On March 7, the United States Environmental Protection Agency (EPA) announced the approval of genetically modified mosquitos in Fresno and Tulare counties as part of an experimental use permit (EUP).
The original EUP was granted in May 2020 and allowed Oxitec to field test their OX5034 mosquitoes in Florida and Texas through April 2022. Oxitec is a UK-based, US-owned biotechnology company that develops genetically modified insects to assist in insect control.
The EUP amendment that was granted last month expanded the EUP to four counties in California for the first time, consisting of 29,400 acres in Stanislaus, Fresno, Tulare, and San Bernardino counties. Oxitec is allowed to conduct testing in these areas until April 30, 2024, to generate efficacy data in different climactic zones.
Donna Liebenberg, Account Manager and Oxitec representative, revealed that there were several California counties interested in partnering with them, but there are criteria that have to be met in order to be selected. This criteria include: abundant, local pest population and logistics of project planning (distance, number of houses, community interest).
“Since one of our metrics is mating success, if local numbers of invasive Aedes aegypti females are low, then our boys have a harder time finding and mating with them,” Liebenberg stated. “Several districts in the Central Valley, including Consolidated Mosquito Abatement District and Delta Mosquito & Vector Control District, are in the Goldilocks zone. They have abundant local Aedes aegypti, and logistically appealing sites.”
According to the EPA, these genetically engineered mosquitoes are designed to eventually reduce the number of Aedes aegypti — the breed that can transmit diseases to humans. It could also eliminate the need for pesticides for mosquito control.
“Aedes aegypti mosquitoes, which are among the most common invasive mosquito species in the United States, can transmit diseases such as dengue, Zika, and chikungunya to humans; therefore, mosquito control is important for protecting human health,” the EPA wrote in a press release. “Additionally, the use of species-specific modified mosquitoes could reduce the use of pesticides for mosquito control. This may be especially beneficial for densely populated communities with environmental justice concerns. These communities could be at higher risk for exposure to mosquitoes, virus transmission, and exposure to pesticides from mosquito control.”
Oxitec’s genetically engineered mosquitoes are regulated under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) like all pesticides. According to the EPA’s press release, data submitted by Oxitec demonstrate that OX5034 mosquitoes meet FIFRA standards of not causing unreasonable adverse effects to humans or the environment.
The press release continues by saying that the California Department of Pesticide Regulation must approve this testing before additional testing can take place. Following approval from the State, Oxitec will be allowed to release male OX5034 mosquitoes — which do not bite people — in the approved release areas.
“The male mosquitoes have a protein (the tTAV-OX5034 protein) that prevents female offspring from surviving when male OX5034 mosquitoes mate with wild female mosquitoes. The absence of female mosquitos in the release area results in mosquito population decline,” the EPA stated.
Additionally, the consumption of OX5034 male mosquitoes would not harm endangered species or any other organisms such as birds, bats, or fish.
The EPA will ensure that no OX5034 female mosquito offspring survive by restricting release of OX5034 mosquitos within 500 meters of potential sources of tetracyclines, as there is a remote chance that environmental sources of tetracycline could have enough tetracycline present to act as a counter agent to the OX5034 female mosquito-lethal trait. In order to do this, releases must not occur within 500 meters from the outer perimeter of:
- Wastewater treatment facilities,
- Commercial citrus, apple, pear, nectarine, and peach crops; and
- Commercial cattle, poultry, and pig livestock facilities.
The EPA assures that this 500-meter distance creates a conservative buffer zone between OX5034 release points and potential environmental tetracycline sources.
Additionally, EPA mandates that Oxitec monitor and sample the mosquito population every week to ensure no OX5034 female mosquito offspring survive. So far no genetically modified female OX5034 mosquitoes have been detected during Oxitec’s field testing so far, and no detections are expected based on EPA’s risk assessment.
EPA continues to maintain the right to cancel the EUP at any point during the 24-month period.
As of now, Kern County has no plans to release any genetically engineered mosquitoes and will continue to follow standard protocol.
