Sterile insect technique is the process of treating insects with radiation to damage their DNA to render them unable to reproduce, and then releasing them into populations of the same species. Within a generation the numbers plummet. This is a great approach for A. egyptii mosquitoes, as a genetic solution can slow spread of Yellow Fever, Dengue, Malaria, Zika, West Nile and a host of other diseases. It is better to control insects with genetics rather than insecticides.
Oxitech takes this one further and produces sterile insects using a larval-lethal gene that they can turn off in the lab. Lab grown mosquitoes grow just fine, adults are sorted into males and females, and males are released to mate and pass on the lethal gene to populations that spread disease. The next generation, well, isn't.
But control is not complete and by definition, the engineered mosquitoes must mate with local populations. It is important to note that the local populations of A. egyptii are invasive and not native.
A recent report monitored populations and described that the introduced GE mosquitoes were mating with local ones, and that the Oxitech genetic background decreased with time. As it should.
But that didn't stop a few speculative statements from the paper to be blown out of proportion.
GM Watch, always looking for a way to trash technology, notes that the GE mosquitoes are "out of control" and that "GM mosquitoes are spreading in Brazil." Neither statement is true.
The transgene was not detected, just some of the native genetics from the introduced population. The transgene is lethal. Not all mosquitoes pass on the transgene, but do mate, so an invasive non-native strain was mating with another invasive non-native strain. As predicted.
The numbers also crashed, as predicted. And in several generations the introduced genetics decreased in abundance and as of today are not detected. Things are not running amok. They are not even walking amok.
This week's Talking Biotech Podcast covers the story in detail. Please listen and understand this important topic, as this technique may save millions of lives if fully implemented.