Genetically engineered male mosquitoes can kill females with their semen, according to Australian research. This approach can limit outbreaks of many mosquito-borne diseases worldwide. The toxic semen will control the mosquito population.
The Method
The genetically engineered male mosquitoes will produce sea anemones and spider venom proteins. They will inject these proteins into the females during mating. The act will kill the females, thus controlling the mosquito population. The researchers at Macquarie University have been testing this technique, which they call “toxic male technique.” They tried it on a species of mosquito that spreads viruses like Zika and dengue. The test subjects were fruit flies.
According to Sam Beach (lead author), this species-specific method can suppress outbreaks of many mosquito-borne diseases. One of these illnesses is dengue fever, which produces 390 million cases globally every year. Spraying so many types of insecticides is not necessary anymore. Skipping insecticide spraying will spare millions of local insects and ecosystems.
The scientists injected a new gene into fresh mosquito eggs. They used tiny glass needles. It was a tedious process that was necessary to produce toxic males. The females will mate within a day or two of hatching from the eggs. They are the only blood feeders because they need to nourish the eggs they produce. The females can live on for many weeks and bite people. They will stop once they are ready to lay their eggs. Research shows that this technique could decrease blood feeding rates by 40% to 60%.
The Growing Mosquito Problem
Many scientists are aware of pesticide resistance, which is already a global problem. That is why many experts are developing alternative pest management techniques. The bad news about pesticide resistance is that mosquitoes develop it and they can also spread it. Mosquitoes can evolve to become resistant to pesticides. They can spread this trait by getting on planes and boats. Another contributor to the crisis is climate change. It causes mosquitoes to suddenly appear in areas they had not been present before.
Despite the growing mosquito issue, some scientists believe that the ideal solution to the crisis is to control mosquito populations rather than eradicate them completely. Although they are vectors of diseases, they are still part of the food web. Mosquitoes are valuable food sources for small animals like bats and fish. These insects are also valuable pollinators.
Poisoning the Females
As of now, scientists are making fruit fly males poisonous to the females. Toxic proteins are derived from a sea anemone and a Brazilian spider—both with potent venom. The proteins are expressed in the seminal fluid-producing glands of the male fruit flies. In theory, the injection of the modified seminal fluid into the eggs will poison the females.
The toxic proteins should have low molecular weight to pass from the receiving reproductive organs to the vital organs until they reach the central nervous system. The fluid proteins will bind to the receptors in the CNS. Again, in theory, the male mosquitoes will not be affected by the toxic proteins. Scientists believe that the toxic male technique (TMT) may decrease blood feeding. The toxic males must be fertile to ensure many females die during mating.
Targeted Females
The targets are not the female offspring of wild females and modified males. The TMT targets are the wild females. An Aedes aegypti female has a lifespan of two to three weeks. They will mate within 24 to 48 hours of emerging from eggs. They will need about 0.63 to 0.76 blood meals each day. Female mosquitoes that mate with modified males may not have fertile offspring, but they can still destroy crops or spread diseases.
What About the Natural Predators?
Researchers are considering the impact of the venoms on the organisms that prey on mosquitoes. Amphibians, birds, and bats are the most common. The authors reassure everyone that the venoms in the seminal fluid are far more toxic when injected than when ingested. They say that the venom-filled seminal fluid is meant only for the wild females during mating.
Genetically engineered male mosquitoes are meant to kill wild females during mating. Some say that this is an effective way to remove the populations of the deadliest animals on earth. Others say that these insects must not be harmed but controlled. There will be more ways to prevent the spread of mosquito-borne diseases. Hopefully, this one could make a dent.