Location: Beneficial Insects Introduction Research Unit
2021 Annual Report
Objectives
Objective 1: Investigate key biotic factors influencing the spatial and temporal dynamics of wood-boring pest (including ALB and EAB) populations in their native range, focusing on exploration and quarantine service for effective, host-specific natural enemies (parasitoids) for biocontrol.
Subobjective 1a - Explore for parasitoids of ALB and EAB in the pests’ native range (Asia).
Subobjective 1b - Evaluate the role of the key natural enemies in regulating the spatial and temporal dynamics of ALB and EAB in the area of collection in Asia.
Subobjective 1c - Evaluate the host specificity of parasitoids discovered for introduction to North America for ALB and EAB control.
Subobjective 1d - Quarantine services to support research on exotic insect pests and their natural enemies.
Objective 2: Conduct field releases and evaluate impacts of extant (indigenous) and previously introduced parasitoids on populations of wood-boring beetles such as EAB and ALB in the United States, while elucidating factors that influence successful establishment of introduced biological control agents, such as climate adaptation, release methodology, genetic variation in founder populations and risk-spreading (diapause) strategy.
Objective 3: For newly discovered parasitoids of ALB, EAB and other invasive pests, and based on studies of life histories and reproductive biology, develop effective rearing technologies for these natural enemies, focusing on optimizing host stage, host substrate complex, temperature, photoperiod and relative humidity.
Subobjective 3a - Characterize the reproductive biology, risk-spreading (diapause) strategy and key life history parameters of most promising parasitoid species.
Subobjective 3b - Determine the optimal host stage and host-substrate complex in association with host density and host-to-parasitoid ratio.
Subobjective 3c - Determine the optimal environmental conditions for adult parasitoid survival, oviposition and progeny development including diapause induction and termination.
Approach
Using the approaches relevant to the knowledge base of the targeted pests and their natural enemies, we will conduct foreign explorations for new natural enemies from the pests’ native home (Northeast Asia) and construct life tables of the target pest populations to evaluate the impact of the natural enemies on the pests’ population dynamics in Northeast Asia. After selecting the most promising (or efficient) natural enemies, we will test the selected natural enemies against non-target wood-boring insects in North America to delineate their host range for biological control introduction against the target pests. Upon regulatory approval for environmental releases of the discovered natural enemies in North America, we will conduct field experiments to assess their establishment, dispersal and impacts on the target pests’ population in the U.S. Laboratory studies will also be conducted to collect information on the parasitoid’s biology, risk-spreading and reproductive strategy and life history and to develop efficient rearing methods for mass-production of the introduced natural enemies for biological control releases. In addition, this project will provide quarantine services, host range data and mass-rearing technologies for natural enemies of high priority plant pests to state and federal agencies.
Progress Report
ASIAN LONGHORNED BEETLE (ALB) RESEARCH: In collaboration with the Chinese Academy of Forestry and Seoul National University, limited surveys for (ALB) parasitoids were conducted during 2020 in both centuries by our collaborators. In China, surveys using logs infested with young ALB larvae collected several parasitoid species. A total of 167 cocoons and 14 adult wasps of the most common species (Spathius anoplophorae) were shipped on 10 November 2020 to our quarantine. We successfully established a laboratory population of the parasitoid on ALB in maple bolts. The parasitoid is currently under evaluation for its potential to be used as a classical biological control agent for ALB. Some aspects of S. anoplophorae biology and host range have been investigated. S. anoplophorae had female-biased offspring (about 80% females), produced about 26 offspring per female with immature developmental time ranging from 22 days at 21 °C to 11 at 33 °C. Preliminary host range tests in China showed that S. anoplophorae could parasitize the larvae of Anoplophora chinensis, Aromia bungii, Monochamus alternatus, Eucryptorrhynchus, and Agrilus planipennis in no-choice tests but only attacked A. glabripennis and M. alternatus in choice tests. In South Korea, surveys using sentinel logs with living and ovipositing adult ALB females collected two individuals of an egg parasitoid larvae (a possible Aprostocetus species) and an unidentified Spathius sp. attacking young ALB larvae. The surveys will be continued this summer with the goal of finding and successfully rearing the egg parasitoid. In collaboration with APHIS and the University of Massachusetts, we are conducting field release trials (from June to September 2021) to assess the potential for a North American parasitoid (Ontsira mellipes) to parasitize and reduce ALB populations in the ALB regulated zones in Worcester, Massachusetts, in conjunction with, and as an augmentation to, current eradication efforts. We have obtained all necessary federal and state permits for