title: [Changes of pyrethroid resistance and P450 monooxygenase activity with age in Anopheles sinensis in Huainan City, Anhui Province, China].
abstract: OBJECTIVE
  To study the effect of mosquito age on the pyrethroid resistance and P450 monooxygenase activity in Anopheles sinensis in Huainan City, Anhui Province, China, as well as the molecular mechanism of pyrethroid resistance.
  
  
  METHODS
  Anopheles mosquito larvae were collected in fields, and were emerged to adults. Then the pyrethroid resistance and P450 monooxygenase activity of female mosquitoes were detected 1, 3, 6, 9, 12, 15 d and 20 d after emergence. Meanwhile, the resistance level and P450 monooxygenase activity of the sensitive mosquitoes in lab were detected as the control group.
  
  
  RESULTS
  curves of pyrethroid resistance and P450 monooxygenase activity changes with the mosquito age presented unsymmetrically reversed "U" type. At 1 d after emergence, the resistance level and P450 monooxygenase activity were lower, and then they increased quickly. When 3-9 d after emergence, the resistance level and P450 monooxygenase activity rose to the highest level, and entered into plateau, then declined gradually. Compared to the sensitive mosquitoes in lab, the P450 monooxygenase activity of those in the field was higher at 3-12 d after emergence, but lower at 1 d after emergence, and at 15 and 20 d after emergence, they were almost equal to each other.
  
  
  CONCLUSIONS
  The mosquito age is a confounding factor in the detection of resistance level and enzyme activity. The promotion of activity of P450 monooxygenase may be one of the reasons of the resistance. Using female adults with different ages in the field as study subjects may underestimate the real resistance level of mosquitoes, and mislead the use of insecticides.
authors.affiliation: Chinese Center for Disease Control and Prevention, Key Laboratory of Parasite & Pathogen Biology, Ministry of Health, WHO Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai 200025, China.
authors.forename: Tie-Long
authors.initials: TL
authors.lastname: Xu
authors.forename: Dai-Bin
authors.initials: DB
authors.lastname: Zhong
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fang
authors.forename: Lin-Hua
authors.initials: LH
authors.lastname: Tang
authors.forename: Shui-Sen
authors.initials: SS
authors.lastname: Zhou
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000201:enzymology*; D002681:China; D009033:Culicidae / Q000187:drug effects* / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D000072472:Cytochrome P450 Family 6; D005260:Female; D006801:Humans; D019476:Insect Proteins / Q000378:metabolism*; D007305:Insecticide Resistance; D007814:Larva / Q000187:drug effects; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D019476:Insect Proteins; D011722:Pyrethrins; D003577:Cytochrome P-450 Enzyme System; C092307:CYP6D1 protein, Musca domestica; D000072472:Cytochrome P450 Family 6