Malaria mosquitoes can be tricked into not producing offspring
9 August 2011
A female malaria-spreading mosquito cannot tell if the male that she has mated with is fertile or ‘spermless’ and unable to fertilise her eggs, according to a new Medical Research Council funded study. The research could help scientists to prevent the spread of malaria by interfering with the mosquitoes’ ability to reproduce.
Malaria is a debilitating disease that affects more than 300 million people every year, and kills nearly 800,000 annually. Public health experts are working towards its eradication, but there is a recognised need for better and lower cost tools to achieve this goal. This study, by scientists at Imperial College London and the University of Oxford, focuses on Anopheles gambiae, the species of mosquito mainly responsible for the transmission of malaria in Africa.
Female mosquitoes mate just once in their lives, after which they lay a batch of eggs. In the study, the researchers observed that this behaviour was the same regardless of whether or not the mating encounter had produced fertilised eggs that could hatch into new mosquito larvae. They were surprised to discover that after mating with a spermless male, the female made no attempt to find a supplementary mate, effectively missing out on the opportunity to reproduce and pass on her genes.
Dr Flaminia Catteruccia, the lead author of the study from Imperial College London, said:
“In the fight against malaria, many hope that the ability to genetically control the mosquito will one day be a key part of our armoury. In order for these currently theoretical control strategies to work, we need to make sure that the insects continue to mate as normal, unaware that we have interfered with their sexual functions. This study strongly suggests that they cannot tell the difference between a fertile and a spermless mate.”
The results support the idea that in the future it will be possible to control the number of malaria-carrying mosquitoes, by introducing a genetic change that makes the males sterile.
Sir Andrew Haines, chair of the Medical Research Council Global Health Group, said:
“Malaria is one of the grand challenges of global health that the MRC aims to tackle. Although cases have recently declined, thanks to the many medical innovations and control mechanisms that have been developed, malaria still kills one child around every 45 seconds in Africa. We are now starting to see new genetic insights into how we can control the spread of insect-borne disease, and it is a very exciting time for research in this field.”
The paper, ‘Spermless males elicit large-scale female responses to mating in the malaria mosquito Anopheles gambiae’ by J Thailayil, K Magnusson, HCJ Godfray, A Crisanti, and F Catteruccia, is published in the journal Proceedings of the National Academy of Sciences. The study was also funded by a European Community FP7 Collaborative Project grant called Malbecblok.
