Survival and development of Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) on Conyza bonariensis L. and Amaranthus viridis L.

Fall armyworm, Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), is a polyphagous species capable to develop on several cultivated and non-cultivated host plants, including weeds. On this basis, we evaluated the survival and development of S. frugiperda on leaves of hairy fleabane (Conyza bonariensis L.; Asteraceae) and slender amaranth (Amaranthus viridis L.; Amaranthaceae) in laboratory trials. Spodoptera frugiperda neonates were initially fed on leaves of non-Bt maize and then were transferred to hairy fleabane or slender amaranth leaves at different time points. On hairy fleabane leaves, only 12% of larvae in L5 and L6 stages developed into pupae and adults, with similar duration of immature stage of those developed in maize leaves. In contrast, S. frugiperda larvae from L1 to L6 stages developed into pupae on slender amaranth leaves, but only those from the L2 stage onwards originated adults (9–65%). On maize, > 64% of neonates developed to adulthood. Surviving larvae fed on early instars on slender amaranth leaves had up to 10 d longer developmental time of neonate-to-pupa and neonate-to-adult periods compared to those developed on maize. Pupal weights of surviving insects on slender amaranth leaves were also lower (104.9–67.4 mg/pupa) than on maize (207.4 mg/pupa). In summary, our findings indicate that the hairy fleabane is not a suitable host for S. frugiperda, whereas slender amaranth is a viable food source for the survival end development of this species, mainly for advanced instars. [ABSTRACT FROM AUTHOR]