Parasites & Vectors (Feb 2014)

Assessing quality of life-shortening Wolbachia-infected Aedes aegypti mosquitoes in the field based on capture rates and morphometric assessments

  • Heng Lin Yeap,
  • Jason K Axford,
  • Jean Popovici,
  • Nancy M Endersby,
  • Iñaki Iturbe-Ormaetxe,
  • Scott A Ritchie,
  • Ary A Hoffmann

DOI
https://doi.org/10.1186/1756-3305-7-58
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 13

Abstract

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Abstract Background Recent releases have been carried out with Aedes aegypti mosquitoes infected with the w MelPop mosquito cell-line adapted (w MelPop-CLA) strain of Wolbachia. This infection introduced from Drosophila provides strong blockage of dengue and other arboviruses but also has large fitness costs in laboratory tests. The releases were used to evaluate the fitness of released infected mosquitoes, and (following termination of releases) to test for any effects of w MelPop-CLA on wing size and shape when mosquitoes were reared under field conditions. Methods We monitored gravid females via double sticky traps to assess the reproductive success of w MelPop-CLA-infected females and also sampled the overall mosquito population post-release using Biogent Sentinel traps. Morphometric analyses were used to evaluate infection effects on wing shape as well as size. Results Oviposition success as assessed through double sticky traps was unrelated to size of released mosquitoes. However, released mosquitoes with lower wing loading were more successful. Furthermore, w MelPop-CLA-infected mosquitoes had 38.3% of the oviposition success of uninfected mosquitoes based on the predicted infection frequency after release. Environmental conditions affected wing shape and particularly size across time in uninfected mosquitoes, but not in naturally-reared w MelPop-CLA-infected mosquitoes. Although the overall size and shape do not differ between naturally-reared w MelPop-CLA-infected and uninfected mosquitoes, the infected mosquitoes tended to have smaller wings than uninfected mosquitoes during the cooler November in comparison to December. Conclusion These results confirm the lower fitness of w MelPop-CLA infection under field conditions, helping to explain challenges associated with a successful invasion by this strain. In the long run, invasion may depend on releasing strains carrying insecticide resistance or egg desiccation resistance, combined with an active pre-release population suppression program.

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