Therese M. Poland

We studied the effects of trapping intensity and lure combinations on Scolytinae (Coleoptera: Curculionidae) collections, using funnel traps at 16 sites including forests and Christmas tree farms near Erie, Pennsylvania and Toledo, Ohio, United States of America. In 2002, using 16 or 64 traps per site, all baited with α-pinene + ethanol, we collected 146 627 specimens from 40 species altogether. With 16 traps, 15–24 scolytine species were collected per site, whereas 28–31 species were collected with 64 traps. On average, 55% of all scolytine species collected with 16 traps were collected when subsampling with one trap per site, 78% with four traps, 89% with eight traps, and 95% with 12 traps. A bootstrapping analysis indicated that relatively few new species were gained by subsampling more than six traps per site. On average, similar numbers of species were collected in forests and Christmas tree farms. In 2003, we compared scolytine captures in traps baited with α-pinene, ethanol, α-pinene + ethanol, a three-component exotic Ips lure, chalcogran + methyl 2,4-decadienoate, or lineatin, or in unbaited control traps at eight sites. Overall, 31 977 scolytine specimens from 38 species were collected. Traps baited with α-pinene + ethanol captured the most scolytine species and individuals per trap in absolute terms.

In Michigan, United States of America, where Asian parasitoids were released to manage emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), we monitored four native parasitoids that also attack the invasive beetle – Atanycolus cappaerti Marsh and Strazanac, A. simplex (Cresson), and Spathius laflammei Provancher (all Hymenoptera: Braconidae), and Phasgonophora sulcata Westwood (Hymenoptera: Chalcididae) – using yellow pan traps and tree dissections. Adult A. cappaerti, followed by A. simplex, had the broadest seasonal activity, S. laflammei was captured primarily in the first half of the growing season, and P. sulcata was restricted to mid-summer. Adult abundances of native species varied among years but, except for P. sulcata, were never significantly lower than the established Asian emerald ash borer larval parasitoids, Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius galinae Belokobylskij and Strazanac (Hymenoptera: Braconidae). Densities of emerald ash borer larvae parasitised by A. cappaerti or P. sulcata did not differ significantly from those of the two Asian species. Although adult A. simplex and S. laflammei were frequently captured, we did not confirm parasitisation of any emerald ash borer larvae by these two species, suggesting that they rarely attack emerald ash borer. We did not find any negative correlations between adult or immature parasitoid abundance of any parasitoid species, suggesting that any interspecific competition that may be occurring is negligible.

A checklist of 488 fall webworm Hyphantria cunea (Drury) natural enemies was compiled based on documentation in previous research across its world distribution, including 289 predators and 199 parasitoids. Predators in the checklist include 67 species from 17 families of Insecta, 1 species of Chilopoda, 183 species from 22 families of Arachnida, 1 species of Reptilia, 4 species from 2 families of Amphibia, 33 species from 18 families of Aves. In addition, the checklist includes fall webworm parasitoids from 18 families of Insecta. Among continents, 128 predators and 76 parasitoids were distributed in North America, 78 predators and 62 parasitoids in Asia, and 88 predators and 68 parasitoids in Europe.

Emerald ash borer (EAB) (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is the most destructive insect to invade North American forests. Identifying habitat features that support EAB natural enemies is necessary to enhance EAB biological control. In many forest ecosystems, tree species diversity has been linked with reduced pest abundance and increases in natural enemy abundance. We assessed the influence of tree species richness, ash density, and proportion of total ash basal area on ash canopy condition, EAB larval densities, and biocontrol by woodpeckers and parasitoids in pairs of healthy and declining overstory (DBH > 10 cm) and recruit-sized ash (DBH 2–10 cm) in 4 post-invasion forests in Michigan, USA. Tree species richness and ash density were not significantly associated with EAB larval densities, ash canopy dieback and transparency, and woodpecker predation of EAB larvae. In declining and healthy overstory ash, woodpeckers killed 38.5 ± 3.9% and 13.2 ± 3.7% of larvae, respectively, while the native parasitoid Phasgonophora sulcata Westwood killed 15.8 ± 3.8% and 8.3 ± 3.0% and the introduced parasitoid Spathius galinae Belokobylskij & Strazanac killed 10.8 ± 2.5% and 5.0 ± 2.6% of EAB larvae. Parasitism by P. sulcata was inversely related to ash density while parasitism by S. galinae was positively associated with ash density. Ash density, but not tree diversity, appears to differentially influence biological control of EAB by parasitoids, but this effect is not associated with reduced EAB densities or improved canopy condition.

DR. MICHAEL L. MCMANUS passed away at age 85 in his home in Hamden, Connecticut, 16 November 2023. Mike was born on 8 December 1937 and was raised in the south side of Chicago. The high points of his childhood were summers he spent with his mother’s family in Winamac, Indiana, where he could escape the city and learn about nature. Mike earned all of his degrees at Purdue University: a B.S. in agriculture in 1959, an M.S. in entomology in 1962, and a Ph.D. in entomology in 1966. During his Ph.D., he worked with Ron Giese on the effect of forest meteorology on insect populations, especially those of the Columbian timber beetle.

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

Atanycolus yangi sp. nov. (Hymenoptera, Braconidae), a new species parasitizing the flatheaded wood borer, Lamprodila nobilissima bellula (Lewis) (Coleoptera: Buprestidae), is described. Lamprodila nobilissima bellula is a serious wood boring pest of Rosacea trees in North China. We collected adult specimens of A. yangi sp. nov. searching for hosts on infested tree trunks and confirmed the host-parasitoid association by dissecting parasitized hosts from infested trees in the field and rearing the parasitoid from L. nobilissima bellula -infested host tree logs in the laboratory. Adult images for both sexes of the new parasitoid species are provided. A morphological identification key to Oriental and Palaearctic species similar to A. yangi sp. nov is also presented.

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.

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.