New RNAi Technology Takes the Bite out of Corn Rootworm
Corn rootworm is about to find a new foe in the cornfield, thanks to Ribonucleic acid interference (RNAi) technology.
Corteva Agriscience officials announce they have received U.S. Environmental Protection Agency approval for the company’s new Vorceed Enlist corn products, containing a novel RNAi active ingredient to control corn rootworm (CRW).
RNAi technology works in CRW as it feeds on corn roots by turning off, or silencing, functions the pest needs for growth and sustainment.
Corteva expects to market the technology in Vorceed Enlist hybrids ranging in the 93- to 100-day relative maturity for farmer use, starting in 2023.
Layering MOAs for Protection
In total, Klemm says Vorceed Enlist corn products contain three modes of action (MOA) for above-ground insect protection, three MOAs for below-ground insect protection and tolerance to four herbicide modes of action to help address weed resistance -- 2,4-D choline, glyphosate, glufosinate and FOP herbicides.
The company reports reduced corn root damage and a 99% reduction in adult beetle emergence, thanks to the layered MOAs.
“The trait allows the broadening of our genetics which will result in higher-yielding hybrids,” says Tony Klemm, Corteva vice president, corn portfolio. “We'll quickly ramp up production, and this product will be our leading corn rootworm trait offer in the portfolio by mid-decade.”
He adds that the technology is expected to be available in products across all Corteva seed brands, including Pioneer, Brevant Seeds, AgVenture, Dairyland Seed, Hoegemeyer, NuTech and Seed Consultants.
During the introductory phase, Qrome-based corn products will continue to lead the Corteva CRW trait portfolio.
Klemm says the company is seeing even better overall hybrid performance with Vorceed Enlist.
“We’re seeing improved performance, because our root protection is about 17% better, on average,” Klemm says. “That is what's helping us get the yield lift, which we’ll be able to tie into our large germplasm pool.”
Environmental Stewardship Improves
The development of the RNAi technology continues “to move agriculture towards more environmentally friendly insecticides,” report researchers in a journal article published in Insects in January 2022 (see https://bit.ly/3u8Ogzc).
The first corn hybrids containing RNAi technology to fight corn rootworm are being launched commercially this season under the brand SmartStax PRO. The hybrids offer three MOAs for corn rootworm – a double-stranded RNA targeting the CRW snf7 gene, in combination with Bt proteins Cry3Bb1 and Cry34Ab1/Cry35Ab1.
Historically, control techniques used in rootworm management have included treating seed corn with neonicotinoid insecticides and planting transgenic corn hybrids expressing Bacillus thuringiensis (Bt) toxins.
However, in the past decade, the four insecticidal Bt proteins currently in the marketplace – Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34Ab1/Cry35Ab1 (now classified as Gpp34Ab1/Tpp35Ab1) – have seen CRW resistance build to varying degrees across the Corn Belt.
Researchers expect the RNAi technology will help farmers regain the upper hand over CRW and in a more environmentally sound manner.
“The lessons learned with western corn rootworm, the first insect to be targeted with an RNAi technology, can serve as an example for the development of novel RNAi insecticides in other insect pests, providing a safe and efficient MOA,” says the article in Insects, which was developed by researchers in the Department of Entomology, University of Nebraska-Lincoln, in cooperation with Corteva and Bayer Crop Science.
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