Orange County Implements Mosquito Sterilization Program to Combat Disease Spread

As the mosquito season begins in Southern California, residents can expect an increase in these tiny pests seeking hosts for blood meals. Recognizing the nuisance and health risks associated with mosquito bites, the Orange County Mosquito and Vector Control District has launched a pioneering project to curb the population of the invasive Aedes aegypti mosquito, known for transmitting diseases like dengue, Zika, and chikungunya.

Aedes aegypti, a small black and white mosquito originating from West Africa, was first spotted in Orange County in 2015. Since then, its numbers have grown, prompting local officials to seek innovative solutions. The district is adopting the sterile insect technique, a method with roots dating back to a 1996 program that released sterile Mediterranean fruit flies to protect agriculture in California.

The strategy involves releasing sterile male mosquitoes, which compete with wild males to mate with females. When a female mates with a sterilized male, she produces no viable offspring, gradually reducing the overall mosquito population. Beginning in May, the district plans to release up to 100,000 sterile male mosquitoes weekly in Mission Viejo, continuing through the fall.

Lab procedures for sterilization are conducted at the OC Vector facility. Mosquito larvae are grown in a colony exceeding 100,000 individuals. When these larvae mature into pupae, males and females are separated. The males are then chilled to facilitate handling and subjected to sterilization via X-ray exposure. To monitor the process, the lab marks sterilized males with a fluorescent dye that glows under UV light, ensuring they can be distinguished from wild mosquitoes in samples.

This targeted approach aims to reduce disease transmission risks, particularly for illnesses like dengue, which can cause severe symptoms such as high fever and headaches. Last year, 54 cases in Orange County were linked to travelers bringing the virus from abroad.

Residents are advised to take simple steps to further reduce mosquito breeding sites, such as regularly inspecting their properties for standing water, which provides ideal breeding grounds for Aedes mosquitoes. Common containers like water bottles and plant saucers can hold enough water for eggs to develop. Maintaining a habit of weekly inspections can significantly contribute to controlling local mosquito populations.

The effort exemplifies a modern, science-based approach to vector control, combining laboratory work with community participation to protect public health.

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