Because of their services to agriculture most ladybirds (Coleoptera: Coccinellidae) are intensively studied predators of mainly phytophagous pests. The study of the long-term variation in the composition of their communities was stimulated by recent dramatic changes in the abundance of some species. We review and evaluate possible effects of the main causes cited in the literature. Agricultural and habitat changes (particularly urbanization) affect coccinellid abundance, both negatively and positively. In the temperate zone dominant species occur most frequently associated with abundant prey populations on crops, weeds and planted stands of trees resulting from human activity. Invasive non-native species of coccinellids may endanger native species through intraguild predation or competition for resources, but their supposed serious negative effects on native species can differ considerably. Climatic change may influence coccinellid species in several ways, including indirect effects through lower trophic levels and desynchronisation of the phenologies of host plants, prey and coccinellid populations. In the near future we do not expect climate warming to have important effects on ladybird diversity globally, but local changes in the composition of coccinellid communities and abundance of particular species could occur.

Center for Ecology Evolution and Environmental Changes and Azorean Biodiversity Group Department of Biology University of the Azores 9501 801 Ponta Delgada Portugal

CzechGlobe Global Change Research Institute of the Czech Academy of Sciences Belidla 986 4a 60300 Brno Czech Republic

Group Function of Invertebrate and Plant Biodiversity in Agro ecosystems Crop Research Institute 16106 Prague 6 Ruzyně Czech Republic

References provided by Crossref.org