Tag Archives: mosquito

Genetically modified insects and the precautionary principle

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Last week the Guardian newspaper reported on the findings from the UK House of Lords’ science and technology committee into the development and use of GM insects. According to the committee’s chairman, Lord Selborne:

“GM insect technologies have the potential not only to save countless lives worldwide, but also to generate significant economic benefits for UK plc, where we are an acknowledged world leader.”

No surprises there. The case for GM insects to be developed as a form of vector control has many proponents and seizing an economic opportunity is to be expected from the Lords. Apart from a cursory explanation of the means of developing GM insects, and a mention of the fact that the committee would like to see a reform of European Union regulation around GMOs (more on this later), the reporter fails to consider any environmental issues that may arise from the release of transgenic insects, in what seems to me to be a failure of research and the rehashing of the committee’s summary report.

Thankfully, in an attempt to provide a balanced argument the Guardian also published a piece that was more critical of the report, describing it as  “an unsophisticated form of moral blackmail” and laying out the possible extinction risks associated with gene drive systems. The scientific knowledge gap is highlighted by these authors, who write:

“We are not against GM insects. Our point is that we do not know enough. Nobody knows enough.”

Though I commend these authors for responding to the Lords’report in a more critical way, there are still a couple of findings in the report that hadn’t been directly addressed and which I think need exploring further.

The first is the issue of EU regulations of GMOs that the Lords describe as “failing lamentably” and would like to see amended. This critique is aimed at EU Directive 2001/18/EC which states that “due attention be given to controlling risks from the deliberate release into the environment of genetically modified organisms”. This is to be conducted through case-by-case environmental risk assessments, public consultation, a requirement to consult all relevant scientific and ethical committees, and development of “a mechanism allowing the release of the GMOs to be modified, suspended or terminated where new information becomes available on the risks of such release” before consent will be granted. It is a very robust piece of legislation which, when linked with Regulation (EC) No 1946/2003 that restricts the release and transboundary movement of any GMO within EU member states, makes this not “lamentable” as the Lords would have us think, but sound legislation based on the Cartagena Protocol which states that products from new technologies must be based on the precautionary principle and allow nations to balance public health against economic benefits. And which allows countries to ban imports of a genetically modified organisms if they feel there is not enough scientific evidence that the product is safe. It seems to me that an attack on the governing EU legislation is also an attack on the Cartagena Protocol which environmentalists need to be aware of.

The international consensus of the definition of the Precautionary Principle is:

“When human activities may lead to morally unacceptable harm that is scientifically plausible but uncertain, actions shall be taken to avoid or diminish that harm.”

And this brings me to my second concern about the House of Lords report, wherein Professor Rosemary Hails states that:

“the Precautionary Principle properly applied would also take into account the risks of not developing a particular technology and the benefits forgone. It is a misuse of the Precautionary Principle that has led us to this place.”

This reconstitution of the Precautionary Principle is a matter of great concern and has already been discussed at some length by the House of Commons Science and Technology Committee in their Fifth Report: Advanced Genetic Techniques for Crop Improvement: Regulation, Risk and Precaution wherein Sir Mark Walport framed the precautionary principle not as a response to scientific uncertainty, but as a guide to evidence-based decision-making. He said:

“Decisions must be informed by the best evidence and expert advice. The application of the ‘precautionary principle’ can help to guide this. This simple idea just means working out and balancing in advance all the risks and benefits of action or inaction, and to make a proportionate response. All too often, people citing this principle simply overreact: if there is any potential hazard associated with an activity, then it should not be done, or, if it is already being done, it should be stopped.”

By removing the imperative for evidence and advice that is provided to governments to be based on the principles and rigour of scientific enquiry, the report is effectively providing ministers with a means of bypassing environmental legislation. A recent example of this is when George Eustice MP recently cited food security as a reason to maintain the use of neonicotinoid pesticides under this bastardised definition of the Precautionary Principle.

If it were as simple as Sir Mark maintains to identify and stop hazardous activities we would not be facing some of the world’s current health and environmental catastrophes. That is why we must legislate against them and that is why scientific evidence needs to be the basis for that legislation. And when that evidence is lacking or inconclusive, aren’t we safer not taking the risk in the first instance?  If, as Prof. Hails maintains we need to consider the risks of not using certain technologies for their potential benefits we have to ask ourselves whose benefits are we talking about.

Mosquito extinction. Is it really a good thing?

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A few years ago I read an op-ed piece in the journal Nature that celebrated the potential demise of mosquitoes as scientists prepared to release genetically modified mosquitoes in Brazil in an attempt to eradicate populations carrying malaria. What most struck me about the piece was that the author concluded that mosquitoes performed no ecological function and that the world would be a better place without these pestiferous nuisances. This statement left me feeling a little uneasy. How certain could we actually be that mosquitoes performed absolutely no ecological function?

“Eradicating any organism would have serious consequences for ecosystems — wouldn’t it? Not when it comes to mosquitoes…”

In 2014 I listened to a podcast produced by Radiolab that reiterated the pointlessness of mosquitoes and again I wondered whether this could really hold entirely true. Apart from David Quammen’s valiant effort to convince us of the mosquito’s general innocence (it is after all only the females that bite, and even this is only in order to produce young). He also asks us to imagine just how quickly deforestation and exploitation of the tropics would have progressed without the relative protection afforded by the mosquito and all of it’s diseases.

