Abstract: The major component of the sex pheromone of S. litura (F.) female, Z9, E11-14∶Ac(A), elicited all steps of the male behavioral sequence, i. e., searching for the odor, oriented upwind flight, approaching the source and displaying hairpencils. No males showed oriented flight when Z9, E12-14∶Ac (B), Z9-14∶Ac©, E11-14∶Ac (D) were assayed individually. Component B was able to enhance the activity of A, but larger amount of B in mixture strongly inhibited males from approaching the source and displaying hairpencils. The components of C and D had no effect on male behavior, but larger amount of C in a mixture of A and B inhibited males approaching the source and displaying hairpencils. There was a significant difference between the ratio of A to B in the filter paper lure and that in volatile from the filter paper lure. The ratio of A to B in volatile from the most effective lure in the wind tunnel was approximate to the natural ratio of A to B in the sex pheromone gland. In the field, the attractiveness of trap for male moths changed with the ratio of the components with most males being caught in traps baited with a ratio of 9∶1(A∶B). The attractiveness of traps with ratios of 1∶1(A∶B) was lower than the attractiveness of traps baited with single component A.

Key words: Spodoptera litura, sex pheromone, wind tunnel, field trapping test