Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/1999
Publication Date: N/A
Citation: Interpretive Summary: The European corn borer causes 10-15% losses to yield every year in Iowa and other corn-production states. Developing new lines of corn with natural resistance to leaf-feeding insects is one of the goals of this project. The objective of this laboratory study was to characterize the effect of chemical extracts of leaf tissue from leaf-feeding resistant Peruvian corn on growth, development and fecundity of the European corn borer. Water extracts of the Peruvian leaves were incorporated into an artificial diet and fed to European corn borer caterpillars. Extracts of several Peruvian lines of corn significantly reduced the growth, development and fecundity of the European corn borer. Use of maize, which has natural resistance to European corn borer, will help reduce the need for insecticides and eliminate soil and water contamination resulting from excessive use of insecticides. Decreased use of insecticides will benefit farmers by lowering their expenses for pest management and the general public will benefit by having a healthier and cleaner environment.
Technical Abstract: Twelve Peruvian maize, Zea mays L., accessions were selected for this study because of their relatively high level of field resistance to first- generation European corn borer (ECB), Ostrinia nubilalis (Hubner), larval leaf feeding. Water extracts of freeze dried, powdered, leaf tissue were incorporated into a standard ECB diet, fed to larvae, and their effects on larval growth, development, and fecundity were measured. Larval and pupal weights were monitored as well as the time elapsed in the larval, pupal, and adult stages. Adult fecundity and egg fertility was recorded. The experiment was a randomized block design (larvae and pupae) or a completely randomized design (adults) and analyzed with ANOVA (alpha = 0.05). Pair- wise comparisons were made between groups of insects (least squares means test) (alpha = 0.05) grown on diets containing extracts from the Peruvian lines, a standard diet, or diets containing extracts of a known susceptible einbred, WF9, and a known resistant inbred line, CI31A. Survival to pupae and adults was analyzed with a chi-squared test (alpha = 0.05). Peruvian accessions PI 485320, PI 503723, and PI 503720 significantly reduced female larval and pupal weights, pupal and adult development time, and survival to adults. Water extracts of Peruvian accessions also had a pronounced impact on males; PI 503723 and PI 485320 significantly reduced pupal weight and extended the time required to pupate, while PI 485320 reduced male survival to adults. The results indicate that water-soluble factors from resistant Peruvian accessions inhibit the growth, developmental time, and survival of ECB. These resistance factors could be useful in the development of maize germplasm with insect-resistant traits.