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Spathius galinae is a larval parasitoid native to the Russian Far East that was approved for release in the United States in 2015 for biological control of the emerald ash borer (EAB), Agrilus planipennis , an invasive beetle from Asia responsible for widespread mortality of ash trees (Fraxinus spp.) in North America. From 2015 to 2017, 1,340–1,445 females of S. galinae along with males were released into each release plot, paired with a nonrelease control plot (1–12.5 km apart), at 6 postinvasion forested sites containing abundant pole-sized ash trees in Michigan. By 2018, S. galinae had spread to all but one control plot. Based on the first year that S. galinae was found in trees in each control plot and the distances of those trees to the parasitoid release point within each site, we estimated that S. galinae spread at 3.7 (±1.9) km per year after its initial releases in 2015. The proportion of sampled trees with S. galinae broods, brood densities within sampled trees, and parasitism of EAB larvae increased sharply in both control and release plots after the last field releases in 2017, with the highest parasitism rates (42.8–60.3%) in 2020. Life table analysis showed that S. galinae alone reduced EAB's net population growth rate by 35–55% across sites from 2018 to 2020. These results demonstrate that S. galinae has established an increasing population in Michigan and now plays a significant role in reducing EAB populations in the area. [ABSTRACT FROM AUTHOR]

The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive woodboring pest of ash trees (Fraxinus sp.) in North America. Among the Asiatic parasitoids being released for the management of EAB in North America, Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) is the only EAB egg parasitoid. To date, more than 2.5 million O. agrili have been released in North America; however, few studies have examined its success as a biological control agent of EAB. We conducted studies to assess O. agrili establishment, persistence, spread, and EAB egg parasitism rates in Michigan at the earliest release sites (2007–2010), as well as at more recent release sites (2015–2016) in 3 Northeastern United States (Connecticut, Massachusetts, New York). In both regions, we documented successful O. agrili establishment at all but one release site. In Michigan, O. agrili has persisted at release sites for over a decade and spread to all control sites located 0.6–3.8 km from release sites. Overall, EAB egg parasitism ranged from 1.5% to 51.2% (mean of 21.4%) during 2016–2020 in Michigan and from 2.6% to 29.2% (mean of 16.1%) during 2018–2020 in the Northeastern states. Future research efforts should focus on factors affecting the spatiotemporal variation in EAB egg parasitism rates by O. agrili, as well as its potential range in North America. [ABSTRACT FROM AUTHOR]

The emerald ash borer (EAB), Agrilus planipennis Fairmaire, is the most destructive invasive pest on ash (Fraxinus spp.) in the United States. We determined whether ash trees injected with emamectin benzoate (EB) could protect untreated neighboring ash trees. We also determined whether the selective treatment of ash trees with EB injections had adverse effects on the establishment of introduced larval parasitoids Tetrastichus planipennis Yang and Spathius galinae Belokobylskij & Strazenac. In experiment one, trees were treated with EB and then retreated 3 years later. Five years post initial treatment, we found that 90% of treated ash trees retained healthy crowns, significantly higher than those of untreated control ash trees (16%). For experiment two, trees only received one treatment of EB and after 2 years 100% of treated ash trees retained healthy crowns, significantly higher than those of untreated ash trees (50%). In both experiments, we found that distance from the central EB-treated tree was not a significant predictor for tree health or presence of EAB exit holes. Although distance from the EB-treated trees appeared to have a significant positive relationship with woodpecker feeding signs on neighboring trees, such relationships did not result in significant differences in the proportion of neighboring ash trees retaining healthy crowns between EB treatment and control plots. The introduced EAB parasitoids appeared to have established equally well between treatment and control plots. Findings are discussed in the context of integration of EB trunk injection with biological control for protection of North American ash against EAB. [ABSTRACT FROM AUTHOR]

