The harlequin ladybird (Harmonia axyridis) in Denmark: spread, phenology,colour forms and natural enemies in the early phase of establishment

Abstract: Harmonia axyridis arrived in Denmark in 2006, was established by 2007 and now hasspread to the southern and eastern part of the country. The rate of spread in Denmark has beensurprisingly low, and except for a few strongholds with large populations H. axyridis has mainlybeen recorded as single specimens. Studies of the phenology of H. axyiridis in Denmark indicatebivoltinism and show that it is currently not well adapted to Danish conditions. The frequency ofoccurrence of four colour forms has not changed within the first two years after its establishmentin Denmark. At present, f. succinea is the dominant colour form (~94%) and the nominate colourform f. axyridis is rare (0.6% prevalence). Among the native natural enemies interacting withH. axyridis are phorid flies (Phalacrotophora sp.), entomopathogenic fungi and thehymenopteran parasitoid Dinocampus coccinellae.