Next generation insecticides show promise in US trials

A new generation of highly selective insecticides being developed by US scientists is a step closer, after trials showed successful control in potatoes.

RNA interference, a by-product of gene research, has the potential to deliver an insecticide that controls pests such as cabbage stem flea beetle in oilseed rape without affecting any other species.

See also: Biopesticides may offer an answer to arable woes

“The major problem with conventional insecticides is they affect non-target organisms,” explained Jeff Scott, a professor of entomology at Cornell University.

He is currently developing an RNA insecticide for the Colorado Potato Beetle, which causes $100m (£64m) a year of damage in the US.

RNA is present in all living cells and acts as a messenger carrying instructions for making proteins from DNA. The spray works by breaking down a particular strand of RNA, effectively silencing the gene that the insect can’t do without.

“This is an insecticide that is based on a specific gene. Thus, you might be able to kill only that specific insect, and that would be a phenomenal breakthrough in pest control,” he said.

One concern was that the spray would rapidly degrade, but new results published last month in Pest Management Science showed it survived 28 days, controlling beetles that ate the leaves

“That finding dispels concerns that the genetic material will quickly degrade in rain and sunlight.”

But he cautioned that the insecticide needs more work before it is ready to market. For example, Prof Scott highlighted that the cost of making RNA insecticide is currently much higher than conventional insecticides.

Insects need to eat sprayed leaves for it to work so insects that don’t eat leaves, such as houseflies, or those that suck sap, such as aphids, won’t be harmed.

Finally, he said that some insects are simply unaffected, perhaps due to gut enzymes that break down the RNA.

“It may take some tweaking, but its potential to be specific is going to be hard to beat,” concluded Prof Scott.

NOVEMBER
3

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