SoCal officials unleash sterile mosquitoes in bid to curb disease — with promising results

• Releasing sterile male mosquitoes reduced the population of invasive pests in parts of Southern California by up to about 82%, studies found.
• Some vector control officials say bringing the technique to larger areas would be a big undertaking requiring additional funding.
• Aedes aegypti mosquitoes, known for biting ankles, are at the heart of recent unprecedented local transmission of dengue in California.

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The idea was to drive down the mosquito population because eggs produced by a female after a romp with a sterile male don’t hatch. And only female mosquitoes bite, so unleashing males doesn’t lead to transmission of diseases such as dengue, a potentially fatal viral infection.

The data so far are encouraging.

One agency serving a large swath of Los Angeles County found a nearly 82% reduction in its invasive Aedes aegypti mosquito population in its release area in Sunland-Tujunga last year compared with a control area.

Another district, covering the southwestern corner of San Bernardino County, logged an average decrease of 44% across several heavily infested places where it unleashed the sterile males last year, compared with pre-intervention levels.

Overall invasive mosquito counts dropped 33% across the district — marking the first time in roughly eight years that the population went down instead of up.

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