Media reports about GMO mosquitoes dutifully report that Oxitec’s tests concluded with an 80% reduction in the species. But is this where the story ends? Not quite. The GMO mosquito product requires *continuous and regular releases* as well as simultaneous use of pesticides. It’s not as simple as releasing some GMO mosquitoes and “poof,” the problem is gone.
The Oxitec product sets up a *competition* between wild mosquitoes and genetically modified ones. Because of their crippling artificial genes, the GMO mosquitoes are not as successful in mating or survival as the wild type. In the Cayman Islands, Oxitec released up to *25 times* as many GMO mosquitoes as wild ones that already existed.
The Cayman’s test which reported “80% reduction” sounds less convincing when it’s fully explained. Oxitec released 4 million GMO mosquitoes in increasing quantities over three different areas for a period of 6 months, then counted the number of eggs found in artificial traps they laid. They compared the number of traps with at least one egg (called the ovitrap index) between the treated areas. At the last egg count, 49% of the traps in the untreated areas had at least one egg while 10% had eggs in the areas with the heaviest, most sustained GMO mosquitoes release. ((49-10)/49=80%).
On average, 50% of the trapped eggs had Oxitec’s fluorescent marker and 50% did not. What this means is that, even after heavy, constant application (3x week) of the GMO mosquitoes, about 5% of the wild type mosquitoes still survived.
It doesn’t take a biologist to figure out what will happen when the GMO mosquito release is discontinued. If nature hasn’t already filled the vacuum with another competitive mosquito species, the original wild type mosquitoes will simply rise up to their previous top competitor position and replicate in the same (or larger) numbers, since the strongest, most adaptable individuals are the ones who will survive the GMO and pesticide sprays.
Oxitec has never released any information about what happens when the GMO mosquito program is discontinued, nor shown any test results from the DNA of captured mosquitoes after allowing a tested environment to return to its natural balance of wild mosquitoes. In other words, there isn’t any information about the story’s end because Oxitec expects to supply this product forever.