Poster: Plant insect-nematode interactions

Abs # 493: Methylation of an anthocyanin increases its ability to inhibit growth of corn earworm larvae

Presenter:	Johnson, Eric T, johnet@ncaur.usda.gov
Authors	Johnson, Eric T (A)   Dowd, Patrick F (A)
Affiliations:	(A): USDA-ARS-Crop Bio-Protection

The anthocyanins are synthesized by flowers primarily to attract pollinators and seed dispersers. A few studies have determined that some anthocyanin compounds, such as cyanidin-3-β-glucoside, can reduce insect feeding. Our objective was to determine if this activity could be extended to an insect pest of corn. Purified cyanidin chloride did not inhibit the growth of corn earworm (CEW) larvae at 1000 ppm in insect diet, but purified peonidin chloride significantly reduced the growth of the larvae at the same concentration. Peonidin has the same structure as cyanidin except that its 3’-hydroxyl group is methylated. In order to confirm these findings, we also tested plant materials that contain cyanidin and peonidin-type anthocyanins. We excised colored and white sectors from striped petunia flowers and fed them separately to CEW larvae. After two days of feeding, the CEW larvae fed significantly less on the colored sectors compared to the white sectors. The reduction in feeding rates was greater in colored sectors containing peonidin-type anthocyanins compared to those containing cyanidin-type anthocyanins. Together these results indicate that expression of relevant anthocyanin molecules at suitable levels in corn may be an effective means to reduce CEW predation of plant tissues.