A study from the University of Kentucky Martin-Gatton College of Agriculture, Food and Environment 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 following year to wreak havoc on corn yields.
The study, published in Current Research in Insect Science, was supported by the USDA National Institute of Food and Agriculture and the U.S. National Science Foundation through the Center for Arthropod Management Technologies.
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 pest-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 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 this 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."
This 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 these 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 added, "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."
Potential long-term research implications
Because rootworms typically require up to six months of simulated winter to complete a normal diapause cycle, breeding them in the lab is a slow process, which holds back efforts to test insecticides or genetic controls. Armed with genetic data from this study, researchers could create colonies that skip or reduce this dormant period in the lab, meaning faster turnaround for experiments and potentially speedier development of control measures.
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, these 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 help limit the costly damage these pests inflict on cornfields.
Changes to rootworm egg-laying behavior and the subsequent diapause also help this pest escape crop rotation. Northern corn rootworms, on the other hand, have developed an extended two-year diapause in some regions, meaning eggs can remain dormant even longer. Teets compares this 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. "Relative to how fast a rootworm embryo can develop, if a human pregnancy lasted that long proportionally, it would be more than a decade. That kind of flexibility means farmers need new solutions, and our genetic data could be a step toward those solutions."
Research reported in this publication was supported by the U.S. National Science Foundation under Award No. 1821936. The opinions, findings, and conclusions or recommendations expressed are those of the author(s) and do not necessarily reflect the views of the U.S. National Science Foundation.
This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Hatch Project under award number 1010996. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the Department of Agriculture.