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Emerald ash borer (Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)), an invasive phloem-feeding beetle native to Asia, has devastated North American ash forests since its detection in Michigan, United States in 2002. As the emerald ash borer has continued to spread, the potential for successful long-term management hinges upon the release, establishment, and spread of introduced larval and egg parasitoids for biological control. Here, we focus on the establishment and evidence for spatial spread of introduced larval parasitoid, Spathius agrili Yang and Spathius galinae Belokobylskij & Strazanac (Hymenoptera: Braconidae) in the state of Maryland. To assess each species, we analyzed historical release and recovery data and resampled previous release sites and nonrelease sites for establishment. We found little evidence of establishment or spread for S. agrili, despite a comparatively large number of release locations, events, and individuals. By contrast, despite much lower propagule pressure and shorter history of releases, we detected multiple established populations of S. galinae at release sites and at sites up to 90 km from the nearest release point approximately 3 yr after its most current release. Our findings show that S. galinae has established and spread rapidly following field releases whereas its congener, S. agrili has not. Although it may still be too early to evaluate the level of population control and ash protection afforded by S. galinae, these findings indicate the need for continued investment in S. galinae for emerald ash borer classical biological control efforts. [ABSTRACT FROM AUTHOR]

Climate is a critical factor considered in predicting the potential distributions of species. However, the distribution of susceptible host plants is another important constraint in retrospective and predictive analyses of invasive insect pests, particularly for wood-boring insects. In the present study, we first modeled the geographic distribution of the invasive emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), and its susceptible host trees using MaxEnt. We then compared the differences between the predicted and actual distribution of EAB in its native (China) and invaded (the United States and Canada) ranges by incorporating the distribution of its susceptible host plants. Results from our models indicate that: (1) in addition to climatic factors, the presence of susceptible host tree species plays a major role in delineating the pest's distribution; (2) it is more accurate to project EAB's potential range distribution by considering the suitability of potential areas for its susceptible host plants; and (3) there is a high risk of EAB expanding its current distribution areas in both its native and invasive ranges. The inclusion of susceptible host plant presence as a factor enables more effective predictive modeling and risk assessment for biological invasions, especially for oligophagous insects. [ABSTRACT FROM AUTHOR]

The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), native to Northeast Asia, is the most destructive invasive ash (Fraxinus spp.) pest in the United States. In the present study, we evaluated the effect of exposure of diapausing mature fourth instars (J-shaped larvae, JL) of EAB to cool temperatures, either 1.7 or 12.8°C for 1–9 mo, on their post-chill development including adult emergence, longevity, and lifetime fecundity under standard rearing conditions (26 ± 0.5°C, 16:8 h L:D). In addition, we determined the effect of different stages of the larvae chilled at 12.8°C for 3 mo on the subsequent post-chill development to EAB adults. Findings from the study revealed that a period (≥2 mo) of chill at 12.8°C is required for the termination of the EAB diapause. However, chill treatment of the larvae at the near zero temperature (1.7°C) does not result in the post-diapause larval development to adults, regardless of the chill time (1–9 mo). In addition, our results showed that chill treatment of immature young larvae (L1–L4 prior to JL) results in little production of EAB adults, indicating that EAB diapause predominantly as JL. Findings of this study may be useful to laboratory rearing of EAB from eggs through continuous generations and help us understand the pest's voltinism resulting from the diapause and post-diapause development under different climatic conditions. [ABSTRACT FROM AUTHOR]

Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids. It is native to North America but can readily attack the exotic Asian longhorned beetle, Anoplophora glabripennis (Motschulsky). This study aimed to develop an efficient rearing system for this parasitoid, as a potential novel association biocontrol agent for the beetle, by investigating the effects of different densities of host (two, three, or four larvae) and parasitoid (one, two, three, four, five, six, seven, and eight female wasps) on Ontsira 's parasitization efficiency and reproductive outcomes. Results showed that overall parasitism and total numbers of parasitized hosts or progeny produced increased with host and/or parasitoid densities, but the number of parasitized hosts or progeny produced per female parasitoid decreased with parasitoid density at each given host density. Nonlinear regression indicated a consistent pattern of mutual interference as parasitoid density increased. Additional experiments showed that superparasitism (indirect interference) did not occur probably because the parasitoid detects hosts through vibration cues from host feeding and attacked (thus paralyzed) hosts are no longer detectable. Thus, the interference probably results from direct or exploitative competition. Interestingly, female parasitoids responded to increased parasitoid density with a significant increase in clutch size. Overall, per capita parasitization efficiency or reproductive outcomes were optimized at a low parasitoid–host ratio but with large group size of hosts and parasitoids. Therefore, an optimal combination of exposing three or four parasitoids to four hosts is proposed for efficient mass-rearing of this parasitoid. [ABSTRACT FROM AUTHOR]

Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), is a high-risk invasive forest pest worldwide. We surveyed Asian longhorned beetle parasitoid guilds and their seasonal abundance using field-deployed sentinel host logs infested with Asian longhorned beetle eggs or newly hatched (early-instar) larvae in three different sites of China (Beijing City, Shanghai City, and Jilin Province) from 2015 to 2018. Our survey detected 12 species of hymenopteran parasitoids (four Pteromalidae, three Braconidae, two Eupelmidae, one Eurytomidae, one Ichneumonidae, and one Bethylidae) attacking sentinel Asian longhorned beetle larvae or eggs deployed in these sites. Total parasitism by all the parasitoid species varied with different sites and across different years of the survey (averaging 7–16% in Beijing, 4–11% in Shanghai, and 0–0.2% in Jilin Province). In addition, the seasonal pattern of parasitism also differed among different sites, with parasitism peaking in July in the northern site (Beijing, 19%) and June in the southern site (Shanghai, 16%). Among all the parasitoid species recovered, Oxysychus sp. (Hymenoptera: Pteromalidae) was the most abundant parasitoid species in both Beijing and Shanghai (with 42–66% relative abundance and an average of 6% Asian longhorned beetle parasitism). The second most abundant species was Bracon planitibiae Yang, Cao et Gould (Hymenoptera: Braconidae), which accounted for 35% of the species collected and caused an average of 5% Asian longhorned beetle parasitism. Relevance of our findings to Asian longhorned beetle biocontrol is discussed. [ABSTRACT FROM AUTHOR]

