Pieris rapae (Ledidoptera : Pieridae) females avoid oviposition on Rorippa indica plants infested by conspecific larvae

We studied oviposition preference of Pieris rapae females toward Rorippa indica plants exposed to different treatments (uninfested, artificially damaged and infested by P. rapae larvae)in a cage at an experimental field site. The females preferred uninfested plants to infested or artificially damaged ones and artificially damaged plants to infested ones. The data suggested that the females used chemicals emitted from damaged leaves to avoid unsuitable host plants. We conclude that the avoidance behavior of Pieris females towards infested food plants is adaptive for offspring from the viewpoint of not only resource availability but also parasitoid avoidance.