Geographical Variation in the Pheromonal Response of Fall Army Worm Spodoptera frugiperda (J E Smith)

Gas chromatogram analysis of Spodoptera frugiperda female gland extracts identified three pheromone compounds: (Z)-9-tetradecenylacetate (Z-9-14-OAc), (Z)-7-dodecenyl acetate (Z-7-12-OAc), and (Z)-11-hexadecenyl acetate (Z-11-16-OAc). Based on these findings, six pheromone blends were formulated and tested using electroantennography (EAG) across different geographic populations.The Karnataka population exhibited maximum EAG response to a binary blend of Z-9–14-OAc and Z-7–12-OAc (98:2), while Gujarat and Tamil Nadu populations responded optimally to a ternary blend of Z-9–14, Z-11–16-OAc, and Z-7–12-OAc (87:12.5:0.5). The Karnataka population demonstrated substantial EAG response even in the absence of Z-11–16-OAc. Increasing the concentration of Z7–12: OAc resulted in progressively diminished male antennal response across all populations. These findings highlight the importance of geographic variation in pheromone perception and provide critical insights for developing region-specific monitoring and management strategies for this economically significant pest in India.