UNIVERSITY PARKThe com earworm causes the loss of more than 76,000 bushels of com in the United States annually, and there is mounting evidence that increasingly extreme weather events and temperatures will exacerbate the damage done to agricultural output by insect pests. Responding to that threat, a team of researchers at Penn State conducted a study that demonstrated that genetic lines of com have inherent compounds that serve as insecticides, protecting them from the larvae that feed on them.

In findings recently published online ahead of the March issue of Plant Stress, the researchers reported that com earworm larvae feeding on the silks, husks and kernels of com lines containing high levels of flavonoids — chemicals that play essential roles in many biological processes and responses to environmental factors in plants — grow much more slowly and many die, compared to larva feeding on com lines without flavonoids.

In addition to increased mortality and reduced body weight, larvae feeding on high-flavonoid com lines developed a leaky-gut-like syndrome, the researchers found, suggesting involvement of microbiome changes in the larval gut. Moreover, the expression of gut health-related genes was changed in larvae consuming the flavonoid-rich husks. hi the study, the researchers compared how com earworm larvae survived on genetically identical strains, except for a few specific, known differences of com — in this case, with some expressing high flavonoid content in silks, husks and kernels; some not. The com, grown at the agronomy farm at Penn State’s Russell E. Larson Agricultural Research Center, included a line engineered to have a gene that triggers flavonoid production and a line that was conventionally bred to produce flavonoids, which was developed over the last two decades by Chopra’s lab from cross-breeding a mutant line of com.

Researchers pointed out that they noticed ‘a stark difference’ in mortality and bodyweight between com earworm larvae feeding on flavonoid-overproducing lines as compared to control lines. Both the genetically engineered line and the line bred from the mutant had similar effects on the larvae.

‘This research is important because it may be an early step toward the development of com lines resistant to insect pests ideal for organic production,’ said research team leader Surinder Chopra, professor of maize genetics. ‘These findings, which suggest a novel option for integrated pest management for com earworm larvae, shows that high-flavonoid maize has the potential to be used in a breeding program to develop specialty com lines tolerant of multiple insect pests.’

More research is needed before plant breeders could be expected to try developing flavonoid-producing corn lines that also protect against other insects for organic farmers, Chopra noted.

‘Future studies will investigate the mechanisms behind flavonoid-mediated damage to the gut of corn earwonn larvae and will explore the broader impacts of flavonoid content on plant-insect interactions,’ he said.

The study was spearheaded by Debamalya Chatterjee, a former postdoctoral scholar in the Chopra lab who is currently an assistant professor at Skidmore College. Contributing to the research were Charles Colvin, undergraduate researcher in plant science; Tyler Lesko, doctoral student in the Department of Plant Science; Michelle Peiffer, research support assistant and lab manager in the Department of Entomology; and Gary Felton, professor and head of the Department of Entomology. The U.S. Départaient of Agriculture’s National Institute of Food and Agriculture financially supported this work, rm larvae and will explore the broader impacts of flavonoid content on plant-insect interactions,’ he said.

The study was spearheaded by Debamalya Chatterjee, a former postdoctoral scholar in the Qiopra lab who is currently an assistant professor at Skidmore College. Contributing to the research were Charles Colvin, undergraduate researcher in plant science; Tyler Lesko, doctoral student in the Department of Plant Science; Michelle Peiffer, research support assistant and lab manager in the Department of Entomology; and Gary Felton, professor and head of the Department of Entomology.

The U.S. Department of Agriculture’s National Institute of Food and Agriculture financially supported this work.