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PART I
Could we (should we) eliminate mosquitoes?
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DOI: 10.4324/9781003056034-1
Am I not mosquito enough to out-mosquito you?
âD.H. Lawrence, âThe Mosquitoâ (1920)
Global warming is ushering us into a new mosquito epoch. Ready or not, mosquitoes are coming faster than before, both indigenous and non-, human-biting and not, disease-carrying and sometimesâdisease-carrying. What are we to do with these buzzing creatures, and what has been done with them so far? Usually perceived as a pest or at least as a nuisance, their mere presence often prompts us to take action. Are we able to control, or locally exterminate them, and with what side effects? Or is it more realistic to admit that the three most threatening mosquito generaâthe disease carrying Aedes, Anopheles and Culexâare really controlling us? In recent years, yellow fever has kept spreading even as malaria has been retreating, but over half of the worldâs population is still exposed to these and other dangerous mosquito-carried diseases which also include dengue, West Nile, chikungunya and Zika. Control them we should; we must do, if we are to avoid the next pandemic and survive our mosquito-borne Anthropocene. COVID-19 has been humanityâs latest collective horror, but across deep time, and likely into the foreseeable future, mosquitoes will be responsible for inflicting incalculably greater degrees of suffering and anguish.
But there are important reasons to protect mosquitoes, and not just because these creatures are amazing products of millions of years of evolutionâsince protecting them may in some instances assist us in the battle against various human diseases. Most obviously, we may want to save some mosquitoes for the simple reason that one needs to preserve a few of them in order to figure out how to kill the rest of themâwith other practical reasons detailed below. Yet more subtle justifications for saving mosquitoes centre, for instance, on food web dynamics, whereby in our efforts to poison these creatures, or disrupt their habitat, or rearrange their DNA, we may, through ecological loops, actually cause damage to other biological entities, such as mosquito predators, and end up increasing a mosquitoâs fitness and its ability to multiply and spread across the earth. Perhaps the sciences of mosquito control, or certain sectors of them, have not yet advanced to a stage that we can trust.
Some years ago, Nature journalist Janet Fang posed the simple but powerful question about what the ecological consequences might be of eradicating mosquitoes (Fang 2010). A concerted campaign across the twentieth and twenty-first centuries, after all, has been dedicated to this very goal. In sifting through the evidence, Fangâs final answer is that in the case of this blood-sucking insect, humanity and even ecosystems could probably get along just fine without it. She reports on the views of one ecologist who feels that mosquitoes could readily be replaced in the food web, with many mosquito predators eventually able to switch to moths or houseflies or other sources of food. Although she outlines a host of possible disruptions stemming from the disappearance of mosquitoes, such as the loss of their pollination activities and other ecosystem services, she concludes by quoting entomologist Joe Conlon who believes that ecosystems âwill hiccup and then get on with life. Something better or worse would take over.â Or as Conlon elaborates in his own blog, âI would rather eat raw onions and celery for the rest of my life if I could do away with the little bastardsâ (Conlon 2011).
In these introductory pages we highlight some of the main arguments for saving mosquitoes, before reminding ourselves of vital reasons for setting out to control and eradicate them. Ours is not a comprehensive list, and our main goal here is to stimulate readers to begin thinking about the many reasons for saving or else exterminating these creatures, while outlining some pressing points that will be taken up in subsequent chapters. Confronting this question of how far we can, or should, pursue the goal of mosquito elimination is our central purpose of this book, seeing if there may be a kind of peaceful coexistence that we can achieve with these creatures. In the end, rather than pushing an ultimatum that it must be us or them, can humanity promote and practice a kind of âMosquitopiaâ with these little humming creatures, humanityâs most dangerous companions? Could we develop a relationship with this insect that will allow healthy cohabitation?
The project of searching for and identifying a possible harmonious coexistence involving humans and mosquitoes has implications for the lives and lifestyles of many millions of people affected by mosquito-borne pathogens. But it also becomes a crucial test case for identifying the proper place of people in the natural world. Although mosquitoes are amongst the most intimate of animals accompanying humanity across millennia, similar questions may be asked about scores of other species, including such charismatic ones as bears, dolphins, rhinos and orangutans, whose prospects are shaky, to say the least. The majority of humanâanimal interactions, as well as the greater part of the sixth species extinction crisis we are experiencing, involve many smaller jewels in the treasure box of creation. The mosquito then becomes one example, and an emblematic one to start with.
Some reasons for saving mosquitoes
The first reason for making our truce with mosquitoes is strategic. We must remind ourselves that we are ultimately battling diseases, not mosquitoes, and that there may be more effective, more economical, and more ethical ways to do this than killing that little, ubiquitous insect. Malaria, for instance, once emanated from swamps and the bad air they produced, although with more evidence it became clear that mosquitoes, rather than effluvia, were the vectors (or transmitters) of the malaria parasite. Should we be putting greater efforts into battling this microscopic Plasmodium rather than the carriers of them, as by developing more effective malaria drugs? Or should we be focusing at still-smaller levels, as by managing the chemical reactions set in motion by the Plasmodium, or else by treating the resulting symptoms, to let the body take care of itself? Two generations ago, zoologist Marston Bates considered the use of the powerful insecticide, DDT, to be the âsledge hammer approach to mosquito controlâ since this chemical caused so much collateral damage to other living things, from birds and fish to desirable insects such as bees (Bates 1953). An early anti-malarial medication such as Atabrine was itself a sledge hammer approach in the human bloodstream, since people often felt quite nauseous after taking it. With the ecological knowledge accumulated and the microbiological techniques developed since then, isnât it more realistic to see all population-level control techniques, whether applied to wetlands or to human bodies, as sledge hammers? And as our understanding of mosquito-borne diseases becomes more precise and accurate, the surgical response of today may seem like a sledge hammer tomorrow.
