance breeding: where are we now in developing Emerald ash borer–resistant ash?

5.2.  Technological advances in management and early detection

5.3.  Emerald ash borer–associated microbiota—future for emerald ash borer biocontrol?

6.  Conclusions

An important part of the review is a Supplementary Table Summary of currently used or previously tried EAB detection and control methods, their success, and challenges.

Summary points:

1.  Remote sensing combined with advanced imaging technology techniques will hopefully aid in early detection, the major roadblock to limiting emerald ash borer (EAB) spread, in the future. This approach could be combined with targeted on-site detection and management practices, such as branch sampling and chemical control.

2.  Planting of susceptible ash species, especially as monocultures, should be avoided, given that the wide-scale presence of native (in the United States) or planting of introduced (in European Russia, Ukraine, and China) susceptible ash trees is the key reason for the spread of the pest.

3.  Ash breeding to improve the resistance of susceptible species is slow, but advances in understanding the genetic basis of resistance, as well as the availability of new breeding and genetic engineering tools, will likely aid in this task in the future. Meanwhile, widerscale use of naturally resistant trees (at least in EAB’s native range), for example, as urban ornamental trees, is encouraged because ash breeding will likely not improve widescale EAB management in the near future.

4.  The biological control program in the United States has been moderately successful in reducing EAB damage but is likely insufficient to control EAB without combining it with chemical control and use of more resistant ash trees. New parasitoid or microbial control agents and/or the emergence of RNA interference–based control may help in control efforts in the future.

5.  Investigation of EAB-associated microbiota in both native and invasive ranges, incorporating microbiota from both resistant and susceptible tree species, would benefit future biocontrol efforts, as well as improving our understanding of the role of microbiota in species invasion and management.

8. The Network was presented at a virtual meeting of the International Forestry Quarantine Research Group

In November 2023, the EPPO Secretariat presented the Network to the attendees of the virtual meeting of the International Forestry Quarantine Research Group (IFQRG; https://www.ippc.int/ru/partners/organizations-page-in-

ipp/internationalforestryquarantineresearchgroup/). This group supports the International Plant Protection Convention (IPPC) Community by addressing critical forestry quarantine issues for the global plant protection community through scientific analysis, discussion and collaborative research. Its goals are to: 

− Identify and respond to high priority questions that the international forest phytosanitary community face;

− Carry out collaborative independent research and analysis as required;

− Provide carefully considered advice to the regulatory community including the bodies of the IPPC.

Members of the IFQRG and attendees of the meeting were invited to join the Network.

9. New dissertations using Agrilus planipennis as a model

Recently, one MSc and three PhD dissertations which used A. planipennis as a model (or one of the models) were prepared and publicly presented:

Ebersole W (2023) An examination of the effect of Fraxinus ash tree health on diversity and structure of the soil microbiome. Master's thesis. Bowling Green State University.

OhioLINK       Electronic       Theses       and       Dissertations       Center.

http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1692372259747792  

Abstract: Fraxinus ash trees in North America a threatended by the invasive Agrilus planipennis, emerald ash borer (EAB). EAB infestation has wide ranging economic, cultural and ecological impacts upon the North American environment. This study aims to look at the biological impact that infestation of ash trees can have on the soil microbiome around the tree’s roots. A previous study has already examined the possible geochemical effects of the trees sampled, and by looking at the effects on the microbiome through 16S ribosomal sequencing, we hoped to gain some estimation of the effect imposed on microbiota surrounding the tree. With a combination of alpha, beta, and network analysis, we can see some possible changes within the rhizosphere associated to the health of trees. Alpha diversity was inconclusive as there was inconsistent data amongst our sampled set of trees.

There is confounding points in the data pertaining to geographic differences in sample locations. However, when stratifying to sample locations, beta and network analyses show shifts in the microbiome are significant, with site 2 and 4 beta diversity showing a progression of microbiome makeup to change as health state changed. Differential networks between health states indicate a change in taxa between healthy and unhealthy tree rhizospheres exist. The network topography as well as the strength of edges between networks showed a difference in taxonomic makeup comparing health states with some phyla of note being Verrucomicrobia, Nitrospirae, and Acidobacteria. Because our sample size within each location was small, we recommend further studies be done to explore those differences.

