Spotted Wing Drosophila Activity Early in 2015

Last week, the first spotted wing drosophila (SWD) activity of 2015 was detected from one of our SWD traps in Caldwell County. This SWD trap was placed in a small strawberry planting. Along with other drosophila fruit flies, it contained three female SWD and one male. This capture is 3 weeks earlier than what we experienced in 2013 and 2014; however we are using more traps earlier in the year. This week we have detected SWD activity in Fayette and Daviess counties as well. Traps in Allen, Breathitt, Christian, Crittenden, Daviess, Fayette, Scott, and Trigg have been negative to date for SWD (Figure 1).

Figure 1. SWD activity detected in counties with green shading; gray shading indicates trapping without SWD detection. (Photo: Ric Bessin, UK)

Figure 1. SWD activity detected in counties with green shading; gray shading indicates trapping without SWD detection. (Photo: Ric Bessin, UK)

In the previous 2 years, strawberries, June raspberries, and early and midseason blueberries escaped damage before SWD became active. This pest (Figure 2) can lay its eggs under the skin of soft-skinned fruit resulting in small larvae infesting the fruit at harvest. It can attack fruit as they begin to color and soften.

Figure 2. Spotted wing drosophila fruit flies can be identified with either a hand lens or under a microscope. (Photo: Ric Bessin, UK)

Figure 2. Spotted wing drosophila fruit flies can be identified with either a hand lens or under a microscope. (Photo: Ric Bessin, UK)

Management

  • On farms where SWD has been detected, we recommend growers begin spraying for SWD on a weekly basis through the end of harvest of susceptible small fruit crop. If they have other susceptible small fruits, they will need to control SWD during the harvest period on those crops. For a list of recommended insecticides and more information on management see the publication, Spotted Wing Drosophila Management (ENTFACT 230).
  • For others growing strawberries as well as other susceptible small fruits (raspberries, blueberries, blackberries, some grapes, and elderberries), we recommend monitoring for SWD adult activity. If you find SWD on your farm, we recommend that you begin control actions immediately. If you don’t detect SWD in your traps, then we recommend that you do not spray for this pest.

Information on identification and trapping can be found in Spotted Wing Drosophila, Biology, Identification and Monitoring (ENTFACT 229).

Weekly Updates

We have a Facebook page that provides weekly updates on SWD trapping from 21 counties in Kentucky.

 

Ric Bessin, Extension Entomologist

 

Posted in Fruit