Nav: Home

Infected 'zombie ants' face no discrimination from nest mates

March 13, 2018

Carpenter ants infected with a specialized parasitic fungus are not subjected to aggression or isolation from their nest mates, and they continue to share in the colony's food resources until they leave the nest for the last time to die, according to a study led by Penn State researchers.

The findings suggest that, although the fungus is deadly to infected individuals, it is only a chronic condition for the colony -- one that does not induce the kind of strong defensive measures thought to be common in social insect societies, the researchers said.

Studies have shown that fungal pathogens from the genus Ophiocordyceps -- known as "zombie ant fungus" -- control the behavior of carpenter ant workers, compelling them to climb vegetation and bite the veins or margins on the underside of leaves. The infected ants die, remaining attached to the vegetation postmortem. There, the fungus grows and releases spores onto the forest floor below, where they can infect other foraging ants.

"Previous work suggested that insect societies protect the colony through social immunity," said lead author Emilia Solá Gracia, postdoctoral scholar in biology, Penn State. "It was thought that during social interaction, ant workers detect infections in their peers and display aggression toward them or remove them from the nest.

"This fungus, which co-evolved with its host, takes 14 to 21 days to develop in infected individuals before compelling them to leave the nest and perform their last act. The question is, during this development, does the pathogen change how infected ants interact with others or alter the chemical cues they emit, which allows nest mates to detect the infection? Such detection would be optimal for the colony since infected workers die near foraging trails where the fungus releases spores that infect other members of the colony."

To test the hypothesis that infected individuals are recognized by healthy colony members, the research team looked at whether infected ant workers are attacked by nest mates, whether they spend more or less time in trophallaxis -- socially exchanging food -- and whether they are spatially separated from other colony members inside the nest.

The researchers collected ants from forested areas in South Carolina and established three colonies in a Penn State laboratory, each colony consisting of three groups of worker ants. One of the three groups was untreated -- healthy, the second was injected with a growth medium containing the parasitic fungus and a third received the growth medium alone. The ants were marked with unique dot patterns on their head, thorax and gaster so individuals could be followed over time.

They affixed a modified GoPro camera fitted with both an infrared lens and a macro lens on top of the colonies to capture recorded video virtually 24 hours daily.

While observing 1,240 hours of video footage, the researchers, who reported their findings in the online journal PLOS ONE, saw no attacks toward individuals injected with the fungus and found no significant difference in food sharing between infected and uninfected individuals.

The team did find that infected individuals spent considerably more time inside near the nest entrance and spent more time outside the nest than healthy workers.

"It could be that spending more time outside the nest is an early signal of fungal manipulation, which ultimately requires its host to leave the nest for fungal reproduction to occur," Solá Gracia said. "But the most significant finding is that this co-evolved parasite doesn't seem to directly affect social dynamics within the colony."

Taken together, these results suggest healthy individuals do not detect the parasite inside their nest mates, according to senior author David Hughes, associate professor of entomology and biology.

"The colony's inability to detect infected individuals allows the fungus to develop within the colony, while receiving food and protection from natural enemies that could damage or kill its ant host before the parasite has completed its development," he said. "Based on our observations and the biology of the fungus, we suggest that the pathogen is a chronic parasite of the colony that is able to survive without triggering strong behavioral defenses in the society -- in short, the parasite is able to fly under the radar of the colony's defenses."
Other researchers on the project were Charissa de Bekker, assistant professor of biology, University of Central Florida, and Ephraim Hanks, assistant professor of statistics, Penn State.

The National Science Foundation supported this work.

Penn State

Related Fungus Articles:

Single fungus amplifies Crohn's disease symptoms
A microscopic fungus called Candida tropicalis triggered gut inflammation and exacerbated symptoms of Crohn's disease, in a recent study conducted at Case Western Reserve University School of Medicine.
A novel anticandidal compound containing sulfur from endophytic fungus
There is a continuous search for new, safe and relatively cheaper drugs with the advent of new diseases and increasing antibiotic resistance.
Plants cheat too: A new species of fungus-parasitizing orchid
Plants usually produce their own nutrients by using sun energy, but not all of them.
How a fungus inhibits the immune system of plants
A newly discovered protein from a fungus is able to suppress the innate immune system of plants.
What happens to a pathogenic fungus grown in space?
A new study, published this week in mSphere, provides evidence that Aspergillus fumigatus, a significant opportunistic fungal threat to human health, grows and behaves similarly on the International Space Station compared with earth.
Fungus a possible precursor of severe respiratory diseases in pigs
Pneumocystis carinii causes mild forms of pneumonia in pigs and was considered of low diagnostic relevance.
Rare fungus product reduces resistance to antibiotics
Microorganisms, among them fungi, are a natural and rich source of antibiotic compounds.
How to organize a cell: Novel insight from a fungus
University of Exeter researchers have found novel insight into the ways cells organise themselves.
Deadly fungus threatens African frogs
Misty mountains, glistening forests and blue-green lakes make Cameroon, the wettest part of Africa, a tropical wonderland for amphibians.
Invasive amphibian fungus could threaten US salamander populations
A deadly fungus causing population crashes in wild European salamanders could emerge in the United States and threaten already declining amphibians here, according to a report released today by the US Geological Survey.

