Agrilus Planipennis Fairmaire Research Articles

A collaborative approach to preparing for and reacting to emerald ash borer: a case study from Colorado

AbstractCollaboration has been the key to success for urban forest management in Colorado, not only collaboration amongst agencies at all levels of government but also in engaging industry allies, coordinating education and outreach efforts and in fostering community support. A unique interagency team, the Emerging Pests in Colorado (EPIC) Workgroup, was formed in 2009 to address the immediate threat from Thousand Cankers Disease (TCD) of walnut and to plan for the arrival of other invasive urban forest pests to Colorado. When the emerald ash borer (Agrilus planipennis Fairmaire) (EAB) was detected in Boulder, Colorado in 2013, it marked the westernmost occurrence of EAB in the US, threatening millions of planted and naturalized ash trees representing over 25 percent of the tree canopy throughout Colorado’s urban and riparian forests. The detection in Boulder prompted the development of a second multi-agency group, the Colorado EAB Response Team (CORT). The preparedness and established working relationships between stakeholders and responsible authorities allowed for a quick, decisive and unified response. We review as a case study: (1) the formation and history of collaborative interagency groups in Colorado; (2) how the interagency collaborative planning and post-detection EAB response have supported community forestry programmes throughout the state; (3) development of the post-detection EAB management plan and economics behind the strategy in Boulder, Colorado; and (4) the proactive EAB planning and outreach efforts underway in Denver, Colorado.

Assessment of the Systems Approach for the Phytosanitary Treatment of Wood Infested With Wood-Boring Insects.

Addressing the risk from pests present in wood and wood products destined for international trade is an essential step towards minimizing the movement, introduction and establishment of invasive species. One method of managing the pest risk associated with wood commodities is the use of a systems approach that incorporates multiple independent measures applied along a production pathway. However, quantifying the reduction of risk can be difficult because the approach requires raw material infested with the pest of interest at a sufficient density to be able to quantify changes in pest abundance. We tested a systems approach for the production of sawn wood using green ash, Fraxinus pennsylvanica Marshall (Lamiales: Oleaceae), infested with emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), by quantifying the change in pest density during the milling process and the precise effect of heat treatment on insects in situ. Greater than 90% of emerald ash borer were removed at the first step of the milling process (debarking) and >99% were removed before the production of green sawn wood. No insects survived kilning or heat treatment. All life stages of emerald ash borer were killed at 56°C and above. Heat, however, had no sublethal effect on emerald ash borer performance. These results show that the application of a systems approach to mitigate emerald ash borer in heat-treated, sawn wood is effective. Moreover, the model-system approach developed in this study can be a template for investigating the effect of systems approaches for other phloem-feeding insects.

Phenology of Emerald Ash Borer (Coleoptera: Buprestidae) and Its Introduced Larval Parasitoids in the Northeastern United States.

Biological control offers a long-term and sustainable option for controlling the destructive forest pest emerald ash borer (EAB), Agrilus planipennis Fairmaire, in North America. Three larval parasitoids, Spathius agrili Yang (Hymenoptera: Braconidae), Tetrastichus planipennisi Yang (Eulophidae), and Spathius galinae Belokobylskij & Strazanac, have been introduced to North America from the native range of EAB (northeastern Asia). While T. planipennisi appears to be persisting where it has been introduced in northern United States, S. agrili failed to establish in northeastern states. The more recently identified parasitoid S. galinae was recovered from the Russian Far East and climate matching suggests it should be suited for release in colder climates. We collected data on the phenology of EAB and its introduced larval parasitoids from colonies established in an insectary, growth chambers, and field-caged trees in Syracuse, New York to determine whether asynchrony between parasitoids and EAB or climate could impact establishment and persistence. Phenological data indicated EAB has one and 2-yr life cycles in New York, with parasitoid-susceptible EAB larvae available spring to fall for parasitism. Insectary and growth chamber studies indicated S. galinae and T. planipennisi were synchronous with EAB phenology, and field studies suggested both species could overwinter in northeastern climates. Spathius agrili was asynchronous with EAB phenology and climate, emerging when fewer parasitoid-susceptible EAB larvae were available and temperatures were not optimal for survival. Our results suggest S. galinae and T. planipennisi are suited for biological control of EAB at the northern limits of its range in North America.

