Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/1995
Publication Date: N/A
Interpretive Summary: The corn earworm is a serious pest of maize in the United States. Controlling this pest is accomplished by using pest-management strategies. When available, corn earworm resistant cultivars should be included in pest management control schemes. This should reduce the use of pesticides, which will in turn help protect our environment. We evaluated 15 maize accessions from the National Plant Germplasm System with pure red kernels for new sources of corn earworm silk-feeding resistance. Four accessions were identified as resistant at two locations - Ames, IA and Tifton, GA. Three of the four had high levels of the chemical maysin while the fourth was low in maysin. In another test of 8 selected Plant Introduction accessions, one was resistant at both Ames and Tifton. These new sources of corn earworm resistance are available to plant breeders for development of resistant cultivars.
Technical Abstract: New sources of corn earworm, Helicoverpa zea (Boddie), silk-feeding resistance are needed to protect the maize, Zea mays L., crop without increasing the use of pesticides. Previous evaluation of popcorn germplasm with red pericarp color showed a high incidence of resistance. Within the National Plant Germplasm System (NPGS), there are 15 maize accessions with pure red pericarp color. These 15 accessions were grown in the field at Ames, IA and Tifton, GA. Fresh silks were collected, dried and incorporated into a standard pinto bean diet for rearing corn earworms. Diets were infested with neonate larvae and the larvae were weighed after 8d. Results of the diet testing identified four PI accessions that produced 8d larval weights equal to the resistant check, 'Zapalote Chico'. The 15 accessions were analyzed for the presence of maysin, three of its analogues and chlorogenic acid. One accession, PI 245138, had low levels of maysin but was resistant. In addition, 8 maize accessions acquired by the NPGS from 1948-1951, were evaluated for corn earworm silk-feeding resistance at Ames and Tifton. One accession, PI 172328, was rated resistant at both locations.