Maarg Manthan · Topic 11.28

Genetically Modified Mosquito for Vector Control

Science & Technology › Biotechnology – Applications · Topic 11.28

Genetically modified mosquitoes are mosquitoes whose genes have been changed to reduce the number of disease carrying mosquitoes or to stop them from spreading pathogens. Mosquitoes of the genus Aedes spread dengue, chikungunya, Zika and yellow fever, and Anopheles mosquitoes spread malaria. The best known approach is the self-limiting Aedes aegypti developed by the company Oxitec, in which released males carry a gene that kills their offspring before adulthood, so the wild population falls. Other approaches include gene drives that spread infertility or resistance genes, and population replacement. The non-genetic Wolbachia method, which uses a natural bacterium that blocks viruses, is often discussed along with them.

5 min read · UPSC Prelims · Science & Technology · Biotechnology – Applications

At a Glance

Target diseases Dengue, Zika, malaria
Main strategy Self-limiting males
Spreading strategy Gene drive
Non-GM option Wolbachia
Company Oxitec
Exam link UPSC Prelims, Science & Technology: Biotechnology – Applications

Where Does It Fit?

This topic follows the UK gene editing licence. It applies gene technology to public health, where the aim is to reduce mosquito borne disease by changing the mosquito itself. Previous topic: UK’s Approval of Gene-Editing License Research. Next topic: DBT’s “Sohum” Newborn Hearing Screening Device.

What Are the Strategies to Control Mosquitoes by Genetics?

Strategy	How it works
Self-limiting Aedes	Males carry a gene that causes offspring to die before adulthood. Released males mate with wild females, and the wild population shrinks. The effect disappears without repeated release
Sterile insect technique	Males sterilised by radiation are released. Used for some insects and tested for mosquitoes
Gene drive for suppression	A gene that causes female infertility spreads through the population and may crash it
Population replacement	Mosquitoes are engineered to be unable to carry the parasite or virus, and the trait spreads
Wolbachia	Mosquitoes carry the bacterium Wolbachia, which blocks dengue virus. Males with certain strains cause egg failure when they mate with uninfected females
Conventional methods	Larvicides, bed nets, repellents and removal of breeding sites remain the base of control
Integrated vector management	Combines all methods, with community participation

What Do Trials Show and What Are the Concerns?

Cayman Islands: Oxitec first released engineered Aedes in 2010 and reported large drops in the local mosquito population
Brazil: releases in Piracicaba and other cities reported strong reductions in Aedes numbers in treated areas
United States: the Environmental Protection Agency permitted trials in Florida Keys and California, with releases from 2021
Wolbachia trials: the World Mosquito Program reported large falls in dengue cases in Yogyakarta, Indonesia
Gene drive progress: drives were shown in cages to crash mosquito populations, but field release is not yet approved
Concerns: effects on ecosystems and food webs, replacement by other mosquito species, gene escape and public trust
Consent: communities must be informed and agree before release
Cost: repeated release of many males is expensive compared with other control methods

What Else Should You Remember?

Aedes and Anopheles: Aedes aegypti bites in the day and breeds in small clean water containers, while Anopheles bites at night and carries malaria
Dengue in India: India reports hundreds of thousands of dengue cases some years, with increases after monsoon, and the National Centre for Vector Borne Diseases Control coordinates programmes
Indian trials: a 2010s collaboration between Oxitec and an Indian company planned work with the Genetic Engineering Appraisal Committee, but there has been no approved large scale release, so check the latest status
Wolbachia in India: the Indian Council of Medical Research has studied Wolbachia mosquitoes in Puducherry and elsewhere
Biosafety: release of genetically engineered mosquitoes in India would need approval under the 1989 Rules, as in Biosafety Protocols
Cartagena Protocol: movement of engineered mosquitoes across borders is regulated as living modified organisms
Target Malaria: a research consortium working on gene drive mosquitoes for Africa, funded by foundations
Self-limiting versus gene drive: the first fades with time, while the second is meant to persist and spread, so regulators treat them differently
Mosquito free zones: a long term goal that needs more than genetics, including clean water, drainage and surveillance
Climate change: warming expands the range of Aedes, so more regions face dengue risk
Link: broader insect methods are discussed in Genetically Modified Insects
Link with CRISPR: gene drives rely on CRISPR, as in Gene Editing (CRISPR) and Gene Therapy
Vector control principle: vector control means lowering the number of disease carrying insects or their contact with people, and genetic methods are one more tool beside nets, spraying and drainage
Cost per person protected: trials report costs per person per year, and public programmes compare these with larvicides and fogging before adopting a method

Why Does It Matter for the Exam?

