MODIFYING PLANTS, to produce genetic materials that disable critical genes in insects that eat the plants, could provide a strategy for agricultural-pest control. This a new way to protect plants from pests.

Researchers turned to a mechanism known as RNA interference, in which segments of the genetic molecule RNA block the translation of information from a target gene. They found RNA sequences that would target critical genes in the western corn rootworm and two other related pests, and then modified corn so that it would generate those sequences.

In rootworms that fed on the modified corn, RNA from the plants shut down the target gene, stunting or killing the insects’ larvae, the researchers report. Modified corn plants infested with corn-rootworm eggs suffered less root damage than did normal corn.

In another study, scientists used a similar trick to increase the cotton bollworm’s sensitivity to gossypol, a defense chemical produced by the cotton plant.

Although large doses of gossypol stunt the growth of bollworm caterpillars, the pests can tolerate the chemical at low concentrations. The research team found the insect gene responsible for this tolerance, and then modified Arabidopsis, a widely used lab plant, to produce silencing RNA for that gene. Insects that ate the modified lab plants ingested the RNA, and stopped growing when fed gossypol.

Previous research had shown that RNA injected into insects could also shut down specific genes. The critical innovation of the new work is oral delivery of the silencing RNA from plant to insect.

For many years, farmers have planted crops engineered to possess a bacterial gene that produces an insect poison known as Bt. But this poison doesn’t work on all insects, and scientists worry that pests could eventually evolve resistance to it.

With the appropriate choice of target gene, in principle, the [RNA] strategy is applicable to any herbivorous insect. And the ability to carefully design the RNA sequence could allow researchers to evade insect-resistance strategies.

More research will be needed to show how applicable the technique is to other pests and how well it would work in the field. Government regulatory bodies would have to grant permission before such crops could be grown in open fields. But the initial results suggest that RNA interference could be a powerful strategy for controlling insect pests.

Researchers on pest management at VSU (in the department where I belong) have always been on the lookout for new ways to control insets and other pests. This killer gene concept is certainly an excellent opportunity to do that. By Manny Palomar, PhD (EV Mail July 24-30, 2023 issue)