Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/22/2007
Publication Date: 5/1/2007
Citation: Daves, C.A., Williams, W.P., Davis, F.M. 2007. Impact of plant resistance on southwestern corn borer (Lepidoptera: Crambidae) biology and plant damage. Journal of Economic Entomology. 100:969-975. Interpretive Summary: Southwestern corn borer populations can adversely impact corn production in the southeastern United States. The larvae of this insect pest attacks the corn plants in the whorl and tassel stages of growth causing damage to the plant by leaf feeding, and by tunneling throughout the stalk of the plant. This damage can result in substantial yield losses. Inbred lines with leaf feeding resistance to the southwestern corn borer are available and have been released by USDA-ARS scientists. The objectives of this study were to determine the impact of two resistant corn hybrids produced from resistant inbred lines on the southwestern corn borer, and to evaluate the effectiveness of the plant resistance in reducing damage by this insect pest. This research was conducted under field and laboratory conditions. The results of this study clearly show the effectiveness of the plant resistance in reducing damage caused by this pest. That plant resistance had negative effects on the southwestern corn borer was indicated by reduced larval survival, slower growth and development, and a reduction in weight. The resistance also reduced the amounts of leaf feeding and stalk tunneling normally caused by this pest. The results indicate that resistance improves the chances of the corn plants to reach normal growth levels and optimal production levels by reducing the overall damage of southwestern corn borer larvae.
Technical Abstract: Southwestern corn borer, Diatraea grandiosella Dyar (Lepidoptera: Crambidae), is a major insect pest of corn in the southern United States. Germplasm lines with resistance to southwestern corn borer have been developed and released by USDA-ARS. Two single-cross hybrids produced by crossing germplasm lines with resistance to southwestern corn borer and a susceptible single-cross hybrid were infested with southwestern corn borer larvae in a 2-year field test conducted in Mississippi. The susceptible hybrid sustained significantly more leaf damage and stalk tunneling than either resistant hybrid. The number of tunnels and the length of tunneling were significantly less on the resistant hybrids. In 2003, up to 15 times more tunneling was observed on the susceptible hybrid. Larvae feeding on the resistant hybrids were slower in their movement from the whorl to the stalk and larval survival was 50% less on the resistant hybrids than on the susceptible hybrid. The time required for larval development was extended up to 14 days on the resistant hybrids. Larvae recovered from the susceptible hybrid 7 to 14 days after infestation weighed twice as much as those recovered from the resistant hybrids. Similar differences in larval weight were observed in the laboratory when larvae were reared on diets prepared from lyophilized tissue from the three hybrids. These results provide a foundation for other investigations designed to identify and determine the roles of specific genes and gene families associated with southwestern corn borer resistance in corn.