Ground beetles as predators of oilseed rape pests: Incidence, spatio-temporal distributions and feeding

Abstract

Ground beetles or carabids are amongst the most abundant invertebrate predators in fields of oilseed rape in Europe. The immature stages of the six major pests of oilseed rape i.e., cabbage stem flea beetle, pollen beetle, cabbage seed weevil, cabbage stem weevil, rape stem weevil and brassica pod midge, are vulnerable to predation by carabids when they are in or on the soil from mid-September to mid-July. About 42 species of carabid are common in rape fields. The community composition varies between countries, between spring and winter crops and with crop management, as species differ in distribution and habitat requirements. The ten most widespread and dominant species are A. similata, Anchomenus dorsalis, Bembidion lampros, Harpalus affinis, Harpalus rufipes, Loricera pilicornis, Nebria brevicollis, Poecilus cupreus, Pterostichus melanarius and Trechus quadristriatus. A field-scale study found within-field spatio-temporal coincidence of T. quadristriatus and Pterostichus madidus with cabbage stem flea beetle eggs, of A. similata, N. brevicollis and Asaphidion spp. with pollen beetle larvae, and of A. dorsalis with larvae of cabbage stem weevil, cabbage seed weevil and brassica pod midge. Carabid within-field distributions are influenced by their life cycles, habitat preferences, mobility and food availability. Evidence of predation from analysis of gut contents of field-collected individuals and laboratory feeding trials is reviewed in relation to carabid functional morphology, prey size and diel periodicity of activity. Feeding trials suggest that Clivina fossor also has potential as a predator of oilseed rape pests. The implications for biocontrol-based integrated pest management are discussed. © 2010 Springer Science+Business Media B.V.