Discovery Could Yield Ways to Reduce Corn Rootworm
26 November 2013 
Western corn rootworm beetles strip tissue from the leaves of mutant corn.
Photo credit: Purdue University/Anoop Sindhu
Researchers have discovered a novel corn mutant whose leaves are highly susceptible to attack by Western corn rootworm beetles, a pest that feeds primarily on corn silks and pollen and causes more than $1 billion in damage annually in the U.S., according to a new Purdue University report.
“While Western corn rootworm beetles were previously thought to avoid corn leaves based on food-source preference, study of the mutant suggests that normal corn plants have an active defense mechanism that deters the beetles from feeding on their foliage,” the report says of the discovery by Purdue and University of Illnois researchers. “Identifying this mechanism could lead to new strategies for controlling Western corn rootworm, which is the most destructive insect pest of corn in the U.S.”
“This opens up a whole new opportunity to understand more about the mechanism of defense in corn to control this beetle,” said Gurmukh Johal, Purdue professor of botany and plant pathology. Johal and Stephen Moose of Illinois independently discovered the mutant around the same time.
“In identifying the genetic pathway involved in resistance, we can develop better ways of controlling this pest without having to use insecticides,” Johal said.
Because the leaves of the corn mutant are attractive only to Western corn rootworm beetles, the mutant could be used to lure the beetles to a specific location where they can be controlled, said Christian Krupke, assistant professor of entomology and co-author of the study.
“Once you can get them where you want, you can use efficient, cost-effective ways of controlling them, either by directly targeting and eliminating them or by keeping them away from your main crop,” he said.
According to the Purdue report, the mutant corn is “virtually indistinguishable from normal corn plants, which may be why it was not discovered earlier,” said Johal.
Its leaves do not become vulnerable to attack by rootworm beetles until it reaches the vegetative stage, about five to six weeks into the growth process.
Further research is being done on the possibility of using the mutant in pest control strategies and identifying the genetic pathway in normal corn plants that prevents Western corn rootworm beetles from consuming their leaves, according to Purdue. The genes could be used to make corn plants more pest-resistant, Johal said.
The paper was published online in PLoS ONE and is available at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0071296;jsessionid=127B91804B4E522B97208869322F0D7B
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