LAWRENCE, Kan. (DTN) -- Somewhere, my high school English teacher is smiling. It turns out words really do matter as much as sticks and stones, a lesson the agricultural industry is learning the hard way.
As insect resistance to Bt proteins continues to mount across the world, some scientists are worried that squabbles over the very definition of the word "resistance" are limiting our ability to act quickly against it.
The problem has played out like a textbook lesson on the importance of semantics.
Most academic scientists such as University of Arizona entomologist Bruce Tabashnik define "resistance" in insects as a "genetically based decrease in susceptibility to a pesticide." They do NOT include the economic impact of this decreased susceptibility as part of the definition, Tabashnik explained to me.
Others, namely industry players from biotechnology and agrochemical companies, prefer that resistance be defined as "a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendations for that pest species."
Whew. Beyond being much more of a mouthful, this second definition requires a pesticide to fail repeatedly before the word resistance can even be proposed.
Tabashnik is one of five authors of a new study that laments the dangers of this after-the-fact definition. "By the time a product has failed repeatedly, it is too late to respond most effectively to resistance," he wrote. He and others worry that this "all or none" approach to resistance is damaging the industry, government, and farmers' ability to react quickly and early to changes in insect populations.
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What distresses him most, however, is that the disputed definition is distracting people from getting anything done. "The concern is that disagreement about definitions and the discussions that ensue can be not very productive," Tabashnik said. "So instead of dealing with a problem, you end up with potentially endless debates about definitions. That precludes being proactive and doing what needs to be done."
Tabashnik's study proposes that the type of product-failing resistance that industry recognizes be given the term "practical resistance." The study urges people to become comfortable talking about different degrees of resistance, specifically these five proposed categories:
1 - Incipient resistance: a statistically significant decrease in susceptibility, but less than 1% of the insects in a field or population show resistance;
2 - Early warning of resistance: between 1% to 6% of insects show resistance;
3 - Between 6% and 50% of insects show resistance;
4 - More than 50% of insects show resistance and reduced efficacy of a product is expected but not reported;
5 - More than 50% of insects show resistance and reduced efficacy of a product is reported (practical resistance).
"Why so many words to define just one?" you might ask. Or whimper.
Well, if people could get comfortable with acknowledging very early levels of resistance that do not mean a pesticide has failed, the word "resistance" would stop being a virtual PR-wrecking ball that scares farmers away and makes industry understandably skittish.
For example, Australia has an extensive and proactive monitoring system that detected a tiny increase in the fraction of insects resistant to one toxin in Bt cotton -- less than 1% -- which they recognize and classify as incipient resistance. This gave scientists, government and farmers valuable time to consider new practices or products to ensure that resistance would remain rare, Tabashnik said.
"We're trying to move toward a language that's more neutral and objective -- where resistance isn't all or none," he explained. "Now we can say, by the standards proposed here, we'll call what we're seeing in this field 'incipient resistance.' So it's not a totally susceptible population, and it's not a situation where growers would want to stop planting that particular crop. Now let's move on to more important stuff. What do we do about incipient resistance?"
The answer to that question isn't settled yet, but many possibilities exist. The identification of a low level of resistance in an insect population could trigger warnings for companies and growers, for example. Those warnings could include suggestions or protocols for increased refuges, a switch to another pesticide, or the addition of other pest controls.
In the end, this is more than a war of words. At stake is the survival of a valuable group of pesticides. Tabashnik's definition of resistance aims to extend the life of the biotech traits, and that's something everyone should agree on.
Emily Unglesbee can be reached at firstname.lastname@example.org
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