Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-22000-031-017-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 30, 2021
End Date: Aug 31, 2023
Objective:
The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera:Buprestidae), accidentally introduced from China in the 1990s, is a devastating invasive pest of ash trees, Fraxinus spp. (Lamiales: Oleaceae), in North America. Since it was first detected in Southern Detroit, Michigan, in 2002, EAB has now established in 35 U.S. states including all Midwestern, Mid-Atlantic, Northeastern States and several Southern States such as Georgia, Alabama, Texas, and Louisiana. However, natural enemies previously introduced to the U.S. for EAB biocontrol originated from the colder regions of Northeast Asia (the Russian Far East and Northeast China); thus they may not be suitable against EAB in southern U.S.
This project will explore for natural enemies from the warmer region of the pest's native range (central and south China), which may be more suitable for biocontrol introduction against EAB in southern U.S. The specific objectives are:
1: Survey, collection, and identification of natural enemies (parasitoids) associated with emerald ash borers and/or other buprestids infesting ash trees (Fraxinus spp.) in central and southern China such as Beijing, Shandong, Henan, and/or more southern regions such as Sichuan province.
2: Investigate the role of natural enemies in regulating the pest populations in central and southern part of EAB’s native range.
Approach:
With the assistance of Chinese cooperators, this agreement will identify and locate ash and/or fringe trees in central and southern China, and artificially stress these host trees three to six months prior to sampling of various live EAB stages (eggs and larvae). Sampling procedures will include collecting and examining loose bark from EAB infested trees for egg parasitoids and debarking EAB infested trees/logs for larval parasitoids. These sampling methods have been proven effective and used for EAB parasitoid survey and collection in several published studies. Specimens of natural enemies, primarily egg and larval parasitoids that show significant impact on wood borers in girdled trees will be collected, identified and shipped to the USDA ARS quarantine facility in Newark, DE for further evaluation of their potential for use in biological control programs. The USDA ARS Systematic Entomology Laboratory in Beltsville, MD will assist in the taxonomy and identification of collected egg and larval parasitoids. The step-wise procedures are outlined below:
Locate at least three study sites where ash and/or fringe trees occur in central and southern China, and artificially stress these host trees three to six months prior to sampling of various live emerald ash borer stages (eggs and larvae). We will target to girdle 10 - 15 ash trees (DBH > 8 cm) at each study site from central and southern China (including Beijing, Shandong, and Henan) in the late winter of 2021. For study sites where ash trees can be girdled, we will deploy sentinel logs with inoculated EAB larvae from the spring through summer of 2022.
Girdled ash will be felled and sampled for immature EAB live stages (eggs and larvae) and associated parasitoids in the fall of 2022. In case that no naturally occurring emerald ash borers are found at the study sites, two-thirds of the girdled trees will be artificially infested with laboratory produced emerald ash borer eggs in early summer of 2022 and sampled in the fall of 2022.
From the spring to summer of 2022, sentinel larvae (or eggs if available) in sites without girdled ash tree will be deployed, collected and dissected to find natural enemies of EAB every two to three weeks.
Natural enemies discovered from the field sampling will be brought to Chinese Academy of Forestry laboratory and packaged appropriately for hand-carry or shipment to the USDA ARS Beneficial Insects Introduction Research Unit for further evaluation.
