1. Agroscope, Research Division Plant Protection , Route de Duillier 60, 1260 Nyon 1 , Switzerland
2. Manchester Institute of Biotechnology, University of Manchester , 131 Princess Street Manchester M1 7DN , UK
3. Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich , 8093 Zürich , Switzerland