Vector facts: which mosquito carries which disease
Strategies: self-limiting, gene drive, Wolbachia
Biosafety: approval requirements
Current affairs link: dengue outbreaks and trials
Common errors: calling Wolbachia a genetic modification, or confusing Aedes and Anopheles

As an analytical point, genetic tools could add to dengue and malaria control, but they cannot replace sanitation and surveillance. Community consent and phased trials are key to safe use.

Why Is This Topic Important?

Vectors Aedes and Anopheles
Methods Self-limiting and drive
Safety Consent and approval

What Came Next?

The next topic covers the Sohum newborn hearing screening device. Next topic: DBT’s “Sohum” Newborn Hearing Screening Device.

Key People and Terms

Vector Carrier of a pathogen
Self-limiting Effect that fades
Gene drive Biased inheritance
Wolbachia Virus blocking bacterium
Larvicide Chemical killing larvae
IVM Integrated vector management

Exam Corner

Points to Remember

Aedes: dengue, Zika, chikungunya.
Anopheles: malaria.
Oxitec trials began in 2010.
Wolbachia is a bacterium.
Gene drive spreads; self-limiting fades.

Do Not Confuse With

Aedes and Anopheles Dengue vector versus malaria vector
Wolbachia and GM mosquito Natural bacterium versus altered genes
Sterile and self-limiting male Sterilised by radiation versus lethal gene in young

Memory Hook

Aedes for dengue, Anopheles for malaria; males that limit, drives that spread, Wolbachia that blocks.

Mains Angle

Questions ask about strategies and ecological concerns. These points help.

Promise Disease reduction
Risks Ecological and social
Way Integrated control

A Question You May Face

An original practice question, not a past paper question.

“Evaluate the potential and risks of genetically modified mosquitoes for the control of vector borne diseases in India.”

How to Answer

Disease burden Dengue, malaria.
Methods Self-limiting, drive, Wolbachia.
Risks Ecology, consent.
Way Integrated control.

GS Relevance

Prelims: Aedes versus Anopheles, self-limiting mosquitoes, Wolbachia, gene drive. GS Paper 3: science and technology, health, biotechnology and biosafety.

Frequently Asked Questions

What is a genetically modified mosquito?

A genetically modified mosquito is a mosquito whose genes have been altered to reduce disease transmission. In self-limiting strains, released males carry a gene that causes their offspring to die, so the wild population falls. Other strains use gene drives or make mosquitoes unable to carry viruses or parasites.

How do self-limiting Aedes aegypti mosquitoes work?

Self-limiting male Aedes aegypti carry a lethal gene. When they mate with wild females, the offspring inherit the gene and die before adulthood, so fewer mosquitoes are born. Since the released males die within days, the gene does not persist, and releases have to be repeated to keep the population low.

How is Wolbachia different from genetic modification?

Wolbachia is a natural bacterium that lives inside many insects. When it is introduced into Aedes aegypti, it reduces their ability to carry dengue viruses. The mosquito's own genes are not changed, so the method is not genetic modification, though it is a biological control strategy applied to mosquitoes.

What is a gene drive?

A gene drive is a genetic system that makes a gene pass to almost all the offspring of an organism rather than half, so the gene spreads rapidly. In mosquitoes, gene drives are being studied to cause infertility and reduce populations of malaria carrying Anopheles, but they have not yet been released in the wild.

Which mosquito spreads dengue and which spreads malaria?

Dengue, chikungunya and Zika are spread mainly by Aedes aegypti mosquitoes, which bite during the day and breed in small containers of clean water. Malaria is spread by female Anopheles mosquitoes, which usually bite at night and breed in ponds, paddy fields and slow moving water.

PYQ Practice — Statement Analysis

1 Anopheles mosquitoes transmit malaria.

True

Female Anopheles.

2 Wolbachia mosquitoes carry altered mosquito genes.

False

The bacterium is introduced, not the genes changed.

3 Self-limiting mosquitoes produce offspring that die before adulthood.