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), quickly established itself as an invasive species in North America after it was first detected near Detroit, Michigan, USA, in 2002. Just 1 yr later, emerald ash borer was introduced accidentally into Maryland, USA, on imported ash nursery stock. After quarantine and eradication efforts failed, a classical biological control program was initiated in Maryland in 2009 with the release of 2 larval parasitoids: Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius agrili Yang (Hymenoptera: Braconidae), and 1 egg parasitoid, Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae). Timing is critical to the success, efficiency, and cost-effectiveness of classical biological control programs where release of parasitoids must coincide temporally with that of susceptible stages of the host. In 2017, periodic field surveys at 2 sites in central Maryland were conducted to assess emerald ash borer phenology using green funnel traps to sample adults, and debarking infested ash trees to sample larval stages. Adult emerald ash borer first appeared in traps on 18 May 2017 (479 growing degree d base 10 [GDD10]), peaked on 15 Jun (823 GDD10), and were absent from 13 Jul (1,301 GDD10) through 12 Oct (2,598 GDD10) when surveys were terminated. Larval sampling in early Aug (1,698 GDD10) found all larval instars present, the most common being the second instar (46%), followed by the third instar (28%), fourth instar (20%), first instar (5%), and prepupal J-shaped larvae (J-larva) (0.5%). J-larvae are so called because after excavating a pupal chamber, the head is bent down 180 degrees to the rest of the body, resembling the shape of the letter J. Larval sampling in late Oct (2,710 GDD10) found J-larvae to be the dominant stage present (92.2%), followed by fourth instar (4.8%), third instar (2.4%), and second instar (0.6%). We found that emerald ash borer was univoltine, and that nearly 50% of emerald ash borer larvae had developed to stages susceptible to parasitism (third and fourth instar) by early Aug (1,698 GDD10). By late Oct (2,710 GDD10), 92% had developed beyond parasitoid susceptible stages (J-larvae). These findings suggest that egg parasitoid releases are best targeted from early May to late Jun at an approximate GDD10 range of 300 and 1,100 with larval parasitoid releases best targeted between 1,400 and 2,500 GDD10. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Numerous researchers have observed native parasitic Hymenoptera attacking exotic pest species, yet few have documented their potential to adapt to novel hosts. Host-adapted parasitoids may be particularly important in new-association biocontrol programs, especially if their behaviors and physiologies can be affected in such a way as to enhance their virulence on novel hosts. Here, we investigated the potential of the native parasitoid, Ontsira mellipes, to adapt to a novel, invasive cerambycid host, Anoplophora glabripennis, under laboratory conditions. Although not significantly different, there is an apparent increase in parasitism of A. glabripennis larvae (from 45.5 to 65.7%) and in the percentage of pupae eclosing to adults (from 65.1 to 82.9%) between the F1–2 and F68–71 generation parasitoids. Moreover, later generation (F41–44 and F68–71) parasitoids produced significantly more progeny on average than did first-generation (F1–2) parasitoids, and parasitoid generation had no significant effect on the secondary sex ratio or ovipositor length. Results indicate that older generation parasitoids have an increased efficacy in parasitizing and utilizing this novel host. This study demonstrates that continuously rearing of a generalist parasitoid on a newly acquired novel host can enhance host parasitism rates, parasitoid development, and fitness and thus may improve the efficacy of new-association biocontrol. [ABSTRACT FROM AUTHOR]

We conducted field surveys of the emerald ash borer (EAB), Agrilus planipennis Fairmaire, and associated larval parasitoids in western and central Pennsylvania (Cranberry Township in Butler County and Granville in Mifflin County) in the spring and fall of 2009. The survey procedure involved destructively debarking sections of the main trunk (bole) of EABinfested green ash (Fraxinus pennsylvanica Marsh.) trees from the ground to the height of 2 m. Three species of the hymenopteran parasitoids were consistently recovered from EAB larvae observed in both survey sites, including two indigenous species of braconids, Spathius laflammei Provancher (= Spathius benefactor Matthews) and Atanycolus nigropyga Shenefelt and the exotic (accidentally introduced) eupelmid Balcha indica (Mani & Kaul). In addition, there are three unidentified species of hymenopteran parasitoids including two braconids Atanycolus sp. [possibly Atanycolus disputabilis (Cresson)] and Spathius sp. (at the Butler Co. site) and one ichneumonid Dolichomitus sp. (at the Mifflin Co. site). These parasitoids together parasitized 0.5-4.6% and 0.5-1.5% of the sampled EAB hosts at the Butler and Mifflin Co. sites, respectively. Parasitism rate by each species or group of those hymenopteran parasitoids varied between the two survey sites-with parasitism rates being generally higher at the Butler Co. site than at the Mifflin Co. site. Studies are needed to determine if those new associations of North American indigenous braconid parasitoids with EAB may play a complementary role in controlling this invasive pest. [ABSTRACT FROM AUTHOR]

