Context: Transgenic mosquitoes transfer genes to native mosquito species, a scientifc study reveals.
Relevance: GS 3 Science and Technology- developments and their applications and effects in everyday life, GS 2 Health
What are the findings?
- Contrary to claims made, genes from genetically-modified Aedes aegypti mosquito were found to have been transferred to naturally-occurring A. aegypti mosquito population in three areas in Brazil where transgenic mosquitoes were released.
- It is unclear if the presence of transgenic mosquito genes in the natural population will affect the disease transmission capacity or make mosquito control efforts more difficult.
- Researchers from Yale University studied 347 naturally-occurring A. aegypti mosquitoes for the transfer of genes from the transgenic insects. (The transgenic strains can be distinguished from naturally-occurring mosquitoes by using fluorescent lights and filters)
- Find that some transgenic genes were found in 10-60% of naturally-occurring mosquitoes.
- The naturally occurring A. aegypti mosquitoes carrying some genes of the transgenic mosquitoes were able to reproduce in nature and spread to neighbouring areas 4 km away.
A.aegypti mosquitoes are responsible for transmitting
- Chikungunya and
- Zika virus
Why this method of transferring genes is necessary?
To control these viruses:
- The genetic strategy employed to control A. aegypti population known as RIDL (the Release of Insects carrying Dominant Lethal genes) is supposed to only reduce the population of the naturally occurring A. aegypti mosquitoes and not affect or alter their genetics.
- The genetic strategy works on the premise that the transgenic male mosquitoes released frequently in large numbers would compete with the naturally occurring male mosquitoes to mate with the females. Offspring from the mating of transgenic male mosquito and naturally occurring female mosquito do not survive to the adult stage.
- This is because tetracycline drug, which prevents the dominant lethal gene from producing the lethal protein during rearing in labs, is not present in sufficient quantity in nature.
- In the absence of tetracycline, there is an overproduction of the lethal protein causing the larvae to die.
- Earlier was the claim that the gene would not transfer as offspring of these two would die, but the case was reversed.