Flea beetle movement in a broccoli monoculture and diculture

Colonization of Brassica oleracea monocultures and broccoli-white clover Trifolium repens dicultures by Phyllotreta cruciferae (Coleoptera: Chrysomelidae) was observed at Ithaca, New York. A simple continuous time model of P. cruciferae movement was developed, and instantaneous immigration and emigration rates were estimated. Immigration was 1.3 times faster into monocultures than into dicultures, and emigration was c2 times faster from dicultures. This differential movement resulted both from differences in host plant quality and presence or absence of white clover. Results provide strong, direct support for the hypothesis that host plants are harder to find and easier to lose in vegetationally diverse habitats than in monocultures. After perturbation, population densities rapidly returned to unperturbed levels. This implies that P. cruciferae can rapidly respond to changes in its environment, which might underlie its success as a crop pest. -from Authors