Augmentation of native North American natural enemies for the biological control of the introduced emerald ash borer in central Canada

Agrilus planipennis Fairmaire (Col: Buprestidae) (EAB) has been spreading rapidly throughout North America, killing millions of ash trees, Fraxinus spp. L. (Oleaceae). Eradication is not viable, so biological control using natural enemies is now the leading management strategy. Little information is available on whether native parasitoids and predators can be manipulated to increase EAB mortality. We moved freshly cut ash logs infested with EAB parasitoids to field sites where there was no record of EAB mortality by native North American natural enemies. Changes in EAB parasitism, EAB density, and woodpecker predation were monitored over the following three years. Higher parasitism of EAB by Phasgonophora sulcata Westwood (Hym: Chalcididae) (16.67 ± 16.67%) and Atanycolus spp. Foerster (Hym: Braconidae) (48.18 ± 4.29 %) was observed in all plots over three years after native parasitoids were released. However, no reduction was seen in EAB density between the treatment and control plots or over time. There was no significant relationship found between predation by woodpeckers and year or between control and parasitoid-release plots. However, woodpecker predation increased significantly with EAB density. Movement of ash logs containing native parasitoids to sites newly infested by EAB, but with low native natural enemy populations, can increase long-term EAB mortality as an added component in management strategies to slow its spread.

Legacy effects of emerald ash borer on riparian forest vegetation and structure

High levels of ash (Fraxinus spp.) mortality have been reported in areas of North America following invasion of emerald ash borer (EAB) (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), but little is known about the impacts of EAB in riparian forests, particularly along first order streams. We delineated canopy gaps resulting from EAB-caused ash mortality along four first order streams in each of three distinct watersheds, which represented a temporal gradient of the EAB invasion across southern Michigan. Time lapsed aerial imagery showed canopy gaps were apparent by 2005, 2010, and 2012 in southeast, central and southwest sites, respectively. We assessed overstory trees, regeneration, shrubs, herbaceous plants, coarse woody debris, and photosynthetically active radiation in each canopy gap and in forests surrounding the gap. Canopy gaps were originally dominated by green ash (F. pennsylvanica) and black ash (F. nigra) but more than 85% of ash basal area was killed by EAB across all sites. Live basal area was greater in forests than in gaps, but was similar among all three watersheds. A lower percentage of dead ash trees remained standing and volume of ash coarse woody debris was higher in southeastern sites, with the longest history of EAB invasion, than in central and southwestern sites. Species richness of overstory trees was higher in forests (34 species) than in gaps (27 species). Photosynthetically active radiation, measured 1.5 m above ground, was 55% higher in canopy gaps than in adjacent forests during summer, but was similar during winter. Species composition of pre-EAB forest overstories and current saplings were similar among canopy gaps; overall, 66.3% of saplings were ash. Sapling species in forested areas adjacent to gaps were often dominated by Acer rubrum, while Quercus rubra, Prunus serotina, Acer saccharum and A. rubrum were common in overstories. Seedlings were rare within gaps now dominated by dense mats of sedges (Carex spp.). Although ash has been functionally lost from riparian forest overstories in most of southern Michigan, consistently high sapling densities, combined with reduced EAB densities, could facilitate ash persistence in post-invasion areas. If EAB densities increase, however, recruitment of ash saplings into the overstory will be limited. Continued monitoring will be important to assess the future status of ash and overstory dynamics in of post-EAB riparian forests.

