For Steven Juliano, it's not how you kill disease-carrying mosquitoes. It's when.
“I don't do mosquito control,” said the distinguished professor of ecology at Illinois State University. “I provide the information on where they're vulnerable.”
Juliano has received a three-year, $435,000 grant from the National Institutes of Health to study the best time in a mosquito's life cycle to kill them without the unintended consequences of surviving mosquitoes becoming stronger or even more numerous—what's called “overcompensation.”
The four types of mosquitoes targeted in Juliano's research carry viruses that cause diseases such as Zika, West Nile encephalitis, LaCrosse encephalitis, yellow fever and dengue.
Juliano and the students assisting him are “investigating the paradox that if you try to kill larvae, but don't kill every last one of them,” the survivors benefit and “you have the potential to make bigger mosquitoes and even more mosquitoes.”
To continue the war analogy, attacking larvae at the wrong time could result in winning a battle but losing the war. Juliano compared it to what happens when you plant seeds. If the plants that sprout are too numerous, they crowd each other out competing for resources, but if you thin them out, the surviving plants grow bigger and stronger, he explained.
“The same thing happens with mosquitoes,” he said.
The researchers are “imposing mortality”—killing mosquito larvae—in the lab in a controlled way, either early or late in the development cycle and at different percentages, Juliano said.
They are studying not only how the timing affects the development of the survivors, but also whether, as theorized, different species respond in different ways, he said.