Location: Invasive Species and Pollinator Health
Project Number: 2030-22300-032-010-A
Project Type: Cooperative Agreement
Start Date: Nov 1, 2018
End Date: Jun 30, 2021
1) To mass rear two generalist pupal parasitoids of spotted wing drosophila (SWD); 2) to conduct parasitoid releases in non-crop habitats adjacent to berry fields; 3) to explore whether augmentation of parasitoids in non-crop habitats helps control SWD in adjacent crop fields.
Two generalist pupal parasitoids of spotted wing drosophila (SWD), Pachycrepoideus vindemiae and Trichopria drosophilae, will be mass reared at the Kearney Agricultural Research and Extension Center in Parlier, CA. Parasitized SWD pupae will be stockpiled for eventual release. Parasitoid numbers will be augmented in non-crop habitats adjacent to berry fields starting in November in Years 1 and 2, after berry production has stopped in crop fields and SWD has returned to overwinter in non-crop habitats. There will be two treatments, with parasitoids not augmented or augmented. There will be at least six sites for each treatment, for a total of at least 12 sites. Twelve organic cane berry (e.g., raspberry, blackberry) fields adjacent to riparian areas containing wild blackberry (Rubus species), a known host of SWD, have been located for this study in the Watsonville and Castroville areas of California. To determine whether parasitoid releases elevate parasitoid populations, parasitism rates on SWD pupae will be monitored in non-crop areas while releases are ongoing. Sentinel SWD pupae will be used for this purpose. SWD larvae will be reared in the laboratory to the pupal stage. Pupae will be placed by hand in traps consisting of clear plastic containers with holes punctured in their sides to allow flies and parasitoids to enter. Comparing parasitism rates (proportions of pupae parasitized) between augmentation sites and non-release control sites will determine if releases successfully elevated parasitoid numbers.