Kyle K E (2023) Using eDNA to bridge the gap between species presence and detection: implications for conservation and invasive species management. A dissertation. Rutgers, The State University of New Jersey, School of Graduate Studies. ProQuest Dissertations Publishing. 30687873.

https://www.proquest.com/openview/bf91be3b8d72fcdaf7b5cf44797bc5b4/1?pqorigsite=gscholar&cbl=18750&diss=y  

Abstract: The use of environmental DNA (eDNA) for the detection of rare and elusive species has boomed over recent decades, making its way into terrestrial landscapes in more recent years. Because eDNA in terrestrial landscapes can be randomly dispersed, we must be thoughtful about how to sample in an effort to maximize the probability of detection given the target species. Due to the sensitivity of these methods, they can be very useful for detecting invasive species when rare in the landscape and to aid with delimiting surveys for more effective control and management. Similarly, eDNA methods can aid in detecting species of conservation concern when they are rare or elusive. The goal of my dissertation was to broaden the utility of eDNA methods to unlock new suites of species capable of being surveyed. In doing so, we had to think about how to access new ‘pools’ of eDNA that we could access in these detection efforts. First, I evaluated the deployment of a published eDNA sampling method, roller aggregation, in a novel way to detect a terrestrial reptile species beneath artificial cover objects. Second, I trialed a novel eDNA sampling method utilizing a 1” increment hammer to extract tree cores from hosts infested with a woodboring beetle. Lastly, I deployed a suite of eDNA methods to observe which would work well to detect eDNA of a nocturnal invasive beetle pest in a tropical island habitat. Thus far, the use of eDNA has not been extensively used in island habitats for detection of invasive invertebrates, so we explored that utility here.

Rosner S (2023) Importance des frênes pour la biodiversité dans les forêts ripariennes sous influence du castor (Castor canadensis) et de l’agrile du frêne (Agrilus planipennis). Thèse. Gatineau, Université du Québec en Outaouais, Département des sciences naturelles, 160 p. [Rosner S (2023) Importance of ash trees for biodiversity in riparian forests under the influence of the beaver (Castor canadensis) and the emerald ash borer (Agrilus planipennis). Thesis. Gatineau, University of Quebec in Outaouais, Department of Natural Sciences, 160 p.] (https://uqo.ca/nouvelles/52730) 

Abstract: With the invasion of North America by the emerald ash borer (Agrilus planipennis), ash trees (Fraxinus spp.) are under severe threat and the vast majority are destined to disappear in the coming years. In temperate deciduous forests, ash can be a dominant genus of riparian forests. These forests are considered to be very important ecological zones, as they form the interface between two ecosystems and play numerous ecological roles. They are also known to harbour significant plant and animal biodiversity. The sudden disappearance of a genus that may be dominant in this type of forest therefore has the potential to significantly impact the biodiversity of this type of environment and the ecosystem services that derive from it. We also know that ash is a genus that can be appreciated by beavers (Castor canadensis), which have a considerable influence on the structure of riparian ecosystems. Through their food selection, beavers can in fact shape forest composition, favoring species they avoid and disfavoring species they select. The pivotal role that ash trees could play in the dynamics of beaver colonies and in the maintenance of a particular biodiversity within riparian forests has not been the subject of specific studies. The disappearance of ash trees also has the potential to impact invertebrate communities, not only through a sudden change in forest structure, but also through the disappearance of ash litter, known for its lability, which could reduce the decomposition rate of the remaining litter. This question has not yet been the subject of specific studies either: in the literature, studies seem to focus mainly on the effects of structural modification of the forest, and only on certain families of invertebrates. To answer these questions, we carried out three separate studies in Parc national de Plaisance, which will be presented in three chapters of this thesis.

The first chapter of this thesis will aim to assess the exact place of ash in the beaver's diet, and how the beaver's feeding behaviour might be altered by the disappearance of ash. It has been shown that ash is indeed the most important food resource for beavers among those tested. In fact, only two other species (musclewood, Carpinus spp., and poplar, Populus spp.) were more likely to be consumed than ash, but their low abundance in the park meant that they could not be considered the most important food resource. We were also able to demonstrate that musclewood saplings could see their probability of consumption increase with the disappearance of mature ash trees. On the other hand, if the abundance of the ash saplings decreased, it is possible that the probability of consumption of mature maple, basswood and musclewood saplings could decrease. However, this latter effect could be due to a case of apparent competition. 

The aim of the second chapter of this thesis was to determine whether the disappearance of ash have the capacity to reduce the densities of the beaver population. Being a social and territorial species, the population densities may be regulated by group size, territory size, or both. We were able to show that the density of ash in the territories positively influenced the size of the group, but had no effect on the territory size, which is surprising for such a territorial species. The disappearance of ash is therefore likely to reduce beaver populations in riparian forests dominated by this genus.

Finally, in the third chapter, our first objective was to determine whether ash was indeed the genus that positively influenced lability in a litter composed mainly of ash and maple (Acer spp.). Secondly, we wanted to determine whether, in addition to the effects of altered forest structure, altered litter had the capacity to influence invertebrate communities. We were able to determine that the rate of litter decomposition was, indeed, largely determined by the percentage of ash in the litter. We were also able to show that ash, probably through its litter, influences invertebrate communities: the family assemblages were different depending on the proportion of ash trees in the canopy, demonstrating that some ash-associated communities are singular. Finally, some families had a taxonomic diversity positively influenced by litter decomposition rate, implying that the disappearance of ash could have negative effects on biodiversity at the scale of riparian forests.

