Attraction of Trichogramma Wasps to Butterfly Oviposition-Induced Plant Volatiles Depends on Brassica Species, Wasp Strain and Leaf Necrosis

Within the Brassicaceae, wild as well crop species are challenged by specialist herbivores including cabbage white butterflies ( Pieris spp.). The crucifer Brassica nigra responds to oviposition synergistic expression of two egg-killing traits. Genotypes that express a hypersensitive response (HR)-like necrosis (direct egg-killing) also emit oviposition-induced plant volatiles (OIPVs) attracting Trichogramma egg parasitoids (indirect egg-killing). This so-called double defense line can result in high butterfly mortalities. It remains unknown whether this strategy is unique B. or more common species. To test this, we examined different evanescens lines OIPVs emitted and three close relatives napus, rapa , oleracea ). Furthermore, evaluated HR-like played role attraction toward volatiles. Our results show specificity wasp Three out four attracted specific T. strain, crops napus . Parasitoid was positively affected presence one findings imply that, despite being true generalist terms host range, shows intraspecific variation during searching, which should be taken into account when selecting parasitoid for biocontrol certain crops. Finally, conclude plants within Brassicaceae family possess traits exert double-defense may enable effective selection breeders.