ALB-log deployment and interstate movement and release of this parasitoid. In collaboration with the ARS European Biological Control Laboratory, we evaluated a specialist egg parasitoid (Aprostocetus fukutai) for biological control of the citrus longhorned beetle Anoplophora chinensis. We investigated the reproductive biology and optimal laboratory conditions for the rearing of the parasitoid. We found that this parasitoid emerged with a substantial portion (43.7%) of mature eggs, matured more eggs within 4–8 days, and preferred to attack young over older host eggs. We determined that high relative humidity (100% RH) and mild winter temperatures (12.5°C) are the most suitable conditions for the parasitoid’s diapause survival. These results provide novel information that may help improve protocols for future rearing, study, or field-release of this parasitoid against A. chinensis. Two manuscripts on these studies have been submitted (Log No’s 384650, 384653).
EMERALD ASH BORER (EAB) RESEARCH: With university and local state cooperators, we were able to collect data on the establishment and impact of previously introduced biocontrol agents (egg and larval parasitoids) in mid-Atlantic (Maryland), Midwest (Michigan), and Northeast (Massachusetts, New York, and Connecticut) of the U.S. with a focus on assessing the establishment, spread, phenology and impact of several previously introduced biocontrol agents on the invasive emerald ash borer. Findings from these field studies showed that the most recently introduced larval parasitoid (Spathius galinae) along with the earlier introduced agent (Tetrastichus planipennisi) had established self-sustaining populations that have been spreading widely and attacking EAB throughout the growing season. Our field studies also indicate that the two parasitoid populations in these forests show strong differentiation in presence, abundance, and/or host attack rates in ash trees of different size classes, with S. galinae parasitism being more frequent in larger diameter and pole size trees and T. planipennisi dominating in saplings. Although host larval abundance decreases significantly with the height of a sampled tree or sapling because of the reduction in the tree phloem volume, the abundance of the parasitoid broods is not affected by the tree height but strongly driven by the EAB larval abundance in the sampled section of their preferred tree-size classes. This suggests that these two introduced specialist parasitoids complement one another in protecting trees of different size classes against EAB, and thus both are needed in successful biocontrol of EAB in North America. Findings of these field studies have been reported in manuscripts (Log Nos 380572, 381725, 384286) submitted to the journal Biological Control. For the fiscal year 2021, we conducted laboratory experiments to determine the optimal temperature and relative humidity for long-term cold storage of emerald ash borer eggs and its egg parasitoid (Oobius agrili) during diapause. Results showed that both low temperature (35 – 55oF) and high relative humidity (65 – 100%) are optimal conditions for long-term storage of host eggs and diapausing egg parasitoid larvae. This laboratory study is expected to be completed by early 2022.
SPOTTED LANTERN FLY (SLF) Research: With the assistance of cooperators at APHIS and the University of Delaware, we participated in ongoing collections of SLF eggs laid by the 2020 fall generation of SLF adults to monitor for the presence of native egg parasitoids (none have been found in our region this far) and to provide host material for behavioral studies. We initiated behavioral assays in quarantine of the response by the Asian egg parasitoid Anastatus orientalis to a key non-target planthopper, Poblicia fuliginosa. In initial no-choice host range testing, it has shown intermediate levels of parasitism by A. orientalis compared to the attack on SLF by examining the response of A. orientalis to kairomone cues deposited on glass slides by SLF adult females and by females of P. fuliginosa. Foraging behavior by A. orientalis differed from controls for all movement parameters evaluated: faster turning; greater distance moved, longer time spent on the slide, and a slower walking speed. Poblicia fuliginosa did not differ from controls in any comparison. Concentrations of hexane-rinsed slides that had been exposed to adult planthoppers were too low to detect chemical components of the putative kairomone. While initial no-choice host range tests show that A. orientalis can develop in the native P. fuliginosa, our results indicate that the non-target planthopper would not be detected as readily as the invasive SLF. We will attempt to increase the concentration of spotted lanternfly chemical traces so that components altering parasitoid searching behavior can be identified. Further non-target testing with other species is ongoing. Much more research needs to be completed before a risk assessment can be developed for possible A. orientalis release. Through a cooperative agreement with the Chinese Academy of Forestry, native range studies of the natural host range in non-target species in China have also been initiated, although Covid restrictions have delayed the start of fieldwork (Agreement 58-8010-0-014F). With incoming FY2021 Farm Bill funds, we are also developing NACAs with South Korean collaborators for surveys of SLF natural enemies in the invaded South Korean range.
