Bengaluru: Mosquitoes killed around 300 Indians in 2024 alone, according to the National Centre for Vector Borne Diseases Control. But what if they stopped existing? Scientific research has found a new way to eradicate the entire species of infectious mosquitoes through gene editing, though it comes with its own set of ethical and ecological challenges.
“Once we remove mosquitoes, should we go after poisonous snakes? What about wasps and bees that sting us?” said Guha Dharmarajan, a disease ecologist at Krea University, while speaking to ThePrint.
India’s dependence on rainfall-related agricultural practices, as well as its climatic conditions, offers a conducive environment for mosquitoes to bite, breed, and spread.
Vector-borne diseases such as dengue and malaria have even put the country behind its crucial development goals, according to a study published in the Journal of the American Mosquito Control Association in 2023. Elsewhere in the world, too, scientists have mulled over ways to keep mosquito-borne infections at bay. A new way to stop these diseases is to eradicate the entire species of infectious mosquitoes through gene editing.
“The entire mandate of these genetically modified mosquitoes is to eliminate a particular targeted species, and that, in my opinion, has serious ethical and ecological consequences,” Dharmarajan added.
The gene drive
In genome editing, DNA is altered resulting in a change to inherited traits of a cell or organism. The changes can be made to somatic cells (non-heritable) or germline cells (heritable, if used for reproduction). Edits in germline cells not used for reproduction (e.g., research-only embryos) do not result in inheritance but are still biologically germline.
In 2016, researchers engineered a mosquito responsible for malaria in Africa called Anopheles gambiae. The mosquito was designed to pass on genes that cause infertility in the next generation of females, according to a study published in the journal Nature.
In that study, biologists Tony Nolan and Andrea Crisanti identified two copies of a changed fertility gene are responsible for infertility among females, and, even though the effect of the gene editing takes place naturally, natural selection wards off the passing of the mutated gene by ensuring only a single mutated gene is inherited by the offspring.
However, through gene drive, scientists ensured that even if an offspring inherited a single mutation, it would undergo chromosome editing and end up with two mutations. Thus, sustaining the presence of the infertility gene. In this way, the CRISPR/Cas9 gene editing tool could prevent fertility in malaria-causing mosquitoes.
Another 2015 study, published in the journal Neglected Tropical Diseases, reported the benefits of genetically modified (GM) mosquitoes to fight dengue in parts of Brazil. The GM males were released over a year, and found that the local mosquito population fell by 95 percent.
While, on a small scale, it has been proven that it is possible to make infectious mosquitoes infertile, the feasibility of a gene drive on a large scale raises a host of ethical questions.
There are ecological concerns regarding the role of mosquitoes in the food chain, said Nitin Gupta, associate professor, Department of Biological Sciences and Bioengineering (BSBE) at IIT Kanpur.
In their book Conservation Biology for All (2010), Navjot Sodhi and Paul Ehrlich argue that diversity should ensure the “variety of life in all its manifestations”.
However, in a paper published the same year in the journal Nature, science writer Janet Fang argues that “the romantic notion of every creature having a vital place in nature may not be enough to plead the mosquito’s case”.
So, is it okay to wipe out mosquitoes?
On this question, the debate enters the realm of philosophy. While the consensus among ethicists and ecologists is that humans operate on a higher plane of moral status, it does not preclude other non-sentient species from having a moral status.
Instead, a 2010 paper published in the Southern Journal of Philosophy, David DeGrazia, an American moral philosopher, argues that moral status has several degrees and other sentient animals are at grades lower than humans.
However, when it comes to mosquitoes, there’s no consensus. Organisms are replaceable, researcher Fern Wickson argues in another Nature paper, published in 2010. She adds that the damage of eliminating a mosquito species is relatively lower. “Perhaps another organism will come along to fill the niche eventually.”
Mosquitoes are largely considered to rank lower in moral order than humans. So, “it seems that sacrificing mosquitoes for human lives is morally permissible,” according to a 2022 study published in the Journal of Bioethical Inquiry.
Nonetheless, some ecologists are wary of humans playing god.
“This kind of mass eradication of an entire species is almost equivalent to genocide. So, once you do this, there is no going back,” Dharmarajan told ThePrint.
Ecological systems, he explained, are sensitive to slight changes. Any intervention to eliminate mosquitoes should be made cautiously. Apart from the ethical considerations, perhaps even more importantly, the ecological and evolutionary role of the species has to be considered when discussing a tool that could potentially wipe out an entire species.
“There is some evidence that they are pollinating plants… it is not that the only role (of mosquitoes) is to bite human beings,” Dharmarajan added.
Among other concerns about such mass eradication is also the possibility of the gene drive getting transferred to other species in a random spillover, which is a risk, even though the chances are low, according to Dharmarajan.
Dr Rakesh Mishra, director at the Tata Institute for Genetics and Society in Bengaluru, suggested that before playing around with genes to eliminate a species, one can consider other ways, such as understanding the behaviour of mosquitoes and using plants and repellents to divert the mosquitoes from biting humans.
“We have to choose which is the best mechanism for us to operate,” Mishra said. Even if there should be an intervention of genetically modified mosquitoes, engaging with citizens is crucial. “We must also see the social acceptance of any technology,” he added.
The 2022 study in the Journal of Bioethical Inquiry further said the release of genetically modified mosquitoes will depend on transparency, community involvement, and cooperation between different nations. “Otherwise, your solution is only a dream,” said Mishra, speaking to ThePrint.
Jina Dcruz, lead health scientist at the Centre for Disease Control and Prevention (CDC), while speaking to ThePrint, further echoed this view. “Whatever fancy technology we have, none of that is going to work until we build that public trust to make that intervention effective.”
Dcruz clarified that her views were personal and did not reflect the views of the CDC.
Since 2009, Oxitec, a British biotech company, has used experimentally tweaked mosquitoes to fight dengue in Brazil. The experiment was partly successful. But there was no dialogue between the community and the authorities. According to a 2017 study published in the Journal of Responsible Innovation, the drive partly failed to build trust.
“People fear things that they don’t understand, even if it’s good science,” said Dcruz. “We need to engage the cultural gatekeepers of a community. And without engaging them, there would not be transparency. That needs to happen before you implement the technology.”
(Edited by Sanya Mathur)
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