More nitrogen in mosquito diet reduces its ability to transmit Zika

A female Aedes aegypti mosquito acquiring a blood meal from a human.
A female Aedes aegypti mosquito acquiring a blood meal from a human

Feed mosquitoes more nitrogen when they’re young, and the adults are less likely to transmit the Zika virus, University of Florida scientists say. Now, researchers want to know why, and they’re determined to discover how the findings can help further their research into the dangerous virus.

In a new study, researchers with the UF Institute of Food and Agricultural Sciences and the University of Southern Mississippi examined how quality and quantity of food ingested by the yellow fever mosquito affect its biology, including its ability to become infected by, and potentially transmit, the Zika virus.

“Studies such as these lay the groundwork for future research that will help us understand the relationships between nutrition and the process of infecting mosquitoes,” said Barry Alto, a UF/IFAS associate professor of entomology and lead researcher on the new study.

Scientists are interested in the virus because it can make people sick and in rare cases may cause paralysis (Guillain-Barré Syndrome) and birth defects. Zika made frequent headlines in 2015 and 2016 after an outbreak of the virus in Brazil made its way to people in Florida and other places. Scientists believe the yellow fever mosquito – scientifically known as Aedes aegypti — was the primary culprit behind that Zika outbreak.

In the new study, researchers manipulated the amount and type of detritus — animal and plant material – provided to mosquito larvae.

They discovered that mosquitoes developed more rapidly and grew larger as adults if they were reared in a nitrogen-rich environment. Scientists also found the young mosquitoes with more animal material in their diets were less susceptible to infection and transmitting the Zika virus as adults.

Conversely, scientists found that mosquitoes fed no animal material were more likely to become infected and transmit the Zika virus. Although scientists don’t know why that’s the case, it’s likely that changes in the animal and plant material they eat — and its associated nutrition — relates to the mosquitoes’ immune system response, said Alto, a faculty member at the UF/IFAS Florida Medical Entomology Laboratory (FMEL) in Vero Beach, Florida, and also an affiliate member of the Emerging Pathogens Institute.

For the experiment, Alto supervised a research team that put 10 treatment groups of mosquitoes into buckets of water with varying amounts of dead crickets – the animal material — and leaves, or so-called “detritus.” Scientists raised mosquito larvae in the buckets and captured adults.

Then, they gave the adult female mosquitoes a blood meal infected with the Zika virus. Following a 15-day incubation period, scientists tested various aspects of mosquitoes, including their saliva for the Zika virus. They also measured the amount of nitrogen and carbon in the mosquitoes. They found that the more nutrient-deprived conditions made mosquitoes more prone to get infected with Zika and transmit the virus.

Among those Alto supervised for the experiment was Andrew Paige, a post-baccalaureate research fellow with the National Institutes of Health, who helped conduct this research while at FMEL.

“We hope this research will lay the foundation for understanding how nutrition can factor into outbreaks of viral disease, improve our predictive modelling and ultimately work toward preventative measures,” Paige said. “Before we can stop transmission, we need a holistic understanding how it works in the lab and in nature.”

Written by: Brad Buck