Chemical and behavioral evidence for a third pheromone component in a North American population of the black cutworm moth, Agrotis ipsilon

The sex pheromone of Agrotis ipsilon had been previously identified as a blend of (Z)-7-dodecenyl acetate (Z7-12:Ac) and (Z)-9-tetradecenyl acetate (Z9-14: Ac). A synthetic blend of Z7-12: Ac and Z9-14: Ac (30 μg: 10 μg) is effective in attracting males in the field. In several countries, addition of (Z)-11-hexadecenyl acetate (Z11-16:Ac) to the previously identified blend increases male captures, but this had not been demonstrated in North America. We found Z11-16:Ac, in addition to Z7-12:Ac and Z9-14:Ac, from pheromone gland extracts of females from North America. The mean ratio of Z7-12:Ac, Z9-14:Ac, and Z11-16:Ac produced by individual females was 70.5:14.2:15.3, respectively. In Kentucky, addition of Z11-16: Ac (60 μg) to a two-component blend o f Z7- 12: Ac and Z9-14: Ac significantly increased the trap capture rate in the field. Traps baited with this three-component blend were 3.3 times (1995) and 4.6 times (1996) more effective in capturing male A. ipsilon than the two-component blend. This improved effectiveness resulted in detection of A. ipsilon in 60% more of the sampling periods in the two years. In the wind tunnel, males flew upwind and contacted a rubber septum loaded with a three-component blend including Z11-16: Ac significantly more frequently than they did to any two-component blend. These results demonstrate that Z11-16:Ac is a pheromone component in this North American population of A. ipsilon.