[hirvi74]

I could be incorrect, but I think I remember reading something about pest-resistant crops and how they are often implemented incorrectly when I was in university taking ecology classes.

Basically, if you take crop like corn as an example. Say our example corn has been genetically modified to resist various pests. However, you cannot just go and plant an entire field of said corn and expect it to be pest-resistant forever.

What farmers are supposed to do is plant non-pest-resistant corn crops for every n number of GMO corn corps in the same field. So, any given row of corn would have something like a non-pest-resistant corn plant after every 4 GMO corn plants.

This causes the said modified corn to retain its pest resistance for longer amounts of time, and the non-pest-resistant crops serve as honeypots for the pests. (You know path of least resistance and all).

However, doing this technically hurts the yields of a farmer's crops and more yield = more profit, thus many farmers forgo this practice. Even if done correctly, I still do not think it works forever, but it does slow down the microevolution of said pests -- at least hypothetically.

Not sure if that is correct, but I would love to know either way.

[IntrepidWorm]

I cannot confirm, but that sounds plausible. This is the same logic for using antibiotics sparingly and in manners that will maximize their effect, to reduce the rate at which resistant strains of organisms dangerous to us can mutate.

[searine]

You and the person you were replying to are confusing two kinds of GMO crop:

Pest-resistant (kills bugs) and Herbicide-resistant( makes the plant robust to chemicals which kills weeds)

You're right about refuges, they only slow things down. To truly prevent resistance genes in pests from appearing, you need multiple modes of action. This was used effectively in HIV treatment. The virus was developing resistance to AZT treatment alone, eventually new drugs came along and patients were treated with 3 or more drugs at once. Multiple modes of action makes it too hard for the virus (or pest) to adapt in time. We don't really have multiple modes of action in plants yet, but one day, maybe?

The person you were replying to was describing herbicide resistant crops, which are sprayed (sometimes oversprayed). This isn't so cut and dry as they describe though. Things like glyphosate are much milder compared to older herbicides and GMO crops encourage things like 'no til' agriculture which greatly improves soil quality. So we're still spraying, but it's better, and has ecological benefits.