Abstract. 1. The harlequin ladybird, Harmonia axyridis, is an invasive alien species that arrived in Britain in 2003 and has spread across most of the country.2. This spread has been accompanied by a decline in some native coccinellid species, in particular, the two spot ladybird Adalia bipunctata and the ten spot ladybird Adalia decempunctata. One reason for this decline could be intraguild predation (IGP) of the Adalia species by H. axyridis.3. A DNA-based approach was used to look for evidence of coccinellid IGP in the wild. Adalia bipunctata-and A. decempunctata-specific Polymerase chain reaction primers were developed to analyse the gut contents of field collected H. axyridis larvae for the presence of Adalia DNA. Harmonia axyridis larvae (156) were collected from lime trees at four sites in eastern England over 3 years.4. Adalia bipunctata DNA was detected in 7.7% and A. decempunctata DNA in 4.5% of H. axyridis larvae. DNA from both Adalia species was detected in two larvae.5. This is the first demonstration of specific IGP interactions between H. axyridis and other coccinellid species in wild populations in Britain.

Intraguild predation (IGP) is a potential mechanism of negative effects on native species populations by invasive non‐native species such as Harmonia axyridis. Molecular techniques (polymerase chain reaction) were used to probe for the presence of various insect (coccinellid, syrphid and chrysopid) prey DNA in the guts of 177 H. axyridis larvae field‐collected in England, France, Germany, Slovakia and the Czech Republic in 2010. Three of the four target prey species were detected in the guts of H. axyridis at the following rates: Adalia decempunctata 9.6%, Adalia bipunctata 2.8% and Episyrphus balteatus 2.8%. IGP on Chrysoperla carnea was not detected. IGP detection of at least one target species was made in England, France, Slovakia and the Czech Republic, but not in Germany. These results strengthen the evidence that H. axyridis is a very generalist predator. Results are discussed in the context of their ecological significance.