In January 2018, lab-bred Aedes aegypti mosquitoes carrying wolbachia bacteria were released in South Miami, Florida. It was the first phase of the Miami-Dade County Mosquito Reduction Test Program, which targeted a one-half square-mile treatment area that received the altered mosquitoes and a corresponding control area within the city.
After initial monitoring, more wolbachia mosquitoes will be released into South Miami each week for several months1 — 666 million in all2 — with the ultimate goal of reducing mosquito populations and their potential for disease transmission.
The project is being conducted by the Miami-Dade County Mosquito Control & Habitat Management Division in collaboration with MosquitoMate, Inc., which created the technology. They’ve already been tested in Key West, Florida, (although due to Hurricane Irma, results of the tests are still pending),3 Kentucky, California and New York. Interest in releasing lab-made mosquitoes has peaked in recent years in response to the Zika virus scare, which has since petered out in the U.S.
If preventing Zika was their aim, government officials missed the boat on this one. Although Miami-Dade County was previously designated as a Zika cautionary area, that designation was removed June 2, 2017.4 No Zika virus disease cases have been reported with illness onset in 2018 in the U.S., according to the U.S. Centers for Disease Control and Prevention (CDC), while in 2017 there were only four cases of Zika virus reported that were presumably acquired via local mosquitoes (two in Florida and two in Texas).5
If Zika virus isn’t even circulating in the area, it’s unclear how the government plans to measure the “success” of their mosquito release in order to definitively say whether or not it’s helping anything. It’s curious timing, to say the least, unless there are some unknown beneficiaries behind the scenes.
Interestingly, the Daily Mail reported, “MosquitoMate also collaborated with Verily Life Sciences, an offshoot of Google’s parent company Alphabet Inc., and Fresno County’s Consolidated Mosquito Abatement District, this past summer to release the bacteria-infected mosquitoes in Fresno, California.”6
What Are Lab-Made Wolbachia Mosquitoes?
MosquitoMate’s lab-bred male mosquitoes are infected with wolbachia bacteria, which is naturally occurring in up to 60 percent of insect species, but not in Aedes aegypti mosquitoes. When the male wolbachia mosquitoes mate with female mosquitoes in the wild (which do not carry the bacteria), the resulting eggs do not hatch, which means the number of Aedes aegypti mosquitoes in the area should ultimately decrease.7
Male mosquitoes don't bite humans, but rather feed off flower nectar. Female mosquitoes are the ones that require meals of blood in order to develop and lay eggs. Their bites are at best an itchy nuisance and, at worst, can transmit serious diseases like malaria, yellow fever, dengue, encephalitis, chikungunya and West Nile virus. This is why MosquitoMate only releases male mosquitoes.
That said, in the case of the wolbachia mosquitoes, once they’re released (and they already have been), there’s no stopping them from mingling with wild mosquitoes. While this may help to reduce the spread of certain viruses (although this remains to be seen), it may also have other unintended, as yet unknown consequences.
Mosquitoes infected with wolbachia were also released in Brazil and Colombia in 2017 as part of The Eliminate Dengue research program, an $18 million project funded in part by the Bill and Melinda Gates Foundation.
The altered mosquitoes were tested in open trials in dengue-affected communities since 2011, but not to the level as the 2017 tests, which released the insects in large, heavily populated urban areas. It took decades for researchers just to figure out how to introduce wolbachia into Aedes mosquito eggs, but once they did they started experimenting with releasing them into the wild.
Field tests suggest the bacteria spread to the vast majority of local mosquitoes, and as Eliminate Dengue said, is a “self-sustaining” system8 — which is both the point and the problem.
There’s No Failsafe With Wolbachia Bugs
In some cases, experimental GE mosquitoes have been genetically engineered to die in the absence of the antibiotic tetracycline (which is introduced in the lab in order to keep them alive long enough to breed). They were designed this way assuming they would not have access to that drug in the wild, a failsafe (though not a perfect one, especially since antibiotics are now showing up in waterways) to ensure that the GE insects could theoretically be removed from the environment if necessary.
This isn’t the case with wolbachia mosquitoes; now that they’re released, there’s no going back. While MosquitoMate’s wolbachia mosquito program involves only male insects, other programs exist that are releasing both females and males with the bacteria.
The World Mosquito Program is among them, which notes a potential problem with the male-only route: “This technique requires the release of a large number of male mosquitoes to reduce the overall mosquito population. As with insecticides, this technique would need to be reapplied over time as the population of mosquitoes gradually returns.”9
There’s also the potential ramifications to the ecosystem, which can occur whenever any species is removed or drastically reduced. While mosquitoes are primarily viewed as a nuisance and vector for deadly diseases like malaria, there may be “undesirable side effects” of eradicating them entirely, according to Florida University entomologist Phil Lounibos, Ph.D. BBC News reported:
“ … [Lounibos] says mosquitoes, which mostly feed on plant nectar, are important pollinators. They are also a food source for birds and bats while their young — as larvae — are consumed by fish and frogs. This could have an effect further up and down the food chain … He warns that mosquitoes could be replaced by an insect ‘equally, or more, undesirable from a public health viewpoint.’ Its replacement could even conceivably spread diseases further and faster than mosquitoes today.”
The World Mosquito Program operates under the premise that mosquitoes with wolbachiaare less able to transmit diseases to people. By releasing both male and female mosquitoes with wolbachia, the idea is to establish the bacteria in the entire mosquito population, which they say can occur over a small number of generations.
While male mosquitoes with wolbachia and female mosquitoes without it cannot successfully reproduce, male wolbachia mosquitoes that mate with female wolbachia mosquitoes produce offspring that also contain the bacteria. In addition, when female wolbachia mosquitoes mate with males without it, the offspring will still have wolbachia. According to the program:10
“[T]he World Mosquito Program's Wolbachia method is unique because it is self-sustaining and does not need to be continually reapplied, making it an affordable, self-sustaining, long-term solution.
Our method reduces the ability of mosquitoes to transmit dengue, Zika and chikungunya on to people, without suppressing mosquito populations and potentially affecting ecosystems. We are currently adapting our approach for use in large, urban environments and targeting a cost of US$1 per person.”