Wolbachia is a genus of bacteria that has evolved complex relationships with the many insects that can host it. It is named for the American pathologist Simeon Burt Wolbach, who identified it along with Marshall Hertig in 1924.
In 1971, researchers discovered that when male Culex mosquitoes infected by Wolbachia bacteria fertilised healthy eggs from a female, the eggs died. The bacteria modified the male’s sperm cells in a way that only the bacteria could reverse. So if the female mosquito was uninfected, her egg cells would be damaged. But if the female was infected by Wolbachia, the eggs would be viable if the male was uninfected or infected by the same strain of Wolbachia. This means infected female mosquitoes gain a reproductive advantage over time as the amount of Wolbachia in the population increases.
Wolbachia can also reduce the rate at which chikungunya and yellow fever viruses multiply in infected mosquitoes. Scientists have also found that some Wolbachia species can strongly protect some mosquito species against the malaria parasite. So they are currently studying a way to have the right strain of Wolbachia rapidly spread in a particular mosquito population, in the right environmental conditions, such that the bacteria can suppress malaria transmission. If this is achieved, it will be a significant weapon in our millennia-long fight against mosquito-borne diseases.
