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  2. The contribution of gut bacteria to insecticide resistance and the life histories of the major malaria vector Anopheles arabiensis (Diptera: Culicidae)

The contribution of gut bacteria to insecticide resistance and the life histories of the major malaria vector Anopheles arabiensis (Diptera: Culicidae)

  • Sci Rep. 2019 Jun 24;9(1):9117. doi: 10.1038/s41598-019-45499-z.
Kirsten Barnard 1 Alexander C S N Jeanrenaud 2 3 Basil D Brooke 2 3 Shüné V Oliver 4 5
Affiliations

Affiliations

  • 1 School of Molecular and Cell Biology, Faculty of Science, University of the Witwatersrand, Johannesburg, South Africa.
  • 2 Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa.
  • 3 Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-disciplinary Research on Malaria,School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
  • 4 Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa. shuneo@nicd.ac.za.
  • 5 Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-disciplinary Research on Malaria,School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. shuneo@nicd.ac.za.
Abstract

The gut microbiota of mosquitoes is a crucial determinant of their fitness. As such, the biology of the gut microbiota of Anopheles arabiensis, a major malaria vector of Southern Africa, was investigated. Two laboratory strains of An. arabiensis were used; SENN, an insecticide susceptible strain, and SENN-DDT, a resistant strain. The strains were supplemented with either non-commensal bacteria or Antibiotics via a sucrose source to sterilize the gut. The strains were fed the broad-spectrum bactericidal Antibiotic gentamicin, or a preferentially gram-positive bactericidal (vancomycin), gram-negative bactericidal (streptomycin) or broad-spectrum bacteriostatic (erythromycin), either by sugar supplementation or by artificially-spiked blood-meal. The effects on adult mosquito longevity and insecticide resistance phenotype were assessed. Bacteria from the midgut of both strains were characterised by MALDI-TOF mass spectroscopy. Bactericidal Antibiotics increased longevity in SENN-DDT. Bacterial supplementation increased insecticide tolerance. Antibiotic supplementation via sugar decreased tolerance to the insecticides deltamethrin and malathion. Blood-supplemented vancomycin decreased insecticide resistance, while gentamicin and streptomycin increased resistance. SENN showed a greater gut Bacterial diversity than SENN-DDT, with both strains dominated by Gram-negative bacteria. This study suggests a crucial role for bacteria in An. arabiensis life history, and that gut microflora play variable roles in insecticide resistant and susceptible mosquitoes.

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