The right way to eliminate an invasive fruit fly? Researchers look to a different international bug –


GRAND RAPIDS, Mich. (WOOD) — Most Michigan fruit growers are fairly aware of the noticed wing drosophila, an invasive fruit fly that may wreak havoc on a number of crops if not tended to fastidiously. After years of analysis, Michigan specialists imagine they might have a stable answer: introducing one other international insect.

Spotted wing drosophila — or SWD within the entomology world — is native to Asia. The tiny fruit flies have a saw-like appendage that may lower by means of skinny fruit skins, lay their eggs after which enable the larvae to feast on the fruit because it grows.

They have been first noticed in Michigan in 2010 and had taken a agency maintain by 2012. Based on Nikki Rothwell, the director of the Northwest Michigan Horticultural Research Center, it’s been an issue ever since.

A noticed wing drosophila. (Courtesy MSU Extension)

“As soon as the larvae are within the fruit there’s nothing you’ll be able to actually do to kill them. So that you’re actually concentrating on the adults,” Rothwell informed Information 8. “As a result of it’s a fruit fly, the actual stressor for us is the reproductive capability of this insect.”

Rothwell’s crew has been studying SWD for years. She mentioned SWD usually age from larvae to grownup in seven days, however within the lab underneath ideally suited situations, the bugs have reached grownup stage in 5 days.

“You can begin out at very low numbers, however then over time they’ll have a number of generations and we might be coping with tens of millions of pests,” she mentioned.

Michigan’s apple growers don’t want to fret about SWD and neither do the state’s wineries, however SWD can affect a number of harvests, together with cherries, blueberries, blackberries, raspberries and strawberries.

In 2016, an estimated 20% of the state’s cherry crop was misplaced to SWD. One other large loss? The autumn raspberry market.

“The trade that in all probability was hit the toughest, although it’s a really small trade, is the autumn raspberry trade,” Jim Nugent informed Information 8.

Nugent is a cherry grower who beforehand led the Northwest Michigan Horticultural Analysis Middle and had served because the chairperson for the Michigan Tree Fruit Fee. He stays plugged in to rising developments throughout the state.

“(There was) a whole lot of it in southeast Michigan the place they’ve pick-your-own operations or direct markets. However that trade has actually been devastated and a whole lot of growers have simply given up on fall raspberries,” Nugent mentioned.

That misplaced harvest means large bucks for farmers.

“These was once an actual gold mine for farm entrepreneurs as a result of they have been pretty simple to develop. They didn’t have a whole lot of inputs and so they get fairly some huge cash for a pint or a quart of raspberries,” Rothwell mentioned.

For now, many farmers have turned to pesticides to maintain their crops wholesome, however it’s one thing that must be accomplished routinely to take out the quickly producing SWD. Rothwell’s crew has additionally discovered some strategies to assist maintain SWD away — together with heavier pruning and holding orchards mowed — however nothing to successfully restrict the insect’s inhabitants.

Researchers on the MSU Extension are learning whether or not the samba wasp, additionally a species native to Asia, might be launched to the native ecosystem and wipe out the noticed wing drosophila. (Courtesy MSU Extension)


As a substitute of turning to chemical substances, researchers have additionally regarded to the pure world to see how the ecosystem handles this pest. That’s how they landed on the samba wasp.

“We have to have nature assist us convey these populations down,” Nugent mentioned.

Let’s be clear, this isn’t your typical wasp. They’re in regards to the measurement of a grain of rice and don’t have stingers. It’s a parasitoid, which means it’s an insect that lays its eggs inside one other. Rothwell describes the unappetizing course of, likening it to a horror story.

“Principally, that wasp egg hatches contained in the SWD after which the wasp larva eats the SWD from the within out,” Rothwell mentioned.  

The 2 key takeaways from the analysis on the samba wasp is that it may be an efficient answer to tamp down SWD — studies estimate between 20% and 65% — but it surely’s little menace to our ecosystem.

“It’s very particular to SWD. It’s not going to only lay its eggs in random fruit flies, it’s going to put its eggs in SWD. It’s a really specialised wasp or parasitoid,” Rothwell mentioned.

Mentioned Nugent: “Now we have 18 native species (of fruit flies) in North America. Scientists can prepare them genetically and know the place SWD suits type of throughout the genetic variability of drosophila. And (for the samba wasp), it had no impact on 16 of the 18 natives and solely had a slight impact on the 2 that have been most genetically near SWD.”

Rothwell’s lab in East Lansing has been working for a number of years now to develop its personal colony of samba wasps and have found out the best variables to assist them thrive. They may proceed to develop the colony and carry out choose releases to attempt to introduce it to the ecosystem.

They’ve carried out two small releases thus far, one in a cherry orchard in northwest Michigan and one other in a blueberry field in southwest Michigan.

“It looks like child steps proper now, however I really feel like as an entomologist it was thrilling,” Rothwell mentioned. “I feel it’s going to be actually nice for growers. It’s a enjoyable story to inform from a science perspective but in addition a real-world perspective.”

The issue remains to be a good distance away from being solved, however Nugent believes scientists are heading in the right direction.

“All of us as growers and scientists have our fingers crossed that that is going to turn out to be established and assist us, assist nature scale back the inhabitants of this pest in order that our efforts as growers have a greater probability of being profitable,” he mentioned.


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