Weill_2001_J.Am.Mosq.Control.Assoc_17_238

In the mosquito Culex pipiens various alleles at the Ester locus provide insecticide resistance These resistance alleles display a heterogeneous geographical distribution particularly in China where they are highly diverse A new resistance allele Ester9 coding for the overproduced esterases A9 and B9 is characterized and compared to the known resistant allele Ester8 isolated from the same southern China sample from Guangzhou Both alleles provide low but significant resistance to chlorpyrifos relative synergism ratio RSR 3 and temephos RSR 1.4 which is consistent with the low level of gene amplification they display 15 copies for Ester9 and 4 copies for Ester8 The full genomic sequence of the allele coding A8 and A9 is presented which allowed us to set up a polymerase chain reaction assay to specifically identify these alleles The peculiar situation in southern China where numerous resistance alleles coexist is discussed in comparison with the Mediterranean situation the only one with a similar diversity of overproduced esterases