Scientific Risk Assessment Shows Wolbachia Mosquitoes Are Safer Than GMO.

A New Zealand study from March, 2016 provides the kind of comprehensive risk assessment for Wolbachia mosquitoes that’s missing from Oxitec’s GMO product push. The entire methodology is disclosed and conclusions examined in detail. Overall, Wolbachia mosquitoes have a far smaller range of risks and those risks are of lower impact than GMO mosquitoes.

Mosquitoes infected with the Wolbachia bacteria cannot transmit dengue, Zika, West Nile, or yellow fever (these are all viruses in the same family, Flavivirus). Wolbachia affects only insects and cannot be passed to human beings. In addition to stopping the spread of  human disease, Wolbachia shortens the mosquitoes’ lifespan and reduces the overall population.

Following the model of risk assessments used for hospitals, engineering projects, and nuclear power plants, the study participants laid out all of the potential consequences of releasing Wolbachia-infected mosquitoes near human populations with the intent to reduce the spread of dengue, Zika, and other human diseases. A numeric value was assigned to the likelihood of each risk.

Two things are notable about this study. First, the authors solicited a wide range of experts and community participants to help determine the real types of risks that might exist and the severity of each. Then, separately, all of these parties weighed on how likely those events were to happen. The level of outside expert involvement and community engagement in this risk assessment provide a striking contrast to the simple “low risk” conclusions that are passed off in the Oxitec FDA Report.

The second thing that’s notable is the actual range of issues the participants came up with. The study asked about possible effects on health, the environment, the economy (including tourism), and even the impact on eradication and public education efforts by a mosquito control district. The most likely bad outcome is that the population might come to rely on Wolbachia and forget about eliminating breeding containers on the ground. In contrast, the potential risks for GMO mosquitoes are long, complicated, and downright disturbing.


A Bayesian Network is a graph used to predict the likelihood and severity of risks. This is the table of outcomes in which Wolbachia mosquitoes might “cause more harm.”

A mathematical model called a Bayesian Network was used to calculate the numeric probabilities of the potential outcomes. It found a 12% chance that releasing Wolbachia mosquitoes could make things worse (in any of the categories), with the biggest contributing factor being a need for more “boots on the ground” (10%) to continue public education and eradication of mosquitoes around homes.

The EPA recently approved a Wolbachia test for the Florida Keys using a strain grown in the University of Kentucky lab. Unlike Oxitec’s artificial animal OX513A, the non-GMO Wolbachia bacteria is also not patented and can be used by any city or mosquito control district without a commercial license.

Other studies have shown that, even 6 months after Wolbachia releases were discontinued, the local mosquito population was still infected — and still suppressing the transmission of human disease. No Oxitec study has ever addressed what happens when their product is discontinued.


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