Evaluation of Pure Red Pericarp and Eight Selected Maize Accessions for Resistance to Corn Ear worm (Lepidoptera: Noctuidae) Silk Feeding

Abstract

New sources of com ear worm, Helicoverpa zea (Baddie), silk feeding resistance art' needed to protect the maize, Zea mays L., crop without increasing the use of pesticides. Previous evaluation of popcorn germ plasm with red peri carp color showed a high incidence of resistance. Within the National Plant Germ plasm System, there are 15 maize accessions with pure red peri carp color. These 15 accessions were grown in the field at Ames, lA, and Tifton, GA. Fresh silks were collected, dried, and incorporated into a standard pinto bean diet for rearing corn ear worms. Diets were infested with neonates, and the larvae were weighed after 8 d. Results of the diet testing identified four plant introduction accessions that produced 8-d larval weights equal to the resistant control, ‘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, eight maize accessions acquired by the National Plant Germ plasm System from 1948 to 1951 were evaluated for corn ear worm silk feeding resistance at Ames and Tifton. One accession, PI 172.328, was rated resistant at both locations.