title: Status of insecticide resistance in Culex pipiens field populations from north-eastern areas of Italy before the withdrawal of OP compounds.
abstract: BACKGROUND
  Heavy and constant use of organophosphorus (OP) larvicides selected Culex pipiens L. resistant populations through two main mechanisms of genetic resistance, the increased activity of detoxifying esterase and the production of alterate acetylcholinesterase-1 (AChE1) by G119S mutation. The aim of this study was the assessment of the distribution of Cx. pipiens populations resistant to temephos and chlorpyrifos in the north-eastern regions of Italy and the occurrence of the insensitive AChE in these populations. Data describe the situation in the last years before European legislation prohibited the use of OP larvicides in mosquito control, up until 2007.
  
  
  RESULTS
  For the first time a high level of OP resistance in the samples from Ravenna (182-fold, 80% A4/B4 or A5/B5 esterases and 38.3% Ester(5)), Emilia Romagna region, was detected; therefore, new data from the Veneto and Friuli Venezia Giulia regions were obtained and reinforced existing knowledge about resistance previously studied along the Adriatic coast. Nearby, in the Villa Verucchio locality, the highest (87.5%) AChE1R was found.
  
  
  CONCLUSIONS
  Cx. pipiens resistance esterases A5/B5 and A4/B4 spread southward along the Adriatic coastal plain while OPs were being used in mosquito control, as confirmed by the first molecular screening of the AChE1 gene in these populations.
authors.affiliation: Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy. luciano.toma@iss.it
authors.forename: Luciano
authors.initials: L
authors.lastname: Toma
authors.forename: Michela
authors.initials: M
authors.lastname: Menegon
authors.forename: Roberto
authors.initials: R
authors.lastname: Romi
authors.forename: Elvira
authors.initials: E
authors.lastname: De Matthaeis
authors.forename: Mario
authors.initials: M
authors.lastname: Montanari
authors.forename: Carlo
authors.initials: C
authors.lastname: Severini
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D004390:Chlorpyrifos; D003465:Culex; D004950:Esterases / Q000378:metabolism; D019476:Insect Proteins / Q000378:metabolism; D007305:Insecticide Resistance; D007306:Insecticides; D007558:Italy; D009032:Mosquito Control / Q000331:legislation & jurisprudence / Q000379:methods*; D009943:Organophosphorus Compounds; D000002:Temefos
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D009943:Organophosphorus Compounds; D004950:Esterases; D000110:Acetylcholinesterase; D004390:Chlorpyrifos; D000002:Temefos