Populations of European corn borer, a major corn crop pest, have declined significantly in the eastern United States. That suggests, according to Penn State University researchers, that use of genetically modified, ECB-resistant (Bt) corn hybrids may now be unnecessary at least in some areas.
Bt hybrids have been very effective and widely adopted by farmers – which accounts for the decline. So it poses a "Which comes first: The chicken or the egg?" issue.
But they're expensive. And with more normal corn markets, they warrant reassessment as they can decrease potential profits, suggests John Tooker, Penn State Extension entomologist.
Not that long ago, ECB-related crop losses approached $1 billion nationwide, and $35 million in the Northeast. "Bt hybrids have been widely adopted because 99.9% of ECB larvae are expected to die when they feed on plants expressing Bt toxins," he adds.
Widespread ECB population decline
Tooker and graduate student Eric Bohnenblust assessed larval damage in Bt and non-Bt hybrids at 29 Pennsylvania farm sites in four growing zones during 2010, 2011 and 2012. Then in each September, they assessed corn borer damage.
"With less ECB damage around, non-Bt hybrids in our tests yielded just as well as Bt hybrids," notes Bohnenblust. "So the ECB decline provides an opportunity for growers to generate greater profits by planting non-Bt seed, which is much cheaper. And, planting more non-Bt corn will reduce the potential for ECB to develop resistance to Bt toxins as corn rootworms have done in about a dozen states so far."
PestWatch has predictive potential
The researchers also examined PestWatch network's predictive ability. In brief, the network traps ECB and other moth species as they fly and provides data about their prevalence.
"While traps within the PestWatch network provide insight on ECB population size, their utility as a predictive tool, particularly for field corn, has been limited," acknowledges Bohnenblust. ECB moths captured in the PestWatch network correlate well with in-field populations of ECB in field corn. That means PestWatch has predictive potential to inform growers about whether Bt or non-Bt hybrids are in needed different parts of the state.
Tooker's money-saving advice is: Scout non-Bt acreage toward the end of the growing season. If you have low ECB populations, and PestWatch reflects low moth captures in your area, give competitive non-Bt hybrids a try on some of those acres.