Rail transport as a vector of emerald ash borer

Abstract The emerald ash borer (EAB) Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive woodboring beetle native to northeastern Asia that continues to expand its range within North America and European Russia. The insect reproduces within and kills most North American species of ash Fraxinus spp. Because both the adult and larval life stages of EAB are difficult to detect prior to development of tree symptoms, much work has focused on quantifying spread and clarifying the potential movement pathways to improve early detection and monitoring strategies. In the present study, we retrospectively analyzed county‐level infestations of emerald ash borer in the state of Iowa, U.S.A., subsequent to the initial detection of EAB in 2010. Visual data analysis had suggested that new infestations were not in accordance with the expected patterns of establishment along roads, near campgrounds or by large population centres. We found a positive correlation between the establishment and detection of EAB in Iowa counties and the length of railroads in each county. To our knowledge, this is the first statistically significant association between rail pathways and the spread of EAB on the North American continent.

Differential Impacts of Emerald Ash Borer (Agrilus planipennis Fairmaire) on Forest Communities Containing Native Ash (Fraxinus spp.) Species in Eastern North America

Abstract Invasion by emerald ash borer (EAB; Agrilus planipennis Fairmaire), an exotic pest, is disrupting natural processes and hindering our ability to conserve genetic diversity and perpetuate ash ecosystem services and functions. The goal of this project was to identify forest communities most at risk in terms of having altered ecosystems following EAB invasion. Using recent data available from the USDA, Forest Service, Forest Inventory and Analysis program, we calculated Shannon–Wiener species diversity index values for forests containing each of the six native ash species found in the eastern United States. These forest communities differed in their species diversity index values, and diversity indices varied across ecosystem provinces and states. In addition, communities containing ashes that are restricted by a narrow range of suitable environmental conditions consistently had lower diversity index values than communities of ash species with greater geographical ranges. Finally, forest stand cohorts (i.e., seedlings, saplings, and canopy trees) had similar species diversity indices across forest communities containing a single ash species. The tree species diversity index values quantified for communities with a single ash species will provide managers with additional information for prioritizing EAB control measures and restoration efforts following EAB invasions.

Horizontal Transmission of the Entomopathogenic Fungal Isolate INRS-242 of Beauveria bassiana (Hypocreales: Cordycipitaceae) in Emerald Ash Borer, Agrilus planipennis (Coleoptera: Buprestidae).

Emerald ash borer (EAB), Agrilus planipennis Fairmaire, is an invasive and destructive beetle that causes extensive damage to ash trees in North America. The entomopathogenic fungus Beauveria bassiana Vuillemin is considered as an effective biological control agent for EAB adult populations. Using an autodissemination device with a fungal isolate of B. bassiana, our research aims to investigate the possibility of horizontal transmission of the fungal disease from infected to uninfected EAB adults during mating. Results show that the efficiency of fungal transmission is significantly related to the sex of EAB carrying the fungal pathogen. EAB males are the promising vector to transmit mycosis to their partners during mating. Results strengthen the potential of the fungal autodissemination device as a powerful biological strategy to control EAB populations.

Semiochemical and Communication Ecology of the Emerald Ash Borer, Agrilus planipennis (Coleoptera: Buprestidae).

