Evaluation of Brassicaceae seedlings as trap plants for Bagrada hilaris Burmeister in Caper bush cultivations

The caper bush, Capparis spinosa (Brassicales: Capparaceae), is intensively grown on Pantelleria Island (Trapani, Sicily, Sicilian channel) where it has been granted protected geographical indication (PGI) by the EU. On this island, Bagrada hilaris, a stink bug native of Asia and Africa, is the major pest of caper crops. Recent studies have shown the attraction of B. hilaris to volatiles of brassicaceous plants at the seedling stage. The objective of this study was to evaluate three cotyledon-stage seedlings of host plants, Brassica oleracea var. botrytis (cauliflower), Eruca sativa (rocket) and Brassica carinata (Abyssinian cabbage), as potential trap plants for B. hilaris. The relative preferences of these species were first evaluated in laboratory and field experiments, carried out during summer when the level of B. hilaris infestation was the highest. Behavioral bioassays in the laboratory conditions showed that adults of B. hilaris preferred to orient toward seedlings of B. oleracea and E. sativa over B. carinata. Field experiments confirmed these results. Then seedlings were tested in trap plant trials, by sowing them in artificial pots formed with aluminum trays and placing them in caper fields infested with B. hilaris. Results showed that E. sativa and B. oleracea diverted hundreds of B. hilaris individuals from the capers to these sources of attraction. Overall, these results suggest that B. oleracea and E. sativa seedlings used as lure inside traps or as trap plants may be a useful tool in the management of B. hilaris populations.