Verily, the life sciences unit of Google’s parent company Alphabet Inc., plans to release up to 20 million sterile male mosquitoes throughout Fresno County, California in an attempt to reduce the impact that disease-carrying mosquitoes have on human health.

The main target of this project is the Aedes aegypti mosquito, which is responsible for the spread of diseases like dengue, zika and chikungunya.

The project, called Debug Fresno, will launch this Friday, July 21. A swarm of 1 million mosquitoes will be released every week for 20 weeks.

This is Verily’s first field study in the U.S. The test will be carried out in collaboration with MosquitoMate and Fresno County’s Consolidated Mosquito Abatement District

The sterile male mosquitoes have been bred to be infected with the naturally-occurring, common bacteria Wolbachia, which has the ability to change reproductive behavior. Unlike other proposed methods of mosquito control that involve genetically-engineered insects, there’s no genetic modification involved with this project.

Male mosquitoes do not bite humans and Wolbachia doesn’t infect humans. It also cannot be transmitted to humans via an insect bite. So the idea of Debug Fresno is to release the male mosquitoes infected with Wolbachia and let them mate with wild female mosquitoes. The eggs will not hatch, so the Debug Fresno collaborators believe the next generation will be smaller, eventually leading to the elimination of localized populations of A. aegypti and other harmful species of mosquitoes.

The series of releases will test whether this technique could work on a larger, global scale. The test area includes two neighborhoods that are each about 300 acres in size, according to Verily. After the 20 weeks, the team will compare adult population density and egg hatching of A. aegypti in the two experimental neighborhoods with two control neighborhoods. The team hopes the results will show significant decline in the presence of the mosquitoes in the targeted communities. If successful, the results will demonstrate the technique can be implemented on a greater scale.

 Previous research projects, particularly from the Bill and Melinda gates Foundation, have used Wolbachia as a form of mosquito-borne disease control in other parts of the world.

But the unique aspect of Verily’s project is that they created machines that can automatically rear, count and sort mosquitoes by sex. This enables the team to release large batches at one time. The mosquitoes will be released via Verily’s bug-releasing van and its automated device, saving time and reducing the man power needed. Previous mosquito releases relied on individuals manually releasing groups of insects by hand from jars.  

Aedes aegypti is an invasive species. The mosquitoes first entered the Fresno area in 2013. While California has not seen a significant outbreak of mosquito-borne diseases since their arrival, the Debug Fresno team hopes to stay ahead of any potential outbreaks.

The Debug Fresno van. Photo: Verily