Biodiversity of predaceous coccinellidae in relation to bioindication and economic importance

Their pioneering role in the development of biological pest control has rendered the Coccinellidae of great practical and scientific interest. About 90% of the approximately 4200 coccinellid species are considered beneficial because of their predatory activity, mainly against Homopterous insects and mites. Coccinellids live in all terrestrial ecosystems: tundra, forest, grassland, agrosystems, and from the plains to mountains. Knowledge of coccinellid life history requires investigation of their bio-ecology. Being holometabolous insects, coccinellids present all types of voltinism. They reproduce in different habitats and show a wide range of behaviours, from stenotropism to eurotropism. In spite of their polyphagy, adults tend to prefer certain types of food (or essential prey), which are eaten voraciously. Many aphidophagous and monovoltine coccinellid species migrate in response to unfavourable environmental conditions; however, in most cases adults endure hostile environmental changes by entering a temporary dormant state, i.e., hibernation, aestivation or aestivo-hibernation. Despite these adaptive behaviours, the coccinellids are very vulnerable to several limiting factors, including natural enemies and anthropological influences. Therefore, many precautions must be taken throughout the year to protect them. Seasonal changes influence the occurrence of aphid outbreaks, the type of plant infested and the behaviour of coccinellids. Reciprocally, the species found in different geographic zones can be recruited as bioindicator insects owing to their climatic and trophic characteristics. In the context of biological control, the coccinellids represent an important cause of mortality of coccids, aphids and mites. The peculiar aggregation behaviour of coccinellids remains to be exploited for acclimatization of a new species in a new country. Their migratory abilities pose challenges and opportunities for the development of effective biological control programs against aphids. Future research on the genetics, physiology and behaviour of coccinellids combined with studies of their flight aerodynamics and interactions with agricultural ecosystems will undoubtedly lead to improvements in coccinellid-based aphid control programs.