We live at the confluence of two ages: the first rush of climate change, which is bringing new species and new pathogens to territories they've never been known in; and the nascent age of genetic engineering, which holds out the promise of eliminating these pathogens, and not just in the wealthy territories they've moved into, but throughout the world, including the poor countries where they are deadly scourges.
A favorite target in these crosshairs is the disease-bearing mosquito, whose dengue, malaria, zika and other pathogens are among the world's deadliest killers, and whose range has pushed relentlessly north as the world has warmed.
One possibility is to use CRISPR and gene-drives to directly intervene in the genomes of mosquitoes to kill them off.
But another -- possible less controversial -- tactic is to tweak the pathogens that attack mosquitoes, like Wolbachia bacteria, which can be bred into to male mosquitoes (who don't bite and therefore can be released in large numbers without concern that this will increase the number of everyday stings inflicted on people), and who will transmit the infections to females they mate with, rendering them sterile.
Google sister company Verity and a company called Mosquitomate have teamed up to conduct a trial of this approach in Fresno, where an invasive population of mosquitoes has reached such mass that people can no longer comfortably sit outdoors during mosquito season.
The theory goes that since the mosquitoes are invasive to Fresno, eradicating them will not stress the ecosystem by removing a key organism from the food-web. Earlier trials of the technique in Innisfail, Australia, have been successful, and in this, the second season of Fresno trials, the results are very encouraging: 2017's run reportedly reduced mosquito populations by two thirds; and this year's improved program is reporting a 95% success rate.
However, the plans for this technique are not limited to territories where mosquitoes are invasive; Verity has mooted using the technique to kill all the disease-bearing mosquitoes in the world, rendering them extinct. The role these species play in food-webs is not well studied, so it may be that this creates its own raft of problems. However, I think it's pretty likely that someone will try this: when policymakers are asked to weigh the speculative harms from mosquito extinction against the public health crises created by their pathogens, the answer is likely to be a grim one for mosquitoes.
In videos of the original trials, you can see Holeman, the Fresno County scientist, gingerly blowing the mosquitoes out of a tube. The release van is now filled with proprietary technology, including software that determines exactly what areas of a neighborhood mosquitoes should be released in and a laser sensitive enough to count every single one as it exits, generating loads of data that can later be used to fine-tune the process.
At Verily’s headquarters, the “factory” where the mosquitoes are bred incorporates even more automation. Once the eggs are laid, robots rear the mosquitoes to adulthood, packaging them in containers filled with water and air, feeding them, and keeping them warm. Still other robots sort them by sex, first by size (females are bigger) and then optically, using proprietary technology. Mosquitoes are all given a digital identifier that makes it possible to follow them from egg state to the specific GPS coordinate where they’re released.
With this year’s season wrapping up, the company has yet to decide whether it will further expand the program next year. Verily wouldn’t say how much it costs to manufacture and release tens of thousands of mosquitoes every day, but it’s a safe bet that it’s still an expensive proposition.
Google’s Parent Has a Plan to Eliminate Mosquitoes Worldwide [Kristen Brown/Quint]
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