Knowledge of buprestid chemical ecology is sparse but the appearance of the invasive pest Agrilus planipennis Fairmaire in North America has provided the impetus to study in detail the semiochemistry and ecology of this important buprestid. The macrocyclic lactone (3Z)-12-dodecenolide [(3Z)-lactone] is identified as a key antennally-active compound that is produced by females and attracts males. Though a weak trap attractant alone, when combined with the host kairomone (3Z)-hexenol and the important visual cue of a green canopy trap, significant increases in male trap capture occur, thus defining (3Z)-lactone as both a sex pheromone of A. planipennis as well as the first and only known buprestid pheromone. The non-natural stereoisomer (3E)-12-dodecenolide and the saturated analog, 12-dodecanolide also exhibit mimetic activities towards male A. planipennis, suggesting a notable plasticity in this pheromonal structural motif. Efficient synthetic routes to these compounds have been developed. A series of fluoro-12-dodecanolides has also been synthesized containing CF2 groups as a strategy to bias the conformational space accessed by these macrolides and to assess if the analogs may act as mimetics for 12-dodecanolide pheromones associated in A. planipennis. These compounds also afford a unique opportunity to study the binding affinities of lactone surrogates with A. planipennis chemosensory proteins and olfactory receptors. Some progress has also been made in identifying the genes involved in the reception, processing and degradation of volatiles in this invasive insect. It is now evident that the behavior and ecology of A. planipennis involves a complex pattern of sensory modalities, including visual, tactile, olfactory and potentially acoustic components. Earlier reviews focused on studies of attractive host volatiles in development of a trapping system for early detection and visual and contact phenomena in A. planipennis mate finding. This review will update the semiochemistry and chemical ecology of A. planipennis and discuss studies on chemistry and behavior that have identified female-produced pheromone components and host kairomones.

Potential Changes to Louisiana Hardwood Timber Industry Economic Contributions Following Emerald Ash Borer (EAB) Invasion: An Input-Output Approach.

The emerald ash borer (EAB) Agrilus planipennis (Fairmaire, Coleoptera: Buprestidae) will have untold impacts on the contributions hardwood timber products provide Louisiana's economy. We modeled a scenario where ash mortality was assumed to follow a PERT-Beta distribution to kill essentially all Louisiana ash within 25 yr. Future ash mortality volumes were discounted to the present and valued using market prices to estimate a present effect on timber receipts. Assuming the dead timber would have otherwise been typical trees of average quality, stumpage was presently valued at US$1.57 million, with deliveries totaling US$3.48 million. A salvage arrangement using the double declining balance method coupled with a second PERT-Beta distribution centered upon Louisiana's current 2.84% harvest-to-inventory proportion depreciated the timber's value monthly over 1 yr. Following salvage, average stumpage revenue declined -US$1.54 million, mill deliveries fell -US$3.41 million, whereas state timber severance tax collections declined by -US$46,800. The value added and employment direct effects to Louisiana's economy averaged -US$882,400 and -41.6 jobs, respectively. The multiplier effects of these losses emanating from the timber industry resulted in additional declines averaging -US$2.56 million in value added and -45.6 jobs across the state economy on the drop in output of -US$4.51 million. The total economic effects summed to -US$3.44 million in value added and -87.1 jobs on output declines of -US$9.46 million.

The predicted effect of the polar vortex of 2019 on winter survival of emerald ash borer and mountain pine beetle

We use simulation models of the winter biology of two forest insects — emerald ash borer (Agrilus planipennis Fairmaire, 1888) and mountain pine beetle (Dendroctonus ponderosae Hopkins, 1902) — to illustrate the anticipated effect of the polar vortex of the winter of 2019 on overwintering survival. Cold spells in late January and early and mid-February were cool enough that relatively high levels of mortality of both species may be expected in many parts of northern Canada. However, the high mortality response is not ubiquitous, and neither is it particularly severe compared with winter weather patterns from earlier decades. Forest insect pest managers will be required to carry on their usual work of population assessment and response. As Earth’s climate continues to warm, overwintering survival should, on average, increase in both species. However, the common occurrence of a split polar vortex associated with increasingly meridional jet stream flows should bring the odd winter of heavy mortality.