Literature studies in North America (US and Canada), Europe, and Asia (particularly Russia, China, Japan, and the Korean peninsula) were reviewed to identify parasitoid guilds associated with Agrilus woodborers. There are at least 12 species of hymenopteran parasitoids attacking eggs of Agrilus beetles and 56 species (36 genera), attacking Agrilus larvae infesting various host plants in North America, Asia, and Europe. While most of the egg parasitoids (9 species) belong to the family Encyrtidae, a majority of the larval parasitoids are members of five families: Braconidae (24 species/11 genera), Eulophidae (8 species/4 genera), Ichneumonidae (10 species/9 genera), and Eupelmidae (6 species/5 genera). The highest rate of Agrilus egg parasitism (>50%) was exerted by encyrtid wasps (4 species) in North America, Asia, and Europe. In contrast, the highest rate of Agrilus larval parasitism (>50%) was caused by species in two genera of braconids: Atanycolus (North America) and Spathius (Asia), and one eulophid genus, Tetrastichus (Asia and Europe). Reported rate of Agrilus larval parasitism ichneumonids was frequent in North America, but generally low (<1%). Potential for success in biological control of emerald ash borer (Agrilus planipennis Fairmaire) in the USA with North American native parasitoids and old-association Asian parasitoids is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Three hymenopteran parasitoids native to China are being released in the United States as biological control agents for the emerald ash borer (EAB), Agrilus planipennis Fairmaire, an Asian buprestid species responsible for mortality of ash trees (Fraxinus spp.) in North America. Two of these hymenopterans, Spathius agrili Yang (Braconidae), a larval ectoparasitoid, and Tetrastichus planipennisi Yang (Eulophidae), a larval endoparasitoid, prefer late-instar EAB larvae. This overlapping host preference raises concerns that interspecific competition following field releases may compromise establishment of one or both species. In a series of laboratory and field experiments, we found S. agrili and T. planipennisi exhibited similar parasitism rates when presented alone with EAB larvae for 12–14days. However, S. agrili was more efficient at locating and parasitizing hosts within the first 27h, possibly explaining why S. agrili excluded T. planipennisi in the laboratory trials and nearly excluded T. planipennisi in field trials when the two species were presented together with EAB larvae. We found that S. agrili parasitized larvae previously parasitized by T. planipennisi but not the reverse. However, S. agrili offspring failed to complete development on hosts that were previously parasitized by T. planipennisi. We recommend releasing these species separately in time or space to avoid the antagonistic interactions observed in this study. [Copyright &y& Elsevier]

A 14-d continuous dietary exposure bioassay using nymphs of the insidious flower bug, Onus insidiosus (Say) (Heteroptera: Anthocoridae), was conducted to assess nontarget impacts of genetically modified corn event MON 863 expressing the Cry3Bb1 protein for management of corn rootworms, Diabrotica spp. (Coleoptera: Chrysomelidae). Nymphs of O. inridiosus were continuously fed a bee pollen diet inoculated with a maximum hazard exposure dose (930 µg/g of diet) of the Cry3Bb1 protein for 14 d. The Cry3Bb1 protein at a concentration of 930 µg/g of diet had no adverse effect on the survival and development (to adults) of O. insidiosus nymphs. In contrast, when O. insidiosus nymphs were fed bee pollen diet treated with a hazard dose of the protease inhibitor E64 (53 µg/g of diet) or the stomach poison potassium arsenate (8.9 µg/g of diet), all nymphs died before developing to adults. Furthermore, statistical power analysis indicated that at levels of 80% power and a 5% type I error rate, the study design would have been able to detect a minimum 30% reduction in survival of test nymphs and a 20% reduction in nymphal development to the adults relative to the buffer control groups. Based on the maximum level (93 µg/g) of the Cry3Bb1 protein expressed in MON 863 corn tissues including leaves, roots, and pollen, findings from this study indicate that corn hybrids containing the MON 863 event have a minimum 10 times safety factor for nymphs of O. insidiosus and thus pose minimal risk to this beneficial insect. [ABSTRACT FROM AUTHOR]