Related Fungus Reading:

Fungi: Mushrooms, Toadstools, Molds, Yeasts, and Other Fungi (Class of Their Own (Paperback))
by Judy Wearing (Author)

There are hundreds of thousands of different known fungi with many still to be discovered and developed. This interesting book features an examination of the four major groups: yeasts, toadstools, chytrids, and bread molds. Key characteristics of fungi are highlighted, such as spore production, fungis need to feed, and their use of long, branching cells known as hyphae to absorb nutrients from the environment. Special sections explore such varieties as saprophytes, which feed on dead and decaying matter; parasites, which often do considerable harm to other species; and species that form... View Details

Teaming with Fungi: The Organic Grower's Guide to Mycorrhizae (Science for Gardeners)
by Jeff Lowenfels (Author)

From the bestselling author of Teaming with Microbes and Teaming with Nutrients

Teaming with Fungi is an important guide to mycorrhizae and the role they play in agriculture, horticulture, and hydroponics. Almost every plant in a garden forms a relationship with fungi, and many plants would not exist without their fungal partners. By better understanding this relationship, gardeners can take advantage of the benefits of fungi, which include an increased uptake in nutrients, resistance to drought, earlier fruiting, and more. Learn how the fungi interact... View Details

The Kingdom of Fungi
by Jens H. Petersen (Author)

The fungi realm has been called the "hidden kingdom," a mysterious world populated by microscopic spores, gigantic mushrooms and toadstools, and a host of other multicellular organisms ranging widely in color, size, and shape. The Kingdom of Fungi provides an intimate look at the world's astonishing variety of fungi species, from cup fungi and lichens to truffles and tooth fungi, clubs and corals, and jelly fungi and puffballs. This beautifully illustrated book features more than 800 stunning color photographs as well as a concise text that describes the biology and ecology of... View Details

by Silvia Moreno-Garcia (Editor), Orrin Grey (Editor)

A collection of fungal wonders...and terrors. In this new anthology, writers reach into the rich territory first explored by William Hope Hodgson a century ago: the land of the fungi. Stories range from noir to dark fantasy, from steampunk to body horror. Join authors such as Jeff VanderMeer, Laird Barron, Nick Mamatas, W.H. Pugmire, Lavie Tidhar, Ann K.Schwader, Jesse Bullington, Molly Tanzer and Simon Strantzas through a dizzying journey of fungal tales. Feast upon Fungi. View Details

The Fungus Link: An Introduction to Fungal Disease, Including the Initial Phase Diet
by Doug A. Kaufmann (Author), Beverly Thornhill Hunt (Editor), Wm. Lee Cowden (Editor)

The Fungus Link to: allergies, arthritis, digestion, respiration, mental health, heart health, women's health, and pain. View Details

Fungi: A Very Short Introduction (Very Short Introductions)
by Nicholas P. Money (Author)

The variety of the mycological world is far greater than most people imagine. Tens of thousands of fungal species have been described and many more are known only from the abundance of their genes in soil and water. Fungi are hugely important as agents of wood decay in forests, and, as parasites, they have caused the deaths of millions of people by ravaging crops and reshaping our natural ecosystems.

Fungi also perform a variety of essential functions in ecosystems, and are important to both agriculture and biotechnology. Their importance is now becoming greatly appreciated among... View Details

The Rise of Yeast: How the Sugar Fungus Shaped Civilization
by Nicholas P. Money (Author)

The great Victorian biologist Thomas Huxley once wrote, "I know of no familiar substance forming part of our every-day knowledge and experience, the examination of which, with a little care, tends to open up such very considerable issues as does yeast." Huxley was right. Beneath the very foundations of human civilization lies yeast--also known as the sugar fungus. Yeast is responsible for fermenting our alcohol and providing us with bread--the very staples of life. Moreover, it has proven instrumental in helping cell biologists and geneticists understand how living things work, manufacturing... View Details

Fungus the Bogeyman: The 35th Anniversary Edition
by Raymond Briggs (Author)

Life in Bogeydom is full of snot, smells, slime, scum and other unspeakable things, and Bogeymen live under the ground revelling in allthe nastiness imaginable. Briggs has created a whole new world in this sophisticated cartoon-strip picture book for older children which will entice the most reluctant of readers into books. View Details

The Book of Fungi: A Life-Size Guide to Six Hundred Species from around the World
by Peter Roberts (Author), Shelley Evans (Author)

Colorful mysterious and often fantastically shaped fungi have been a source of wonder and fascination since the earliest hunter gatherers first foraged for them Today there are few if any places on Earth where fungi have not found themselves a home And these highly specialized organisms are an indispensable part of the great chain of life They not only partner in symbiotic relationships with over ninety percent of the world s trees and flowering plant species they also recycle and create humus the fertile soil from which such flora receive their nutrition Some fungi are parasites or... View Details

The Kingdom Fungi: The Biology of Mushrooms, Molds, and Lichens
by Steven L. Stephenson (Author)

The ubiquitous fungi are little known and vastly underappreciated. Yet, without them we wouldn’t have bread, alcohol, cheese, tofu, or the unique flavors of mushrooms, morels, and truffles. We can’t survive without fungi.

The Kingdom Fungi provides a comprehensive look at the biology, structure, and morphological diversity of these necessary organisms. It sheds light on their ecologically important roles in nature, their fascinating relationships with people, plants, and animals, and their practical applications in the manufacture of food, beverages, and pharmaceuticals.... View Details

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

The Consequences Of Racism
What does it mean to be judged before you walk through the door? What are the consequences? This week, TED speakers delve into the ways racism impacts our lives, from education, to health, to safety. Guests include poet and writer Clint Smith, writer and activist Miriam Zoila Pérez, educator Dena Simmons, and former prosecutor Adam Foss.
Now Playing: Science for the People

#466 Wildfire
This week we're talking about fire: in particular, wildfires. How they spread and how we manage them, but also the deeper history of wildfires on our planet and how they've been shaping our world for a long, long time. We speak with Andrew Scott, Emeritus Professor of Geology at Royal Holloway, University of London, about his book "Burning Planet: The Story of Fire Through Time", learning about wildfire on our planet now and in deep history. And we catch up with Caroline Weinberg, interm executive director of the March for Science organization, about this year's march on April 14.