Trap cropping: An agroecological approach to management of flea beetles on sugar beet

Two-year field experiments were carried out in four farms in Northern Italy with the aim of developing an agroecological approach to manage flea beetles, Chaetocnema tibialis (Illiger) and Phyllotreta spp. (Chevrolat) (Coleoptera: Chrysomelidae) on sugar beet by using trap crops. In each farm, two treatments were compared: i) trap crop, in which was a plot of sugar beet with an edge consisting of a mixture of Sinapis alba (L.) and Brassica juncea (L.); ii) control, which was a plot of sugar beet with bare soil at the field margin. An overall significant reduction (approximate to 40%) in flea beetle damage was detected on sugar beets grown nearby trap crops in comparison with control plots. Furthermore, in the trap crop treatment, flea beetle damage varied with the distance from the trap crop border, as the highest damage was detected at 2 m from the border, whereas lower damage was found at increasing distances from the trap crop. Trap cropping has potential as an ecological way to reduce early sugar beet damage and the need for insecticide applications.