Flightless Females Brings Hope For Future

A new technique which renders female mosquitoes flightless has been put forward at a novel control mechanism for Dengue Fever.

Dengue fever, or ‘Bone Crusher disease’ as it has been named, is a tropical disease with 50-100 million reported cases each year. The World Health Organisation claims 40% of the world’s population are now at risk from the disease. It is carried by yellow fever mosquitoes and transmitted through the anti-blood clotting saliva injected during a females bite.

It causes headaches, severe muscle and joint pains as well as shock and haematological effects. There is no treatment currently in use and the disease is managed through treating the symptoms, although there have been some promising developments in recent years.

Along with the problem of treatment there are few effective environmentally friendly control methods for Dengue fever. There is a reliance on pesticides, which can be very harmful to the natural environment.

This new technique works by genetically altering male mosquitoes to possess a gene that will result in any female offspring having disrupted wing muscle development. By doing this, it is hoped that the yellow fever mosquito population will be under control within 6-9 months of implementation.

The discovery was made when it was observed that a region of DNA coding for ‘Mosquito Actin 4’ was found highly concentrated in the indirect flight muscles of the female larvae and of low abundance in males. Gametes were then constructed to have lethal genes fused to the Actin 4 gene, which in adults results in the death of cells where Actin 4 is programmed to be present. The fusion gene was also made to be dominant to the natural form of the gene so that it is successfully inherited by future generations.

In the above image a red fluorescent tag has been attached to the lethal fusion gene and it can be seen in high density in the wing muscle area of females

In the wild, this technology could be implemented by placing the genetically mutated males in fresh water lake. Once hatched the males will fly off and seek a mate. As they will only seek to mate with a female yellow fever it is a very specific treatment. Once mating has occurred and the eggs have matured the female will lay her eggs. They will hatch and the males will fly away. Due to the genetic mutation, the females will be unable to do so and will die resulting in them being unable to transmit Dengue fever.

Whilst this is a promising technique, it remains to be seen whether it will be successfully employed. If it is implemented then the theory could be adapted for other species of mosquito, to target other conditions such as malaria.

Reference:

Female-specific flightless phenotype for mosquito control; Anthony A. James et al; PNAS; 22/02/2010

 

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