SASKATOON – When today’s most powerful chemicals aren’t up to the job, bring in the fossils.
That’s what pest control companies and government scientists have been doing to crush the spread of ever more resistant rusty grain beetles, and they may help the environment as they do it.
“Resistance (to pesticides) is slowly developing around the world,” said Winnipeg-based Agriculture Canada researcher Noel White. “We haven’t seen significant resistance in Canada yet, but it will happen.”
Phosphine, in the pesticide Phostoxin, is the only treatment for rusty grain beetles, which in a bad year can devour millions of bushels of wheat and penalize farmers and shut down elevators.
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White and other grain industry scientists hope using the fossilized corpses of ancient sea organisms can give them a backup if resistance develops.
While there is a possible Canadian application of the treatment called diatomaceous earth, the best potential probably lies in the Third World.
Unlike Canada, where the cold can kill many pests, most Third World nations have warm climates in which pests thrive.
Methyl bromide, a highly toxic substance, is not used in Canada for stored grain, but it is used in many countries around the world. Because of its link to global warming, it is being phased out in most advanced countries and Third World nations have only a few years left to get rid of it.
This should create a good market for diatomaceous earth, said White.
Diatomaceous earth, used in the Protect-It product now being tested by the federal agriculture department and in an older product called Insecto, is mined from the earth in areas where ancient seas left deep layers of microscopic organisms.
As they were fossilized their body spaces were filled with silicon dioxide. That’s mainly what is left when the diatomaceous earth is collected, said White.
A dusting of diatomaceous earth demolishes the beetle’s skeleton and sucks its life out.
“It absorbs the fat out of their cuticle – their outside skin,” said White. “When they lose that they lose the ability to regulate water loss. They desiccate, dry out and die.”
The substance is mainly natural, but White said the companies that are commercializing forms of it, process it to make it more effective.
Diatomaceous earth is augered into bins along with the grain before any infection.
And while it will generally kill rusty grain beetles, it won’t destroy 100 percent, an advantage of most chemicals.
But Canadian Grain Commission entomologist Chris Van Natto said even if diatomaceous earth can’t guarantee it will kill every insect, it’s tougher for insects to develop resistance to it compared to chemical controls.
Some applications of diatomaceous earth have caused problems, Van Natto said, because a lot had to be used to treat grain and that affected the test weight and led to the grain being downgraded.
But Protect-It uses much less and apparently doesn’t affect test weight, Van Natto said.