Research on DROSOPHILA SUZUKII PARASITOIDS reported in the publication list below was described in the report for Newark project 8010-22000-033-00D.
QUARANTINE SERVICE: We provided essential quarantine services for two other ARS projects at Beneficial Insects Introduction Research Unit (BIIRU) as well as several ARS cooperators (Objective 1d – 12-month milestones). These activities included receipts of a total of 45 permitted consignments of three targeted pests and five species of natural enemies, consisting of incoming shipments of 3254 EAB beetles, 5400 EAB larval, and egg parasitoids (1800 Spathius agrili, 2400 Tetrastichus planipennisi and 1200 Oobius agrili), 181 ALB larval parasitod (Spathius anoplophorae), 150 BMSB adults and 15-30 egg masses, and 256 CLB parasitoids (Anastatus orientalis). We also had one outgoing shipment of 2400 mummies of Aphelinus certus, six outgoing shipments of 8400 EAB larval parasitoids (Spathius galinae), and five shipments of 328 ALB eggs to support cooperator’s research programs at several universities, including the University of Maryland, University of Kentucky, University of Massachusetts, and the University of Minnesota.
Accomplishments
Review Publications
Wang, X., Lee, J.C., Daane, K.M., Buffington, M.L., Hoelmer, K.A. 2020. Biological control of Drosophila suzukii. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources. 15. Article 054. https://doi.org/10.1079/PAVSNNR202015054.
Dang, Y., Zhang, Y., Wang, X., Xin, B., Quinn, N.F., Duan, J.J. 2021. Retrospective analysis of factors affecting the distribution of an invasive wood-boring insect using native range data: the importance of host plants. Journal of Pest Science. https://doi.org/10.1007/s10340-020-01308-5.
Daane, K.M., Wang, X., Hogg, B.N., Biondi, A. 2021. Potential host ranges of three Asian larval parasitoids of Drosophila suzukii. Journal of Pest Science. https://doi.org/10.1007/s10340-021-01368-1.
Wang, X., Walton, V.M., Hoelmer, K.A., Pickett, C.H., Blanchet, A., Straser, R.K., Kirk, A.A., Daane, K.M. 2021. Exploration for olive fruit fly parasitoids across Africa reveals regional distributions and dominance of closely associated parasitoids. Scientific Reports. 11: 6182. https://doi.org/10.1038/s41598-021-85253-y.
Ramadan, M.M., Wang, X. 2021. Male impact on female reproductive performance of the larval tephritid parasitoid Diachasmimorpha tryoni (Hymenoptera: Braconidae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toab063.
Wang, X., Aparicio, E.M. 2020. Reproductive traits of Ontsira mellipes (Hymenoptera: Braconidae), a North American parasitoid, as a novel biological control agent for exotic Anoplophora glabripennis (Coleoptera: Cerambycidae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toaa160.
Wang, X., Wang, X., Kenis, M., Cao, L., Duan, J.J., Gould, J., Hoelmer, K.A. 2020. Exploring the potential for novel associations of generalist parasitoids for biological control of invasive woodboring beetles. Biocontrol. https://doi.org/10.1007/s10526-020-10039-6.
