Summer is almost here, which means that people are starting to look up best practices — from what colors to wear to what insecticides to buy — to avoid mosquito bites. And for good reason: Mosquito-borne diseases, such as dengue, malaria and Zika, cause more than 600,000 deaths worldwide per year.
While the majority of the world just wants to swat mosquitoes, three University of Washington researchers — Willem Laursen, UW assistant professor of biology; Andrea Durant, UW assistant professor of biology; and Jeffrey Riffell, UW professor of biology — find mosquitoes fascinating. They told UW News what it’s like to study mosquitoes and why these critters are actually really important.
“The incalculable misery that mosquitoes exert on humans and other animals certainly overshadows any appreciation for the importance of mosquitoes in nature. Many species of mosquitoes are critical to biodiversity and are actually fundamental to the food chain.”
Why is it important to study mosquitoes?
Willem Laursen: Mosquitoes have been an enduring scourge of humanity for millennia. Their bites are a nuisance to humans and animals alike, and ancient texts describe illnesses consistent with mosquito-borne diseases, such as malaria, long before the source of transmission was understood.
Globalization and climate change are expanding the geographic range of many mosquito species, and their increasing resistance to insecticides threatens the long-term effectiveness of current control strategies. As a result, we urgently need new approaches for controlling mosquito-borne disease.
If we can better understand the genetic and sensory basis of mosquito behavior, we might be able to find new opportunities to disrupt disease transmission. Critical behaviors such as host seeking and blood feeding are highly specialized and difficult to model in other organisms, making it essential to study these mechanisms directly in mosquitoes themselves.
Andrea Durant: These mosquito-related problems are not just for humans. Warmer winters and early-season snowmelt have led to massive swarms of mosquitoes coinciding with wildlife migration, which changes foraging patterns in the Arctic tundra and forces animals like caribou to use precious energy reserves on evading these mosquito-blackened skies. Mosquito swarms are also a big problem for agriculture, particularly cattle herds.
What do you study?
AD: My lab studies how mosquitoes maintain a stable internal environment when faced with changing external conditions. Mosquitoes start their life as an egg that is deposited in or near water, and the larval, or juvenile, stages are aquatic. Unlike the terrestrial flying adult mosquito that has agency in its choice of residence, a mosquito larva is tied to wherever it hatches — it must survive and develop there, or die.
Sometimes the aquatic reservoirs where an adult female has selected to lay her eggs can be quite extreme, such as very polluted freshwater and seawater. We study specialized adaptations that allow these larvae to survive — most mosquito species require clean freshwater for larval development. Our goal is to reveal how mosquitoes have been able to successfully expand their habitats to places like urban sewage systems and salty coastal habitats.
WL: In my lab, our research focuses on understanding how mosquitoes sense things at the cellular level. We are trying to determine what proteins mosquitoes use to detect human-associated cues, such as heat and humidity. By identifying the cellular and molecular machinery mosquitoes use to find hosts, food sources, mates and egg-laying sites, we hope to better understand how specialized behaviors, such as blood feeding, evolve, and to uncover new targets for controlling the transmission of mosquito-borne diseases.
Jeffrey Riffell: My lab studies the “how” of mosquito biting behavior. We also study how they visit flowers and plants — yes, they can pollinate certain plants! — to understand their natural behaviors. By learning more about mosquito physiology and behavior, we would like to develop new tools for traps and ways to control mosquitoes around people’s homes.
Tell us what it’s like to be someone who studies mosquitoes.
JR: Mosquitoes, all day and all the time. Although we try to minimize the potential for mosquito biting in the lab and in our field sites, you have to grin and bear it when dealing with these little vampires.
WL: Being around large swarms of mosquitoes all day does desensitize me a bit. Sometimes I will be out hiking or camping with family members and I won’t be paying much attention until I start hearing complaints about the mosquitoes. Working with mosquitoes also leads me to do funny things, such as collecting sweat or wearing a nylon stocking for days to collect human odors for behavioral assays.
Rearing transgenic mosquitoes in the lab is a bit like ranching: We have to keep track of large herds of animals. Because the life stages live in different environments, we have to constantly shuttle them around between water-filled trays, for the larvae/pupae, and cages, for the terrestrial adults. We also have to move the adults around on a specific schedule to make sure they have access to our artificial blood feeders. Some lab members jokingly put a sign on the door that says “Welcome to The Ranch.”
AD: Willem is to a rancher as I am to a protagonist in “Swamp People.” We often venture outside of the lab to hunt mosquitoes in their natural habitat in urban and peri-urban areas. Sometimes we find ourselves in picturesque places like the beautiful pillow basalt coastlines of the San Juan Islands. Most often, I can be found headfirst in a nutrient-rich septic system in someone’s backyard filled with mosquito larvae or marching into the fray of massive swarms of saline-tolerant mosquitoes that await in tidal marshlands and mangrove forests.
What is the coolest mosquito fact you know?
WL: There are over 3,500 species of mosquitoes, with vastly different appearances, life histories and host preferences. Many are generalists. A few strongly prefer humans and some feed from cold-blooded animals like frogs or earthworms. The large amber-encased Toxorhynchites elephant mosquito shown in the movie “Jurassic Park” feeds on other mosquito larvae and doesn’t actually drink blood at all.
JR: I like Sabethes. These mosquitoes are very pretty, and they shoot their eggs into tree holes.
What’s one thing you wish people understood about mosquitoes?
AD: The incalculable misery that mosquitoes exert on humans and other animals certainly overshadows any appreciation for the importance of mosquitoes in nature. Many species of mosquitoes are critical to biodiversity and are actually fundamental to the food chain. There are numerous examples of areas with reduced breeding success and animal survival because there have been effective vector control programs and non-targeted mosquito eradication efforts.
JR: Mosquito larvae, or wigglers, are the “chicken” of the pond. They are an important food resource for other invertebrates, such as dragonflies.
Also adult mosquitoes — by spreading disease-causing pathogens — are thought to impose an “ecological taxation” on animals in nature that live a relatively long time, such as ungulates like deer and elk. So even though we think of them as pests, mosquitoes play an important role in the natural environment.
For more information, contact Laursen at wlaursen@uw.edu, Durant at durantan@uw.edu and Riffell at jriffell@uw.edu.