Effects of Postharvest Cold Storage on the Development and Survival of Immature Drosophila suzukii (Diptera: Drosophilidae) in Artificial Diet and Fruit.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) attacks a wide range of host plants, including crops such as blueberries, cherries, caneberries, and strawberries. We evaluated the influence of three temperatures (1.1, 3.9, and 5.0 °C) and four exposure durations (6, 12, 24, and 72 h) that were selected to represent typical grower practices on survival and development time of immature D. suzukii in artificial diet and one temperature and duration (1.67 °C for 72 h) in fruit (blueberries and raspberries). Cold storage at 1.1 °C for 24 h decreased larval survival, but shorter durations generally did not affect larval survival. No eggs or young larvae survived when held for 72 h at 1.1 °C, and fewer older larvae survived after 72 h at 1.1, 3.9, and 5.0 °C than at 20 °C (control). Development time in diet was longer for all life stages following at least 12 h at any of the storage temperatures. In blueberries, no eggs survived to pupation when stored at 1.67 °C for 72 h, and survival of third instars was reduced by 41%. In raspberries, egg, second instar, and third instar survival was significantly reduced following storage at 1.67 °C for 72 h. Drosophila suzukii larval development time was shorter in raspberry than in blueberry, but it was significantly longer in both fruits when stored at 1.67 °C for 72 h. Our results indicate that cold storage can reduce survival and increase development time of immature D. suzukii, and it could be a useful part of an integrated program to manage D. suzukii infestation.

Variation in selection and utilization of host crops in the field and laboratory by Drosophila suzukii Matsumara (Diptera: Drosophilidae), an invasive frugivore.

BACKGROUND: Drosophila suzukii, a pest of soft-skinned berries and stone fruits, has recently rapidly expanded its global range. The impacts of D. suzukii infestation and subsequent fruit damage in North America and Europe have been profound. The aim of the present work was to assess host selection of D. suzukii in the field and laboratory, with an emphasis on hosts commonly grown in the southeastern United States, where D. suzukii has been established since 2010. RESULTS: Raspberries were infested at a greater rate than blackberries in the field, and varieties within both species were infested at different rates. Primocane-fruiting blackberries were often the least heavily infested. Further, blackberries and raspberries grown under high tunnels were infested at lower rates than those grown outside. Fruit and artificial substrates with a lower surface penetration force were more heavily infested than firmer substrates in the laboratory; no eggs were laid in artificial substrates exceeding 52.00 cN surface penetration force. CONCLUSION: Infestation rates differ between species and varieties within species of Rubus in the southeastern United States. Fruit penetration force is one potential measure of host susceptibility, but host attractiveness will likely depend upon additional factors, such as soluble sugar content.