Why do matings between Wolbachia-Aedes males and non-Wolbachia-carrying females produce eggs that do not hatch?
When male Wolbachia-carrying Aedes aegypti mosquitoes mate with urban female Aedes aegypti mosquitoes that do not carry Wolbachia, their resulting eggs do not hatch. This is because Wolbachia causes cytoplasmic incompatibility (CI), a phenomenon where sperm and eggs are unable to form viable offspring. Scientists are still trying to understand how Wolbachia causes CI, but it is thought that Wolbachia modifies sperm such that they cannot successfully fertilise eggs that do not carry Wolbachia.
On the other hand, females that do carry Wolbachia can produce viable eggs after mating with males, regardless of whether or not the males carry Wolbachia. As Wolbachia is maternally transmitted, the offspring (both male and female) of Wolbachia-carrying females will inherit Wolbachia from their mothers. This is how we are able to rear large numbers of Wolbachia-Aedes mosquitoes in the lab.
Confirming CI in our Wolbachia-Aedes mosquitoes
As the Wolbachia-Aedes suppression strategy exploits CI to suppress field populations of Aedes aegypti, we want to make sure that CI works in our male Wolbachia-Aedes mosquitoes. Read on to see how we confirm this in the lab.