Eradicating any of the mosquito-borne diseases may therefore necessitate the extermination not of mosquitoes, but of the pathogens themselves. The malariologistsâ phrase of âanophelism without malariaâ (or, the presence of anopheles mosquitoes without malaria) is known in many countries where the disease practically disappeared decades ago. Notwithstanding the differences in ecologies of other vectors and their transmission mechanisms, can we aim at parallel situations of âaedeism without dengueâ or âculexism without West Nileâ? The distancing of a pathogen from a human populationâand even its total eliminationâmay be less challenging and less problematic than insect eradication. Because there are pros and cons to every health remedy, we need to return to ecological principles as well as costâbenefit analyses, before marching forward with any one strategy for disease control.
A second justification for preserving mosquitoes centres on medical reasoning. Modern epidemiological research reveals that there may be important benefits to maintaining discrete, residual levels of pathogens in a population so as to maintain immunological signals that our bodies can react to and maintain resistance against. Madagascar provides a telling example: when malaria was largely eradicated from parts of that large island between 1960 and 1980, it returned there several years later with more deadly virulence. Maintaining some mosquitoes there, and with them the diseases they transmit, means that human physiologies would not become naively adapted to an environment only temporarily free of this or that disease (Carter and Mendis 2002). A related issue is that certain kinds of less dangerous malaria can provide a degree of protection from more dangerous forms of it: a person infected by Plasmodium vivax is often given some resistance against being infected by the more lethal Plasmodium falciparum (Snounou and White 2004). In this case, a normal, mosquito-transmitted vivax malaria can be the lesser evil of contracting falciparum malaria.
There are also important ecological reasons for keeping mosquitoes buzzing, based on arguments pointing to the special role of these arthropods in ecosystems. Metric tons of flying biomass certainly alter natural processes, whether as foodstuff for other organisms or as modifiers of animal behaviour, as in the case of caribou and Homo sapiens who move or migrate to avoid them. Enormous numbers of friendly insects fall victim to the many projects of mosquito control (Török et al. 2020). Mosquitoes carry parasites and pathogens, not only to humans, but also to many other mammals, birds and reptiles. Microbes transmitted by mosquitoes to bats help control the numbers of the latter, thereby controlling the human diseases spread by these winged mammals. Moreover, it is only female mosquitoes that transmit pathogens by feeding on blood while their male counterparts generally subsist innocuously on plant nectars. Some mosquitoes even control other species of mosquitoes, since certain adult species feed on larvae of other species (Roux and Robert 2019). These mosquito-borne benefits are a sampling of reasons for maintaining at least some mosquitoes in ecosystems, or else bringing many of them back if drastically reduced.
Yet another rationale for saving mosquitoes is the evolutionary one. As an example, parasites and hosts coevolve, sometimes with beneficial results for both, since both members in such relationships generally become more tolerant of the other through time. Or at least this is the argument of Nobel laureate Joshua Lederberg for why the virulence of parasites can diminish over decades and centuries (MĂ©thot 2012). Cautious hands-off approaches to vector control therefore allow nature to take its course, with harmful results balanced increasingly by beneficial ones over the longer run. There appear to be indispensable long-term roles for many of our bodily symbionts, and human acts of interference in their transmission may, over the short or long term, cause more harm than good.
From a more cognitive perspective, we may identify ethical reasons for leaving mosquitoes alone. Do humans have the right to kill or exterminate other creaturesâor the right to transform or disrupt whole ecosystems? Is it justifiable to exterminate when we are still quite unsure how the many parts of an ecosystem fit together? If we are placing humans at the top of the pyramid of creation, what does that tell us about ourselves and our place in the future? To date, we have never been able to rid islands or continents of mosquitoes despite dogged efforts to do soâor at least not for very long: what makes us believe we can exterminate them now? More often than not, hubris has been the rule, not the exception, in describing humanityâs attitude towards managing the non-human world. The question of eliminating mosquitoes should not be undertaken while being detached from wider global and environmental contexts. Our current and ongoing sixth mass extinction episode is gathering force, already eliminating thousands of species, while impoverishing the biosphere and annihilating millions of years of evolution. Such dramatic changes carry with them exceptional uncertainty, notably as potential adverse repercussions, be they ecological, political and/or economic. A key general guideline is the precautionary principle which may be phrased: âin case of doubt, stop.â Such precautions may be more applicable to biodiversity preservation than to almost any other environmental problem (Myers 1993).
The scope of the extinction crisis may contribute to a notion of helplessness, by assuming that the saving of a few species of insects is a marginal concern that would not change much. Yet the severity of the crisis may pose a super-premium on applying the precautionary principle even more broadly: the burden of proof is on those aiming at eradicationâcall it deliberate extinction. As in so many other issues, a decent portion of modesty is a key strategy for making the right decision.
And yetâis it even thinkable that humans can propose a moral justification for not seeking every means possible to curtail or eliminate disease-spreading organisms? Is it ethically responsible t...
