Corn rootworm possesses ‘secret weapon’ to survive winter

A study from the University of Kentucky offers fresh insights into a billion-dollar problem for U.S. corn producers each year.

New research shows how two notorious pests — western and northern corn rootworms — survive cold winters and return the next year to wreak havoc on corn yields.

According to a university news release, researchers identified mechanisms that regulate an underlying process corn rootworms use called diapause.

By pinpointing the genetic mechanisms that help rootworm eggs “pause” underground during the winter, the research may lay the groundwork for improved management strategies.

“It’s incredible if you think about it — this tiny embryo in the soil essentially locks in place, waiting for spring,” said Nicholas Teets, an associate professor in the department of entomology at the University of Kentucky and one of the study’s lead investigators. “When the conditions improve in spring, it picks up where it left off and hatches right around the time corn roots are available.”

According to Teets, diapause is a phenomenon similar to hibernation, and in this species, it involves eggs that remain dormant in the soil for approximately nine months. During that time, the insects dial down many energy-costly processes while boosting protective functions that help them endure the cold.

“There’s really two parts to this research,” Teets said. “First, we’re interested in the basic science, how insects survive winter through diapause. Secondly, we’re focused on the economic side because corn rootworms cause significant annual losses, and diapause is a big reason they’re so hard to control.”

The study is significant for farmers and the agricultural industry because diapause helps corn rootworms synchronize their lifecycle with the planting schedule, emerging just in time to feed on young corn roots. By understanding how those pests orchestrate their genetic pause, scientists can look for ways to disrupt that timing.

While the current work does not instantly translate into new in-field practices, Teets believes it marks a step in that direction.

“This discovery doesn’t immediately change what farmers do in the field,” Teets said, “but it could lead to new tools in the long run. We’d also like to shorten or skip the diapause phase in laboratory strains of these pests to make research faster, because right now it takes six months or more to go through the full dormant period.”

Teets says another longer-range possibility centers on using “gene knockdown” technology to undermine the rootworms’ ability to withstand winter. Scientists have shown that when adult rootworms ingest specific RNA molecules, those molecules pass into the eggs and can disrupt specific genes.

If future research pinpoints the genes most critical to diapause, the door could open for new pest-control products designed to disable the eggs’ built-in survival systems. Though such a solution is not yet on the market, it represents a path that may one day limit costly damage.

Changes to rootworm egg-laying behavior and the subsequent diapause also help that pest escape crop rotation.

Northern corn rootworms have developed an extended two-year diapause in some regions, meaning eggs can remain dormant even longer. Teets compares that to prolonging a pregnancy by several years — a biological feat that highlights the insects’ resilience and raises the stakes for controlling them.

“It’s amazing how adaptable rootworms can be,” Teets said. “That kind of flexibility means farmers need new solutions.”