title: Insecticide resistance and cytochrome-P450 activation in unfed and blood-fed laboratory and field populations ofCulex pipiens pallens.
abstract: Understanding the mechanisms of insecticide resistance to vector mosquitoes is critical for the implementation of effective control measures. A nulliparous susceptibleCulex pipiens pallens(KSCP) laboratory colony and two field strains from Paju (PAJ) and Jeonju (JEO) Korea were evaluated for susceptibility to five pesticides by microapplication techniques. Unfed PAJ and JEO females demonstrated increased resistance compared to unfed KSCP females, respectively. While blood-fed KSCP females demonstrated <10-fold decreased susceptibility to pesticides compared to unfed KSCP females, blood-fed PAJ and JEO females demonstrated 25.0-50.0- and 16.0-38.6-fold increased resistance compared to unfed PAJ and JEO females, respectively. Unfed and blood-fed groups were assayed for α- and β-esterase, glutathioneS-transferases, and cytochrome P-450 (P450) enzyme activity assays. P450 activity was 58.8- and 72.8-fold higher for unfed PAJ and JEO females, respectively, than unfed KSCP females. P450 enzyme activity of KSCP females assayed 1 and 7 days after a blood meal increased by 14.5- and 11.8-fold, respectively, compared to unfed KSCP females, while PAJ and JEO females demonstrated 164.9- and 148.5- and 170.7- and 160.4-fold increased activity, respectively, compared to unfed females of each population. However, other three resistance-related metabolic enzymes showed low activation at <10-fold after a blood meal. The data demonstrate that P450 acts on elevated insecticide resistance after blood meals in resistant field populations. Our findings might reveal that suppressing of the P450 protein by artificial gene mutation increases insecticidal susceptibility ofCx.pipiensand will promise effective vector mosquito control.
authors.affiliation: National Institute of Health, Korea Center for Disease Control and Prevention, Cheongju-si, Chungbuk 28159 Republic of Korea.
authors.forename: Kyu-Sik
authors.identifier: 0000-0003-1838-2898
authors.initials: KS
authors.lastname: Chang
authors.affiliation: 5th Medical Detachment, 168th Multifunctional Medical Battalion, 65th Medical Brigade, Unit 15247, APO, AP 96205-5247 USA.
authors.forename: Heung-Chul
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Medical Department Activity Korea, 65th Medical Brigade, Unit 15281, APO, AP 96205-5281 USA.
authors.forename: Terry A
authors.initials: TA
authors.lastname: Klein
authors.affiliation: National Institute of Health, Korea Center for Disease Control and Prevention, Cheongju-si, Chungbuk 28159 Republic of Korea.
authors.forename: Young Ran
authors.initials: YR
authors.lastname: Ju
keywords: Culex pipiens pallens; Cytochrome; Detoxification; Esterases; Glutathione S-transferases; Insecticide; P450; Resistance