Carabid beetles in sustainable agriculture: a review on pest control efficacy, cultivation impacts and enhancement

This review article on carabids in sustainable agro-ecosystems of the temperate Northern hemisphere presents a compilation of the available knowledge on the significance of carabids for natural pest control and the effects of cultivation methods (except pesticides) and landscape structural elements. Field carabids are species rich and abundant in arable sites, but are affected by intensive agricultural cultivation. For sampling, fenced pitfall trapping or pitfall trapping is recommended according to the type of study. Many of the assumed beneficial pest control activities of carabids are still based on laboratory feeding records. In the field, carabids have been demonstrated to reduce cereal and sugar beet aphid populations in their early colonization phase, mainly by foraging on aphids that have fallen from the vegetation. Egg predation on Dipteran eggs, e.g. the cabbage root fly, has been overestimated in earlier literature. Scattered data indicate carabidforaging on certain coleopteran pest larvae. In North America, some evidence has been found for control of pest lepidopterans. Larger carabids, e.g. Abax parallelepipedus, can effectively control slugs in greenhouses. Because of their spermophagous feeding habits, certain species of Harpalus and Amara could have some potential for biological weed control. As a result of their sensitive reaction to anthropogenic changes in habitat quality, carabids are considered of bioindicative value for cultivation impacts. Carabids seem to be negatively affected by deep ploughing and enhanced by reduced tillage systems. No negative effects have been found for mechanical weed control and flaming. Carabid recruitment is enhanced by proper organic fertilization and green manuring. Intensive nitrogen amendment might indirectly affect carabids by altering crop density and microclimate. Field carabid assemblages are not bound to a certain crop type, but shift in dominance according to the crop-specific rhythmicity of cultivation measures and changes in crop phenology and microclimate. Crop rotation effects could also be influenced by field-size dependent recolonization capability of carabids. They are enhanced by crop diversification in terms of monocrop heterogeneity and weediness as well as by intercropping and the presence of field boundaries, although corresponding increases in their pest reduction efficacy have not yet been evidenced.