1a. Objectives (from AD-416):
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.
1b. Approach (from AD-416):
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.
3. Progress Report:
Asian Longhorned Beetle (ALB) Research: Working with cooperators from the University of Delaware (8010-22000-028-09S) and Chinese Academy of Forestry (8010-22000-028-11S), we surveyed natural enemies attacking immature stages of ALB populations infesting poplar and willow trees in northwest China (Objective 1A/1B). Data from the survey indicate that the parasitic beetle (Dastarcus helophoroides) is the dominant natural enemy species, but causes only low levels (<5%) of parasitism. A population of this natural enemy collected from ALB in China has been imported to the Beneficial Insects Introduction Research Unit (BIIRU) and its host association with ALB is confirmed. Working with the University of Delaware we determined the optimal ambient temperature and host ALB stages for rearing the North America native braconid parasitoid (Ontsira mellipes), which could be used for a mass-rearing program (Objective 3b/3c). Emerald Ash Borer (EAB) Research: With support from the U.S. Forest Service International Program and cooperators at the Chinese Academy of Forestry (8010-22000-028-22S), we girdled ash trees at sites in central and southwest China (Henan, Guanxi and Shichun Provinces), where EAB is rarely observed and is not a major pest, and we artificially infested the damaged trees with beetle eggs to survey for their natural enemies. A trip to China has been planned for next spring to inspect the survey trees and sample immature EAB stages and associated natural enemies in these regions (Objective 1a/1b). In cooperation with cooperators from University of Maryland (8010-22000-028-04S), University of Massachusetts (8010-22000-028-01S), and Michigan State University (8010-22000-028-13S), we continued to release and evaluate the establishment and impact of previously introduced EAB parasitoids (Oobius agrili, Tetrastichus planipennisi, Spathius agrili and S. galinae) on EAB populations in Maryland, Michigan, Massachusetts, New York and Connecticut (Objective 2). All four biocontrol agents have been recovered following their releases at most sites in these states; however, only T. planipennisi and O. agrili have been consistently recovered more than one year following their releases. Our data indicates that the introduced biocontrol agent T. planipennisi is providing significant biocontrol services at the earliest release sites in southern Michigan, where releases of T. planipennis were conducted previously. In addition, we successfully determined the optimal host density and/or host-to-parasitoid ratio for effectively rearing EAB egg parasitoid (O. agrili) under different temperature/photoperiod regimes (Objective 3b/3c). Quarantine Services: Essential quarantine support was provided for three ARS research projects at BIIRU as well as several ARS cooperators (Objective 1d) with the BSL2+ containment facility. These activities included receipts of a total of 76 APHIS-permitted consignments, consisting of 8,575 pest specimens, and 15,484 parasitoids in 5 genera. A total of 47 outgoing shipments were sent, with 3,939 pest specimens, and 443,347 parasitoids in 5 genera. In addition, 14 identification requests were submitted to the ARS Systematic Entomology Laboratory.
1. Significant biocontrol of emerald ash borer in ash saplings. The emerald ash borer (EAB) is a serious invasive forest pest that has devastated natural and urban ash forests and threatens the existence of North American ash species. A classical biocontrol program began with the introduction of three insect parasitoid species from Northeast China in 2007, five years after EAB was first detected in Southern Michigan. For the first time, our study in Michigan demonstrated that one of the introduced parasitoids, Tetrastichus planipennisi, established a self-sustaining population several years after its release, has spread to other infested areas, and is providing significant biocontrol of EAB in ash saplings, which are critical for gradual recovery of ash forest ecosystems in North America.
Duan, J.J. 2017. Can ash communities and their dependent species be partially protected through biological control of emerald ash borer? In Van Driexche, Roy G. and Reardon, Richard C. Suppressing Over-Abundant Invasive Plants and Insects in Natural Areas by Use of Their Specialized Natural Enemies. United States Department of Agriculture. pp. 41-47.
Golec, J.R., Duan, J.J., Hough-Goldstein, J. 2017. Influence of temperature on the reproductive and developmental biology of Ontsira mellipes (Hymenoptera: Braconidae): Implications for biological control of the Asian Longhorned Beetle (Coleoptera: Cerambycidae). Environmental Entomology. 46(4):978-987. doi:10.1093/ee/nvx100.
Duan, J.J., Schmude, J.M. 2016. Biology and life history of Atanycolus cappaerti (Hymenoptera: Braconidae), a north american larval parasitoid attacking the invasive Emerald Ash Borer (Coleoptera: Buprestidae). Florida Entomologist. 99(4):722-728.
Abell, K.J., Bauer, L.S., Duan, J.J., Van Driesche, R.G. 2016. Monitoring the establishment and flight phenology of egg and larval parasitoids of emerald ash borer (Coleoptera: Buprestidae) in Michigan, USA using sentinel eggs and larvae. Florida Entomologist. 99(4):667–672.
Zhang, K., Wang, Y., Yang, Z., Wei, K., Duan, J.J. 2016. Biology and natural enemies of Agrilus fleischeri (Coleoptera:Buprestidae), a newly emerging destructive buprestid pest in Northeast China. Journal of Asia-Pacific Entomology. 20:47–52.
Jennings, D.E., Duan, J.J., Bean, D., Rice, K., Williams, G., Bell, S., Shurtleff, A., Shrewsbury, P.M. 2017. Effects of the emerald ash borer invasion on the community composition of arthropods associated with ash tree boles. Agricultural and Forest Entomology. 19:122–129.
Larson, K.M., Duan, J.J. 2016. Differences in the reproductive biology and diapause of two congeneric species of egg parasitoids (Hymenoptera:Encyrtidae) from northeast Asia: implications for biological control of the invasive emerald ash borer. Biological Control. 103:30-45.