By John P. Roche, Ph.D.
The Colorado potato beetle (Leptinotarsa decemlineata), a pest of potatoes and other members of the nightshade family, causes about half a billion dollars in crop losses globally each year. Chemical insecticides can be used to try to manage this pest, but with continued use the beetles often develop insecticide resistance to these chemicals. A new insecticide has been developed using a process called RNA interference that suppresses elimination of a damaged protein in the beetles and offers promise to help provide control.
Graduate student Samuel Pallis and principal investigator Andrei Alyokhin, Ph.D., at the University of Maine at Orono and Brian Manley, Ph.D., Thais Rodrigues, Ph.D., Ethann Barnes, Ph.D., and Kenneth Narva, Ph.D., of GreenLight Biosciences in North Carolina tested the effects of this RNA insecticide, known as ledprona, on mobility and reproduction in Colorado potato beetles, reporting their findings in a study published in March in the Journal of Economic Entomology.
Ledprona is what’s termed a “biopesticide” because it is based on double-stranded RNA (dsRNA), a biological molecule. It is manufactured by GreenLight Biosciences, under the brand name Calantha. The dsRNA in ledprona uses a gene-silencing process called RNA interference (RNAi), and ledprona is one of the first insecticides on the market using RNAi. Ledprona inhibits the expression of an enzyme in Colorado potato beetles that facilitates the breakdown of proteins. With this enzyme inhibited, metabolites accumulate, which, if allowed to continue, eventually leads to mortality. “Ledprona has a totally new mode of action unlike any other insecticide,” Alyokhin says. “The majority of insecticides target some kind of a protein inside their target pests. Ledprona, on the other hand, prevents a protein from being synthesized by targeting mRNA".