Google’s parent company Alphabet has attracted some attention recently base on its request to release up to 32 million mosquitoes in Florida and California. No, it’s not part of a master plan to annoy people or spread disease. Believe it or not, it’s actually an effective method to reduce mosquitoes and the risk of mosquito borne disease.

The reason this seemingly counterintuitive action works comes down to the biology of the relationship between mosquitoes and a bacterium called Wolbachia, which infects many types of insects and parasites. In veterinary medicine, its most significant role is in heartworm disease in dogs, in which Wolbachia are beneficial to the heartworms themselves, so part of the treatment for heartworm is using antibiotics to kill the Wolbachia.

But in mosquitoes, Wolbachia are harmful, not helpful, so we can use this to our advantage. The plan is to release male Aedes aegypti mosquitoes that are infected with Wolbachia. Remember that male mosquitoes don’t bite, so since they don’t feed on blood they don’t spread disease, but they are important for making future generations of mosquitoes.

  • If an infected male mosquito mates with an uninfected female, no viable mosquito larvae are produced, leading to fewer mosquitoes overall.
  • If an infected male mosquito mates with an infected female, viable offspring are produced, but they are also infected with Wolbachia. This is still helpful though, because infected females have shorter lifespans, and the Wolbachia infection also reduces the survival and transmission of various important pathogens in the females, including dengue virus, zika virus, chikungunya virus and yellow fever virus.  

This is in fact a well proven approach to mosquito control. It’s similar to the release of sterile male flies for eradication of New World screwworm, which is being ramped up even more since the first two cases of the current outbreak were detected in Texas earlier this week. (Check out our previous post on NWS for Canadian veterinarians, and the CFIA announcement on new control measures at the Canadian border.)

This is one of those plans that at first glance may make some people wonder what’s going on. It feeds the conspiracy theory crowd that doesn’t like when anyone does anything, but it’s actually a safe and proven process. Mosquitoes have been called the world’s deadliest animal for good reason, because mosquito borne diseases are leading killers internationally. Using biology to counter biology is both a crude and elegant way to address this problem.

Mosquito image source: https://en.wikipedia.org/wiki/File:Aedes_aegypti.jpg