Predation of native coccinellids by the invasive alien <i>Harmonia axyridis</i> (Coleoptera: Coccinellidae): detection in Britain by PCR-based gut analysis

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