Cool, crisp air. The sun dipping beneath the horizon before it feels like the day has even begun. And chubby, bumbling mosquitoes that would rather drink nectar than suck blood? These are indeed all hallmarks of impending winter in Ohio.
Mosquitoes don’t bite in the winter, instead going into a special, dormant state called diapause when the seasons start to change. During this time, they crave sugar—loading up on nectar and packing on the fat (the same way hibernating bears do). Relying on these plant-powered meals instead of blood, their bodies also change so they can’t lay eggs or reproduce.
 |
CFAES researchers think there might be a way to hijack the way mosquitoes perceive seasons and stop them from biting all year-round.
If they can understand how mosquitoes are able to sense seasonal cues, like fewer hours of daylight and cooler temperatures, maybe they can manipulate mosquitoes to go into this type of “insect hibernation” during spring and summer, says Ohio State entomologist Megan Meuti, who researches diapause extensively. Studying everything from genes to light pollution, Meuti’s team is working hard to unravel this important mystery of mosquito management.
Besides just being a nuisance, mosquitoes have a big impact on public health in Ohio. When these critters suck our blood, they can transmit deadly diseases like West Nile virus, Eastern equine encephalitis, and St. Louis encephalitis. Meuti’s diapause team focuses on the Northern house mosquito, which can spread West Nile. Limiting their ability to bite and better understanding this seasonal slump could help prevent mosquito-borne diseases from spreading to humans.
 |
This research is also the first in-depth exploration in any animal of how seasonal cues are converted to chemical signals in the body that influence behavior. For instance, it’s not just mosquitoes that hibernate or go into a type of survival-mode when they experience environmental triggers. Many other animals also go into dormant states in the winter, such as butterflies, bears, kangaroos, and even armadillos.
Connecting the Dots
Just like people have circadian rhythms that regulate what times they sleep and wake up, CFAES researchers found that mosquitoes have special “circadian clock” genes that regulate hibernation. When researchers suppressed these genes in the lab, mosquitoes that were raised in winter conditions behaved as if it were summer, producing eggs and sucking blood, and vice versa.
Now that scientists know what genes are involved, they hope to manipulate mosquitoes, tricking them into confusing the seasons and stopping them from biting. Researchers are studying how these “clock” genes are connected to hormone levels, insulin signaling, and other biological responses to seasonal changes. To accomplish this, Meuti’s team wants to explore CRISPR genome editing and knock out these clock genes permanently.
Searching Mosquito Spots
Mosquitoes live everywhere: in woodlands, in parks, on farms, all over cities, and in your backyard. Alden Siperstein, a graduate student in Meuti’s lab, hunts down mosquitoes across these environments, even venturing into underground drainage systems—a favorite wintertime shelter for mosquitoes—to collect them.
By trapping and then analyzing these mosquitoes every fall, winter, and spring, Siperstein hopes to understand when exactly their hibernation starts and ends. Collecting data on the timeframe of diapause will help researchers better understand how and when mosquitoes react to the seasons. Analyzing seasonal differences in mosquito abundance may also help managers target pest control efforts.
|
|
City-Stickers
As the human population grows, cities do too. With these urban environments comes increased light pollution. And, more roads and sidewalks trap heat and increase surrounding temperatures—a phenomenon called the heat island effect. Given that mosquitoes depend on factors like daylength and temperature to tell them when winter is coming, CFAES researchers want to determine if light pollution and heat islands could be postponing mosquitoes’ wintertime hibernation, keeping them active even as seasons change.
Graduate student Lydia Fyie, who works in Meuti’s lab, collects mosquitoes from heat island and non-heat-island locations across Ohio State’s campus to compare the number of mosquitoes in diapause in each place. She’s now expanding her work to study artificial light and conduct further experiments in the field.
Lighting up the Lab
While studying mosquitos in the natural environment is critical, Meuti’s team also examines mosquito hibernation behavior in the lab. Using homegrown test subjects from her “Buckeye” strain of mosquitoes, Meuti exposes populations of mosquitoes to both winter and summer conditions to compare diapausing and non-diapausing mosquitoes.
She locks about 3,000 “winter” mosquitoes in the fridge, forbidding her team from opening the door and exposing them to light except during specific hours of the day. She feeds them honey from sponges and sugar water for the first two weeks of their life. After that, the mosquitoes survive from their fat resources for 3-4 months. Meuti exposes the 3,000 summer subjects to heating elements and lots of light and feeds them chicken blood so that they can keep laying eggs. Graduate student Matt Wolkoff also sets each batch of mosquitoes free in special fly boxes to study daily changes in their activity levels. Analyzing their behavior up-close in these controlled environments helps researchers better understand how diapause affects mosquitoes.
Bro Code
While lady mosquitoes do all the biting and are the only ones that go into hibernation, Meuti’s lab also studies male mosquitoes. Researchers think certain chemicals in mosquito sperm may influence female mosquitoes’ reactions to the seasons and impact diapause.
After doing RNA sequencing in each type of mosquitoes, they found that male mosquitoes do change the composition of their ejaculate in response to seasonal cues. Moreover, summer-reared females that mated with summer-reared males were more likely to bite and produce eggs than if they mated with winter males. These findings suggest that differences in gene expression thanks to seasons translate to differences in mosquito reproductive physiology and behavior.
- Read more about the different mosquito-borne diseases in Ohio.
- Learn how to better protect yourself from mosquitoes.
- Check out mosquito-borne disease stats from the Ohio Department of Health.
- Explore more research from the Meuti Lab.
- Get familiar with the Northern House Mosquito and the Asian Tiger Mosquito.
-
Find other KX content about mosquitoes.