Scientists study crop-killing cutworms


Prairie project | Researchers collaborate on three-year, $525,000 project

The makers of the movie Alien could easily have been inspired by the sight of parasitic wasps emerging from the body of a cutworm. As wasp life begins, the cutworm dies.

The scenario is playing out in laboratories at Agriculture Canada’s Lethbridge Research Centre, as well as in fields across Canada.

It is a welcome sight for farmers with crops damaged by some of the many cutworm species on the Prairies.

The acts in the lab are part of a three-year research project to better identify cutworm species and their natural enemies and provide farmers with tools to identify and combat them.

The $525,000 project, funded by the Canola Agronomic Research Program (CARP), is headed by Lethbridge-based research scientist Kevin Floate, but its tentacles reach into all prairie provinces.

Researchers from the universities of Alberta, Manitoba and Lethbridge are involved, as are government entomologists from the three prairie provinces, Agriculture Canada staff in Beaverlodge, Alta., Lacombe, Alta., and Saskatoon, Alberta Agriculture staff in Lacombe, researchers at Lethbridge College, Canola Council of Canada staff and prairie farmers.

“It’s quite a large project,” said Floate as he observed work in the research centre lab May 25.

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However, the research team is also large and will build on work done by others, notably research scientist Bob Byers, now retired but also contributing to the project.

Cutworms are a major economic issue for agriculture because of their variety, life cycles and appetites for almost anything green.

“We like to think of it as a pest complex because you can’t point at one target and come up with a magic bullet. It’s a moving target and it keeps changing shape,” said Floate.

He describes the cutworm project as having four main objectives:

  • develop tools to better identify the many different cutworm species. Floate said there are seven or eight species of particular interest to farmers, among them the dingy, army, redbacked, glassy, darksided, pale western and bertha
  • obtain more information on the biology of cutworms. Some species are the same colour and some worms of the same species can be different colours. Some feed above ground and some below. Various species attack crops at different times in the growing season. Tools are needed to better identify the species and ways to control them
  • obtain more information on natural enemies to cutworms, such as parasitic wasps. Floate said wasps can control cutworm outbreaks but can’t be relied upon for good control. There are many species of parasitic wasps, some of which haven’t been identified and named. Research at the U of M is focused on parasitic wasp identification as part of the project
  • develop extension tools for producers, including photographs and charts for accurate identification of species and potential control measures. “I think it’s entirely feasible to come up with a kit to identify cutworms,” said Floate. He envisions online photographs and charts to help producers identify the species, as well as service labs that could also provide quick and accurate species identification

Not all cutworm species are crop pests, but there are two types of pests: those that overwinter and those that blow in as moths. The latter species doesn’t commonly overwinter in Canada.

Floate said cutworm outbreaks tend to be cyclical, and the Prairies are now in the middle of a cycle. Cutworms have already been reported this spring, although the extent of early damage is still unknown.

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“In terms of why the outbreaks are sporadic, it can depend on weather patterns in the United States for those pests that come up from the U.S. or it could depend on how cold the winters have been,” said Floate.

Weather, temperature, moisture conditions and soil tilth are additional factors.

Cutworms can go through several generations during the growing season, depending on the species, which creates an even greater control challenge.

As well, many species can feed on the same crop, and the same species may feed on different crops. Some species feed in the day and some at night.

“In some cases, you’ll have a cutworm but no crop. In a stubble field, they’ll start feeding on weeds,” said Floate.

“It’s a challenge.”

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