Intercropping mitigates incidence of the oilseed rape insect pest complex

Oilseed rape (OSR, Brassica napus) is a major crop requiring numerous phytosanitary treatments. It is of paramount importance to find sustainable insect pest management to guarantee long term OSR availability. Therefore, we aimed to evaluate the effect of OSR intercropping with faba beans (FB, Vicia faba) on the OSR insect pest complex. In addition, we aimed to understand the underlying mechanisms of crop protection via intercropping by distinguishing between the effects of visual and physical disruptions caused by companion plants and those of olfactory disruptions in host location and selection, and to evaluate whether this effect is direct or indirect. In a field trial run over 2 years, OSR was grown either as a monocrop or intercropped with winter FB (WFB, frost-resistant), spring FB (SFB, frost-sensitive), or polyethylene artificial plants (ART) designed to mimic FB.

Compared to the monocropped OSR the OSR + FB intercropping systems significantly reduced the feeding damage caused by cabbage flea beetles (Phyllotreta spp.), the immigration of adult cabbage stem flea beetles (Psylliodes chrysocephala), the number of rape stem weevil (Ceutorhynchus napi) oviposition punctures on stems and the number of pollen beetle (Brassicogethes aeneus) per inflorescence. The intercropping with SFB had a stronger impact on C. napi and B. aeneus than intercropping with WFB. Compared to the monocropped OSR the ART treatment significantly reduced Phyllotreta spp. damage on leaves, C. napi oviposition punctures and the number of B. aeneus. The yield of OSR intercropped with SFB was higher than monocropped OSR, while the other treatments did not affect yield.

This study shows that intercropping reduces the incidence of the OSR insect pest complex. Mechanisms of action include the direct visual and physical disruption provided by the companion plants. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.