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

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

Interactions between the fungal pathogen Beauveria bassiana and three species of ladybird: Harmonia axyridis, Coccinella septempunctata and Adalia bipunctata.

Harmonia axyridis is a predatory coccinellid, native to central and eastern Asia. It has been available in many countries for use as a biological control agent of pest aphids and scale insects. In many of these countries, including the USA, H. axyridis has established. It is now considered an invasive alien species for a number of reasons, including its impact on functional biodiversity. Beauveria bassiana is known to be a natural mortality agent of overwintering coccinellids and is a potential candidate for the biological control of H. axyridis. In this paper we compare the susceptibility of three species of coccinellid, H. axyridis (cultures derived from Japan and Britain), Coccinella septempunctata and Adalia bipunctata to infection by B. bassiana (commercial strain GHA) after exposure at three doses (105, 107, 109 conidia ml–1). The two subpopulations of H. axyridis (Japanese and British) were more resistant to B. bassiana infection than either A. bipunctata or C. septempunctata. This is exemplified by the median lethal doses at 10 days post-inoculation (LD50) of 106.2, 106.0, 108.3, 109.6 conidia ml–1 for A. bipunctata, C. septempunctata, H. axyridis (Japanese) and H. axyridis (British), respectively. Only doses of 109 conidia ml–1 resulted in mortality of H. axyridis, in contrast, 80% of C. septempunctata and 70% of A. bipunctata exposed to 107 conidia ml–1 of B. bassiana succumbed to infection. The fecundity (cumulative mean egg production over 10 days) of A. bipunctata and H. axyridis (UK) was also assessed. The fecundity of C. septempunctata could not be assessed because this species requires diapause prior to the onset of reproduction and these studies were on beetles that had recently eclosed (2–8 weeks). Harmonia axyridis (Japan) produced no eggs in most treatments including the control and so was excluded from analysis. High dose (109 conidia ml–1) inoculation reduced the fecundity of A. bipunctata to zero but egg production was similar for individuals inoculated with doses of 105, 107 conidia ml–1 and control individuals. In contrast, all doses of B. basssiana reduced H. axyridis (UK) egg production dramatically. We discuss these results in relation to the potential for control of H. axyridis using B. bassiana

Harmonia axyridis in Great Britain: analysis of the spread and distribution of a non-native coccinellid

Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is native to Asia, and was widely introduced as a biocontrol agent of aphids and coccids in Europe and North America. In Europe H. axyridis is considered to be an invasive alien species. Although not known to have been deliberately introduced to Great Britain, it was first recorded there in 2004, in south-east England. Harmonia axyridis arrived in Great Britain by various means, primarily from mainland Europe, but also from Canada. Extensive national and local media coverage, and a dedicated website (http://www.harlequin-survey.org), facilitated public involvement in recording H. axyridis in Great Britain; in excess of 4,000 verified records of the species were received between 2004 and 2006. Through detailed mapping, the objective of our study was to quantify and analyse the spread of H. axyridis in its early stages of invasion in Great Britain. Our data shows that between 2004 and 2006, the species spread north through Great Britain at the rate of 58 km year-1 and west at the rate of 144.5 km year-1. In England H. axyridis spread north to Yorkshire and west to Cornwall by the end of 2006, and also reached Wales. Recorded occurrence (of one or more H. axyridis individuals at larval, pupal and/or adult stage) in 10 km squares in Great Britain was: 2004—51; 2005—149; 2006—447. Records of juvenile H. axyridis extend through most of the recorded British range of the species, and we present evidence of bi-voltinism in the population in 2006

Intraguild predation involving Harmonia axyridis: a review of current knowledge and future perspectives.

As an effective generalist predator of aphids and other hemipteran pests H. axyridis has been a successful biological control agent. However, the very functional traits that have contributed to its success in this regard also implicate it as an intraguild predator that poses a significant risk not only to the diversity of other natural enemies of Hemiptera (and their associated ecosystem services), but to biodiversity more widely. In this paper we will specifically review the existing data on intraguild predation involving H. axyridis, and consider the strength and symmetry of such interactions both within its native guild and within exotic guilds where it has established as an invasive alien. We will use these studies to interpret the observed population declines in predator diversity in the field, predict species at risk in regions not yet invaded and consider implications for resulting ecosystem services. We will also indicate gaps in our knowledge that require further study in order to identify opportunities for mitigation

Alien arthropod predators and parasitoids: an ecological approach

Invasive alien species (IAS) coupled with climate change have been referred to as a “deadly duo”. Until recently research on invasion biology has centred mainly on alien plants and vertebrates, despite the numerical dominance of alien arthropods. Arthropods are the largest group of IAS worldwide and many can play a beneficial role, particularly in controlling insect and mite pests. Indeed, 1590 terrestrial arthropod species have been identified as alien to Europe but only a fraction has been shown to cause either an ecological or economical impact, yet knowledge is severely limited by a paucity of data. The IOBC/WPRS Working Group “Benefits and Risks of Exotic Biological Control Agents” developed the theme of this special issue to begin to address the limitations in understanding of this important research area. It represents a timely synthesis of current ecological knowledge and research on alien arthropod predators and parasitoids

Genome-wide association analyses of risk tolerance and risky behaviors in over 1 million individuals identify hundreds of loci and shared genetic influences

Humans vary substantially in their willingness to take risks. In a combined sample of over 1 million individuals, we conducted genome-wide association studies (GWAS) of general risk tolerance, adventurousness, and risky behaviors in the driving, drinking, smoking, and sexual domains. Across all GWAS, we identified hundreds of associated loci, including 99 loci associated with general risk tolerance. We report evidence of substantial shared genetic influences across risk tolerance and the risky behaviors: 46 of the 99 general risk tolerance loci contain a lead SNP for at least one of our other GWAS, and general risk tolerance is genetically correlated (|r^g| ~ 0.25 to 0.50) with a range of risky behaviors. Bioinformatics analyses imply that genes near SNPs associated with general risk tolerance are highly expressed in brain tissues and point to a role for glutamatergic and GABAergic neurotransmission. We found no evidence of enrichment for genes previously hypothesized to relate to risk tolerance