Effects of induced plant growth on the attraction of the parasitoid Cotesia glomerata

Abstract: To test the growth-defence trade-off in plants, we tested the attractiveness of growthinduced plants towards the parasitoid Cotesia glomerata. In this greenhouse study, Brassica nigra plants were grown under light with a low R:FR ratio to simulate plant-plant competition. These growth-induced plants were challenged with Pieris napi caterpillars to allow trapping of the herbivore induced plant volatiles (HIPVs). In addition, a wind tunnel experiment was conducted to see if growth-induced plants differ in their ability to attract the parasitoid Cotesia glomerata from standard-growth plants. We found that growth-induced plants produced a different blend of HIPVs, which lead to a lower attraction of C. glomerata, compared to standard-growth plants. This study gives more insight into the delicate balance between growth and defence in plants and can help to increase the efficiency of biocontrol through parasitoids in the greenhouse.