Assessing the ecological risk posed by a recently established invasive alien predator: Harmonia axyridis as a case study

Invasive alien predators are a serious threat to biodiversity worldwide. However, there is no generic method for assessing which local species are most at risk following the invasion of a new predator. The harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is an alien in Europe and many other parts of the world where it affects other species of ladybirds through competition for food and intra-guild predation (IGP). Here, we describe a method developed to assess which European ladybird species are most at risk following the invasion of H. axyridis. The three components of the risk assessment are: the likelihood that the assessed native species encounters H. axyridis in the field, the hazard of competition for food, and the IGP hazard. Thirty native European ladybird species were assessed through data obtained from field observations, laboratory experiments and literature reviews. The species that are considered most at risk are found on deciduous trees, have immature stages which are highly vulnerable to IGP by H. axyridis, and are primarily aphidophagous. These species should be the focus of specific studies and possibly conservation actions. The risk assessment method proposed here could be applied to other alien predators which are considered a threat to native species through competition and predation

Encounters with an alien: a European perspective

The harlequin ladybird, Harmonia axyridis, was introduced into continental Europe in the 1980s as a classical biological agent of scale insects and aphids. It was never intentionally introduced into Britain, but arrived in the southeastern county of Essex in 2004. The spread of this non-native species across Britain has been spectacular; approximately 100 km per year. The harlequin ladybird is particularly abundant in the southeast of England, but there are many records from central and northern England, Wales and also a few records from Scotland, as far north as Orkney. The UK Ladybird Survey has been monitoring H. axyridis since it arrived in Britain through an online public participation survey: www.ladybird-survey.org. The survey has received more than 30,000 records of this species, and particularly notable are the very large numbers of the beetle which are commonly reported in the autumn each year, when this species enters buildings to locate suitable overwintering sites. The autumn of 2009 is no exception; the survey received approximately 800 records a week during October. The pattern of rapid spread and high abundance of H. axyridis has also been documented across northern and central Europe. Harmonia axyridis has been recorded as established in (order relates to approximate time of establishment): France (first report), Germany, Belgium, Netherlands, Switzerland, Luxembourg, England, Czech Republic, Italy, Austria, Denmark, Norway, Poland, Wales, Liechtenstein, Scotland, Hungary, Slovakia and Bulgaria (last report). Interestingly this species is not so successful in southern European countries

Effects of competition, cannibalism and intra-guild predation on larval development of the European coccinellid Adalia bipunctata and the invasive species Harmonia axyridis

International audience1. Resource competition and intra-guild predation (IGP) are important determinants of the structure of aphidophagous guilds. The likelihood and outcome of IGP is influenced by the density of extra-guild prey and the characteristics of the species involved. 2. The nature of intra-guild interactions between alien and indigenous coccinellids often determines the success of coccinellid invasions, as exemplified by Adalia bipunctata in Japan and Harmonia axyridis in North America and Europe. 3. Harmonia axyridis has negatively impinged on indigenous species in its introduced range, and its recent arrival in Britain poses a threat for members of native aphidophagous guilds. IGP and inter-specific competition between H. axyridis and British coccinellids are predicted to occur. However, the results of such interactions have been little studied. 4. Here we investigate the effects of different diets, designed to mimic possible conditions in the wild, on the survival, development, and adult size of H. axyridis and A. bipunctata . Results demonstrate a skew in the consequences of IGP between the two species: the supplementation of a limited aphid diet with non-conspecific eggs leads to a significant advantage for H. axyridis in respect of all parameters assessed, but gives no benefit to A. bipunctata. 5. We conclude that IGP of A. bipunctata by H. axyridis will contribute to the spread and increase of H. axyridis in Britain. 6. We further conclude that the skewed nature of IGP between A. bipunctata and H. axyridis at least in part explains the limited spread of A. bipunctata in Japan

UK Ladybird Survey Report

There is no doubt that recent times have been eventful for ladybirds (coccinellids). In particular the arrival of the Harlequin Harmonia axyridis (new to Britain in 2004), seen as a major threat to native ladybirds, prompted the development of two on-line recording schemes (www.ladybird-survey.org and www.harlequin-survey.org). The response to the surveys has been fantastic; we have received over 70,000 records in the last three years. We are very pleased to have the opportunity of contributing an annual column to British Wildlife, specifically on ladybirds, during these times of dramatic environmental change

Distribution and identification of the harlequin ladybird Harmonia axyridis

Britain has a new ladybird species—and it is distinctly unwelcome. The Harlequin Ladybird Harmonia axyridis arrived from mainland Europe in 2004 and has rapidly established itself over large parts of south-east England. It is an invasive species, native to Asia where its range includes China, Japan, Korea and Siberia. Other recent ladybird arrivals, such as the Bryony Ladybird Epilachna argus, have largely been welcomed as an interesting and unobtrusive addition to our native fauna. This does not apply to the Harlequin, which poses a major ecological threat to native ladybird species and some other insect groups

Looking beyond the spots: inspiring the public to record ladybirds

The Coccinellidae Recording Scheme, the UK’s scheme for mapping coccinellid distributions, was launched in 1968 and was led by Michael Majerus from the 1980s. In the early years participants tended to be experienced naturalists, so to draw others in, Mike set up a very successful offshoot, the Cambridge Ladybird Survey (CLS), a public outreach survey that ran from 1984 to 1994. The CLS generated a huge amount of data and made a significant contribution to Mike’s New Naturalist ‘Ladybirds’ book (1994). When Harmonia axyridis arrived in the UK in late 2004, Mike realised the potential for involving the public in a unique opportunity to study the spread of an invasive animal from the start of the invasion process. Thus the Harlequin Ladybird Survey was launched in early 2005 as one of the first online wildlife surveys in the UK. Over 26,000 online records have been received, enabling a study of unprecedented detail. Mike was very adept at using the media to convey his message. His expertise extended to the Lepidoptera (including evolutionary studies of the peppered moth Biston betularia) and presidency of the Amateur Entomologists' Society, enabling further outreach opportunities

Chemical protection of Calvia quatuordecimguttata eggs against intraguild predation by the invasive ladybird Harmonia axyridis

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