‘A Sex Biased Population Of Only Male Flies Could Save Crops’ says Genetics Scientists
Genetics scientists from biotechnology company Oxitec, based in Oxfordshire have proposed using genetically engineered Mediterranean fruit flies, whose genes have been modified to cause the Mediterranean fruit fly population drive itself extinct in the long run. This they say would be an innovative way for pest control.
The Mediterranean fruit fly is a worldwide crop pest which destroys more than 300 types of crops, including wild vegetables, fruits and nuts. They have been causing extensive damage in the wild and to farmer yields around the globe.
The current available control mechanisms include insecticides and sterilisation. However, this has not yielded desirable results mainly because insecticides pose a lot of problems one of which being these pests rapidly develop immunity against them. As for sterilisation, the sterile flies don’t mate as well out in the wild as the other flies in the wild mainly because they have been weakened by the sterilisation process.
In a researched published in the journal proceeding of the Royal Society B, scientist have been able to carry out a successful lab test. In which they were able to genetically engineer a lethal gene in the male species of the Mediterranean fruit fly (medfly, Ceratitis capitata Wiedemann).
This gene in the Genetically Modified (GM) male flies could be passed on to the female flies during mating. When the female fly lays eggs, the modified gene will interrupt the development of the female Mediterranean fruit fly in the laid eggs. Meaning, only the eggs with the male flies will hatch.
In the long run, the Mediterranean fruit fly population will have more males than females by a very big percentage. The male species will find it harder and harder to find mates. After several generations, the specie will die off; spelling the automatic extinction of the Mediterranean fruit fly population without using costly, less effective and sometimes hazardous human interventions like pesticides and sterilisation.
Scientists carried out this experiment in a greenhouse and achieved a “population collapse” of the flies’ population. They now propose releasing these GM male flies into the wild where they will mate with the wild female flies, and automatically spark the reduction of their population in the wild. Leading up to saving farmers from losses incurred from these pests, or the cost of buying the associated pesticides to control these pests.
But there is another group of experts who are opposed to the idea. They say releasing the GM flies into the wild could lead to unintended consequences. One outspoken critic of this genetics innovation, is Hellen Wallace from Genewatch – an organization dedicated to monitoring how genetics technology is being used.
She was especially critical of the long-term effect of releasing millions of these GM flies into the wild. She pointed out that the effects cannot be predicted, and she was also very concerned about the fact that the eggs with the female flies which failed to hatch as a result of this ‘lethal’ gene will remain inside the food crops.
Hellen was quoted, “Fruit grown using Oxitec’s GM flies will be contaminated with GM maggots which are genetically programmed to die inside the fruit they are supposed to be protecting. Contaminated fruit won’t be welcome on the market and could be bad for health. Male GM flies will survive for multiple generations and could be spread worldwide when fruit is transported.”
She said that using a gene killing mechanism against these flies was bound to fail in the long run, as the GM flies would eventually develop resistance or simply seek out sites contaminated with the tetracycline antibiotic to breed.
Tetracycline antibiotic is widely used in agriculture by farmers, and it has been used in the labs during tests by scientists to “silence” the lethal genes. Meaning the tetracycline antibiotic can repress the fatal artificially engineered gene in the flies, and allow the flies to reproduce normally.
The lead author, Dr Philip Leftwich, from the University of East Anglia and Oxitec, responded to these concerns. He gave his assurance that the flies have undergone extensive testing, and there is no reason to believe that adverse effects could come by releasing them out in the wild.
He said, “The nature of the modification to the flies, it’s important to stress, is it makes them disadvantageous to their local counterparts in that they can only produce sons. If we stopped releasing these individuals, they would quickly be removed from the gene pool.”
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