Susceptible Corn Hybrids Research Articles

Larval Growth and Behavior of the Fall Armyworm (Lepidoptera: Noctuidae) on Callus Initiated from Susceptible and Resistant Corn Hybrids1

Fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae were reared on callus initiated from two leaf-feeding resistant and two susceptible corn, Zea mays L., hybrids. Mean weights of larvae reared for 7 days on callus of the resistant and susceptible hybrids were 29.5 and 50.0 mg, respectively. When newly hatched larvae were given a choice of callus initiated from resistant or susceptible corn hybrids, twice as many preferred the susceptible hybrids. Therefore, both antibiosis and nonpreference appeared to be mechanisms of resistance operating in the callus of the resistant hybrids. The use of callus offers additional techniques for investigating fall armyworm resistance in corn.

Reaction of a Resistant and a Susceptible Corn Hybrid to Various Southwestern Corn Borer Infestation Levels1

AbstractInfestation of corn (Zea maysL.) by the southwestern corn borer [Diatraea grandiosella(Dyar)] can result in substantial losses. Corn genotypes with resistance to leaf feeding damage by the southwestern corn borer have been developed; however, no data on the effectiveness of this resistance in preventing yield and plant height reductions have been reported. To compare the effects of varying infestation levels on a leaf‐feeding‐resistant and a leaf‐feeding‐susceptible corn hybrid, plants in the 10 to 12 leaf stage of growth were infested with 0 to 40 southwestern corn borer larvae per plant in a field study grown on a Leeper silty clay loam (fine, montmorillonitic, nonacid, thermic, Vertic Haplaquepts) in 1982 and 1983. Plants were evaluated for leaf feeding damage, height, and grain yield. Infestation of the susceptible hybrid with 0 to 40 larvae per plant resulted in a linear decline in plant height and yield as infestation level increased. Infestation with 40 larvae per plant reduced yield 39%. Conversely, neither plant height nor yield of the resistant hybrid was significantly reduced at any infestation level. The level of resistance found in the resistant hybrid was, therefore, adequate to prevent losses.