Blocking hormone activity in mosquitoes could help reduce malaria spread

Disruption of hormone signaling in mosquitoes may reduce their ability to transmit the parasite that causes malaria, according to a new study published in PLOS Pathogens. The findings suggest a potential new approach to combat spread of the disease.

Malaria kills about 500,000 people every year. A person can become infected when bitten by a female mosquito that carries the Plasmodium parasite in its saliva, allowing the microbe to enter the person's bloodstream. Efforts to reduce infection have relied heavily on insecticides that kill malaria-spreading mosquitoes, but the insects are rapidly becoming resistant to these chemicals.

In the new study jointly led by Flaminia Catteruccia and Caroline Buckee of the Harvard T. H. Chan School of Public Health, Boston, Lauren Childs, Francisco Cai, Evdoxia Kakani and colleagues investigate a potential alternative to insecticides. Instead of killing mosquitoes, their method targets the ability of the bloodsuckers to transmit malaria.

To test this method, the researchers exposed adult Anopheles gambiae females, the dominant malaria-spreading mosquitoes in sub-Saharan Africa, to a type of chemical known as DBH. DBH targets the activity of the steroid hormone known as 20-hydroxyecdysone, which plays a role in several biological processes in mosquitoes.

The scientists found that DBH shortens mosquito lifespan, reduces the number of mosquito eggs produced and laid, prevents successful mosquito mating, and blocks development of the Plasmodium parasite.

To further explore the potential of hormone targeting as a malaria control tactic, the researchers fed their experimental results into a mathematical model of the mosquito life cycle. The results suggest that applying DBH to bed nets or spraying it indoors could potentially reduce malaria transmission as effectively as insecticides.