Development of Fall Armyworm on Diets Containing Resistant and Susceptible Corn Silks

Abstract

Growth and development of fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae on pinto bean diet containing dry corn, Zea mays L., silks of resistant, `Zapalote Chico', or susceptible, `Stowell's Evergreen', at 0, 18.75, 37.50, and 67.0 mg silk/ml diet were evaluated at 20, 25 and 30@*C. Weight of larvae that fed on resistant and susceptible silk-diets averaged 38 and 205 mg, respectively. At 20@*C, the weight of larvae that fed on various concentrations of silk/diet did not differ between the resistant and susceptible genotypes or among the various concentrations within each corn genotype. However, at 20@*C, significant differences were found between the resistant and susceptible for development time, weight of pupae and time to adult eclosion for larvae that fed on various concentrations of silk/diet. Significant differences were consistently recorded for all characters measured (P <0.05) between the resistant `Zapalote Chico' and susceptible `Stowell's Evergreen' at 25 and 30@*C. Larvae failed to develop to pupae at the highest concentration (67.0 mg/ml) of resistant silks at 20, 25, or 30@*C.