Genetically Modified Mosquitoes

Genetically modified mosquitoes are insects that have been altered using genetic engineering techniques to reduce the population of mosquitoes that spread diseases such as malaria, dengue, Zika, and chikungunya. This approach aims to control mosquito-borne diseases by targeting the vectors rather than relying solely on traditional methods like insecticides or vaccines. Read to learn more.

Genetically engineered insects (GEIs) are insects whose genetic material has been altered using biotechnology to exhibit specific desired traits.

This biotechnology field holds significant promise for addressing various agricultural, environmental, and public health challenges.

For example, Genetic engineering has been used to create sterile male Mediterranean fruit flies. Releasing these sterile males into the wild reduces the population of this agricultural pest.

Strategies for Genetically Modified Mosquitoes

1. Sterile Insect Technique (SIT):
   • Male mosquitoes are genetically modified to be sterile and then released into the wild. No offspring are produced when they mate with wild females, reducing the population over time.
   • Example: The RIDL (Release of Insects carrying a Dominant Lethal) technique used by Oxitec, which produces males that carry a self-limiting gene causing offspring to die before reaching maturity.
2. Gene Drive Systems:
   • This involves inserting genes that spread throughout the mosquito population, either reducing their ability to reproduce or making them resistant to pathogens.
   • Example: The use of CRISPR-Cas9 technology to create gene drives that spread anti-malarial genes through Anopheles mosquito populations.
3. Pathogen Resistance:
   • Mosquitoes are genetically engineered to be resistant to the pathogens they transmit, thus breaking the cycle of transmission.
   • Example: Engineering mosquitoes to carry symbiotic bacteria or fungi that inhibit the development of malaria parasites.

Benefits of Genetically Modified Mosquitoes

Disease Control:

• Potential to significantly reduce the incidence of mosquito-borne diseases, which cause millions of deaths and illnesses annually.
• Directly targets the vectors of disease, which can be more efficient than treating diseases after they occur.

Environmental Impact:

• This could decrease the reliance on chemical insecticides, which can have harmful environmental effects and lead to resistance in mosquito populations.
• Generally targets specific mosquito species without affecting other insects or wildlife.

Cost-Effective:

• Once established, GM mosquito populations can provide a sustainable method of disease control, potentially reducing the costs associated with medical treatments and vector control programs.

Challenges and Concerns

Ecological Impact:

• Potential effects on ecosystems if mosquito populations are significantly reduced or altered. Mosquitoes serve as food for other wildlife, and their reduction could impact those species.
• The removal or reduction of certain mosquito species might disrupt local biodiversity.

Ethical and Social Issues:

• Concerns about releasing GM organisms into the wild and the potential long-term effects. Public education and engagement are crucial.
• Stringent regulatory frameworks are required to ensure safety and efficacy, which can delay implementation.

Technical Challenges:

• Evolutionary resistance to gene drives can develop, potentially reducing the long-term effectiveness of the technique.
• Ensuring that GM mosquitoes do not spread beyond targeted areas can be challenging.

Why in the news?

2024: Djibouti released GM mosquitoes to fight malaria.

• The method targets female mosquitoes, which are predominantly responsible for malaria transmission.
• By reducing the female mosquito population, scientists hope to significantly decrease the spread of the disease.
• Male mosquitoes do not bite and therefore cannot transmit malaria.
• The release is part of the ‘Djibouti Friendly Mosquito Programme’ started two years ago to stop the spread of Anopheles stephensi, an invasive species of mosquito.
• It is a part of a pilot project by Oxitec Ltd, Djibouti government and Association Mutualis, a non-governmental organisation.
• In 2012, when Anopheles Stephensi was first detected in Africa, Djibouti reported 27 cases of malaria. By 2020, the country’s malaria caseload had crossed 73,000.
• This highly invasive mosquito had migrated to Africa from South Asia and the Arabian Peninsula.
• Anopheles stephensi is well adapted to the urban environment which is particularly dangerous for Djibouti, where 70 per cent of the population lives in the capital city and is exposed to the malaria vector.
• This is the first time a genetically engineered mosquito has been released in East Africa and the second time on the African continent.
• Burkina Faso in West Africa conducted the first-ever release of genetically modified mosquitoes in Africa in the village of Bana.

Examples of GM Mosquito Projects

1. Oxitec’s Aedes aegypti:
   • Project: Release of genetically engineered Aedes aegypti mosquitoes in Brazil, the Cayman Islands, and other locations to combat dengue fever.
   • Outcome: Field trials showed significant reductions in local mosquito populations.
2. Target Malaria:
   • Project: Research consortium aiming to reduce malaria transmission in sub-Saharan Africa using gene drive technology.
   • Outcome: Ongoing research with promising laboratory results.
3. Wolbachia-Infected Mosquitoes:
   • Project: Introduction of Wolbachia bacteria into Aedes mosquitoes to prevent them from transmitting viruses.
   • Outcome: Successful trials in several countries, led to reductions in dengue transmission.

Conclusion

Genetically modified mosquitoes represent a promising frontier in the fight against mosquito-borne diseases.

While they offer significant potential benefits in terms of disease control and environmental impact, careful consideration of ecological, ethical, and technical challenges is essential.

Ongoing research, robust regulatory frameworks, and public engagement will be crucial to the successful and responsible deployment of this technology.

Related articles:

• Genetically modified crops and regulations in India
• Synthetic biology
• Recombinant DNA technology
• GM Rubber

-Article by Swathi Satish