Mutation can occur in insects, so it’s worth considering what would happen in the highly unlikely event that there was a mutation that made the self-limiting gene ineffective.
We regularly check the genetic make-up of our mosquitoes, approximately every 7 generations, so if there was a mutation we may see it during one of these regular checks. The introduced genetics have been stable for over 140 generations, which, if we measured this in humans is well before the Vikings! So the genetics have been very stable so far and we expect this to continue.
We have a marker system in our mosquitoes where the marker gene and the self-limiting gene are adjacent to one another and are inherited by any larvae that are offspring of an Oxitec males or female. So for example we can tell, in the outdoor environment, how far they fly, how well they mate, and how long they live. If for whatever reason the approach does not work – then one would see that through the marker and monitoring programme and stop releases. The mosquitoes that have resistance to the self-limiting gene have no added advantage in the environment, they would still die and OX513A releases can be stopped at any time and conventional methods (chemistry, biological control etc.) can still be applied to control the mosquito population and remove populations of pest mosquitoes.