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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Research Project #444076

Research Project: Establishment and Evaluation of Ganaspis brasiliensis to Suppress Spotted Wing Drosophila

Location: Invasive Species and Pollinator Health

Project Number: 2030-22000-033-016-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Nov 1, 2022
End Date: Jun 30, 2025

Project objectives are to: 1) improve mass rearing of the SWD parasitoid Ganaspis brasiliensis, 2) conduct releases throughout California's susceptible specialty crops, and 3) evaluate effectiveness and adjust release procedures as needed.

This project seeks to rear, release, establish and evaluate Ganaspis brasiliensis as part of a classical biocontrol project for SWD. Work will begin with development of large colonies of G. brasiliensis for field release (Nov 2022 – Dec 2025). Reared wasps will be released into plots of non-crop habitats adjacent to strawberry, and caneberry, blueberry and cherry fields during periods when SWD larvae are present (Mar 2023 – Oct 2023, and Mar 2024 – Oct 2024). Each site will have multiple sampling points spaced in a grid, with 20-50 samples per site pair per season (a third each in the crop interior, crop edge, and non-crop habitat) (Feb 2023 – Nov 2023, Feb 2024 – Nov 2024, Feb 2025 – Apr 2025). To monitor SWD densities, adult traps will consist of a Trécé cup trap, which has red coloration and a large screened entrance on the side to maximize captures of adults. At each station, fruits will be sampled upon ripening, as this is the stage they become susceptible to SWD. Sampled fruit will be weighed to standardize SWD/g, then held in vented containers for 2 weeks to count emerging adults. Parasitism will also be monitored with sentinel traps consisting of fruit infested with 1st instar SWD larvae. Also, larval-pupal parasitoids will be monitored from fruit collections by holding fruits for 3-4 weeks to check parasitoid emergence. While this method is convenient, it is better for samples that contain high numbers of SWD such as the non-crop fruit; the managed crop is expected to have variable SWD numbers. Data will be analyzed with Generalized Linear Mixed Models (GLMM), Spatial Analysis by Distance Indices (SADIE), and landscape ecological analysis.