Location: Horticultural Crops Research2011 Annual Report
1a. Objectives (from AD-416)
The Spotted Wing Drosophila (SWD) is an invasive pest of small and stone fruits including but not limited to blueberries, blackberries, grapes, strawberries, raspberries, cherries, apple, peach, and plum. SWD is established throughout the west coast of the U.S. and Canada where it has caused significant economic damage to both fresh and processed fruit during 2008 and 2009, and urgent action is needed. The overarching objective of our proposal is to develop an integrated systems-based approach to managing manage SWD. We have created a Pacific Coast North American response team to respond that includes with expertise in entomology, horticulture, genomics, pest management consulting, agricultural production, economics, sociology, extension, and policy-making. The primary questions are based on limited knowledge of SWD biology, physiology and ecology or its economic and social/political impacts. Objective 1: Evaluate genetic, biological and ecological parameters of SWD. Objective 2: Develop a SWD management strategy to minimize infestation and reduce risk. Objective 3: Measure impact and success of SWD project. Objective 4: Synthesize existing and new information and provide real-time support.
1b. Approach (from AD-416)
Laboratory studies will determine the stage(s) of ripeness the fruits that are most susceptible to SWD, this information will assist growers with the timing of treatments in the field. A common cultivar of each fruit (blueberry, raspberry, blackberry, strawberry, grape, cherry) will be tested at various stages of ripeness in no-choice and choice studies. Tests will compare methyl eugenol, GF 120, fermenting yeast, apple cider vinegar, and ~20 other semiochemicals available for flies. Preliminary screening will first be done by observing 25 male or 25 female flies in a four-arm olfactometer for orientation towards the odor released from one arm and air (control) from the other three arms. Bioassays will be performed using the formulated products of all small fruit and stone fruit insecticides registered in the states of Oregon, Washington, and California with known or suspected activity against Diptera. While laboratory assays cannot determine which pesticides will perform well in the field, they can determine which pesticides lack activity against this pest. Assays will be performed to determine both the direct spray and residual activity of each product. The experiments will be performed in a randomized complete block design with three replicates each containing 10 20 adult SWD. All bioassays will be performed in disposable 100 x 15 mm Petri plates.
3. Progress Report
The spotted wing drosophila (SWD), Drosophila suzukii, is an invasive pest of small fruit crops. Unlike most other Drosophila, this insect is able to oviposit into and damage ripe and ripening fruit making it unmarketable. Because this is a new pest in the United States, it is necessary to study short-term control solutions with registered insecticides, longer-term solutions with natural enemies, and the basic seasonal activity of the fly to understand when control measures are necessary. To identify registered insecticides to manage this insect effectively in conventional and organic production systems, laboratory bioassays and field trials were conducted to identify insecticides representing various modes of action that are effective in controlling SWD. Products that performed well in the laboratory bioassay also performed well in the field indicating that screening of new chemistries in the laboratory is a worthy exercise. Field application of pyrethoids, organophosphates or spinosyns provided 5-14 d residual control of SWD. The efficacy of the neonicotinoids as adulticides were not satisfactory compared with the other contact mode of action chemistries. Based on the zero-tolerance by the small fruit industry and the individual effects mentioned above, neonicotinoids are not currently recommended for SWD management. Guidelines produced by the results of this research have been used by growers in 2011 for management of small fruit crops in the Pacific Northwest. The minute pirate bug, Orius, has been observed among infested blueberries and raspberries. To test the efficacy of this predator for SWD control, assays were conducted in the laboratory and potted blueberry plants. Orius reduced survivorship of SWD by 41-54% when exposed for at least 2-3 days to blueberries between 0-6 days post-infestation in small containers. This suggests that Orius is eating the 1st or 2nd instar SWD larvae. The presence of 7 Orius in a plastic cages over one week reduced the number of surviving SWD on infested blueberries by 11.6%. The release of Orius into outdoor potted blueberry plants with SWD infestations appeared to reduce the number of surviving SWD by 49% and 17% compared to the control during two trials, respectively, but results were not significant. These results show that Orius is a potential predator of SWD, and further evaluation is ongoing. To monitor winter/spring activity of SWD, monitoring traps were set up in cherry orchards, and activity of flies in outdoor cages were monitored daily. Monitoring traps suggest that some SWD adults are always flying from February to April, with a peak of over a hundred caught within a single field in March. SWD remained active in cages from February 4 to April 8, with the number of active adults generally following temperature trends. These results indicate that adults remain active during colder temperatures and when no crop fruit are available.