Trap Crops and Insectary Plants in the Order Brassicales

This paper reviews the most important cases of trap crops and insectary plants in the order Brassicales. Most trap crops in the order Brassicales target insects that are specialist in plants belonging to this order, such as the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), the pollen beetle, Meligethes aeneus Fabricius (Coleoptera: Nitidulidae), and flea beetles in the genera Phyllotreta and Psylliodes (Coleoptera: Chrysomelidae). In most cases, the mode of action of these trap crops is the preferential attraction of the insect pest for the trap crop located next to the main crop. With one exception, these trap crops in the order Brassicales have been used with brassicaceous crops. Insectary plants in the order Brassicales attract a wide variety of natural enemies, but most studies focus on their effect on aphidofagous hoverflies and parasitoids. The parasitoids benefiting from insectary plants in the order Brassicales target insects pests ranging from specialists, such as P. xylostella, to highly polyfagous, such as the stink bugs Euschistus conspersus Uhler and Thyanta pallidovirens Stal (Hemiptera: Pentatomidae). In the order Brassicales, the three most common trap crops are Indian mustard, Brassica juncea (L.) Czern, Chinese cabbage, Brassica rapa L., and yellow rocket, Barbarea vulgaris R. Br., while the three most common insectary plants are sweet alyssum, Lobularia maritima (L.) Desv., white mustard, Sinapis alba L, and B. vulgaris. Except for Tropaeolum majus L. (Tropaeolaceae) and Capparis decidua (Forssk.) Edgew. (Capparaceae), the tested trap crops and insectary plants in the order Brassicales belong to the family Brassicaceae.