Genetically engineering out the lives of pests is not a new idea. The idea of leveraging sexual reproduction to pass specific gene changes (mutations or alterations) through entire populations to control pests has been proposed as far back as the 1940s, for example, A Strain of the Mosquito Aedes aegypti Selected for Susceptibility to the Avian Malaria Parasite Plasmodium lophurae.
Evolutionary geneticist Austin Burt was credited with the method of cutting DNA to reduce populations of disease-spreading species and the associated idea of â€œGene drivesâ€. The central idea behind a gene drive is to ensure that the engineered module stands a high probability of being passed onto offspring, such that the genetic module can be spread through the population. We can â€œdriveâ€ a genetic mutation into an entire population.
â€œHow do we do this?â€
Imagine if we can genetically engineer the virulence out of mosquito bites â€” nay, letâ€™s engineer the future lives out of an entire species of the worst offenders (these would be the aegypti mosquitoes) â€” and free our communities of chemical pesticides! Kill the pests but spare our environment!
That is what Oxitec is working on. The company is harnessing a pathway that has been explored for killing cancer cells to genetically engineer male aegypti mosquitoes. Male aegypti mosquitoes live long enough to mate with female aegypti mosquitoes in the wild. Males pass along what amounts to a ticking time bomb genetic sequence to their female partners. Their offspring will then carry these gene sequences that produce death-causing proteins.
Female aegypti mosquitoes are the ones that bite and deposit diseases in hosts. Thus rather than working on fatality-causing mutations where an aegypti mosquito embryo wonâ€™t even see the light of day, Oxitec wants the males mosquitoes to mate with the existing biting wild female population. Offsprings will die before adulthood due to the inherited vulnerability or will be too weak to survive the normal assaults of nature.
â€œShould we do this? How far should we do this?â€
Along with questions of possibility and feasibility comes questions of ethics and responsibility.
What are the ethics of genetically extinguishing entire species, even if weâ€™re talking about a loathed species like the aegypti mosquitoes? You will hear bioethicists talk about the impact on the natural food web and the ripple effect of employing such technology (i.e. â€œToday, mosquitoes. Tomorrow, other species maybe even certain humans?â€)
Additionally, one can argue that the very situations fertile for cultivating diseases are not fixed by genetically fixing pests. How does genetically engineering mosquitoes fix the slums and ghettos in which pests and disease carrying insects establish and thrive? How do we know that another species wonâ€™t take the place of one that we genetically extinguished, because the very conditions of poverty remain?
Questions about genetically engineering away virulence and pestilence are complex, and reach beyond what is merely scientifically possible.
We need to consider the law of unintended consequences, and these are complex questions of consequences that are difficult for us to imagine, until weâ€™ve done it.
Then, do we do it? Should we do it?