Beating the 'billion-dollar bug' is a shared burden

January 12, 2021

A lurking threat that has stymied US corn growers for decades is now returning to the forefront: western corn rootworm. Sometimes referred to as the "billion-dollar bug," the species' tiny larvae chew through the roots of corn plants, causing devastating yield losses. In 2003, farmers began planting a genetically engineered variety of corn known as "Bt," which produces a protein toxic to the pest species - but by 2009, the billion-dollar bug had already evolved adaptations for resistance to the toxin.

A new study suggests that slowing the resurgence of western corn rootworm may require a larger-scale strategy than previously thought. The findings, which were published in the Ecological Society of America's journal Ecological Applications, show that when farmers do not follow best management practices for mitigating corn rootworm within a field, they also jeopardize surrounding fields.

Primary author Coy St. Clair and his colleague Aaron Gassmann pinpointed 64 "problem fields" across Iowa, where western corn rootworm had caused greater-than-expected levels of injury to corn between 2009 and 2013 in two varieties of Bt maize: Cry3Bb1 and mCry3A. Compared to fields where rootworm had not damaged Bt maize, the problem fields had higher levels of continuous maize cultivation in surrounding buffer areas.

Corn rows as far as the eye can see in Buchanan County, Iowa. Original image from Carol M. Highsmith's America, Library of Congress collection. Digitally enhanced by rawpixel.

Regular crop rotation is a key strategy for interfering with rootworm's life cycle: when rootworm eggs hatch in a field without corn, the larvae starve before they have a chance to mature and lay eggs. However, continuous planting of corn tends to be more profitable in the short term, leaving corn growers with difficult decisions about how to manage risks.

St. Clair, now a research entomologist for Genective (Champaign, Ill.) who conducted the research as a Ph.D. student at Iowa State University, says that the story of western corn rootworm resistance to Bt illustrates that pest mitigation is a shared responsibility. "If the pest remains susceptible, everyone benefits. If resistance develops, everyone suffers."

Continuous maize cultivation gives nascent rootworm populations a chance to evolve resistance to the Bt toxin - and for those newly resistant offspring to travel to other fields.

"The takeaway here is that a farmer who is employing best management practices - such as frequent crop rotation, or planting of non-Bt maize - will effectively manage rootworm and delay resistance in their own field firstly, while simultaneously helping to delay resistance development in surrounding populations secondly," explained St. Clair. "Conversely, a farmer who is planting multiple years of the same trait will risk resistance in their own field, while contributing to the depletion of the shared resource of trait susceptibility."

As of 2020, agronomists have confirmed that populations of western corn rootworm resistant to the two Bt traits examined in the study are present across the US corn belt, along with two additional Bt traits.  
-end-
Journal article:
St. Clair, Coy, and Gassmann, Aaron, 2021. "Linking Land Use Patterns and Pest Outbreaks in Bt Maize." doi.org/10.1002/eap.2295

Authors:
Coy St. Clair and Aaron Gassman
Department of Entomology, Iowa State University, Ames, IA, USA

Author contact:
Coy St. Clair (coyray03@gmail.com">coyray03@gmail.com)

 

The Ecological Society of America, founded in 1915, is the world's largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 9,000 member Society publishes five journals and a membership bulletin and broadly shares ecological information through policy, media outreach, and education initiatives. The Society's Annual Meeting attracts 4,000 attendees and features the most recent advances in ecological science. Visit the ESA website at https://www.esa.org.

 

Ecological Society of America

Related Corn Articles from Brightsurf:

Making sense of a universe of corn genetics
A new study details the latest efforts to predict traits in corn based on genomics and data analytics.

Redefining drought in the US corn belt
As the climate trends warmer and drier, global food security increasingly hinges on crops' ability to withstand drought.

Speedy recovery: New corn performs better in cold
Around the world, each person eats an average of 70 pounds of corn each year, with even more grown for animal feed and biofuel.

US corn yields get boost from a global warming 'hole'
The global average temperature has increased 1.4 degrees Fahrenheit over the last 100 years.

Genetic discovery may improve corn quality, yields
Researchers may be able to improve corn yields and nutritional value after discovering genetic regulators that synthesize starch and protein in the widely eaten grain, according to a Rutgers-led study.

Pollen genes mutate naturally in only some strains of corn
Pollen genes mutate naturally in only some strains of corn, according to Rutgers-led research that helps explain the genetic instability in certain strains and may lead to better breeding of corn and other crops.

Fungal mating: Next weapon against corn aflatoxin?
Native fungi combinations show promise against aflatoxin.

Scientists discover new 'architecture' in corn
New research on the US's most economically important agricultural plant -- corn -- has revealed a different internal structure of the plant than previously thought, which can help optimize how corn is converted into ethanol.

Breeding corn for water-use efficiency may have just gotten easier
With approximately 80 percent of our nation's water supply going towards agriculture, it's fair to say it takes a lot of water to grow crops.

Changing temperatures are helping corn production in US -- for now
Increased production of corn in the US has largely been credited to advances in farming technology but new research shows that changing temperatures play a significant role in crop yield.

Read More: Corn News and Corn Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.