Utah Pest News Fall 2010

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Spotted Wing Drosophila Detected in Utah

male spotted wing drosophila
Male SWD’s have a single spot on each wing.
female spotted wing drosophila
Female SWD’s have a serrated ovipositor.


This summer, we conducted a survey for spotted wing drosophila (Drosophila suzukii), a pest of local concern, in ten northern Utah orchards and berry fields.  This pest is of concern to our fruit and vegetable growers because female SWD have serrated ovipositors that allow them to attack fruit earlier than other drosophila species, often before the fruit ripens.  Hosts of SWD include all tree fruits, small fruits, and vegetable fruits such as tomatoes and peppers.  Introduced to California in late 2008, SWD has since spread throughout California, Oregon, and  Washington.  Due to a separate introduction in 2009, SWD has also spread from Florida to Louisiana, North Carolina, and South Carolina.

In late August, SWD was detected for the first time in Utah in a trap in raspberries in Kaysville.  To date, a total of 50 SWD have been trapped at the site in raspberries, blackberries, and tart cherries.  SWD has not been detected at any other survey site.  We do not know how SWD was introduced, but it is likely that it was brought in via infested fruit from a state where SWD already occurs.   The Cooperative Agriculture Pest Survey program will intensify monitoring of SWD in 2011 to 50 sites to determine if there is spread from the detection site or additional introductions.

A fact sheet is now available to provide more information on monitoring, identifying, and controlling SWD (click here).  As described in the fact sheet, cheap traps can be made using plastic cups and a lure of yeast and sugar solution.  Male SWD are identified by the presence of a single black spot on each wing.  Other, similar flies have spots on their wings, but only those with a single spot per wing are suspect.  If you believe you have found an SWD, you can forward it to the Utah Plant Pests Diagnostic Lab for identification.  Instructions for doing so can be found by clicking here.

We do not know if this insect is able to overwinter in northern Utah, but to be safe, concerned commercial growers should make sure that the insecticides that are already being applied for other pests are effective against SWD.  Product recommendations can be found on the SWD fact sheet.  When choosing a product, remember that pyrethroids, malathion, and carbaryl can flare spider mites.  You should also consider re-entry intervals, pre-harvest intervals, and maximum residue limits.

-Cory Vorel, USU CAPS Coordinator