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MSU Researchers Lead Efforts to Thwart Invasive Fruit Pest


A tiny vinegar fly from eastern Asia called spotted wing drosophila (SWD) is fast becoming one of the most intensively studied insects at Michigan State University (MSU). That’s because the invasive pest, the size of a grain of rice, infests various fruit crops—a Michigan industry valued at more than $375 million per year.

MSU scientists began studying SWD in 2010 immediately after its first discovery in Michigan. Since then, more than 30 MSU research projects targeting the fly, which has characteristics unlike many other agriculture pests, have launched.

Females are uniquely equipped with a serrated ovipositor that can puncture healthy fruit and deposit eggs. With the capacity to lay 100 eggs per day, SWD populations can balloon quickly. Adult flies can live for weeks under the right climatic conditions, and they do not have distinct generations, making it difficult to target and treat. Instead, populations begin to rise in the spring and peak in the autumn.

Rufus Isaacs

Rufus Isaacs

“We’ve found it pretty much everywhere we’ve looked in the Lower Peninsula, but haven’t done much monitoring in the U.P. yet,” said Rufus Isaacs, AgBioResearch scientist and professor of entomology. “In the first big year we had with it, we estimated a $20 million impact in Michigan. A lot of small farmers who have you-pick farms for fall raspberries, for example, are finding it very challenging to manage. So they are either not growing those fruit anymore or are replanting with summer raspberries because the pressure from the pest is lower earlier in the year.”

“There is a community of natural enemies for SWD in Asia,” Isaacs said. “This pest can build up in wild areas where growers can’t manage them easily, but if biological controls can help to reduce the population pressure, it should allow control measures applied in the fields to work better. Risk assessments are underway to determine if the Asian biological controls are a viable option.”

- excerpted from Cameron Rudolph, “Tiny Fly, Big Problem,” AgBioResearch

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