Tropical x temperate germplasm resistant to corn earworm (Lepidoptera: noctuidae)

Corn earworm (CEW), Helicoverpa zea (Boddie), is a major economic pest of corn both in the US and worldwide. The primary means of controlling CEW on corn is to use host plant resistance because chemical control is costly and inconsistent. The objective of this study was to identify new sources of CEW resistance genes from the Germplasm, Enhancement of Maize (GEM) germplasm with either 25% or 50% tropical background. Seventy-three GEM breeding crosses plus three check hybrids (Pioneer hybrids 3223 and 34K77 and B73 x Mo17) were evaluated in Lubbock, Texas in 1999 and 2000. Significant differences in ear penetration by larvae, ear length, ratio of ear penetration to ear length, and grain mold were found among the genotypes. Over the 2 years BVIR103:S04, DKXL380:S08a, DKB830:S19, GUAT209:N19, and CUBA117:S15 had the lowest CEW damage and may be new sources of CEW resistance. Grain mold was positively related to CEW damage. The breeding crosses with 50% tropical background had significantly lower CEW damage, less grain mold, and longer ears than those with 25% tropical background or the check hybrids. (C) 2003 Elsevier Science Ltd. All rights reserved.