Wolbachia-Aedes Mosquito Suppression Strategy

Phase 2 Field Study

Phase 2 field study

In Phase 2, NEA set out to improve our release methods and address challenges identified in Phase 1. Phase 2 was carried out in Tampines West and Nee Soon East, and involved:

  • Expansion of release sites  and inclusion of buffer zone releases, which counteract migration of females into release sites. 
  • High-floor releases in addition to ground-floor releases.
  • Low-dose X-ray irradiation of sorted pupae to sterilise residual females and prevent establishment of Wolbachia in the urban Aedes aegypti population. Our Impact assessment determined that X-ray irradiation poses no harm to humans or the environment.

Phase 2 findings

  • Phase 2 achieved 70-80% suppression of the Aedes aegypti mosquito population in the release sites, an improvement over Phase 1.
  • Better results were achieved with the expansion of the release sites and the inclusion of buffer releases, suggesting that larger sites are less affected by the impact of migration.
  • High-floor releases resulted in a better vertical distribution of male Wolbachia-Aedes mosquitoes in HDB blocks.
  • The use of low-dose X-ray irradiation to sterilise residual females was effective at preventing establishment of Wolbachia in the field. 

Phase 2 field study findings