Affiliation: | (1) Aphid Biology Group, Department of Biology, Imperial College at Silwood Park, SL5 7PY Ascot, Berkshire, UK;(2) IACR-Rothamsted, AL5 2JQ Harpenden, Hertfordshire, UK;(3) Present address: Department of Biology, Biomedical Sciences Building, University of Southampton, Bassett Crescent East, SO16 7PX Southampton, UK |