Assessing the Efficacy of Seedling Planting as a Forest Restoration Technique in Temperate Hardwood Forests Impacted by Invasive Species

The emerald ash borer (Agrilus planipennis Fairmaire; EAB) is an invasive insect that causes mortality of trees in the genus Fraxinus, creating canopy gaps that may facilitate invasion by exotic plants. Planting native tree seedlings under EAB-infested Fraxinus may accelerate succession and preclude invasive plant expansion; however, the effectiveness of this approach has not been experimentally tested. We assessed understory seedling planting of Quercus rubra, Carya laciniosa, and Juglans cinerea in EAB-infested forests, where the invasive shrub Lonicera maackii (Amur honeysuckle) was removed. We tested whether the use of plastic tree shelters (“tree tubes”) or planting season (fall versus spring) contributed to the success of the reforestation plan by measuring growth rates (cm/yr) and survivorship two and seven years after planting. After seven years, seedling survivorship was <25% for all species and planting techniques. Quercus rubra exhibited poor survivorship with one seedling surviving to the conclusion of the experiment. Juglans cinerea and C. laciniosa had higher survivability and growth rates than did Q. rubra after two and seven years. Effects of tree tubes were weak and temporary. After 2 years, Q. rubra seedling survivorship was higher in tree tubes; however, by the end of the experiment 29 of the 30 Q. rubra seedlings in tree tubes had died. Juglans cinerea seedlings grew faster when planted in the fall compared to the spring, but overall survivorship of these seedlings was unaffected by planting season. Neither the use of tree shelters nor the planting season contributed to the growth or survival of C. laciniosa seedlings. In summary, our results indicate that seedling planting of Carya and Juglans may be a useful way to increase biodiversity in regenerating forests; however, the resource-expensive processes of over-wintering seedlings and using tree shelters may not increase the success of reforestation efforts.

Challenges, tactics and integrated management of emerald ash borer in North America

AbstractEmerald ash borer (EAB) (Agrilus planipennis Fairmaire), discovered in southeastern Michigan, USA in 2002, has become the most destructive and costly invasive forest insect in North America. This phloem-boring beetle has also invaded Moscow, Russia and continued spread of EAB potentially threatens European ash (Fraxinus spp.) species. This review summarizes EAB life history, including interspecific variation in host preference, invasion impacts and challenges of detecting new infestations and provides an overview of available management tactics. Advances in systemic insecticides, particularly emamectin benzoate products applied via trunk injection, have yielded effective and practical options both to protect individual trees and to slow EAB population growth and ash decline on an area-wide basis without disrupting natural enemies. Economic costs of treating ash are substantially lower than removal costs, retain ecosystem services provided by the trees, reduce sociocultural impacts and conserve genetic diversity in areas invaded by EAB. Girdled ash trees are highly attractive to EAB adults in low-density populations and debarking small girdled trees to locate larval galleries is the most effective EAB detection method. An array of woodpeckers, native larval parasitoids and introduced parasitoids attack EAB life stages but mortality is highly variable. Area-wide management strategies that integrate insecticide-treated trees, girdled ash trap trees and biological control can be adapted for local conditions to slow and reduce EAB impacts.

Mapping black ash dominated stands using geospatial and forest inventory data in northern Minnesota, USA

Emerald ash borer (EAB; Agrilus planipennis Fairmaire, 1888) has been a persistent disturbance for ash forests in the United States since 2002. Of particular concern is the impact that EAB will have on the ecosystem functioning of wetlands dominated by black ash (Fraxinus nigra Marsh.). In preparation, forest managers need reliable and complete maps of black ash dominated stands. Traditionally, forest survey data from the United States Forest Inventory and Analysis (FIA) Program have provided rigorous measures of tree species at large spatial extents but are limited when providing estimates for smaller management units (e.g., stands). Fortunately, geospatial data can extend forest survey information by generating predictions of forest attributes at scales finer than those of the FIA sampling grid. In this study, geospatial data were integrated with FIA data in a randomForest model to estimate and map black ash dominated stands in northern Minnesota in the United States. The model produced low error rates (overall error = 14.5%; area under the curve (AUC) = 0.92) and was strongly informed by predictors from soil saturation and phenology. These results improve upon FIA-based spatial estimates at national extents by providing forest managers with accurate, fine-scale maps (30 m spatial resolution) of black ash stand dominance that could ultimately support landscape-level EAB risk and vulnerability assessments.

