The effects of a nutrient-based feeding stimulant, Coax, and a stilbene-based optical brightener, Blankophor P167, on the activity of the nucleopolyhedrovirus of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (SfMNPV) on transgenic sweet corn, Zea mays L., expressing a CryIA(b) toxin from Bacillus thuringiensis (Berliner), were studied in the laboratory. Both Coax and Blankophor P167 increased virus-induced mortality. The effects of both materials did not differ between transgenic and nontransgenic corn. The greatest increase in virus-induced mortality occurred when Coax and Blankophor P167 were combined. Neither material affected the percentage of larvae killed by the CryIA(b) toxin.