Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-22000-031-081-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jun 1, 2024
End Date: May 31, 2025
Objective:
The primary purpose of this agreement is to establish the introduced parasitoid Ganaspis brasiliensis, monitor its impact on spotted wing drosophila and understand some key ecological factors that might affect the establishment and efficiency of this parasitoid in the mid-Atlantic region.
Objective 1 – Field release of G. brasiliensis in mid-Atlantic states
Objective 2 – Evaluations of factors influencing the efficacy and establishment of G. brasiliensis and L. japonica
Objective 3 – Evaluations of factors influencing the overwintering survival of G. brasiliensis
Approach:
Objective 1: ARS will conduct release of G. brasiliensis in Delaware, Maryland, and Pennsylvania, and monitor its establishment and impact SWD through pre- and post-release fruit samplings. In each state, we will select at least 3 sites that preferably represent typical non-crop habitats for SWD in this region. Pre-release fruit samplings will be conducted immediately prior to each release to document the presence /absence of any parasitoids associated with SWD and/or related Drosophila. Post-release fruit samplings will be followed one week after each release and then once per month throughout the fruit seasons to monitor the establishment, dispersal, and levels of parasitism by G. brasiliensis. Collected fruit will be held in plastic containers to rear, collect and identify emerged flies and wasps, and to estimate percentage parasitism.
Objective 2: ARS will collect and test the most common fruits available throughout the fruit seasons in the DE area to quantify potential effect of different host fruits on the efficiency of the larval SWD parasitoids G. brasiliensis and L. japonica. Fruit will be collected when they are matured. For each fruit speceis, one set of the fruit will be reared to monitor the survival, developmental time, and body size of SWD pupae, while another set of the fruit will be used to test the parasitism under different treatments: (1) fruit are exposed to 2 female LJ alone; (2) fruit are exposed to 2 G1 alone; (3) fruit are exposed to one LJ + one GB. Successful parasitism and outcomes of interspecific competition between the two parasitoid speceis on different fruit species will be determined.
Objective 3: ARS will determine if G. brasiliensis (GB) could survive the winter in this region and when the parasitoid will enter diapause and emerge in the spring, parasitized SWD larvae fruit will be placed under field conditions at three field set-up dates in early, middle, and late October. For each set-up date, there will be five treatments: (1) 2 GB females are exposed to 2 infested berries in the vial and the vial will be placed in the trap hanging on a tree; (2) vial containing exposed berries with developing young GB larvae (0-3 days old) is placed in the trap; (3) vial containing exposed berries with developing young GB larvae is buried in the soil in the pot under the tree, (4) vial containing exposed berries with mature GB larvae (10-13 days old) is placed in the trap, and (5) vial containing exposed berries with mature GB larvae is buried in soil in the pot. All treatments will be checked once every two weeks to record emerging flies and wasps continually from November to next June or until all emergence has ceased.