Photoperiodic modulation of diapause induction and termination in Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), an egg parasitoid of the invasive emerald ash borer

Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) is a solitary and parthenogenetic egg parasitoid from China being introduced into North America (NA) as a biological control agent of the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an extremely invasive and destructive pest of ash trees (Fraxinus spp.). Oobius agrili is being released over a broad geographical range in NA where photoperiod varies considerably during the season of parasitoid-host activity. We conducted laboratory studies to determine 1) if photoperiod-induced diapause is modulated maternally, grand-maternally, and/or directly in immature parasitoids; 2) interactions of maternal adult age and photoperiod exposure on diapause induction; 3) the critical day length for diapause induction; 4) the critical age at which photoperiod-induced diapause is modulated in developing larvae; 5) the effects of photoperiod and length of chill on diapause termination; and, 6) the effects of photoperiod on O. agrili biology across a latitudinal gradient. We found that photoperiod exposure of O. agrili larvae developing inside host eggs directly induced diapause, and maternal or grand-maternal photoperiod treatments did not affect diapause induction in their progeny. However, older adults that experienced diapause as larvae produced more progeny that entered diapause when their progeny were exposed to short-day photoperiods. All progeny produced by adults that developed from nondiapaused larvae entered diapause when exposed to short-day photoperiods. Diapause response to photoperiod declined dramatically after larvae were 6–7 days old. The critical day length for diapause induction was between 14.25 and 14.5 h of daylight (at 25 °C). Photoperiod and duration of chill affected diapause termination of diapausing O. agrili larvae. The cumulative number of degree days (base 10 °C) required for adult emergence was highest for the combination of 12 h light:12 h dark (12L:12D) photoperiod combined with the shortest chill period, and lowest for 14.5L:9.5D and 16L:8D combined with the longest chill period. We discuss the effects of photoperiod on parasitoid-host synchrony, population dynamics, and fitness of O. agrili across the geographical area where it is being released.

EPPO perspective on Agrilus planipennis (Emerald Ash Borer) and Agrilus anxius (Bronze Birch Borer)

Abstract One of the main aims of EPPO is to help its member countries to prevent entry or spread of dangerous pests (plant quarantine). The Organization has therefore been given the task of identifying pests which may present a risk (early warning/horizon scanning), evaluating their risk for the region and making proposals on the phytosanitary measures which can be taken against them (Pest Risk Analysis). Standards are also developed, including standards on how to eradicate and control pests. In addition to the development of Standards, activities on communication and citizen science (development of guidelines on raising public awareness and the production of toolkits to use in raising awareness campaigns) have also recently been started. The EPPO Secretariat was alerted by the National Plant Protection Organization (NPPO) of Sweden in 2003, and Norway in 2010, to two potential new pests, Emerald ash borer (EAB), Agrilus planipennis (Fairmaire) and Bronze birch borer, Agrilus anxius (Gory) respectively. Because of the importance of these two pests for forest species in the EPPO region, member countries agreed that EPPO recommendations should be prepared. The different EPPO activities relevant to A. planipennis and A. anxius are presented, highlighting the challenges they currently pose to the region.

Mating Behavior and Reproductive Biology of Emerald Ash Borer (Coleoptera: Buprestidae) and Two of Its Native Congeners, the Twolined Chestnut Borer and the Bronze Birch Borer.

We studied the mating behavior and reproductive biology of three members of the genus Agrilus: the bronze birch borer, Agrilus anxius Gory; the twolined chestnut borer, Agrilus bilineatus (Weber); and the emerald ash borer, Agrilus planipennis Fairmaire. All three species share a highly stereotyped mating behavior. However, the copulation duration of A. planipennis was 90% longer than that of its two congeners. Female reproductive tracts of the three species were anatomically similar, as were the spermatophores. Within the spermatophores, sperm were single in A. anxius and A. bilineatus, while in A. planipennis, sperm were bundled in groups of approximately 20 in a hyaline sheath. We found that field-caught A. anxius and A. bilineatus had higher rates of female insemination than A. planipennis. In additional studies with A. planipennis and A. anxius, we found that mating duration was related to mating success, and fecundity for A. planipennis, but not for A. anxius. For both A. planipennis and A. anxius, the spermatophore was passed to the female toward the end of the copulatory period. Sperm were found in the spermatheca immediately after copulation ended in A. planipennis and 30 min after copulation ended in A. anxius. We present possible explanations for these differences.

