Structure of populations of Myzus persicae (Hemiptera: Aphididae) developing on oilseed rapes in France and dispersal of resistance genes

Myzus persicae is a generalist aphid, which parasitizes a diversity of crop plants. The nearly inverted ratio Mace/kdr (two mutations which are linked with high resistance levels against carbamates and pyrethroïds resp. and were found in most individuals separately) have been evidenced in our lab in populations developing on oilseed rape in France between 2001 (Mace <¼) and 2009 (Mace >¾). Does this result from the expansion of one lineage with Mace present and kdr absent which was very scarcely encountered in 2001 at the expense of the others or does it result from the introduction of some new populations on this crop? This very recently started study aims at, on the longer term, inferring scenarios which may explain so dramatic changes. According to first results, no inversion of population structure is revealed as estimated based on neutral markers, but instead a diversification of major genotypes. At least two populations seem to be mixed together within the different 2009-2010 isolates.