To Modify or Not to Modify?: Environmental Effects of Genetically Modified Mosquitoes

Illustration by Caroline Cao

Illustration by Caroline Cao

Remember the last time a mosquito landed on you? While to most people this is a minor inconvenience, to others it is an immense medical threat. According to a 2014 report published by the World Health Organization, 3.4 billion people in the world are at risk for malaria and 2.5 billion for dengue, illustrating the widespread threat posed by vector-borne diseasesdiseases transmitted by ticks, mosquitoes, and other insects. Current methods of dealing with vector based disease in regions like Sub-Saharan Africa and South America include insecticide application and treated bednets. However, these techniques are quickly becoming dated and inefficient in the face of growing populations of people and vectors, leading to a new propositiongenetically modified mosquitoes (GMMs). Genetic modification of mosquitoes aims to make mosquitoes sterile to lower reproductive rates or to propagate a gene that reduces disease transmission. While its proponents claim that its effectiveness in field trials and simplicity make it a practical choice for use, others believe that it may have consequences we are not yet fully aware of. GMMs can effectively lower transmission rates of diseases, but have environmental impacts that must be responded to with more research and modification.

One approach to genetically modify mosquitoes is through gene drive, a process defined by immunology and health law professors Ostera and Gostin as “a mechanism to spread [genes] in the mosquito population at a faster rate than would be expected of mendelian inheritance.” . Scientists can spread any particular gene, one helpful in making the mosquitoes less susceptible to becoming vectors of disease, through the population. The results from trials suggest that the model can be a successful choice for disease control, but the technique raises concerns about environmental risk environmental risks, including a reduction in mosquito competition and undesired exposure of the gene to other populations. Epidemiologists in Nigeria found it plausible that GM mosquitoes may spread uncontrollably or hybridize with unknown consequences. Several biologists, in a 2002 study of the ecology of GMMs contend that our lack of complete knowledge regarding disease transmission ecology is the main reason for the concerns regarding possibilities. The reports reveal that the developing status of GMM technology is an issue for implementation, highlighting the need for ecologists to focus on gene flow along with mosquito mating and immigration patterns in order for progress to be made.

Another model for the genetic modification of mosquitoes is the production and release of sterile males into an ecosystemknown as the Sterile Insect Technique (SIT). Several researchers assert that this method will promote lower reproductive rates in a population and stop the spread of the disease. A study conducted by immunologist Megan R. Wise de Valdez and her colleagues (2011), for example, studied SIT and found the model to be effective in lowering reproductive rates and even eliminating a population if necessary. This issue is a concern for many critics of genetic modification, however, who further assert that artificially introducing sterility can be a threat to biodiversity. John D. Mumford, a researcher at the Centre for Environmental Policy in the United Kingdom (2012), points out that mass releases are dangerous because the organisms are able to interact with not only their own habitat, but others as well, causing populations to decrease in unintended regions. This is an issue that cannot be addressed by restricting or isolating ecosystems, since the environment is inherently interconnected. As suggested by several researchers, regulatory laws that ensure proper infrastructure are in place to monitor areas and have become a vital part of SIT use. More systems allowing ecosystem surveillance and the monitoring of immigration and emigration rates are necessary to develop a more concrete basis for implementation of SIT.

After looking at the potential environmental benefits and risks for both forms of genetically modifying mosquitoes, it is necessary to compare GMMs to current tools that minimize vector-borne diseases in developing countries to understand which are more environmentally beneficial. According to one study in 2002, mosquito populations may experience growth after insecticide application is halted. However, treated bed nets cause little pollution and provide a reduction of early contact between mosquitoes and children that greatly diminishes the possibility of contracting malaria. These qualities of existing control methods may make them seem like the better option, but the continual use of techniques like insecticides have led to the creation of resistant populations of mosquitoes. Hassan Mshinda, a researcher at the Ifakara Health Research and Development Centre in Tanzania, along with colleagues Killeen, Mukabana, Mathenge, Mboera, and Knols (2004) compounds the pros and cons by stating that while current control techniques are powerful, they are becoming inefficient when used alone. Mshinda’s research, therefore, supports the idea that implementation of GMMs should be performed alongside current methods rather than completely replacing them.

Using genetically modified mosquitoes to combat deadly vector-borne diseases has been proven to have many positive disease transmission effects, but also presents some considerations regarding environmental risks. As an emerging technology, genetic modificationas well as the ecology of mosquitoesrequires more research before it can be implemented. Most importantly, the environmental impacts and a fear of the unknown effects have concerned researchers and those living in areas where GMM releases are being suggested. (Palmer, 2015). However, the United States Food and Drug Administration (2016) most recently declared a finding of no significant negative environmental impact based on results from a trial in Florida, symbolizing a step in the growth of GMMs towards a safer, healthier society for all. Once results from various studies are synthesized and more trials are conducted in developing regions, the world can implement genetically modified mosquitoes and save lives from deadly vector-borne diseases.

Edited by: Amaan Qazi

Illustrated by: Caroline Cao

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