Technology could help insecticides keep pests under control

Many of the pests that eat our crops have been sprayed so heavily with pesticides that they have developed resistance and can no longer be killed, just as some bacteria have developed resistance to antibiotics.

But scientists at UC San Diego can now genetically engineer new insects of the same species that are not resistant to pesticides. And they can easily pass on their traits when they breed with pesticide-resistant bugs.

They’ve done it with fruit flies and say the same thing can be done with beetles, moths and other pests.

“So if you can make the insects sensitive to it again, you can just keep using the same pesticides that already work, but at much lower frequencies and much lower doses,” said Ethan Bier, a professor of biology at UC San Diego. “So the overall impact on the environment could potentially fall by orders of magnitude.”

The beetles developed in the laboratory have a genetic drive that eliminates the pesticide-resistant mutations.

Bier said the drive works quickly because the manipulated insects reproduce with local populations. They can make a local insect population 100 percent vulnerable to pesticides within ten generations. Beetles reproduce in ten generations in about six months.

The genetic information that drives the drive is expected to disappear from the insects over the same period of time. This means that they end up being no different from the insects we knew before they were exposed to the insecticide.

“We were able to use this genetic strategy that we’ve been working on, where you essentially introduce a trait into a population,” Bier said.

“We have succeeded in doing this in such a way that the only thing that remains afterwards is the population as it once was. So they redesigned it and there is no genetic scar whatsoever. No further element will be added.”

Still, these beetles have undergone mutations in the laboratory, and their release into the wild could be controversial.

With that in mind, Bier said all environmental regulations must be met before any of these creatures are allowed to mate with wild populations.

The article describing Bier’s research appeared in Nature Communications. UCSD postdoctoral fellow Ankush Auradkar also co-authored the paper.