Photo by CDC/James Gathany/Wikimedia Commons
In the fight against malaria, researchers have devised a way to create spermless male mosquitoes able to convince females to reproduce with them, according to a study in the Proceedings of the National Academy of Sciences.
Although plasmodia are ultimately responsible for malaria and its deadly consequences, the disease spreads through mosquito bites. In the past, battling the disease with insecticides has led to an increasing number of insects becoming resistant, so scientists have looked for other ways to affect the mosquitoes life cycles — one being interfering with reproduction.
But it gets more complicated. Malaria isn’t transmitted by male mosquitoes; only pregnant females bite people for their blood. By studying one (Anopheles gambiae) of the 40 mosquito species that spread the disease in nature, researchers created 100 male mosquitoes without sperm.
In the experiment, researchers “silenced” a gene called zpg needed for males to produce healthy sperm cells. When they encountered females, they were just as competitive as other males and could mate, but their rendezvous didn’t result in offspring.
So how does tinkering with males’ sex cells affect the behavior of females?
After mating — or thinking they did, females do not mate again, the researchers found. Mating once is typical for the species, but scientists were initially unsure of whether interacting with spermless males would create the same reaction in females. It turns out their idea was successful.
Many insect sterilization efforts have relied on radiation, but it also affected males’ abilities to get with females. The same isn’t true with this new approach.
Though the procedure is far too detailed and time-consuming to apply to wild mosquito populations at this time, there’s still good reason to give these spermless males credit: they’ve shown that they can still compete and trick females into laying unfertilized eggs, which can largely limit insect populations in the long run.
And fewer mosquitoes means fewer chances for them to transmit malaria to humans.
Malaria’s the fifth cause of death from infectious disease worldwide, according to the Centers for Disease Control and Prevention.