Response of Spodoptera frugiperda Adults to Urochloa mutica leaf extracts: Evidence from Y-Tube olfactometer bioassays

Abstract

The fall armyworm (Spodoptera frugiperda) relies heavily on plant volatile compounds for host detection and resource location. This study evaluated the olfactory-mediated behavioral responses of male and female adults to leaf extracts of Urochloa mutica. Extracts were prepared using methanol and n-hexane at a concentration of 2% and tested in a Y-tube olfactometer bioassay with 10 independent replicates per sex for each solvent treatment. Behavioral parameters measured included visit duration, visit frequency, and proportional movement distribution over time. Visit duration differed significantly between extract and solvent arms (p < 0.001). Under n-hexane extraction, females spent significantly longer durations in the extract arm (20 min 19 s), whereas males remained longer in the corresponding solvent control arm (17 min 37 s). Under methanol extraction, both sexes spent significantly longer durations in the extract arm. In contrast, visit frequency did not differ significantly between treatments (p > 0.05). Proportional movement patterns indicated solvent-dependent variation in temporal distribution between sexes. These findings indicate that U. mutica extracts influence behavioral retention rather than visit initiation in S. frugiperda under laboratory conditions. Further chemical characterization and field validation are required to assess the potential application of U. mutica-derived volatile compounds in sustainable pest management strategies.