Infected 'zombie ants' face no discrimination from nest matesMarch 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."
The National Science Foundation supported this work.
Related Fungus Articles:
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.
There is a continuous search for new, safe and relatively cheaper drugs with the advent of new diseases and increasing antibiotic resistance.
Plants usually produce their own nutrients by using sun energy, but not all of them.
A newly discovered protein from a fungus is able to suppress the innate immune system of plants.
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.
Pneumocystis carinii causes mild forms of pneumonia in pigs and was considered of low diagnostic relevance.
Microorganisms, among them fungi, are a natural and rich source of antibiotic compounds.
University of Exeter researchers have found novel insight into the ways cells organise themselves.
Misty mountains, glistening forests and blue-green lakes make Cameroon, the wettest part of Africa, a tropical wonderland for amphibians.
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
The Kingdom of Fungi
by Jens 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
Fungi (Materia Medica Clinica) (Volume 2)
by Massimo Mangialavori (Author), Krista Heron (Editor), John Sobraske (Editor), Betty Wood (Editor)
This second installment of Massimo Mangialavori’s Materia Medica Clinica presents remedies, old and new, from the otherworldly, overlooked kingdom of Fungi. These remedies have enough association to constitute a broad group, while being too disparate to form a homeopathic family. This fascinating menagerie of fourteen remedies is a first attempt to see the commonalities within this mostly unknown territory. Many years ago, Boericke and Allen took steps in this direction, but few have followed since—until now. Like mystical wizards, fungi transform life into death, and the detritus of... 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
The Book of Fungi: A Life-Size Guide to Six Hundred Species from around the World
by Peter Roberts (Author), Shelley Evans (Author)
Title: The Book of Fungi( A Life-Size Guide to Six Hundred Species from Around the World) Binding: Hardcover Author: PeterRoberts Publisher: UniversityofChicagoPress View Details
by Roy Kettle (Author), Harry Adam Knight (Author)
A brilliant London scientist breaks a genetic code that will end world hunger, but something goes terribly wrong in the lab and a plague is released upon Great Britain. The lucky ones die quickly, gruesomely consumed by a ravenous fungus, but others survive and are transformed into something . . . different. London is cut off from the rest of the world by encircling warplanes bent on stopping the spread of the deadly mutation by any means possible. Only a last-ditch suicide mission, a descent into the microbial hell of ground zero, can save mankind from its own invention. With its breakneck... 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
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 Fungus Link : An Introduction to Fungal Disease Including the Initial Phase Diet
by Beverly Thornhill Hunt (Editor), Wm. Lee Cowden (Intro Doug A. Kaufman (Author) (Author)
So it is that the first book we know of to implicate fungus as the cause of debilitation and death has been completed. There is nothing more convincing than observing life-threatening diseases frequently respond favorably to simple antifungal therapy. View Details
The Fungus Link (Know the Cause!, Volume 3)
by Doug A. Kauffmann (Author), M.D David Holland (Author), R.N. Jami Clak (Author)
3rd volume of the Fungus Link series. View Details