A research team, which included Montana State University’s Collage of Agriculture Professors Carl Yeoman and David Weaver, recently published a paper outlining the discovery of a previously unknown microbe that lives symbiotically with wheat stem sawflies.

The wheat stem sawfly is an economically devastating insect that was first discovered in Montana in 1890, where it was originally found in native prairie grasses. As wheat became more prevalent in parts of Canada and the Northern Plains, the crop proved to be an amiable host for the sawfly, first with spring wheat and later winter wheat.

The female sawfly oviposits eggs into the stem of wheat. Once the eggs hatch, they literally chew their way out, inhibiting photosynthesis and weakening the stem so it succumbs to gravity and more often than not, breaks.

Montana, North Dakota and the Canadian provinces of Alberta, Saskatchewan and Manitoba have historically seen the greatest damage induced by sawflies, but the insect continues to creep south through the Great Plains. Parts of South Dakota, Wyoming, Idaho, northwest Kansas, eastern Colorado, western Nebraska, along with the Columbia Basin and Palouse Hills region of Washington have reported losses due to sawflies. All said, it is estimated the insect causes $350 million in wheat yield losses each year with Montana producers suffering between $52 and $80 million in annual losses alone.

Growers and researchers have been hard at work for decades trying to devise ways to mitigate the damage caused by sawflies in wheat. Crop rotations and biological control agents coupled with growing solid-stem wheat varieties has helped, but sawflies still ravage.

That may all be about to change, thanks to some cutting-edge research. Inspired to find new and novel ways to control sawflies, researchers looked at the fact that microbes are a part of living things and often they play an integral, yet covert part in an organism’s system.

“We simply asked the question: ‘Is there a microbe living inside the wheat stem sawfly and does it play a role in the success of that insect?’” stated Yeoman.

Yeoman explained the sawflies used for this particular experiment were sourced from Montana and all of the hands-on research took place on the MSU campus. After years of studying, researchers discovered the answer to their question was yes. By discovering a symbiotic microbe/sawfly relationship, researchers could potentially be one step closer to controlling the insect’s impact.

“This microbe was unknown before, but it is related to a number of other microbes in insect species. This particular one is very different in terms of its functional capabilities,” Yeoman pointed out.

They named the microbe “Spiroplasma sp. WSS” and it was seen in both larvae and adult sawflies. Initial analysis indicates the microbe plays an important role in the sawfly’s nutrition. More specifically, it is believed this microbe helps the sawfly break down sugars and it may also help them garner other nutrients that are lacking in their carbohydrate dense diet.

The task now is to decide what to do with all this new information.

“We certainly want to get to a solution and this is certainly a step in the right direction, but there are a lot of other questions that need to be answered. It’s going to come down to looking more at this microbe and trying a few things out in the lab,” said Yeoman.

This is merely the tip of the iceberg for Yeoman, Weaver and the entire research team. They will be hard at work looking at ways this microbe may be used in the management of sawflies and time will only tell what kind of impact this pivotal discovery will have on U.S. wheat producers.

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