Influence of neighbouring companion plants on the performance of aphid populations on sweet pepper plants under greenhouse conditions

1 Companion plants (CPs) may affect the performance of pests on their hosts because of their potential to emit volatile organic compounds (VOCs) and their effectiveness depends not only on the species, but also on their arrangement in the crop system. 2 The present study aimed to evaluate the effect of intercropping rosemary, lavender or basil on the performance of Myzus persicae populations on sweet pepper plants (Capsicum annum) under greenhouse conditions. 3 In a first set of experiments, sweet pepper plants were neighboured by either one or two CPs. In another set of experiments, rosemary was tested at three distances (0.5, 1.5 and 2.5 m) from the host plant. 4 The first set of experiments showed similar patterns of aphid performance (i.e. number of females and nymphs) when a sweet pepper plant was surrounded by one or two companion plants. However, aphid performance was affected more when sweet pepper plants were intercropped with rosemary compared with lavender or basil. 5 The effect of the companion plant decreased significantly with distance. Rosemary was most effective at 0.5 m, although its effectiveness decreased at 1.5 m, becoming insignificant at 2.5 m. 6 The results suggest that a CP may be effective under greenhouse conditions provided that it is located near the target plant.