Artificial light at night (ALAN) and the broader use of artificial light in agriculture are increasingly recognized to affect the physiology and behavior of nocturnal insects, yet their influence on pheromone-mediated reproductive communication in economically important insect pest species remains poorly understood. Here, we investigated the effects of artificial illumination on calling behavior, sex pheromone production, blend composition, and mating success in the fall armyworm Spodoptera frugiperda, under both laboratory and semi-field conditions. Virgin females were exposed during the scotophase to one of four wavelength-specific treatments, including dark control, red (620 nm), green (520 nm), or blue (460 nm) LED light. Female calling behavior occurred during the early-to-mid scotophase under dark and red light conditions, while it was significantly delayed and suppressed under blue and green light. Specifically, blue light suppressed production of the key pheromone component (Z)-9-tetradecenyl acetate (Z9-14:Ac) and enhanced (Z)-11-hexadecenyl acetate (Z11-16:Ac), altering the species-specific pheromone blend composition. Mating success was significantly reduced under blue light in both laboratory and semi-field experiments. Under controlled laboratory conditions, green light also affected mating success, but this effect was not significant in the semi-field experiment. Blue light imposed the strongest inhibitory effect, reducing mating success by 39% relative to the dark condition. Red light produced minimal effects in all measured parameters, consistent with reduced sensitivity to longer wavelengths in nocturnal moths. These results demonstrate that wavelength-specific artificial light can disrupt several components of the reproductive communication system in S. frugiperda and suggest that manipulation of artificial light may offer a non-chemical approach for disrupting mating behavior in economically important insect pest species within integrated pest management programs.
