Temporal changes in ladybird species assemblages coinciding with the arrival of Harmonia axyridis in the UK

Temporal changes in ladybird species assemblages were studied at seven sites in various arboreal habitats (lime, pine and mixed trees/vegetation) in Cambridgeshire, England from 2006 to 2008. The impact of Harmonia axyridis and other factors (e.g. weather, prey availability) on native ladybirds was assessed. In year one H. axyridis was present but not abundant in Cambridgeshire and was recorded only in very small numbers (0.2% of total ladybirds recorded; n = 1506) in our surveys. In year three H. axyridis was the most abundant species and was breeding at five of the seven sites (pine tree sites were the exceptions). It accounted for 40.3% of the total ladybirds recorded (n = 1513). Only two other species (Aphidecta obliterata and Anatis ocellata) increased in number over the three years, while 13 species decreased. The generalist aphidophagous species Adalia 2-punctata, Coccinella 7-punctata and Propylea 14-punctata suffered the greatest declines. In an attempt to quantify possible levels of intraguild predation, genetic studies have commenced to detect native ladybirds in the guts of H. axyridis collected at some of the survey sites