Wang, X., Aparicio, E.M., Duan, J.J., Gould, J.R., Hoelmer, K.A. 2020. Optimizing parasitoid and host densities for efficient rearing of Ontsira mellipes (Hymenoptera: Braconidae) on Asian longhorned beetle (Coleoptera: Cerambycidae). Environmental Entomology. https://doi.org/10.1093/ee/nvaa086.
Chen, Y., Qu, X., Li, T., Iqbal, A., Wang, X., Ren, Z., Desneux, N., Zang, L. 2020. Performances of six eupelmid egg parasitoids (Hymenoptera: Chalcidoidea) from China on Japanese giant silkworm Caligula japonica (Lepidoptera: Saturniidae) with different host-age regimes. Journal of Pest Science. https://doi.org/10.1007/s10340-020-01271-1.
Biondi, A., Wang, X., Daane, K.M. 2020. Host preference of three Asian larval parasitoids to closely related Drosophila species: implications for biological control of Drosophila suzukii. Journal of Pest Science. https://doi.org/10.1007/s10340-020-01272-0.
Wang, X., Biondi, A., Nance, A.H., Zappalà, L., Hoelmer, K.A., Daane, K.M. 2020. Assessment of Asobara japonica as a potential biological control agent for the spotted wing drosophila, Drosophila suzukii. Entomologia Generalis. https://doi.org/10.1127/entomologia/2020/1100.
Wang, X., Ramualde, N., Aparicio, E.M., Maspero, M., Duan, J.J., Smith, L. 2021. Optimal conditions for diapause survival of Aprostocetus fukutai, an egg parasitoid for biological control of Anoplophora chinensis. Insects. 12(6). https://doi.org/10.3390/insects12060535.
Wittman, J.T., Aukema, B.H., Duan, J.J., Venette, R.C. 2021. Forecasting overwintering mortality of Spathius galinae in North America. Biological Control. 160. https://doi.org/10.1016/j.biocontrol.2021.104694.
Duan, J.J., Van Driesche, R., Schmude, J.M., Quinn, N.F., Petrice, T., Rutledge, C., Poland, T., Bauer, L.S., Elkinton, J. 2021. Niche partitioning and coexistence of parasitoids of the same feeding guild introduced for biological control of an invasive forest pest. Biological Control. 160. https://doi.org/10.1016/j.biocontrol.2021.104698.
Duan, J.J., Schmude, J.M., Larson, K.M. 2020. Effects of low temperature exposure on diapause, development, and reproductive fitness of the Emerald Ash Borer (Coleoptera: Buprestidae): Implications for voltinism and laboratory Rearing. Journal of Economic Entomology. https://doi.org/10.1093/jee/toaa252.
Ragozzino, M., Duan, J.J., Salom, S. 2021. Responses of two introduced larval parasitoids to the invasive emerald ash borer (Coleoptera: Buprestidae) infesting a novel host plant, white fringe tree: implication for biological control. Biological Control. 1049-9644. https://doi.org/10.1016/j.biocontrol.2021.104672.
Broadley, H.J., Gould, J.S., Wang, X., Hoelmer, K.A., Hickin, M., Sullivan, L., Elkinton, J.S. 2020. Life history and rearing of Anastatus orientalis (Hymenoptera: Eupelmidae), an egg parasitoid of the spotted lanternfly (Hemiptera: Fulgoridae). Environmental Entomology. 50(1), 2021, 28–35. https://doi.org/10.1093/ee/nvaa124.
Xin, B., Zhang, Y., Wang, X., Cao, L., Hoelmer, K.A., Broadley, H.J., Gould, J.S. 2020. Exploratory survey of spotted lanternfly (Hemiptera: Fulgoridae) and its natural enemies in China. Environmental Entomology. https://doi.org/10.1093/ee/nvaa137.
Hougardy, E.H., Hogg, B.N., Wang, X., Daane, K. 2019. Comparison of thermal performances of two Asian larval parasitoids of Drosopihila suzukii. Biological Control. 136. https://doi.org/10.1016/j.biocontrol.2019.104000.
Wang, X., Hogg, B.N., Biondi, A., Daane, K.M. 2021. Plasticity of body growth and development in two cosmopolitan pupal parasitoids. Biological Control. https://doi.org/10.1016/j.biocontrol.2021.104738.
