The Harlequin Ladybird Survey
Harlequin ladybird elytra
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Cathleen Thomas


PhD student


University of Hull

Ladybird research keywords

Evolutionary genetics, invasive species, harlequin ladybird.

Description of work

My project aims to understand why the harlequin ladybird (Harmonia axyridis) is such a successful invasive species. Biological invasions are one of the greatest threats to biodiversity, with important economical and ecological consequences, yet it is still not fully understood why only certain species become invasive, what factors determine their success or what impacts they have on the native species with which they interact. The harlequin ladybird is native to Asia, but since 1916 it has been extensively released into agricultural environments outside its native range for biological control, and is now invasive in North America, South America, Africa and Europe. It was first found in the UK in 2004, and is spreading rapidly with potentially devastating impacts.

It is vital to understand the species’ invasion history by identifying potential source population(s) and invasion routes. DNA from individuals collected in the species’ native range, invasive range and some biocontrol stocks is currently being sequenced at a mitochondrial locus, which will be analysed in a traditional phylogeographic format and using more quantitative approximate Bayesian computation methods (DIY ABC). The genetic composition of the founding population will also be assessed using microsatellite markers, as it is crucial in determining how a species will adapt to a novel environment and therefore its capacity for range expansion. It will then be possible to determine whether the invasion of the harlequin ladybird was characterised by high genetic diversity, or if there is evidence of a reduction in genetic diversity. These data can also be analysed in a landscape genetics framework to investigate how factors such as geo-climatic conditions and escape from natural enemies influence invasion success. Ultimately, this project should develop knowledge of the evolutionary processes underlying species invasions, and how genetic factors contribute to invasion success.

Key publications

Thomas, C. (2008). Wanted: Have you seen this ladybird? Friends of Thwaite Gardens Newsletter 22: 9-11.

Orange ladybird

Cathleen's favourite ladybird is the orange ladybird