Research out of Agriculture and Agri-Food Canada indicates wheat midge eggs may not have hatched on a specific variety of winter wheat.
Wheat midge (Sitodiplosis mosellana) is the top insect pest threatening spring wheat. While it can cause significant yield loss and reduce grain quality, the wheat midge tolerant gene (Sm1) has armed farmers with a powerful defense mechanism for over a decade.
But researchers aren’t settling for single gene resistance. Entomologists and wheat breeders can see a future where farmers have additional control options and are working together to try and make that happen.
“Most of the current research is at the level of the plant, meaning we’re working to find new traits that will stop the wheat midge in its tracks or at least reduce wheat midge damage,” says Tyler Wist, research scientist in field crop entomology at Agriculture and Agri- Food Canada (AAFC) in Saskatoon.
Egg Antibiosis Could Ramp Up Sm1
One study was inspired by past AAFC research in Winnipeg that indicated wheat midge eggs may not have hatched on one variety of winter wheat.
“Right now the egg has to hatch on a Sm1 plant and then the larvae have to start feeding and the seeds take some damage before the larvae die,” explains Wist. “If they were dying at the egg stage, the seed wouldn’t take any damage.”
Researchers crossed the egg antibiosis trait into spring wheat lines and conducted trials. While the results proved the eggs were indeed hatching, wheat midge larvae seemed to die faster in the wheat plants that had both Sm1 and the egg antibiosis genetic region.
“So, we may have found a synergist for the Sm1 gene and we’re still looking into that mode of action,” Wist says. “But since we found the genetic region it comes from, we can maybe create a marker to track it and make sure that it’s in the plants that we’re creating.”
Smelly Wheat as a Deterrent
One of the promising traits being studied by a team of Prairie researchers is oviposition deterrents, or chemicals that prevent insects from laying eggs.
Previous research has shown that female wheat midge are deterred from particular strains of wheat due to the odour the wheat emits.
Now, professor of entomology Alejandro Costamagna and post-doctoral fellow Chaminda Weeraddana at the University of Manitoba have found that the smell profile of the wheat that has oviposition deterrents is very similar to the smell profile of wheat that has passed anthesis.
“If you’re a wheat midge female and you smell that, you won’t want to put your eggs on the wheat plant because the likelihood of your offspring surviving is a lot lower post-anthesis,” explains Wist. “It’s very cool research.”
He has also collaborated with other researchers to determine if developing spring wheat carrying the hairy glume could deter wheat midge oviposition.
“Our research found that it did make the wheat midge put her eggs in a slightly different spot, but it didn’t reduce the midge damage to kernels, which is our gold standard benchmark for testing if something is working or not,” says Wist.
While the research has yet to yield a major breakthrough, farmers can rest assured that experts are working to extend the life of the Sm1 gene and develop new ways to manage wheat midge.
