Who Could Have Pre-, No, Actually Worm Resistence To Bt Corn Predicted 20 Yrs Ago Is Here

[hatrack]

It turns out that genetically modified corn may not protect against the corn earworm. Scientists have discovered that the earworm is developing resistance to the corn, which is consistent with predictions that were made almost 20 years ago that were largely ignored.

The genetically modified crop, in this case, is corn that produces a Bacillus thuringiensis (Bt) protein which, in turn produces a toxin called Cry1Ab. This GM corn was originally designed to combat a pest called the European corn borer (Ostrinia nubilalis) and went on the market in 1996.

In the late 1990s, researchers found that Cry1Ab was also affected against H. zea. However, they predicted enough of this species were surviving to develop a resistance to the protein. That's why, 15 years later, scientists wanted to see if resistance was actually occurring.

"We wanted to do an observational study in the field to see how, if at all, things have changed since the work done in the 90s-was there any indication that zea was becoming resistant," said Dominic Reisig, one of the researchers, in a news release. The scientists found that now Cry1Ab now has little or no effect on the number of H. zea compared to non-Bt corn.

EDIT

http://www.scienceworldreport.com/articles/25844/20150522/genetically-modified-corn-effective-against-earworm.htm

[The Velveteen Ocelot]

1. Nature always bats last.

[Agnosticsherbet]

2. Evolution is a constant process. We helped the corn evolve. The worms evolved in the face of a new

challenge.

[mike_c]

3. this is ultimately the fate of every pesticide used against insects...

...and every antibiotic used against bacteria. There was never any question that this would happen. Warnings were not ignored. The problem is simply, how do humans reduce agricultural losses to insects AND produce enough food to feed human populations while making farming a profitable business for farmers? Bt is one tool for accomplishing that, but every time it's used it selects for resistance, just like every other pesticide. Of course, not using it, or another pesticide, is only acceptable if we can live with significant food and fiber loss. Even with chemical controls insect populations consume about a third of all agricultural production world wide-- without them, more people will starve to death.

But I think it's wrong to characterize growing resistance to Bt as the result of warnings being ignored. Rather, it was a matter of knowingly committing to a short term solution for a long term problem. Unfortunately, insects are particularly adept at overcoming toxic controls-- that's the legacy from their coevolutionary arms race with plant defensive toxins. Every chemical control that isn't so toxic to life that it can be released into fields will eventually be overcome.

[appal_jack]

4. Nonsense, Mike. And you should know better.

Bt was used as a spray by organic growers for more than 40 years without observable resistance increasing among target insect pests. Why? Because natural Bt has a very short persistence in the environment. Depending upon weather conditions, within 24-48 hours, the BT has degraded into carbon dioxide, water, etc.

Splice a Bt gene into a corn plant, on the other hand, and you wind up with something quite different. The Bt is in every single cell, all the time. Stems? Bt. Roots? Bt. Corn kernels? Bt. Even root exudates and pollen? Bt. This is NOTHING like an organic farmer using a Bt spray one to three times a season (probably rotating at least once in there to a pyrethrum or spinosad to further reduce resistance), which is why Bt resistance was NOT a problem for more than four decades prior to the widespread adoption of GMO crops.

And about that "matter of knowingly committing to a short term solution for a long term problem?" Funny how all the costs are borne by farmers (especially organic growers who are losing an important tool from an already quite limited repertoire), yet all the profits and other benefits accrue to Dow, Monsanto, Syngenta, etc. Funny how that works, eh?

I think you need to reexamine your bias here if you wish to retain a shred of credibility on the biologist / scientist front.

-app

[mike_c]

5. the Bt isn't materially different-- the exposure rate is increased....

Development of population level resistance is a function of exposure. As far as the mixed function oxidase system for detoxification, there is no material difference between Cry proteins expressed in engineered corn and that applied topically. As you noted, there is a real difference in persistence and exposure. But Bt applied to the exterior of plants at similar dosages leads to the same resistance. It's only a matter of time.

[NickB79]

6. "Bt was used....more than 40 years without observable resistance"

Why was this, you ask?

The answer is simple: organic farms comprise such a small amount of actual farmland that any resistance developed by the local population would quickly be diluted and nullified by continuous breeding with the non-Bt treated conventional fields (this was before Bt crops were introduced). With only a fraction of the insect population being exposed to Bt, continous interbreeding with non-Bt resistant populations from neighboring farms, and Bt resistance conveying no survival benefits outside the few organic farms in existence, the answer is very clear why we never saw Bt resistance before GMO's incorporated it.

It's also pretty much EXACTLY what has been proposed for the past 20 years to prevent this very sort of thing from happening: the planting of crop refuges to stop resistance from arising.

The problem is that, given the scale of GMO cultivation, the paltry area of refuge crops planted have had little effect.