Invasive alien predator causes rapid declines of native European ladybirds

Abstract

Aim Invasive alien species (IAS) are recognized as major drivers of biodiversity loss, but few causal relationships between IAS and species declines have been documented. In this study, we compare the distribution (Belgium and Britain) and abundance (Belgium, Britain and Switzerland) of formerly common and widespread native ladybirds before and after the arrival of Harmonia axyridis, a globally rapidly expanding IAS. Location EuropeMethods We used generalized linear mixed-effects models (GLMMs) to assess the distribution trends of eight conspicuous and historically widespread and common species of ladybird within Belgium and Britain before and after the arrival of H. axyridis. The distribution data were collated largely through public participatory surveys but verified by a recognized expert. We also used GLMMs to model trends in the abundance of ladybirds using data collated through systematic surveys of deciduous trees in Belgium, Britain and Switzerland.Results Five (Belgium) and seven (Britain) of eight species studied show substantial declines attributable to the arrival of H. axyridis. Indeed, the two-spot ladybird, Adalia bipunctata, declined by 30% (Belgium) and 44% (Britain) over 5 years after the arrival of H. axyridis. Trends in ladybird abundance revealed similar patterns of declines across three countries.Main conclusion Together, these analyses show H. axyridis to be displacing native ladybirds with high niche overlap, probably through predation and competition. This finding provides strong evidence of a causal link between the arrival of an IAS and decline in native biodiversity. Rapid biotic homogenization at the continental scale could impact on the resilience of ecosystems and severely diminish the services they deliver.

The harlequin ladybird, Harmonia axyridis: global perspectives on invasion history and ecology

“…As a consequence 294 of the invasion, systematic surveying was set up in Brussels using standardized beating of trees in 295 parks, avenues and roadsides. With the exception of C. quatuordecimguttata, these abundance data 296 reflected the reported large scale trends (Roy et al 2012b). Adalia bipunctata exhibited a 57% 297 decline in its extent of occurrence in the last decade and according to a conservative application of 298 the IUCN guidelines has now become a good example of species that was formerly widespread but 299 now meets the criteria of a red list species (Adriaens et al 2015).…”

“…Also in the USA, Michaud (2002) reported H. axyridis to be displacing Cycloneda sanguinea 269 (L.) in Florida citrus orchards. In the United Kingdom (UK) there is a strong correlation between the 270 declines of seven out of eight native species of ladybird assessed and co-occurrence with H. axyridis 271 (Roy et al 2012b). In Chilean alfalfa fields the abundance of native ladybird species declined after H. Switzerland, on-going long-term population studies have highlighted that, so far, only A. bipunctata 284 has significantly declined since the arrival of H. axyridis (Kenis and Eschen, unpublished data) 285 although risk assessments (Kenis et al 2010) predicted that three other ladybirds sharing the same 286 ecological niches with H. axyridis (A. decempunctata, Oenopia conglobata (L.) and C. decemguttata) 287 were at risk.…”

Characterization of a newly established aggregation of the invasive ladybeetle Harmonia axyridis and current status of the invader in Spain

“…The arrival of H. axyridis is associated to drastic changes in coccinellid assemblages all around the word (Colunga-Garcia & Gage, 1998;Michaud, 2002;Lucas et al, 2007a,b;Pell et al, 2008;Bélanger & Lucas, 2011;Roy et al, 2012). Catalonia has a diverse agriculture dominated by winter cereals, maize, alfalfa, vegetables in open air and greenhouse, fruit orchards and vineyards.…”

Advancing impact prediction and hypothesis testing in invasion ecology using a comparative functional response approach

“…However, we require forecasting methods that can be applied to new and emerging invaders, for example, where a new species has just arrived or is known to be spreading, or indeed potential new invasive species from known donor region 'hotspots' such as the Ponto-Caspian region (Ricciardi and MacIsaac 2000). Invasive species are characteristically more able to rapidly and efficiently utilise resources than native species (Vitousek 1990;Strayer et al 1999;Byers et al 2002;Funk and Vitousek 2007;Johnson et al 2008;Weis 2010;Morrison and Hay 2011;Chapple et al 2012) and thus resources, such as native prey species, are vulnerable to potentially severe declines or extinctions (Clavero and Garcia-Berthou 2005;Snyder and Evans 2006;Salo et al 2007;Cucherousset and Olden 2011;Roy et al 2012). Indeed, difference in resource use is a major tenet of 28 of 29 invasion hypotheses identified by Catford et al (2009).…”