Fighting malaria with spermless mosquitoes
December 8, 2011
Flaminia Catteruccia, a molecular entomologist and new associate professor of immunology and infectious diseases at Harvard School of Public Health, wants to learn everything she can about the reproductive biology of mosquitoes. Her goal is to develop novel methods for mosquito control to reduce the incidence of mosquito-borne malaria, which kills roughly one million people each year and for which no vaccine is yet available. It’s a crucial goal, given that mosquitoes are increasingly resistant to insecticides.
Q: How did you become interested in mosquito reproductive biology?
A: It was an empty niche of research. Nothing was known about the factors and mechanisms that are important for male and female fertility. I thought this area of research offered good opportunities for the development of novel strategies to control mosquito populations. I’ve been involved with this area of study since I started my own research group at Imperial College in London in 2007.
Q: Why is it important to focus on mosquito fertility?
A: In principle, if you knew what was important for mosquito fertility, then you might find ways to interfere with that, which would limit the size of mosquito populations. Rather than killing them, we might be able to stop them from reproducing as they normally would.
Q: Why would it be better to render mosquitoes sterile rather than simply kill them?
This would provide an alternative control method, which is very much needed at the moment, because mosquitoes will try to react to any strategy you use. Right now, insecticides are mainly used, but many populations have become resistant to them. If mosquitoes survive because they’re resistant, then the population that’s resistant will take over, so in a few generations insecticides will be completely useless.
Q: Can you describe your most recent research?
A: We figured out a way to eliminate sperm cells from male mosquitoes. Then we needed to check whether the sterile male mosquitoes would still be perceived as normal by the females. And we found that the females behaved exactly the same. They didn’t reject the males, which is important, because usually mosquitoes mate just one time in their lives. The females store up all their sperm, then use some every time they lay eggs. We were concerned that the females would realize they hadn’t mated properly and might mate again. But they don’t—which means they are sterilized for good.
Q: What are the implications of this finding?
A: In principle, this could be a big deal. But the way we eliminate sperm in the males cannot easily be done on a large scale; it’s quite laborious. So we need to figure out how this can be done on a larger scale.
Q: How will you proceed from here, given the obstacles?
A: We will focus more on understanding why females mate a single time. If we knew the mechanisms that trigger the female to lose her receptivity to mating, we might be able to design chemical compounds that could mimic what happens in females after mating, then use this compound to trick virgin females into thinking they’ve already mated.
Q: How far do you think this line of research could go in reducing the spread of malaria?
A: The malaria community is trying to find a number of different strategies to fight mosquitoes, so if one doesn’t work well, there are others that can be used. If we could find a formulation that includes an insecticide and a sterilizing agent, those females that are resistant to insecticides might be rendered sterile.
photo: Aubrey LaMedica
Female mosquitoes tricked by spermless males (Nature News)