Evaluation location: Mississippi, United States
Stringer, S.J., Sampson, B.J. and Hummer, K.E. (2017). Screening small fruit germplasm for resistance to southern populations of invasive spotted wing drosophila, SWD (Diptera: Drosophilidae). Acta Hortic. (ISHS) 1180:45-52 https://doi.org/10.17660/ActaHortic.2017.1180.7
Bioassays targeted Drosophila suzukii (Spotted-Wing Drosophila abbreviated SWD), a pest currently infesting a blueberry selection and field evaluation site at Stone County, Mississippi. From these, un-infested blueberry fruit samples were harvested from numerous genotypes and then evaluated in the laboratory for possible antixenosis against mass-reared SWD. One hundred berries were sampled from each of the 88 rabbiteye and southern highbush cultivars and selections and examined for the presence or absence of SWD feeding damage or egg laying. Berry samples sometimes had to be refrigerated and, therefore, the effects of cold storage on SWD infestation and OSI were additionally tested. In laboratory bioassays using no-choice arenas, clutch size for SWD (number of eggs per fruit) as well as total brood per fruit were assessed after 3 days and these counts correlated with berry quality attributes, which were independently recorded for each variety [berry weight, percentage soluble solids (Brixo), and harvest seasonality (early-, mid-, and late-season harvest)].
Berry samples of these same cultivars and selections were utilized in a ten replicate laboratory assay where berries were placed in 3 x 6 arrays (arenas) of specially constructed plastic bioassay chambers along with one or two fecundated female spotted-wing Drosophila flies. Partitioning analysis of variance will examine variation in SWD egg output attributable to within and between assay runs, as fruit storage and plant growing conditions may influence bioassay results. We chose 10 replicates per run and a total of 20 replicates for testing repeatability between 2 separate runs, provided there is sufficient time and material to complete 20 replications per genotype.