Bridgehead Effect in the Worldwide Invasion of the Biocontrol Harlequin Ladybird Lombaert, Eric ; Guillemaud, Thomas ; Cornuet, Jean-Marie ; Malausa, Thibaut ; Facon, Benoît ; Estoup, Arnaud Abstract Publication: PLoS ONE Pub Date: March 2010 DOI: 10.1371/journal.pone.0009743 Bibcode: 2010PLoSO...5.9743L