Kathleen finished her senior thesis!

Kathleen is graduating this May, and completed a stellar senior thesis where she reports her work on stage-specific heat waves in the tiger mosquito. Stay tuned to see where it gets published! Great work, Kathleen!

Mike publishes on extinction risk for ornamented dragonflies in human-modified habitat

Dr. Michal Moore, former LEC postdoc and current Assistant Professor at The University of Colorado, Denver published more of his fascinating work on ornamenation in dragonflies. In this study, published June 7, 2024 in Ecology Letters, he found that dragonflies that possess ornaments—melanization on portions of the wings—can buffer dragonflies against the perils they face in urbanized and agriculturalized landscapes. Read more here.

Katie co-authors paper on artificial light and gene expression in mosquitoes

Katie recently published results from a project led by PhD candidate Lyida Fyie at The Ohio State University. The work showed how artificial light at night (ALAN) affects the abundance of clock genes regulating circadian rythms. Their findings indicate that ALAN may inhibit the initiation of diapause in both the tiger mosquito (Aedes albopictus) and house mosquito (Culex pipiens) via the circadian clock. Read more here.

Ben's senior thesis is publised!

After graduating, Ben published his thesis entitled “Genetically based variation in heat tolerance covaries with climate in a globally important disease vector”. The paper is published in Frontiers and featured in The Source.

Congrats Ben!

Katie and Kim are interviewed by Scientific American

In the July 31, 2023 issue of Scientific American, Katie and Kim were interviewed about the outlook for mosquito-borne disease.

Mike's PNAS paper gets press coverage

Mike’s recent PNAS paper has been picked up by numerous press outlets. Great work Mike!

CNN - https://us.cnn.com/2021/07/06/us/dragonfly-wings-climate-change/index.html

 The Guardian - https://www.theguardian.com/environment/2021/jul/06/climate-crisis-causing-male-dragonflies-to-lose-wing-bling-study-finds

 New Scientist- https://www.newscientist.com/article/2283184-male-dragonflies-may-become-less-colourful-as-the-climate-warms/

 ScienceNews - https://www.sciencenews.org/article/climate-change-dragonfly-wing-spots-biology

 Smithsonian Magazine - https://www.smithsonianmag.com/smart-news/warmer-climate-may-cause-male-dragonflies-lose-their-patchy-wings-180978141/

WashU piece - https://biology.wustl.edu/news/male-dragonflies-lose-their-%E2%80%98bling%E2%80%99-hotter-climates-less-pigmentation-keeps-them-cool-could

 St. Louis Post-dispatch - https://www.stltoday.com/news/local/metro/dragonflies-lose-wing-markings-in-warmer-climates-washu-and-slu-study-shows/article_487b4436-96da-5577-b502-e940018c77b3.html

St. Louis Public Radio - https://news.stlpublicradio.org/show/st-louis-on-the-air/2021-07-08/thursday-as-male-dragonflies-adapt-to-climate-change-females-might-be-less-attracted

Michel Ohmer to join us in August as an LEC postdoctoral fellow

Michel Ohmer, PhD, has accepted a 1-year position as a Living Earth Collaborative postdoctoral fellow with Kim, Kasey Fowler-Finn at Saint Louis University, and Lauren Augustine at the St. Louis Zoo as co-sponsors. Michel will be studying to role of microclimate in host-parasite interactions in frogs infected (or not) with the chytrid fungus. Welcome Michel!

We are what we eat, but so are our parasites

Sep 12, 2019

Katie M. Westby

You are a rare human animal in this century if you do not often think about the food you put in your body. Should we only eat organic? Should we limit our food intake and fast intermittently? We are constantly bombarded with ads for junk food followed closely by dire warnings about what happens to our insides if we eat it. Whether the knowledge that your diet has health implications is instinctual to our species or a product of a lifetime of indoctrination, most of us know that a poor diet can make us sick and a hot bowl of soup can ease a cold.

It is not just our collective folk knowledge that leads us to these conclusions; scientists have been studying the impact of host nutrition on infectious disease for a long time. A newer area of research, however, investigates how host nutrition impacts the fitness of the parasites that infects us. While my preamble is clearly framed for privileged human populations, this idea can be applied to all organisms that eat and are parasitized, in other words, all biological organisms.

To learn more about the effects of host nutrition on parasites, my colleagues and I set out to test if hosts that were fed a high vs. low nutritional quality diet or a high vs. low amount of food had differences in the number of parasites that infected them or the size of those parasites. To do this, we turned to one of the world’s most reviled creatures, the mosquito, and a protozoan parasite that infects it, known as a gregarine.

Aedes triseriatus larvae (photo: Leslie Sterling)

Gregarine parasites in larval midgut (photo: Lexie Beckermann_)

We reared mosquito larvae on one of four diet treatments, two food qualities (crickets and oak leaves) and two quantities of those foods. We then experimentally infected our larvae with gregarines in the lab, allowed them to develop, and then counted and measured all of the gregarines that were able to successfully infect them.

Host food affects parasite performance

What we found was that both food quality and quantity affected the parasites, but not necessarily in the same way. Larvae that were fed that high quality, delicious cricket diet had half the number of gregarines compared to those fed the oak leaves. The size of individual parasites was affected by both the type and amount of diet. In general, mosquitoes that were fed a larger amount of food produced larger gregarines.

We also found that the number of gregarines present affected their size, but that this relationship was dependent on what diet quality the mosquito was fed. What this likely means is that the gregarines are competing with each other inside their host, but only under certain food conditions. To put this in privileged human terms, no matter how many of us are at the market, we will not fight over the avocados unless there is a shortage of kale.

