In the first post of this series, I presented a brief overview of the paper called “Transgenic Aedes aegypti mosquitoes transfer genes into a natural population”, which focuses on Oxitec’s recent field trial with (non-gene-drive) transgenic mosquitoes in Brazil. As I mentioned, the paper speculates on the potential impact of gene flow – not of the transgene, but of the rest of the genetic makeup of the released mosquitoes. In this second of two posts, I will focus on the following question “what is the impact of introgressing background genetic information from a release strain into a local population”?

Almost all genetic control systems will do this, unless the released mosquitoes are truly, absolutely, completely incapable of forming fertile hybrids with the local target population. Note that this has little to do with transgenes, and applies equally to classical radiation-based SIT, Wolbachia-based gene drives, etc.