Nutritional Response by Rice and Corn Fall Armyworm (Lepidoptera: Noctuidae) Strains to Dietary Component Substitution in Artificial Diets

Abstract

Progeny from two genetically differentiated strains of the fall armyworm, Spodoptera frugiperda (J. E. Smith), were monitored for growth and development on constituent altered artificial diets. The effect of altered diets on larval growth and pupal weight was contingent on fall armyworm strain (rice or corn). Modified pinto bean diets deficient in vitamin supplements reduced pupal weights of individuals of the rice strain. Larval growth rates were reduced when fall armyworms were reared on a modified pinto bean diet or pinto bean diet augmented with sucrose. However, growth rates were significantly increased when larvae of the rice strain were fed a velvetbean caterpillar diet without sucrose. Strain development on a modified pinto bean diet containing torula yeast had growth rates of 90 mg/d compared with 40 mg/d on a modified pinto bean diet with brewer’s yeast. A velvetbean caterpillar diet devoid of yeast significantly increased corn strain growth rates; however, the same diet decreased development of the rice strain. Larval maturation on the modified pinto bean diet was significantly reduced compared with growth on a modified pinto bean diet without soy protein or when 70% soy protein was substituted for 90% soy protein. The addition of salt to the standard rearing diets dramatically increased larval growth rates.