The corn earworm (Heliothis zea Boddie) commonly causes damage to peanut (Arachis hypogaea L.) in North Carolina. Resistance to the corn earworm has been identified in peanut and correlated with resistances to tobacco thrips (Frankliniella fusca Hinds), potato leafhopper (Empoasca fabae Harris), and the southern corn rootworm (Diabrotica undecimpunctata howardi Barber). Development of corn earworm-resistant cultivars which might also assist in managing several insect pests could be aided by an understanding of the nature and inheritance of corn earworm resistance.

This study was conducted to develop a laboratory procedure to screen for corn earworm resistance, to determine the relationship between laboratory and field measurements of resistance, to determine the chemical basis of resistance, and to determine the inheritance of resistance.

Neither the laboratory measurement of larval growth after feeding of fresh leaf tissue nor after feeding on a synthetic diet containing ground freeze-dried leaf tissue consistently separated resistant and susceptible germplasms. Because of the inconsistency in laboratory tests, the relationship between lab and field results was inconsistent. Since these procedures did not always distinguish resistant and susceptible genotypes, these techniques cannot be used in lieu of field screening. However, these studies do suggest that antibiosis is a major component of corn earworm resistance. Chemical analyses indicate that a flavone glycoside is probably responsible for the antibiotic response. Neither field nor laboratory evaluations of progencies from the cross of NC 6 (resistant) and Florigiant line C (susceptible) could be used to separate plants into resistant and susceptible classes. Antibiosis did appear to be a dominant trait for this cross.