Nov 8, 2010
SWD found in Michigan; team planning a response

The Spotted Wing Drosophila (SWD), a pest of Asian origin that is already established in many of the main fruit-producing regions of the United States, has been found in Michigan, according to Michigan State University.

SWD is a pest of berry crops, grapes and tree fruit, with a preference for softer-fleshed fruit. A monitoring program for SWD found no flies this past summer, but in late September the first flies, both male and female, were found in traps deployed in southwest Michigan. This was well after harvest of most fruit crops, and no pests were found in any fruit, according to MSU.

In October, USDA’s Animal and Plant Health Inspection Service confirmed that SWD had been found in three counties in central Michigan: Ingham, Ionia and Genesee.
An SWD Response Team made up of Michigan State University research and Extension staff, the Michigan Department of Agriculture and Michigan fruit commodity groups is meeting regularly to implement an Early Detection-Rapid Response plan. This will include further monitoring in 2011.

The team is confident SWD can be managed successfully with available Integrated Pest Management (IPM) tactics. Michigan growers are well versed in IPM techniques and will adapt quickly to address this new insect challenge, according to MSU.

“We have been aware of SWD since it was first discovered in 2008 in California,” said Rufus Isaacs, berry crops entomologist at MSU and the chair of the response team. “This insect is originally from Asia but has already been found to be invasive in Hawaii, California, Oregon, Washington, Utah, Florida, the Carolinas and British Columbia. Our response team set up 300 traps in June in more than 100 fruit-growing sites and checked them regularly. The traps were monitored the entire season with no positive finds of SWD until late September in a few fruit farms. This is probably because harvest was complete in July and August, so growers were no longer actively managing pests in those fields.”

Isaacs said that because the pest was found after harvest, there was no threat that the pest was in harvested fruit. He also noted it was found in an area that had minimal insect management.

Because SWD has not been previously found in Michigan, it is not known if it will survive the cold Michigan winter.

“If SWD is detected again next year, it is one more insect pest that Michigan fruit growers will need to add to their crop management programs,” Isaacs said. “IPM strategies will be implemented next year to help monitor and control SWD.”

The SWD Response Team is developing educational programs for fruit growers, including one at the Great Lakes Fruit, Vegetable & Farm Market EXPO in Grand Rapids, Mich., in December. Workshops will be held this winter, to help prepare growers the 2011 season.

For more information on SWD, visit

By Matt Milkovich, Managing Editor

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