San Gabriel Valley Releases 500,000 Wolbachia Mosquitoes to Curb Dengue as Season Extends
Updated
Updated · The Guardian · Sep 17
San Gabriel Valley Releases 500,000 Wolbachia Mosquitoes to Curb Dengue as Season Extends
2 articles · Updated · The Guardian · Sep 17
Summary
Nearly 30,000 male Aedes aegypti mosquitoes a week are being released in the San Gabriel Valley, for a total just under 500,000, in a bid to cut the local population that can spread dengue.
Each lab-bred male carries Wolbachia, a naturally occurring bacterium that causes eggs from matings with certain wild females not to hatch, reducing the next generation rather than killing every mosquito.
The push follows California's first locally acquired dengue cases in 2023 and a 2024 Los Angeles County cluster; a CDC investigation found 14 local cases from August to November 2024, including six hospitalizations.
Warmer conditions are lengthening mosquito activity in Southern California, with officials saying control work now runs year-round; Climate Central found 95% of U.S. cities studied have gained suitable mosquito-weather days since the early 1970s.
San Gabriel Valley officials will judge the program by trap counts of female Aedes aegypti, while earlier studies of Wolbachia releases reported population reductions of 80% to 95% in some areas.