Abstract: Intercropping companion plants (CPs) with horticultural crops could be a method to optimize pest management. It is known that volatile organic compounds (VOCs) emitted by CP can reduce aphid infestation. The aim of this study was to evaluate the effects of VOCs emitted by French marigold (Tagetes patula L. cv. Nana) on the performance of green peach aphid (Myzus persicae) and to understand the mechanism involved: either direct VOCs effects on aphid and/or indirect effects via the host-plant (pepper, Capsicum annuum L.). Laboratory experiments tested the effect of T. patula VOCs on the fecundity and orientation behavior (using a Y-tube olfactometer) of M. persicae. VOCs emitted by T. patula were collected and identified by GC-MS. Flower VOCs (but not the leaf VOCs) significantly reduced aphid reproduction. This difference in VOCs emission depending on the plant part underlines the necessity to consider the phenological stages for evaluating the CP potential. The olfactory tests showed that T. patula VOCs had no significant effect on aphid orientation behavior. Otherwise, aphids were significantly less attracted by pepper associated with T. patula and also by pepper previously intercropped (PIC) with T. patula. This supports the hypothesis of an indirect effect of T. patula VOCs on aphid performance.