Wolbachia-infected mosquitoes are significantly worse vectors for transmitting dengue fever, however, the means in which spread is established and continued among urban mosquito populations remains unclear, according to a new study conducted by researchers at the University of California at Davis (UC Davis) and the Eliminate Dengue Program.
While most mosquito suppression initiatives have focused on mosquito control, the research teams considered harnessing Wolbachia microbes, which are among the most-common parasitic microbes in the world, to reduce their capacity to transmit the virus.
The researchers first released adult Aedes aegypti mosquitoes infected with Wolbachia microbes in three areas that were near suitable habitats in Cairns, Queensland, Australia. Two sites were large, averaging around a square kilometer in size, while the third site was about a tenth the size of the first two sites. Approximately 130,000 and 286,000 mosquitoes were released in the first two sites, while the third received about 35,000 mosquitoes.
The teams then tracked the spread of the microbes over the course of two years by trapping and testing mosquitoes for them.
The researchers found that Wolbachia-infected mosquitoes spread at a rate of about 100-200 meters per year in the larger sites but found little evidence of any spread at the smaller site. This suggested, the researchers said, that as long as the sites were large enough, the microbes could dramatically transform mosquito populations in cities.
The teams also found that mosquito spread could be impeded by certain barriers, including buildings, roads, rivers, are forests.
The study was published in a recent issue of the journal PLOS Biology.