R. Figueroa-Brito, P. Villa-Ayala, J.F. López-Olguín, A. Huerta-de la Pena, J.R. Pacheco-Aguilar, and M.A. Ramos-López. 2013. Nitrogen fertilization sources and insecticidal activity of aqueous seeds extract of Carica papaya against Spodoptera frugiperda in maize. Cien. Inv. Agr. 40(3): 567-577. The damage caused by the fall armyworm Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) to vegetative-stage maize cultivated with chemical nitrogen fertilizers, vermicompost, and Carica papaya L. (Caricaceae) seed extract was estimated. Each shoot was infested with one first instar larva of S. frugiperda. The variables measured included the percentage of germination, length of the second and fifth leaves, stem diameter and plant height, and the estimation of damage caused by S. frugiperda larvae on maize. The results indicated that vermicompost helped seed germination on a relation 3:1 from black soil and vermicompost, the emergence was 100%, while the emergence with black soil was 80%. The ammonium sulfate increased the length of the second and fifth leaves 89.6% and 160.4% respectively, augmented the stem diameter and the plant height 290.2% and 13.3% respectively, respect to water treatment. The exogenous nitrogen sources stimulate S. frugiperda to cause more damage to the plant, the treatment urea showed 70% of damage, with phosphonitrate 62.3% and with ammonium sulfate 51.8%, when were evaluated without aqueous seed extract of C. papaya. Ammonium sulfate + aqueous extract of C. papaya seeds showed the lowest insect damage to maize with 29.6%.