A list of alien ladybird (Coleoptera: Coccinellidae) species to Europe was prepared and the history and circumstances of their introductions were determined. Currently there are 12 alien ladybird species in Europe, originating from Australian, Oriental, Nearctic, Palearctic and Afrotropical regions. All of the species were intentionally released as biological control agents and most are coccidophagous species. The aphidophagous Harmonia axyridis is the only ladybird regarded as invasive in Europe. The main factors leading to successful establishment were food relationship, living in different habitats in different geographical regions and geographic origin. We found that successful invaders, in their native areas, showed adaptability to a wide range of conditions compared to non-invasive species. Larger aphidophagous alien ladybirds were found to develop as fast as native species. Characteristics that did not differ between native and alien species are thermal requirements for development, fecundity and body size. However, unlike other alien ladybirds, H. axyridis had higher potential dispersal ability.Keywords: biological invasion, Europe, fecundity, invasiveness, ladybirds, rate of spread, thermal requirements
INTRODUCTIONMost species of ladybirds (Coleoptera: Coccinellidae) are carnivorous predators that feed on a variety of phytophagous arthropods including aphids, coccids and mites (Giorgi et al., 2009;Weber and Lundgren, 2009) and therefore render important services to agricultural and forest ecosystems through biological control of those pests. As such, non-native coccinellid species have been introduced around the world. Biological control using coccinellids started in the late 1800s with the successful introduction of Rodolia cardinalis Mulsant from Australia to control populations of the coccid Icerya purchasi Maskell infesting citrus orchards in California. Since then, several other ladybird species have been introduced to new regions for classical biological Soares et al.
Successful Establishment of Alien Ladybirdcontrol (Roy and Migeon, 2010). The objective of the imports and releases was the establishment of self-perpetuating populations in order to exert natural control over specific pests (Michaud, 2012). Besides the benefits, this process also bears risks, including the spread and establishment of ladybirds in new geographic ranges. The monetary costs of managing alien species once established are often very high. The environmental costs (e.g., effects of an alien biological control agent on species other than the pest species) may also be high (van Lenteren et al., 2008). Thus preventing invasion in the first place is highly desirable, and in order to do this, knowledge of the pathways of invasion are needed (Hulme, 2015).Whilst there have been numerous intentional coccinellid introductions since the end of the nineteenth century (Hokkanen and Sailer, 1985), the negative impacts were only recently acknowledged (van Lenteren et al., 2003(van Lenteren et al., , 2006. The need for intensive study ...