Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-22000-031-005-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jun 1, 2019
End Date: Sep 30, 2021
Objective:
The primary purpose of this agreement is to continue the project designed to develop biocontrol approaches to supplement the current Asian longhorned beetle (ALB) eradication strategy, which was funded by the Farm Bill Program in 2018. Specifically, ARS will focus on the native North American parasitoid Ontsira mellipes (Hymenoptera: Braconidae) that has developed a new association with ALB larvae. Using this native parasitoid, we will first conduct laboratory testing to assess the host specificity of O. mellipes reared on ALB larvae for over 50 generations (Objective 1) and then determine the efficacy of O. mellipes in suppressing ALB populations under field cage and/or open-field conditions within the quarantined (ALB-infested) area in the U.S. (Objective 2). The proposed research will lead to further development of effective biological control approaches that may supplement the current ALB eradication strategy. Funding by this agreement will enable us to work with cooperators at the University of Massachusetts and APHIS to develop ALB biological control approaches with the native North American parasitoid.
Ontsira mellipes is a native North American parasitoid that can successfully attack the invasive ALB under laboratory conditions. Successful development of the ALB biological control approach may provide a permanent or sustainable solution to supplementing the current eradication and/or management strategy against the target pest. Based on the results of other successful biocontrol projects, the return ratio of the project benefits relative to the cost or research investment (funds required) would be high (normally 10:1 or even higher for successful biocontrol programs). In addition, the information on the host specificity of this native biocontrol agent O. mellipes will allow regulatory agency to conduct a sound non-target risk assessment for augmentative release of this native biocontrol agent against ALB in the quarantine areas of the U.S.
Approach:
To assess the host specificity of O. mellipes (Objective 1), ARS will focus on testing common species of native North American longhorned beetles (Coleoptera: Cerambycidae) infesting major hardwood trees such as maple, birch, and oak. Live adults of different species of North American cerambycids will be collected between May and August each year from the hardwood forests in mid-Atlantic and/or Northeast United States using longhorned beetle traps developed by USDA APHIS Otis laboratory. Adults of different species of native longhorned beetles collected from the traps will then be reared with foliage or twigs of their preferred host plants and sugar water and provided with host logs or other substrates for oviposition at the USDA APHIS Otis laboratory or the USDA-ARS facility in Newark, DE. Native longhorned beetle larvae will be reared on artificial diet until they are of a size comparable to the size of ALB parasitized by O. mellipes (instar 2-3). Once a suitable size is reached, the larvae will be inserted in logs of the appropriate host tree for testing. ARS will expose gravid females of O. mellipes to suitable larval stages (2 – 3rd instars) of different species of native North American cerambycids using the similar procedures described by Duan et al (2015) and Golec et al. (2016). We are targeting testing the major native longhorned beetle species infesting maple, oak, and/or birch trees and determine the potential native host range of O. mellipes. Following host specificity testing, we will conduct series of experiments under field-cage or open field conditions in ALB-infested (quarantined) areas (Wooster, MA and Clement, OH) to evaluate the efficacy of laboratory-reared, ALB-adapted O. mellipes in parasitizing ALB larvae infesting maple logs or live trees.
For Objective 2, ARS is likely to face some challenges to release O. mellipes against ALB in field trials within a quarantine area in either Worcester, MA, Bethel, OH, or Long Island, NY. Because ALB is being eradicated in all the quarantine area, there are not sufficient numbers of naturally occurring beetles to test the searching behavior of the parasitoid in the field. To overcome this challenge, we plan to infest “sentinel” logs with young ALB, deploy the logs within the quarantine zone, release parasitoids, and recover the logs after one month. However, there is concern by the eradication programs about putting live ALB larvae into an area undergoing active eradication, and ARS has already been conducting studies of safety measures that can be taken to reduce risk. To overcome this concern, ARS will also design a cage made of steel hardware cloth that we used to surround a sentinel log containing ALB. The cage will therefore prevent ALB from escaping into the environment yet hopefully the mesh is large enough that parasitoids can find the ALB. In 2019, we will start conversations with state and federal regulatory officials about the safety and feasibility of conducting field trials and work out solutions to alleviate safety concerns over the using sentinel ALB logs for field trials with O. mellipes.
