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Defence mechanisms against insecticides temephos and diflubenzuron in the mosquito Aedes caspius: the P-glycoprotein efflux pumps

Authors

  • D PORRETTA,

    1. 1 Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Rome, Italy, 2Department of Medical and Veterinary Entomology, Agriculture Environment Centre ‘G. Nicoli’, Crevalcore, Italy and 3Department of Plant Biology, University ‘La Sapienza’ of Rome, Rome, Italy
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  • 1 M. GARGANI,

    1. 1 Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Rome, Italy, 2Department of Medical and Veterinary Entomology, Agriculture Environment Centre ‘G. Nicoli’, Crevalcore, Italy and 3Department of Plant Biology, University ‘La Sapienza’ of Rome, Rome, Italy
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  • 1 R. BELLINI,

    1. 1 Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Rome, Italy, 2Department of Medical and Veterinary Entomology, Agriculture Environment Centre ‘G. Nicoli’, Crevalcore, Italy and 3Department of Plant Biology, University ‘La Sapienza’ of Rome, Rome, Italy
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  • 2 A. MEDICI,

    1. 1 Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Rome, Italy, 2Department of Medical and Veterinary Entomology, Agriculture Environment Centre ‘G. Nicoli’, Crevalcore, Italy and 3Department of Plant Biology, University ‘La Sapienza’ of Rome, Rome, Italy
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  • 2 F. PUNELLI,

    1. 1 Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Rome, Italy, 2Department of Medical and Veterinary Entomology, Agriculture Environment Centre ‘G. Nicoli’, Crevalcore, Italy and 3Department of Plant Biology, University ‘La Sapienza’ of Rome, Rome, Italy
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  • and 3 S. URBANELLI 1

    Corresponding author
    1. 1 Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Rome, Italy, 2Department of Medical and Veterinary Entomology, Agriculture Environment Centre ‘G. Nicoli’, Crevalcore, Italy and 3Department of Plant Biology, University ‘La Sapienza’ of Rome, Rome, Italy
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Sandra Urbanelli, Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Via dei Sardi 70, 00185 Rome, Italy. Tel.: + 39 06 4991 7820; Fax: + 39 06 4991 7820; E-mail: sandra.urbanelli@uniroma1.it.

Abstract

Abstract P-glycoproteins (P-gps) are efflux transporters found in cells of a broad range of both procaryotic and eukaryotic taxa, whose action is to relieve the cells of multiple, structurally dissimilar, toxic compounds. The possible role of P-gps in defence against the insecticides temephos and diflubenzuron was investigated in the mosquito Aedes caspius (Pallas), also known as Ochlerotatus (Aedes) caspius (Diptera: Culicidae), and the genomic DNA sequences encoding for P-gp transporters were isolated to provide molecular instruments for future research into the expression and characterization of genes codifying for P-gps in this mosquito species.

Mosquito larvae were treated with insecticides alone and in conjunction with a sublethal dose of the P-gp inhibitor verapamil. The inhibition of P-gps reduced the LD50 values of temephos and diflubenzuron by factors of 3.5 and 16.4, respectively, suggesting the potential involvement of P-gps in insecticide defence. Using a polymerase chain reaction (PCR)-based approach, a 481-bp sequence was isolated. The inferred nucleotide sequence shows high homology with the C-terminal sequence of known P-gps. The isolation and characterization of a putative P-gp sequence from Ae. caspius is the first step towards a better molecular understanding of the role played by multidrug transporters in the defence against insecticides in this species. This knowledge may open the way to a novel control strategy based on the inhibition of pest defences. The beneficial consequences of the inhibition of efflux pumps in improving insecticide performance are discussed.

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