Spotted Wing Drosophila

Appearance

Like other members of the Drosophilidae, "D. suzukii" is small, approximately 2 to 3.5 millimetres in length and 5 to 6.5 millimetres in wingspan and looks like its fruit and vinegar fly relatives. Its body is yellow to brown with darker bands on the abdomen and it has red eyes. The male has a distinct dark spot near the tip of each wing; females do not have the spotted wing. The foreleg of the male sports dark bands on the first and second tarsi. The female has a long, sharp, serrated ovipositor. The larvae are small, white, and cylindrical reaching 3.5 millimetres in length.

Naming

Native to east Asia, "D. suzukii" was first described in 1931 by Shōnen Matsumura, it was observed in Japan as early as 1916 by T. Kanzawa.

"D. suzukii" is a fruit crop pest and is a serious economic threat to soft summer fruit; i.e., cherries, blueberries, raspberries, blackberries, peaches, nectarines, apricots, grapes, and others. Research investigating the specific threat "D. suzukii" poses to these fruit is ongoing.

Distribution

Native to southeast Asia, "D. suzukii" was first described in 1931 by Matsumura. Observed in Japan as early as 1916 by T. Kanzawa, it was widely observed throughout parts of Japan, Korea, and China by the early 1930s. By the 1980s, the "fruit fly" with the spotted wings was seen in Hawaii. It first appeared in North America in central California in August 2008, then was found in Oregon and Washington State by Lee "et al.", 2011: 369  in the Pacific Northwest in 2009, and is now widespread throughout California's coastal counties, western Oregon, western Washington, and parts of British Columbia and Florida. During the summer of 2010 the fly was discovered for the first time in South Carolina, North Carolina, Louisiana, and Utah. In Fall 2010 the fly was also discovered in Michigan and Wisconsin. The fly was first discovered in the northeastern states in 2011 and in Minnesota and Idaho: 369  in 2012. As "D. suzukii" continues to spread, most of the states will most likely observe it. The pest has also been found in Europe, including the countries of Belgium, Italy, France, and Spain.

Predators

Earwigs, damsel bugs, spiders, ants, and Orius especially "O. insidiosus". Likely also ground beetles, crickets, green lacewings' larvae, rove beetles especially "Dalotia coriaria", birds, and mammals.

Cultural

Due to the impact of "D. suzukii" on soft fruits, farmers have started to monitor and control it. There are different types of traps, both commercial and home-made, that are effective in monitoring it. Traps that use apple cider vinegar with a bait made of whole wheat dough have been successful for farmers for both capture and monitoring. Farmers are advised to place these traps in a shaded area as soon as the first fruit is set and to not remove them until the end of harvest. The traps should be checked once a week and farmers should look for the spot on the wing of the males to determine if "D. suzukii" is present.

In areas where "D. suzukii" has already been established or where its activity has been monitored, there are different ways to control it. One way to manage "D. suzukii" is to remove the infested fruit and place it in a plastic bag in the garbage. This method is effective from removing "D. suzukii" from gardens and small areas but is difficult for farmers with larger operations to do this. Farmers can also harvest their soft fruit early which reduces the exposure of fruit to "D. suzukii" and the likelihood of damage.

Farmers have the option of both conventional and organic sprays to control "D. suzukii". Timing of the sprays is important to effectively controlling it. Since "D. suzukii" is more active in the morning and evening those are the best times to control it. Sprays should be in place prior to egg laying and the coverage needs to be thorough because adults often hide in dense portion of the canopy. Depending on the variety of soft fruit and laws in different states and countries, there are many types of organic and conventional sprays that are effective. Different laws and pre-harvest date intervals need to be kept in mind when choosing a type of spray. Most types of sprays need to be applied each week, at a minimum. To prevent resistance to certain sprays, farmers must rotate among different insecticides.