Oviposition and development potential of the spotted-wing drosophila, Drosophila suzukii (Diptera: Drosophilidae), on uninjured Campbell Early grape

The spotted-wing drosophila (SWD), Drosophila suzukii (Diptera: Drosophilidae), originally distributed across a few Asian countries including South Korea, has invaded North America and Europe but is absent from Australia. In order to export the South Korean grape cultivar Campbell Early to Australia, its potential to serve as an oviposition and development medium for SWD must first be determined. In this study, we determined the oviposition and development potential of SWD on Campbell Early, after elucidating the SWD life cycle and establishing an artificial diet-based mass-culturing system. An investigation of the life cycle under five temperature regimes (16, 19, 22, 25 and 28 degrees C) showed that the durations of the egg, larval and adult stages were shortened when temperature was increased from 16, 19, 22, 25 and 28 degrees C, but pupal duration was shortest at 25 degrees C and extended again at 28 degrees C. A test of oviposition and development potential of SWD on Campbell Early grape clusters showed oviposition of 30.8 +/- 6.8 eggs per cluster of injured grapes and 157.7 +/- 16.2 eggs on a culture dish of artificial diet. However, in a similar experiment using uninjured grape clusters, only a single egg was deposited on the grape skin, which soon dried. In light of these results, newly harvested grapes left at vineyards during daily harvests are unlikely to serve as an oviposition and development medium for SWD, as long as the grapes remain uninjured.