Attractiveness of tobacco volatiles induced by Helicoverpa armigera and Helicoverpa assulta to Campoletis chlorideae

The attraction of Helicoverpa armigera- and Helicoverpa assulta-induced and mechanical damage-induced tobacco volatiles to Campoletis chlorideae was investigated, and the induced volatiles were analyzed. In windtunnel, C. Chlorideae was strongly attracted by herbivoreinduced tobacco volatiles. Mechanically damaged tobacco leaves, whether treated with caterpillar regurgitant or water, were more attractive to the parasitoid than undamaged tobacco leaves. GC-MS analysis revealed that only 4 compounds were released from undamaged tobacco leaves, whereas 13 compounds were commonly emitted from herbivore-infested and mechanically damaged tobacco leaves. Compound β-pinene was specifically induced by the infestation of H. Armigera, and (Z)-3-hexenal was only induced by the infestation of H. Armigera and H. Assulta, whereas hexyl acetate was only induced by mechanical damage. Tobacco leaves infested by H. Armigera and H. Assulta released larger amounts of volatiles than undamaged tobacco leaves did. Tobacco leaves treated with artificial damage plus caterpil- lars regurgitant or water emitted the same levels of volatiles, which were higher than that emitted by undamaged tobacco leaves. The emission amounts of single compounds were also different between differently treated plants. The differences were large between herbivore-induced and mechanical damage-induced compounds, and small between H. Armigera- and H. Assulta-induced compounds, and among compounds emitted from mechanically damaged plants treated with water or caterpillar regurgitant.