1985 Fall Armyworm Symposium: Plant Resistance: Plant Resistance and Nuclear Polyhedrosis Virus for Suppression of the Fall Armyworm (Lepidoptera: Noctuidae)

Abstract

The susceptibility of fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae to nuclear polyhedrosis virus (NPV) was studied in relation to host plant resistance in corn, Zea mays L. In laboratory tests, freeze-dried silks of resistant (Zapalote Chico) and susceptible (Stowell's Evergreen) corn lines were incorporated into artificial diets. Larvae treated with the virus before they were held individually on the test diets showed significantly higher mortality due to NPV on the diet containing resistant silks than on the diet containing susceptible silks. When larvae were fed on test diets for 6 days before they were treated with the virus, the larvae grew larger and were less susceptible to the NPV on the diet containing susceptible silks than on the diet containing resistant silks. In a field test comparing five lines of corn with a spectrum of leaf-feeding resistance to fall armyworm, larvae growing on the most susceptible line had the lowest mortality due to NPV. Thus, the susceptibility of fall armyworm larvae to NPV was inversely related to the growth and vigor of the larvae, which was directly related to the susceptibility of the host plant. Therefore, the fall armyworm NPV should be more effective when used on resistant lines of corn than on susceptible lines.