1. Participatory detection and mapping of Spotted wing drosophila distribution in South Dakota
Buyung A.R. Hadi & Amanda Bachmann
Plant Science Department, South Dakota State University
Abstract
The spotted wing drosophila was first reported in California in In the north central region of the US, spotted wing drosophila was first reported in Michigan in In 2012 the invasive fly was reported in Minnesota and Iowa. At 2012 specialty crop grower conference in South Dakota, the primary author discussed the possibility of spotted wing drosophila introduction to the state and secured the collaboration of a South Dakotan grape grower for sentinel traps to be regularly placed in her vineyard to serve as sentinel traps for the fruit fly. Weekly replaced traps were first set in these vineyards on the first week of August The first trapped sample confirmed to be spotted wing drosophila was collected in August 28 of 2013 from a vineyard in Yankton county. Subsequent mapping effort for spotted wing drosophila distribution in the state was conducted with the cooperation of specialty crop growers in the state. Twelve commercial and hobby fruit growers participated in the fly trapping. Trap kits with vinegar baits were mailed out in September of 2012 and the traps were set for a week before the samples were mailed back for identification. Spotted wing drosophila were confirmed in samples received from all participants covering nine counties spread across South Dakota.
Introduction
Results
Discussion
Spotted-wing drosophila was first detected in continental US (California) in Subsequent detection showed populations of spotted-wing drosophila in Oregon, Washington, Florida and British Columbia (2009); in Utah, North Carolina, South Carolina, Michigan, and Louisiana (2010); and in Virginia, Montana, Wisconsin, Pennsylvania, New Jersey, and Maryland (2011) (Lee et al. 2011a). In 2012, spotted-wing drosophila was reported in Minnesota (MDA 2012) and Iowa (Lewis and Jesse 2012).
The invasive vinegar fly exhibited a wide range of hosts, including blackberries, blueberries, cherries, raspberries, strawberries and grapes (Lee et al. 2011b). Unlike other vinegar flies, spotted wing drosophila is considered economic pest due to its ability to infest undamaged fruits.
The numbers of male SWDs found across the trapping sites vary rather widely (Fig 2). No statistical comparisons were attempted. Factors such as the crops in which the traps were located, the ripeness of the fruits during trapping and the size of the cropping areas may explain the large variation of the number of trapped flies. While our effort was largely targeted toward early detection and mapping of the SWD incidence within the state, more systematic sampling of SWD is needed to study the phenology of the invasive fly in South Dakota.
Others have reported the ability of SWD to lay eggs and develop within certain varieties of grape, raspberry, blackberry and strawberry (Lee et al. 2011b). In our participatory detection, traps placed among Aronia berry (Aronia melanocarpa) in Charles Mix county yielded a number of male SWD. Aronia berry, also known as chokeberry, is native to the eastern parts of North America (Hardin 1973). Due to the harsh sour taste of the fruits, raw consumption of Aronia berry is very limited. The berries are historically utilized as a food coloring agent and as an ingredient in liqueur production and folk medicines (Kulling and Rawel 2008). Whether spotted wing drosophila found among the Aronia berry reported here successfully infested the fruits remains a question. The orchard where the trap was set also contained currants and plums, both are known as hosts of spotted wing drosophila.
Fruits and berries production is a very small part of agricultural output in South Dakota. According to 2007 Agricultural Census, South Dakota ranked 48 among all states in its market values of fruits and berry production (USDA 2009). However, the state does have a growing number of small horticultural producer population that are mostly producing grapes, raspberry and strawberry. The introduction of SWD will prove to be an additional challenge particularly to the raspberry and strawberry producers in the state.
Methodology
Following a discussion on SWD as an emergent pest at 2012 SD specialty crop grower conference, a grape grower at Yankton county, South Dakota, agreed for sentinel traps to be regularly placed in her vineyard. Trapping was conducted weekly beginning at the first week of August of 2013 and the first SWD sample was collected on August 28 of 2013.
Following the first trapping of SWD, an alert was sent out to commercial and hobby fruit and growers in the state of South Dakota. The garnered participation of 12 fruit growers in a volunteer based trapping of SWD. Trap kits were sent to these participants. Each kit consists of three 32 oz pint plastic buckets with holes drilled on the side, apple cider vinegar in a 32 oz mason jar and soft wire ties to hang the buckets (Fig 1). The volunteers were asked to fill 1/3 of the plastic buckets with the vinegar bait and set the baited traps in their fruit orchards, vineyards or high tunnels for a week. All trappings were conducted within the first three weeks of September. After a week, the vinegar baits (with all of the trapped insects) from the three buckets were poured back to the glass jar and mailed back to SDSU Extension for processing and identification. Only male SWDs were identified in the samples.
References
Crops on which the traps were set
Hardin J. W The enigmatic chokeberries (Aronia, Rosaceae).  Bull. Torrey Bot. Club 100:
Kulling S.E. and H.M. Rawel HM Chokeberry (Aronia melanocarpa) - A review on the characteristic components and potential health effects. Planta Med. 74: 
Lee, J. C., D. J. Bruck, A. J. Dreves, C. Ioriatti, H. Vogt, and P. Baufeld. 2011a. In focus: spotted wing drosophila, Drosophila suzukii, across perspectives. Pest Manag. Sci. 67: 1349–1351.
Lee, J. C., D. J. Bruck, H. Curry, D. Edwards, D. R. Haviland, R. A. Van Steenwyk, and B. M. Yorgey. 2011b. The susceptibility of small fruits and cherries to the spotted-wing drosophila, Drosophila suzukii. Pest Manag. Sci. 67: 1358– 1367.
Lewis, D. and L. Jesse Spotted wing drosophila fly detected in Iowa (Online extension article). Source:
Minnesota Department of Agriculture MDA confirms new fruit pest in Minnesota (Press Release). Source:
United States Department of Agriculture Census of Agriculture, Vol 1: U.S. Summary and state reports. Source:
Fig 1. Sequences of activity during the participatory trapping of SWD in South Dakota
Blackberry
Grape
Raspberry
Aronia berry
Strawberry (high tunnel)
# of male SWD trapped in a week
1-5
6-15
16-40
>40
Fig 2. Spotted wing drosophila distribution in South Dakota based on 2014 participatory detection and mapping