Taken together, these chapters show that the disappearance of ash trees will most likely reduce beaver population density and alter their feeding behaviour, with consequent effects on forest dynamics. Furthermore, if ash trees were replaced by trees with less labile litter, this could certainly have a negative impact on the biodiversity of soil invertebrates. Although it is not possible to precisely determine what the riparian forests of the future will look like, this thesis will have shown that in temperate forests where ash is abundant, it is a keystone for both animal biodiversity and forest composition, through its effect on beavers.

Studer EA (2023) Do species matter? Examining the niche of white ash (Fraxinus americana L.) and estimating potential subcanopy effects of its loss in north-temperate forests. Dartmouth College. PhD Dissertations. 174

(https://digitalcommons.dartmouth.edu/dissertations/174) 

Abstract: To understand the downstream consequences of the extinction of a species, we must understand its role in an ecosystem. With the impending extirpation of ash (Fraxinus spp.) due to the invasive emerald ash borer (Agrilus planipennis), understanding the role of ash trees is critical to predicting whether its loss will precipitate further species declines and/or ecosystem functions. We evaluated whether subcanopy microbial, invertebrate, and floral communities under four tree species (white ash, American beech, yellow birch, sugar maple) and on two soil hydropedological types (Bh podzol and Typical podzol) varied in species richness, composition, and functional traits in a factorial study. There were frequent strong effects of tree species. White ash frequently differed from the other trees: e.g., lower cation exchange capacity and exchangeable acidity, thinner Oi layer, lower %C and C : N, and, from phospholipid fatty acids, more AM fungi and less gram+ bacteria. We found that the subcanopy vegetation under ash was unique in having more plants of more species compared to the other tree species in the study. We also found an effect of soil type on species richness with Bh podzol having greater richness. However, identity analyses of functional traits of the understory communities revealed few differences by canopy tree species, suggesting that subcanopy communities are functionally redundant under different trees. We also found that soil invertebrate abundance did not vary significantly with tree or soil type, but that a higher diversity of organisms was present under ash and beech trees compared to sugar maple and birch. Finally, we estimated invertebrate abundance and biomass per gram of basal resource (leaf-litter) to provide data to modelers of ecosystem dynamics aiming to incorporate invertebrate data into forest forecasting. Better understanding of the role of diversity and function associated with at-risk organismal communities is important for predicting changes to ecosystem services in human-altered landscapes.

10. New publications on Agrilus planipennis

After the release of the previous Newsletter, information on 19 new publications on A. planipennis (14 journal papers, 4 conference abstracts, 1 collection of papers) has been received (data on new dissertations see in Section 9). The range of topics is very wide and includes the following: 

− Dynamics of spread of A. planipennis in Russia (Zhuravleva & Karpun, 2023), Ukraine (Kucheryavenko, 2022; Skrylnyk et al., 2023; Strygun et al., 2022, 2023) and USA (Hauer,

2023; Zobrist et al., 2023);

− Induced host defensive response to larval infestation (Stanley et al., 2023);

− Transcriptome profiling of Fraxinus excelsior genotypes infested by emerald ash borer (Doonan et al., 2023);

− A pattern of the body size change of A. planipennis to water quality in North America (Nalepa et al., 2023);

− Physiological responses of A. planipennis adults to short-time high-temperature conditions (Dang et al., 2023);

− Testing of heat treatment dose for A. planipennis prepupae (Noseworthy et al., 2023);

− Choice of trap type for the recently spreading jewel beetle pests (Matula et al., 2023);

− Modelling of the impact of introduction of A. planipennis to water quality in North America (Maze et al., 2023);

− Association between A. planipennis residence time and accumulation of invasive plants (Gougherty et al., 2023);

− Change in forest tree composition due to the invasion of A. planipennis and invasive plants (Land et al., 2023);

− General issues of conservation of the common ash (Fraxinus excelsior) (Steinhart & Burzlaff, 2023);

−A review of global expansion, impact, and management practices (Sun et al., 2024); − Distribution of invasive pathogen of ash dieback disease Hymenoscyphus fraxineus in Russia (Zviagintsev et al., 2023).

A reference list and a short summary of each of these publications are given at the end of this Newsletter and also on the Network’s homepage on the webpage of EPPO (www.eppo.int/RESOURCES/special_projects/agrilus_planipennis_network). Most of the papers are available as full text via the provided links; others may be made available on request to the authors. 

11. A closing remark

That is about all for the 3rd issue of the Newsletter. The EPPO Secretariat looks forward to receiving your news and publications, links to recently published papers and conference abstracts by you and your colleagues, any other relevant pieces of information and announcements on Emerald ash borer so the Network can distribute them via these Newsletters. Feel free to inform your colleagues in your country and around the world about the Newsletter. The email for correspondence is dm@eppo.int (Dmitrii Musolin).

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