Photo by Leszek.Leszczynski via Flickr CC
In an effort to slow the spread of malaria, scientists are trying to go to the source -- not just by stopping mosquitoes, but stopping how mosquitoes reproduce. Scientists have bred a spermless male mosquito that could be released into the wild to reduce mosquito populations.A new kind of male mosquito
Back in April we learned about genetically modified mosquitoes that are equipped with the ability to kill off the malarial parasite so that it cannot be transmitted to humans. Now, scientists have taken another approach. Rather than battle a mosquito's ability to carry malaria, it's battling the male mosquito's ability to carry sperm.
"Insect sterilisation isn't new: scientists have attempted to control the sleeping sickness-carrying tsetse fly by exposing them to radiation to render them sterile. A similar approach has been successfully used against the potatoes weevil in Japan and the tropical screwworm that attacks cattle," reports BBC. However the same tactic has not been shown to work with mosquitoes because the males are too frail to mate with females. So, scientists have come up with another strategy.
Turning off genes for reproduction
Entomologist Flamina Catteruccia, along with her graduate student Janis Thailayil, injected 10,000 mosquito embryos with fragments of RNA that turn off the gene essential for sperm development. This resulted in about 100 spermless males, all of which females were willing to mate with. In total, spermless males mated with 34 females in the experiment, essentially tricking them into laying infertile eggs. Since female mosquitoes only mate once in their life, they will continue to lay infertile eggs until they die.
One might be worried about unintended consiquences of such a strategy -- after all, while mosquitoes do carry malaria and other diseases that harm humans, they're also an important food source for many other animals, from insects to bats, birds, spiders and so on. Wiping out populations could have negative effects that trickle along the food web.
However, while the theory may go that researchers could release sterile males until mosquito populations effectively disappear, Dr. Catteruccia states that this method is far too expensive to keep up and have an effect on mosquito populations. Indeed, it took months of labor and thousands of tries to hatch just 100 spermless males. One hundred mosquitoes could be eaten, squashed, or otherwise kick off in just one night, without having the ability to mate with females at all.
Traditional methods of dealing with mosquitoes still reign
Still, the research is important to show that females will mate with spermless males. As mosquitoes become more resistant to insecticides, figuring out ways to make them sterile may be important. And such methods as this may be much more preferable to spraying insecticides, which can harm the humans who handle it, other animal species, contaminate water and have other negative side effects. But for now, the focus for battling malaria must still revolve around clearing out or covering standing water, mosquito nets for people to use at night, and medical treatment for areas hit with malaria outbreaks -- and yes, maybe even lasers.