A dietary exposure bioassay with larvae of the ground beetle, Poecilus chalcites (Say) (Coleoptera: Carabidae), was developed to assess potential nontarget impacts of corn event MON 863 expressing the Cry3Bbl protein for control of corn rootworms, Diabrotica spp. (Coleoptera: Chrysomelidae). The assay involved 28 d of continuous exposure of P. chalcites larvae to an artificial diet treated with a maximum hazard dose (930 μg/g of diet) of the Cry3Bbl protein. Results from this study showed that the Cry3Bbl protein at a concentration of 930 μg/g of diet had no adverse effect on the survival, development, and growth (biomass) of P. chalcites larvae. Furthermore, statistical power analysis indicated that at levels of 80% power and 5% type I error rate, the study design would have been able to detect a minimum 14 (at day 7) to 19% (at days 14, 21, and 28) reduction in survival and a 21 (at day 14) to 18% (at day 28) reduction in biomass of test larvae relative to the negative buffer control groups. Based on the maximum level (93 μg/g) of the Cry3Bbl protein expressed in MON 863 corn tissues including leaves, roots, and pollen, findings from this study indicate that corn hybrids containing the MON 863 event have a minimum 10 times safety factor for larvae of P. chalcites, and thus pose little risk to this nontarget beneficial insect. [ABSTRACT FROM AUTHOR]

• Oobius agrili (OA), native to China, was introduced to U.S. for biocontrol of emerald ash borer (EAB). • We evaluated effects of OA diapause and release times on its reproductive biology in Mid-Atlantics. • Diapause status has no effect on the longevity and fecundity of the released adults. • Non-diapaused wasps produced higher proportion of diapaused progeny than diapaused ones. • Diapause status of released adults affects the establishment of overwintering parasitoid populations. Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), a solitary egg parasitoid native to China, was introduced to the United States for biocontrol of the invasive emerald ash borer (EAB) Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) in 2007. To help develop effective biocontrol-release strategies , we evaluated the effect of parental diapause and release time of the adult parasitoids on their longevity, realized fecundity, and progeny diapause rate under field conditions in the U.S. Mid-Atlantic region in 2016 and 2017. Results from two years of the study showed that both non-diapaused and diapaused O. agrili adults released in rearing containers exposed to field conditions in late spring to early summer (from May 26 to July 20th) successfully survived and reproduced on emerald ash borer eggs provided throughout the study period. The parental parasitoid diapause status and release time did not significantly affect the longevity and life-time fecundity of the released adult parasitoids except that both diapaused and non-diapaused parasitoids released on May 26th of 2017 produced significantly fewer progeny than those from later releases (June 14th and July 20th) of the same year. In both 2016 and 2017, non-diapaused parasitoids consistently produced a higher proportion of diapaused progeny than diapaused parasitoids, regardless of release times. These findings indicate that releases of O. agrili with different diapause status from late spring to early summer may cause variations in establishing overwintering parasitoid populations for biological control of emerald ash borer in the field. [ABSTRACT FROM AUTHOR]

A correction to the article "Progress in the classical biological control of Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) in North America," by Leah S. Bauer and colleagues published in the May 12, 2015 issue is presented.

