Slower than chemicals | Biological controls are less harmful to beneficial organisms
A fungus-laden powder developed at the University of Lethbridge is a proven grasshopper killer and a potential tool for combatting the pest.
However, while researcher Dan Johnson is looking for a commercial partner to help bring the new biological control to growers, he said it won’t replace the conventional in-secticides that growers use — nor should it.
“That’s not really going to happen, and I don’t even think that’s a very good idea. I think we need an integrated approach,” said Johnson, who led the initiative studying the fungus metarhizium anisopliae.
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“But lately the integrated approach has just been different kinds of chemicals, and that list is getting smaller.”
Biological controls are less efficacious than chemical applications, but they can also be less harmful to beneficial organisms while reducing crop residue and resistance pressure.
Johnson said this fungus could be an option in cases where a grower may not need rapid or instant control.
“Whenever I talk about it, the very first thing I say upfront is this is not as fast and not as perfect a killer as some chemicals. So if that’s what you need, then this is not for you,” said Johnson.
“But if you get a situation, and often people do, in which you’d like to suppress the grasshoppers and if it’s done in two weeks or one day doesn’t matter, then this is a possibility.”
Different strains of metarhizium anisopliae are found naturally around the world, usually on the bodies of insects, said Johnson.
Spores germinate once they come into contact with a grasshopper, pierce the insect’s skin and grow into its body.
The fungus has been isolated and developed into commercial products for locust and grasshopper control in other countries, including Australia.
Johnson’s work builds off a strain found in a soil sample in southern Alberta.
“It’s often thought, rightly or wrongly, that if you have an indigenous organism, it’s less likely to have some invasive species or risky features attached to it,” he said.
Johnson used funding from several sources, including Pulse Canada, to replicate the fungus and begin field tests in lentils, grass and mixed pastures in Saskatchewan and Alberta in 2008.
He found that 20 grams per acre of the fungus to be the most effective solution when applied with water and a wetting agent.
Lentil field plots in his Saskatchewan trial saw an 83 percent reduction in grasshoppers. Johnson said results more regularly show a 70 percent reduction.
Infected insects will succumb to the fungus in three to five days under ideal conditions, although Johnson said most of the damage is likely to be done within a 10-day period, hopefully bringing the population down below economic thresholds.
“It’s hard to find a non-chemical method, particularly a biological microbial method, that really works. Many of them have promise … but many of them really don’t do the job,” said Johnson.
“This is the first one we’ve had that really is killing pretty good and pretty fast. We’re pretty happy with that. But nonetheless, it’s slow and less effective compared to chemicals, so it’s a different way of managing. People would have to get used to that.”
Johnson has found the fungus doesn’t harm most non-target species, including parasitoid wasps. Metarhizium anisopliae is also bee friendly and has been used for mite control in hives.
Johnson plans to survey growers and industry members about interest in the fungus.
“If growers don’t want it, then we won’t go any further,” he said.