Physiological Response of Ash Trees, Fraxinus spp., Infested with Emerald Ash Borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), to Emamectin Benzoate (Tree-Äge) Stem Injections

Street- and park-planted ash (Fraxinus spp.) trees infested with emerald ash borer (Agrilus planipennis Fairmaire) ranging in size from 30 to 55 cm (11.8 to 21.7 in) dbh and 10 to 20 m (32.8 to 65.6 feet) in height were measured over two sites. The first group was treated with an emamectin benzoate stem injection at 10 ml/2.54 cm dbh (0.4 g ai) in June 2014, and the second group was left as an untreated control. Chlorophyll concentration and fluorescence was measured to assess plant fitness and vitality over three summers. Trees treated with emamectin benzoate showed improvements in chlorophyll concentration and plant fitness and vitality over the course of the study with peak improvement occurring in the second year. The untreated control trees showed continued signs of decline in each year of the study. This work demonstrates the utility of chlorophyll fluorescence for detecting plant stress related to forest health threats and could potentially inform managers on both short-term and long-term management options.

The Focus of the Emerald Ash Borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) in Tver, on the Northwestern Border of the Invasive Range

The emerald ash borer is a serious pest of ash (Fraxinus spp.) in North America and European Russia. It was introduced to those territories from East Asia in the 1990s. Currently the pest has spread in 12 regions of European Russia. The northwestern border of its range is in the city of Tver. This poses a potential threat to ash trees of St. Petersburg and Western Europe. In 2016 and 2018, green ash trees were surveyed in the summer in several districts of Tver. There are only local foci of the emerald ash borer in the city; mass drying of ash trees is not observed. A species that accompanies the emerald ash borer (the jewel ash beetle Agrilus convexicollis) and a pest parasitoid (Spathius polonicus) were found. Both species are recorded for Tver region for the first time. In addition, parasitoid Coeloides sp. was found inside the bark beetle galleries.

Establishment and Early Impact of Spathius galinae (Hymenoptera: Braconidae) on Emerald Ash Borer (Coleoptera: Buprestidae) in the Northeastern United States.

The emerald ash borer (EAB), Agrilus planipennis Fairmaire, a buprestid beetle native to Asia, has become a serious pest of ash trees (Fraxinus spp.) in North America since the early 2000s. Due to the impracticality of applying insecticides in natural forests, biocontrol is the most viable method to manage EAB in natural ecosystems. Here, we report the first evidence for the establishment and impact of Spathius galinae Belokobylskij & Strazenac, a larval parasitoid first released in North America in 2016 and 2017 at six mixed-hardwood forest sites, in Connecticut, New York, and Massachusetts. We also report current levels of abundance and parasitism of another introduced larval EAB parasitoid, Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), released in 2015 and 2016 in these same sites. Spathius galinae was recovered at all release sites in 2018, and its density in sampled trees had increased 1.5- to 20-fold (relative to the first postrelease sample year), reaching a final density of 2.3-14.3 broods/m2 of phloem area and causing 13.1-49.2% marginal rate of parasitism at four of the six sites. In contrast, T. planipennisi was only recovered in 2018 at four of the six release sites, and both its density (0.1-2.3 broods/m2 of phloem area) and parasitism (0.1-5.6%) were lower than that of S. galinae throughout the study at the four sites where recoveries were made. Our data fill a critical gap in the development of a biocontrol-based EAB management plan to protect surviving ash trees capable of reaching maturity and producing replacement trees.