Resistance in Zoysiagrass (Zoysia spp.) to the Fall Armyworm (Spodoptera frugiperda) (Lepidoptera: Noctuidae)

Abstract

The fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is a pest of most turfgrass species in the United States. Twelve cultivars and genotypes of zoysiagrass (Zoysia spp.) were evaluated for resistance to both neonate and 4-d-old fall armyworm larvae. Three cultivars, 'Cavalier', 'Emerald', and 'Belair', were the most resistant to feeding by neonate larvae with less than 5% of the larvae survived beyond 4-d of feeding. After 10 d, 10% or less of the confined larvae were alive on these 3 cultivars along with 'Meyer', 'Korean Common', 'El Toro' and DALZ8501. When most of the same genotypes were exposed to 4-d-old larvae that had developed on a susceptible host, ca. 20% of the mortality was eliminated. Survivorship for 7-d-old larvae (after 3 d feeding) was 40% or greater on all genotypes except for Cavalier. Only Cavalier, DALZ8501, and Korean Common exceeded 85% mortality after 13 d of feeding. Meyer produced 97.6% mortality of neonate larvae, but only 46.7% of larvae that had first fed on a susceptible host. The 4-d-old larval that fed on the resistant genotypes usually weighed less than half the weight of those fed on susceptible Palisades and DALZ8516. Also, days-to-pupation and days-to-adult emergence were shortest on the 2 most susceptible genotypes. No fall armyworm larvae were able to survive more than 17 d on Cavalier. Several other cultivars were identified with resistance.