 

According to the World Health Organisation (WHO) 17% of the global estimate of all infectious diseases are vector-borne. Of these, mosquito-borne diseases constitute the majority, with malaria causing an estimated 627,000 deaths in 2012 and infecting 1.5 to 2.7 million people a year. Some of the other mosquito-borne diseases that affect humans are Dengue fever, West Nile virus, Yellow fever, Lymphatic filariasis, Japanese encephalitis, Rift Valley fever, and Chikungunya; causing death, suffering and both social and economic hardship.
There are approximately 3,500 named mosquito species in the world. They are found in a variety of habitats in every biogeographic region apart from the Antarctic. Of these, only 40 Anopheles species are known to be effective transmitters of human malarial infection and only around 350 species are regarded as effective in all mosquito-borne human disease transmission.  The catholic nature of mosquitoes in relation to habitat selectivity is best illustrated in the breadth of the geographic area covered by dominant malarial Anopheles mosquitoes.  Mosquitoes are highly speciose, with the greatest species diversity being found in the Neotropical regions as shown in the map below.

 

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This preponderance of mosquitoes to cause such human hardship has led to a variety of campaigns designed to control and eradicate them; from the use of DDT in the 1940s to attempts to sterilise males through exposure to radiation. Though there has been some success with these methods in the past, elimination of mosquitoes in the tropics has always proven difficult due to mosquito resistance, pathogen resistance to treatments, the lack of infrastructure and financial support. Conventional means of avoiding infection from mosquito-borne diseases have been to prevent being bitten through the use of mosquito nets and chemical repellents. I was therefore rather intrigued to hear about the work of Oxitec, the Alphey Lab and others in relation to developing genetic controls to exterminate this “winged scourge”.

The ecological niche filled by mosquitoes is little understood and has been poorly studied. In 2010, at the British Ecological Society’s annual meeting, the chair, Professor Charles Godfray said:
“We know very little about the [mosquito] community ecology… and this is significant because if you were to knock it out then you want to know what would take its place. […] And we don’t know enough, not for the want of trying, about the dispersal of the mosquitoes; how they move from one place to another.”
I simply couldn’t believe that such a large knowledge-gap existed with regards such an ubiquitous insect, so I decided to survey the scientific literature to figure out what is currently understood to be the ecological function performed by mosquitoes. I found that a very small number of papers actually concerned themselves with this topic directly and those that did were generally in relation to highly specific niches like larval processing of detritus chain interactions within pitcher-plants, the pollination of orchids, or focused on other species entirely, such as reindeer and caribou whose migration behaviour is influenced by the predation of mosquitoes and other biting flies. Understandably, most papers concentrated on the mosquito as disease vector – especially in relation to humans – but, apart from noting that mosquitoes constitute an enormous biomass, are found in both freshwater and terrestrial ecosystems at different life stages, and that they are highly speciose; there has been little scientific research into their ecological significance. We can extrapolate that they must be an important food source for a number of other insects, birds, reptiles, fish, amphibians and even mammals, but the data is lacking to support this – we need more research to be conducted to be certain. There is also a possibility that mosquitoes contribute to a disease dilution effect, but further study would be required to support any such claim.
So, is it a good idea to locally exterminate mosquitoes if we really don’t have any idea what will happen to their ecosystems? I would suggest that it probably isn’t the greatest idea. Possible scenarios are a reduction in available food for predators that will cause greater predation on other food sources thereby decreasing these at a faster rate and increasing competition. Increased competition can in turn lead to lower reproductive success and in the worst-case scenarios population collapse of apex predators. At least, I think it would be safe to assume that those ecosystems would no longer operate in the same way – their species composition would shift  to a greater or lesser degree and with that the functional ecology.

And what about the disease dilution effect? Well, if it holds true in the case of mosquitoes then we may witness an intensification of disease virulence and higher infection rates. An alternative hypothesis is that the pathogens might move into other host species and we would be left scrabbling for new control mechanisms.

As someone with a desire to understand the intricately interlinked nature of our world and all the living creatures in it, I couldn’t support the deliberate extinction of any species (despite the detrimental effects it can have on humanity) without first knowing what the knock-on effects of that extinction would be. In doing something that we hope would benefit humanity, we may in fact be creating new and more complex problems.

An American entomologist, Jeremy Lockwood, wrote of the need to establish an ethical basis of “philosophically sound, scientifically consistent” considerations with regards our relationship to insects. He proposed that we refrain from taking actions that would kill or cause nontrivial pain to insects, but not if by avoiding those actions there would be nontrivial costs to human welfare. Genetically modified mosquitoes, and by association other mosquito control mechanisms, would presumably be considered acceptable to most people within this  anthropocentric ethical framework. The irony of this position however is, as Lockwood points out, that a person considered a humanitarian is often referred to as, “one who wouldn’t hurt a fly”.
This blogpost is based on my final-year research paper. For those of you wanting a bit more in-depth information, you can read the full paper here.

References:

Alphey, L. (2014). Genetic Control of Mosquitoes. Annual Review of Entomology59(1), 205–224. doi:10.1146/annurev-ento-011613-162002

Fang, J. (2010) Ecology: A world without mosquitoesNature News, 466(7305), 432–434. doi:10.1038/466432a

Godfray, H. C. J. (2013). Mosquito ecology and control of malaria. Journal of Animal Ecology, 82(1), 15–25. doi:10.1111/1365-2656.12003

Lockwood, J. A. (1987). The Moral Standing of Insects and the Ethics of Extinction. Florida Entomologist70(1), 70 – 89.

Sinka et al. (2012). A global map of dominant malaria vectorsParasites & Vectors5(69). doi:10.1186/1756-3305-5-69

World Health Organisation http://www.who.int/whr/1996/media_centre/executive_summary1/en/index9.html.