Spathius galinae Belokobylskij (Hymenoptera: Braconidae) is among several parasitoids introduced as classical biocontrol agents for control of the invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), in the US. However, the successful establishment of this parasitoid and its efficacy in suppressing emerald ash borer vary among the release sites and regions. We hypothesize that forest microhabitats and parasitoid overwintering life stages affect parasitoid overwintering survival, development, and emergence phenology of adults in the spring. To test this, we placed logs containing 3 different larval stages of S. galinae (early instar larva, late instar larva, and cocoon) in ventilated jars in 2 distinct microhabitat sites, i.e., urban forest and mature natural forest. These were deployed in late fall of 2020 and remained in the field through winter. The emergence of adult parasitoids was recorded in spring through summer of 2021. Parasitoids in the warmer urban site emerged more quickly, emerging 12 d earlier than parasitoids in the cooler mature forest site. None of the S. galinae deployed as early instar larvae diapaused in either urban or forest sites. In both habitats, 27.1 to 32.1% of late instar larvae diapaused. Across overwintering larval stages, the median time of S. galinae emergence was about 24 d in the urban microhabitat, significantly shorter than that (36 d) observed in the mature forest microhabitat. Our findings suggest that environmental factors profoundly affect S. galinae phenology, and consequently emerald ash borer biological control. Spathius galinae Belokobylskij (Hymenoptera: Braconidae) se encuentra entre varios parasitoides introducidos como agentes de biocontrol clásico para el control del barrenador esmeralda del fresno invasivo, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), en los EE. UU. Sin embargo, el establecimiento exitoso de este parasitoide y su eficacia para suprimir el barrenador esmeralda del fresno varían entre los sitios y regiones de liberación. Nuestra hipótesis es que los microhábitats del bosque y los estadios de vida de hibernación del parasitoide afectan la sobrevivencia, el desarrollo y la fenología de emergencia de los adultos en la primavera. Para probar esto, colocamos troncos que contenían 3 estadios larvales diferentes de S. galinae (larva de estadio temprano, larva de estadio tardío y capullo) en frascos ventilados en dos sitios de microhábitat distintos, un bosque urbano y un bosque natural maduro. Estos se desplegaron a fines del otoño del 2020 y permanecieron en el campo durante el invierno. Se registró la aparición de parasitoides adultos desde la primavera hasta el verano del 2021. Los parasitoides en el sitio urbano más cálido emergieron más rápidamente, emergiendo 12 días antes que los parasitoides en el sitio de bosque maduro más frío. Ninguno de los S. galinae se desplegó como larvas de estadio temprano en diapausa en sitios urbanos o forestales. En ambos hábitats, entre el 27,1 y el 32,1% de las larvas de estadio tardío entraron en diapausa. A lo largo de los estadios larvales de hibernación, la media del tiempo de emergencia de S. galinae fue de aproximadamente 24 días en el microhábitat urbano, significativamente más corto que el (36 días) observado en el microhábitat de bosque maduro. Nuestros hallazgos sugieren que los factores ambientales afectan profundamente la fenología de S. galinae y, en consecuencia, el control biológico del barrenador esmeralda del fresno. [ABSTRACT FROM AUTHOR]

• Sentinel logs detected both T. planipennisi and S. galinae at high rates. • Debarking was more efficient for detecting S. galinae than T. planipennisi. • Yellow pan traps captured both species at lower rates than the other methods. • We documented that both species spread > 4 km, 3 years after their release. We compared three detection methods for two larval parasitoids introduced for the control of the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae): Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius galinae Belokobylskij and Strazanac (Hymenoptera: Braconidae). The three methods compared were 1) debarking the lower 2 m of ash trees, 2) yellow pan traps (YPT), and 3) sentinel logs containing manually inserted late-instar EAB larvae. The parasitoids studied were released in a mixed hardwood forest in Cromwell, Connecticut from 2015 to 2017 and had established self-sustaining populations before this experiment. In 2019, we deployed all three detection methods along two transects (4.6 km and 5.7 km long, respectively) radiating out from the parasitoid release area. All three methods detected both parasitoid species. Each parasitoid was detected at the furthest transect point of at least one of the transects. Sentinel logs were the most efficient method for capturing T. planipennisi, with a labor requirement of 2.4 h/detection (139 h/57 broods). Debarking, in contrast, was the most efficient method for S. galinae , with a labor requirement of 3.6 h/detection (172 h/48 broods). YPT were the least efficient technique, capturing only 15 T. planipennisi and 9 S. galinae wasps for the entire trapping period at Cromwell, a labor requirement of 18.7 h/per detection (280 h/15 adults) and 31.1 h/detection (280 h/9 adults), respectively. We discuss the advantages and disadvantages of these three techniques. [ABSTRACT FROM AUTHOR]

