Research on wireworms lagged when effective pesticides came into wider use in Canada. Now that those same pesticides, notably lindane, are no longer in use, wireworm research is being revived.
Haley Catton, research scientist and cereal crop entomologist with Agriculture Canada in Lethbridge, is in year two of a three-year study designed to see how crop rotation affects wireworm populations and those of beneficial insects, including ground beetles.
As of March 28, she was still seeking farmers near Lethbridge to volunteer their fields for this year’s sample collection. Three fields in each of four crop rotation categories are needed.
“They have to be dryland, and they have to have a history of wireworm, so the farmer has to think that there’s a problem there, and they have to be seeded in spring wheat or durum in 2018, and then in 2016 and 2017 they needed to be a cereal on cereal, or cereal-canola, canola-cereal or canola-pulse,” said Catton.
The research involves extensive sampling over the summer, so fields within a two-hour drive of Lethbridge are desired. Members of the research team will set up and maintain six small insect traps per field, starting in April, and check them every week until harvest.
The traps will collect click beetles, the adult form of wireworm, as well as any other insects that fall in. Soil core samples will be taken to examine the larvae.
“The people that do get selected, they’re going to learn a lot about the insects in their fields,” Catton said.
Participants will have information about click beetle and wireworm levels, as well as beneficial insects that make a home in their fields.
Catton said farmers have a general sense that wireworms are becoming more of a problem but there is no hard data to support that. A hiatus in study of the pest is part of the reason but so is the life cycle, longevity and variety of wireworms.
“It’s quite a conundrum right now, so we have to go back to the basics and say, ‘well, what species do we have? When are they active? How do they respond to things like crop rotation?’ We need to learn more about them.”
Wireworm relationship to crop rotation is new ground, she added. Researchers at Agriculture Canada in Charlottetown have found that mustard in the rotation tends to suppress wireworm. Catton’s study aims to see if canola has a similar effect.
“Nobody’s done work on this before, especially on the Prairies. We have a lot to learn about what species are where, what time of the year they’re active. Wireworm is a complex of 30 different species and the ones we have here on the prairie are native.”
Of those species, Catton said she and her team expect to find about five main pests that do the most crop damage. Different species attack the crop in different ways, from shredding to tunnelling.
Ground beetles, which attack many different crop pests, will also be identified with the goal of better assessing their role in controlling click beetles and/or wireworms.
Catton said the study has proven to be more work than originally anticipated, in part because of the need to haul soil samples to the lab and carefully extract the insects and worms.
“They’re also really patchy, so you need to take a lot of samples to get an idea of where and how many. Also they’re long-lived, so … if you find wireworms this year you don’t know if it was a buildup of the past five years or one good year five years ago.”
In addition to learning about click beetle and wireworm activity, Catton also plans to compile a field guide to help people more easily identify the genus and species.
Head technician David Shack will play a major role in that. Using a powerful microscope and numerous texts and keys, he identifies the various beetles and worms found in the traps and soil samples.
Samples from last year have revealed a wide array.
“It is very much a time consuming process,” said Shack, while working in the Agriculture Canada lab.
“It takes a lot of learning. Thankfully we have a lot of different identification keys to help us out.”
A glossary of entomological terms is his bible.
“Some of these features can be very subjective,” said Shack.
When in the field, damage from wireworm can be hard to diagnose because different species damage crops in different ways. They are generalists and feed on many different crop types. Cereals and root crops seem to be particular favorites, according to anecdotal information, but wireworms will eat a lot of things.
As well, their damage can be easily confused with other crop problems. Seed treatments inhibit the worms during the growing season but don’t kill them.
“We are looking at different points of vulnerability,” said Catton.
“The helpless feeling that people have is one of the main drivers of frustration because the problem doesn’t go away and there’s no solutions right now.”
This project, jointly funded by the Alberta Wheat Commission and the Western Grains Research Foundation, is likely only the beginning for Catton.
“My rationale is, I’m at the beginning of my career here at Agriculture Canada and this is a big problem. So I’m in the situation where I should be taking on big problems because I have time.
“This project for me is getting my feet wet, learning about the species and just learning about where to go next. Because yes, it’s going to be a long-term series of studies, I think.”
Catton said Agriculture Canada is assembling a national team to study wireworms that extends across the country.