Location: Beneficial Insects Introduction Research2011 Annual Report
1a. Objectives (from AD-416)
This project seeks to reduce populations of EAB without adverse effects on the environment via biological control approaches relevant to the knowledge base of the target pest and its natural enemies, and has three objectives representing different aspects and/or stages of classical biological control research and development: 1: Explore for natural enemies (parasitoids) of EAB in its native range and evaluate their suitability for introduction. 1a - Explore for parasitoids of EAB in its native range. 1b - Evaluate the suitability of discovered parasitoid for introduction to North America for EAB control. 2: Evaluate impacts of extant (indigenous) and previously introduced parasitoids on populations of EAB, particularly in northeastern and/or Midwestern states. 3: Develop effective mass rearing technologies for hymenopteran parasitoids of EAB and other invasive pests. 3a - Determine the key life history parameters of the concerned parasitoid species. 3b - Determine the optimal host stage and host density (or host to parasitoid exposure ratio). 3c - Determine the optimal environmental conditions for adult parasitoid survival, oviposition, and progeny development.
1b. Approach (from AD-416)
We will conduct foreign exploration for parasitoids of EAB in its native range including the Far East region of Russia, Korea, and China. In each of the study areas, five to 10 sites will be selected for EAB parasitoid exploration covering a wide range of habitats including upland and riparian natural forests with Oriental Fraxinus spp. and plantations of both North American and Oriental Fraxinus spp. At each selected site, ash trees will be examined for signs of EAB infestation in late summer, fall, and/or spring. Ash trees exhibiting any signs of infestation will then be felled, and debarked for sampling different immature stages of EAB and associated parasitoids. Promising parasitoid species collected from the foreign exploration will then be tested in quarantine against a list of North American Native wood-boring beetles to determine their host specificity. After completing host range studies, we will develop an environmental impact assessment (EIA) of proposed releases of the promising parasitoids, which will be selected based on their efficacy against EAB in the native range (Asia) and host specificity against North American native (nontarget) wood boring beetles, and submit the EIA to USDA APHIS (or other regulatory authorities) for review and approval. Once the selected candidate species are cleared for release by Federal and State regulatory authorities, efforts will be directed towards field release and establishment along with development of mass-rearing technologies and impact assessment.
3. Progress Report
EMERALD ASH BORER RESEARCH: Five study sites have been selected in the Russian Far East region, where ash (Fraxinus mandshurica and F. ryhnchophylla) trees at each site were girdled in this spring and will be sampled in next fall. In addition, three species of parasitoids (Hymenoptera) have emerged from EAB egg and larval samples collected last fall: two species of braconids (Braconidae) - Atanycolus sp and Spathius sp, and one species of encyrtid (Encyrtidae). These research activities relate to the project Objective 1a. Studies of the biology and life history traits of EAB larval parasitoids (such as T. planipennisi and Spathius sp) (Objective 3) were once hindered by the lack of efficient methods to rear high quality host larvae. Most recently, however, we have discovered that EAB eggs artificially grafted to freshly cut logs of tropical (F. udhei) ash can successfully hatch, bore into the phloem, and develop into late instars suitable for attack of EAB larval parasitoids (T. planipennisi, Spathius sp, and Atanycolus spp). With the tropical ash-based EAB rearing system, we have successfully studied the biology and life history traits of the previously introduced EAB larval parasitoid (T. planipennisi). Findings from our studies have provided insights into the biology and life history traits of EAB larval parasitoids, and lead to significant improvement in mass production of EAB larval parasitoids such as T. planipennisi and Spathius sp. In collaboration with USDA FS and APHIS, Maryland Department of Agriculture and University of Massachusetts, six study sites in Michigan and two study sites in Maryland have been established for evaluation of the impacts of three previously introduced parasitoids (T. planipennisi, S. agrili, and Oobius agrili). Large numbers of the previously introduced parasitoids were or have been continuously released at each of the study sites. Following the field release of those parasitoids, their establishment in North American ash stands and potential in suppressing EAB populations were evaluated by sampling immature stages of emerald ash borer populations in the spring of 2011. Results from 2011 spring sampling indicated that both larval parasitoid T. planipennisi and egg parasitoid O. agrili were consistently recovered from all the study sites, whereas the other larval parasitoid Spathius agrili was recovered less frequently (only in one study site in Michigan, and one in Maryland). A complex of native North American parasitoids were also frequently associated with EAB larvae across different study sites in both Michigan and Maryland. These research activities relate to the project Objective 2. QUARANTINE SERVICES: A total of 66 permitted consignments were sent or received by the Quarantine Facility, consisting of over 6845 specimens, 5 potential beneficial species). From these consignments and cultures established from previous consignments, a total of 14 outgoing shipments (5008 specimens, 4 potential beneficial species) were shipped out. A total of 13 identification requests were submitted and responded to by the ARS Systematic Entomology Laboratory for determination.
1. Develop a new method for emerald ash borer (EAB) parasitoid rearing. The emerald ash borer is an invasive pest that has killed millions of North American ash trees since its detection in 2002. ARS researchers at Newark, DE, have discovered that EAB eggs artificially grafted to freshly cut logs or twigs of tropical ash can successfully hatch, bore into the twigs, and develop a form that is highly suitable for attack of EAB parasitoids (biocontrol agents). This discovery has allowed us to produce large quantities of high quality EAB year-around for biocontrol agent rearing by using greenhouse-grown tropical ash twigs. The method has been currently adopted by USDA Forest Service Northern Research Station (Lansing, MI) and APHIS-PPQ Otis Laboratory (Buzzard Bay, MA) and APHIS Brighton EAB Biocontrol Laboratory (Brighton, MI) for mass production of EAB biocontrol agents. This discovery will significantly facilitate the large-scale implementation of EAB biocontrol programs in the US because large quantities of the larval parasitoids can now be produced year-around with the EAB hosts reared on alternative host plants.
Ulyshen, M.D., Duan, J.J., Bauer, L.S., Fraser, I. 2010. Suitability and accessibility of immature Agrilus planipennis (Coleoptera: Buprestidae) stages to Tetrastichus planipennisi (Hymenoptera: Eulophidae). Journal of Economic Entomology. 103(4):1080-1085.