The results of our study suggest that not only are we what we eat, but our parasites are too. Our study is far from the end of the discussion about how different food qualities and amounts impact hosts and their parasites, especially for organisms, humans included, that are generalist or omnivorous feeders. As if you didn’t already think about how your diet affects your health enough, now you know that your diet can affect the health of those that infect you.

Westby, K., Sweetman, B., Adalsteinsson, S., Biro, E., & Medley, K. (n.d.). Host food quality and quantity differentially affect Ascogregarina barretti parasite burden, development, and within-host competition in the mosquito Aedes triseriatus. Parasitology, 1-31. doi:10.1017/S0031182019000994

Our over-wintering paper is in the news

Our paper published in the Journal of Applied Ecology last month garnered a bit of media attention. Below are links to a selection of such stories.

https://www.sciencedaily.com/releases/2019/08/190821082240.htm

https://news.stlpublicradio.org/post/asian-tiger-mosquitoes-gain-ground-laying-eggs-survive-harsh-winters#stream/0

https://gizmodo.com/u-s-mosquitos-are-laying-time-capsule-eggs-that-can-ou-1837487542

New paper published on our Asian tiger mosquito work

New research from Washington University in St. Louis shows that invasive mosquitos at the northern limit of their current range are successfully using time-capsule-like eggs to survive conditions that are colder than those in its native territory. (Photo: Shutterstock)

Aug 21, 2019

Mosquitoes push northern limits with time-capsule eggs to survive winters

By Talia Ogliore

When the Asian tiger mosquito (Aedes albopictus) arrived in the United States in the 1980s, it took the invasive blood-sucker only one year to spread from Houston to St. Louis. New research from Washington University in St. Louis shows that the mosquitoes at the northern limit of their current range are successfully using time-capsule-like eggs to survive conditions that are colder than those in their native territory.

The northern mosquitoes have adapted to colder winters, compared to their southern counterparts. This new evidence of rapid local adaptation could have implications for efforts to control the spread of this invasive species, which is considered a “competent vector” of numerous pathogens that are relevant to humans, including Zika, chikungunya and dengue viruses. The work is published Aug. 21 in the Journal of Applied Ecology.

“This all happened within a period of 30 years,” said biologist Kim Medley, director of Tyson Research Center and first author of the new study. “This disease vector has evolved rapidly to adapt to the United States. The fact that this has occurred at a range limit may suggest that there is potential for the species to continue to creep farther northward.”
Mosquitoes respond to the shortening days signaling winter’s onset by laying diapause eggs —  literally, delayed development eggs. These special eggs contain a fertilized embryo that’s in a state of almost-hibernation and has a very slow metabolism. The result is almost like a mosquito time capsule.

The ability to produce eggs that can wait to hatch is not something new. This technique helps mosquitoes survive the winter cold, but it works for dry conditions as well. All mosquitoes lay their eggs in or near standing water, and the larvae need to hatch into standing water. But they can survive getting dried out in between.

Still, diapause eggs are different from regular eggs. Previous research had showed that northern mosquitoes lay more diapause eggs than their southern cousins. What researchers didn’t know was how these eggs actually perform in the conditions in which they’re prepped to perform.

For this new field experiment, Medley and her team, including Katie M. Westby, postdoctoral research associate at Tyson Research Center, collected live mosquito eggs and larvae from cities near the center of the habitat they’ve invaded (Huntsville, Ala.; Macon, Ga.; Beaufort, S.C.) and also from the approximate northern edge of their U.S. range (Peoria, Ill.; Columbus, Ohio; and Harrisburg, Pa.) The researchers hatched and raised these mosquitoes and their subsequent generations in batches in the laboratory.

Then it was time to get cold. The researchers exposed the mosquitoes to shortened periods of light to signal the onset of winter. They collected the diapause eggs that the mosquitoes produced, then dispatched batches of eggs to endure real winters in four different locations: in field sites at the northern edge and core of their current range; in a climate-controlled laboratory site that represented the “optimal” winter conditions in the mosquitoes’ home territory in Japan; and in a far-north site in Wisconsin, clearly outside of the mosquitoes’ current established range.

After that real winter passed, the researchers brought the eggs back into the lab and hatched them out.

“We counted all of the eggs to see how many survived the winter in all of these locations,” Medley said. “What we learned was that the northern mosquitoes’ diapause eggs survived northern winters significantly better than the southern mosquitoes’ eggs did.

“Everybody did OK in the southern range winter,” she said. “They performed about the same.” The same was true for those in the chamber with the optimal conditions. As for Wisconsin? Well …

“Nobody survived that Wisconsin winter,” Medley said.

While the Wisconsin conditions are too harsh for these mosquitoes — at least for now — Medley is particularly interested in the changes that she is observing at the very edge of what is survivable.

“These northern mosquitoes are producing a lot more diapause eggs,” Medley said. “Now we know that these eggs also do a lot better in the winter.”

What Medley and her team learned is important not just for this species but for ecologists studying how animals adapt to new conditions and push the boundaries of their historic ranges.

“Based on theory, we expect that populations at range limits will be small, they will be fragmented and that they will be low in genetic diversity,” she said. “It’s thought that these populations will not have the demographic and genetic robustness to adapt, so they remain at this state of maladaptation.

“That may not be the case with this species,” Medley said.

Read more: Medley, KA, Westby, KM, Jenkins, DG. Rapid local adaptation to northern winters in the invasive Asian tiger mosquito Aedes albopictus: A moving target. J Appl Ecol. 2019; 00: 1– 10. https://doi.org/10.1111/1365-2664.13480