S14 - Session P1- French marigold as a companion plant to control aphids and aphid-borne viruses in pepper crops: service or disservice?

Authors: Alexandra Schoeny *, Guillaume Serra, Mathilde Veis-Barcelli, Grégory Girardot, Laurent Gomez, Hélène Gautier

Aphids and aphid-borne viruses can cause severe economic damage to open field vegetable crops. In conventional croppping systems, synthetic insecticides are often the first option for controlling aphids but their efficiency is challenged by resistant clones, their usage is questioned by environmental and health preoccupations and their relevance is poor to limit non-persistently transmitted viruses where acquisition and inoculation occur in a matter of seconds. Alternative options are thus necessary. Among the numerous agroecological practices that could be implemented, increasing attention is given to companion plants (CP) emitting volatile organic compounds (VOCs) repellent and/or disruptive to pest establishment. French marigold ( Tagetes patula ) is frequently cited and seems to be a promising candidate to control the green peach aphid, Myzus persicae . A study was run under laboratory conditions to evaluate the effects of T. patula on the feeding behavior and fertility of M. persicae on two cultivars of pepper. Experiments were conducted with healthy plants and plants infected by two viruses (PVY and PeVYV) in order to assess the potential benefit (biological regulation service) but also the potential disservice linked with an increased risk of virus transmission.