Recently, the Manchester Museum’s Entomology Department acquired some specimens of the Harlequin Ladybird, an invasive beetle species that appeared in Britain (Essex) in 2004 only, but is now a widespread and even dominant species of ladybirds in the UK.
Harlequin Ladybird – Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) – is a beetle species in the same family with the Seven-spot and Two-spot Ladybirds, both being considered gardener’s best friends as natural enemies of aphids and other garden pests. Harlequin Ladybird was deliberately introduced from east parts of Eurasia, where it is a native species, to many places of continental Europe as a biological agent to control aphids (=greenflies) and scale insects. As Harlequin Ladybird has excellent dispersal abilities (by means of flight), it was just the matter of time until it could have reached the British Isles.
A number of factors have contributed to the successful establishment and dominance of this ladybird species in the UK, particularly, its high reproductive capacity and ability to live in most available habitats. Harlequin Ladybird is also a voracious predator that can feed on other ladybird species.
The UK Ladybird Survey is a citizen science initiative that was launched in 2005, right after the first records of Harlequin Ladybird in Britain had been done. This programme is aimed at encouraging people across Britain to track the spread of Harlequin Ladybird (and other ladybirds) across the UK and submit their records online. Based on this survey, it is clear that by 2014 the Harlequin Ladybird has extended its range by almost half of the country. A decline of seven native ladybird species, which is correlated with the arrival of Harmonia axyridis, has also been demonstrated.
How to control this species and its spread in the UK is a bit unclear. Harlequin Ladybird produces a special, aggregation pheromone to attract other individuals to overwinterwing habitats. It has been proposed to use this pheromone within a network of traps in order to physically withdraw Harlequin Ladybirds from the environment. However, the cost of managing such traps is potentially too high to be feasible. The use of natural enemies of Harmonia axyridis, such as the ectoparasitic mite (Coccipolipus hippodamiae) that is capable to induce sterility in females of Harlequin Ladybirds, has also been considered, but alas with no practical applications so far. Therefore, this species is likely to be staying in the British Isles, apparently becoming another ‘native’ ladybird species with which we are to live (as it already happened with many other insect, crustacean and mollusc species).
In the following interview, Don Stenhouse, the Curator of Natural Sciences at the Bolton Museum, will share with us his own experience in studying the Harlequin Ladybird.
A full story of the Harlequin Ladybird in the UK can be found in the following paper:
Roy H.E. and P.M.J. Brown (2015), ‘Ten years of invasion: Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Britain’ – Ecological Entomology, 40(4): 336–348; online at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4584496/