title: Transcriptome Profiling and Genetic Study Reveal Amplified Carboxylesterase Genes Implicated in Temephos Resistance, in the Asian Tiger Mosquito Aedes albopictus.
abstract: BACKGROUND
  The control of Aedes albopictus, a major vector for viral diseases, such as dengue fever and chikungunya, has been largely reliant on the use of the larvicide temephos for many decades. This insecticide remains a primary control tool for several countries and it is a potential reliable reserve, for emergency epidemics or new invasion cases, in regions such as Europe which have banned its use. Resistance to temephos has been detected in some regions, but the mechanism responsible for the trait has not been investigated.
  
  
  RESULTS
  Temephos resistance was identified in an Aedes albopictus population isolated from Greece, and subsequently selected in the laboratory for a few generations. Biochemical assays suggested the association of elevated carboxylesterases (CCE), but not target site resistance (altered AChE), with this phenotype. Illumina transcriptomic analysis revealed the up-regulation of three transcripts encoding CCE genes in the temephos resistant strain. CCEae3a and CCEae6a showed the most striking up-regulation (27- and 12-folds respectively, compared to the reference susceptible strain); these genes have been previously shown to be involved in temephos resistance also in Ae. aegypti. Gene amplification was associated with elevated transcription levels of both CCEae6a and CCEae3a genes. Genetic crosses confirmed the genetic link between CCEae6a and CCEae3a amplification and temephos resistance, by demonstrating a strong association between survival to temephos exposure and gene copy numbers in the F2 generation. Other transcripts, encoding cytochrome P450s, UDP-glycosyltransferases (UGTs), cuticle and lipid biosynthesis proteins, were upregulated in resistant mosquitoes, indicating that the co-evolution of multiple mechanisms might contribute to resistance.
  
  
  CONCLUSIONS
  The identification of specific genes associated with insecticide resistance in Ae. albopictus for the first time is an important pre-requirement for insecticide resistance management. The genomic resources that were produced will be useful to the community, to study relevant aspects of Ae. albopictus biology.
authors.affiliation: Department of Biology, University of Crete, Heraklion, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece.
authors.forename: Linda
authors.initials: L
authors.lastname: Grigoraki
authors.affiliation: Hellenic Centre for Marine Research, Heraklion-Crete, Greece.
authors.forename: Jacques
authors.initials: J
authors.lastname: Lagnel
authors.affiliation: Department of Crop Science, Pesticide Science Lab, Agricultural University of Athens, Athens, Greece.
authors.forename: Ilias
authors.initials: I
authors.lastname: Kioulos
authors.affiliation: Department of Biology, University of Crete, Heraklion, Greece.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kampouraki
authors.affiliation: Department of Biology, University of Crete, Heraklion, Greece.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Morou
authors.affiliation: Institut des Sciences de l'Évolution, CNRS, IRD, Université de Montpellier, Montpellier, France.
authors.forename: Pierrick
authors.initials: P
authors.lastname: Labbé
authors.affiliation: Institut des Sciences de l'Évolution, CNRS, IRD, Université de Montpellier, Montpellier, France.
authors.forename: Mylene
authors.initials: M
authors.lastname: Weill
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece; Department of Crop Science, Pesticide Science Lab, Agricultural University of Athens, Athens, Greece.
authors.forename: John
authors.initials: J
authors.lastname: Vontas
mesh_terms: D000330:Aedes / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D043182:Carboxylesterase / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005784:Gene Amplification; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D015723:Gene Library; D059014:High-Throughput Nucleotide Sequencing; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007303:Insect Vectors / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D000002:Temefos / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D043182:Carboxylesterase; D000002:Temefos