• Emerald ash borer is responsible for catastrophic decline of ash in the U.S. • Two larval parasitoids of were introduced to control emerald ash borer 2015 – 2017. • Post-release monitoring for phenology and spatial spread occurred in 2020 via sentinel logs. • Both parasitoids were found throughout the sampled area and up to 14 km away from the release site. • Phenologies of host and parasitoids in introduced area align. Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive wood-boring pest of ash trees (Fraxinus spp.) in the United States. It is responsible for catastrophic decline of ash in urban and forested ecosystems, resulting in millions of dollars in economic losses. Biological control is one of the most promising management options available to reduce A. planipennis spread and impact. From 2015 to 2017, two larval parasitoids from the native range of A. planipennis , Spathius galinae Belokobylskij & Strazenac (Hymenoptera: Braconidae) and Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) , were released in forested areas in New York and Connecticut. The purpose of this study was to measure the spread and seasonal phenology of these introduced parasitoids. From May to September 2020, sentinel ash logs containing EAB larvae were deployed in naturally occurring A. planipennis infested trees at each release site and at 2 km intervals up to 14 km away from the release site. Logs were replaced every two weeks and the parasitization rate was recorded. Each month, three trees from each release area were also cut and debarked to record A. planipennis infestation levels, natural parasitization rates, and A. planipennis and parasitoid phenology. We observed that both S. galinae and T. planipennisi emerged from the logs first deployed from the end of May to early June. Parasitization peaked in late July and mid-August, with sentinel logs deployed at each distance producing both species throughout the summer until mid-September. Both S. galinae and T. planipennisi were detected 14 km away from the release sites, the greatest distance away from the release sites sampled. Debarked trees produced similar seasonal patterns of parasitism. Our results indicate that the classical biological control program initiated several years ago has successfully produced a self-sustaining population of both S. galinae and T. planipennisi , which have been spreading widely and attacking the borer throughout the growing season. These findings strongly suggest that future release efforts may allow for wider temporal release windows and larger strategic spacing of release points across geographic regions. [ABSTRACT FROM AUTHOR]

Ontsira mellipes attacked A. glabripennis and did not show a preference between A. glabripennis and other attacked cerambycids (* = significant, ns = not significant, P = 0.05). #Parasitoids used in this trial were reared from M. carolinensis while all other trials used parasitoids reared from A. glabripennis. • Ontsira mellipes is a native North American parasitoid of wood-boring insects. • The parasitoid successfully attacks Asian longhorned beetle (ALB). • It also attacks three of six tested native longhorned beetles as well as citrus longhorned beetle. • O. mellipes does not show a preference between ALB and other attacked host species. • The parasitoid may have a potential for biological control of ALB. The Asian longhorned beetle (ALB), Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) is a high-risk, invasive pest of hardwood trees that has been targeted for eradication in the US since the 1990s. Ontsira mellipes Ashmead (Hymenoptera: Braconidae) is a native North American parasitoid that has been found to be capable of attacking ALB larvae under laboratory conditions. To investigate the potential host range of O. mellipes we exposed six common North American cerambycid species (Elaphidion mucronatum (Say), Monochamus carolinensis Olivier, Monochamus notatus (Drury), Neoclytus scutellaris Olivier, Xylotrechus colonus (Fabricius), and Xylotrechus sagittatus Germar) and the citrus longhorned beetle (Anoplophora chinensis Forster) to adult O. mellipes for possible oviposition. Results showed that O. mellipes successfully attacked A. glabripennis , A. chinensis , E. mucronatum , M. carolinensis and M. notatus , but did not attack N. scutellaris , X. colonus and X. sagittatus in both choice and no-choice tests. Ontsira mellipes did not show a preference between A. glabripennis and other attacked host species, regardless of the host species on which the tested parasitoids were reared. The number of progeny emerging per parasitized host larva was influenced by the attacked host species and by the interaction between the attacked host species and the size of parasitized larvae. Neither host species nor the size of parasitized larvae influenced the sex ratio (≈ 80% females) of the parasitoid's offspring. In terms of progeny fitness, the parasitoid preformed equally well on A. glabripennis as on native hosts such as M. carolinensis. The use of O. mellipes as a biological control agent for A. glabripennis is discussed. [ABSTRACT FROM AUTHOR]