Study of fungi-insect relationships may lead to new evolutionary discoveries

Date: May 24, 2016

Source: Penn State

Zombie ants are only one of the fungi-insect relationships studied by a team of Penn State biologists in a newly compiled database of insect fungi interactions.

"I couldn't find a place with broad information about all groups of fungi that infect insects in the same study," said Joao Araujo, graduate student in biology. "When we organized the information, we started to understand things we wouldn't see before, because the literature was so spread."

From the 150 years of literature, the researchers found that about 65 percent of insect orders can be infected by fungi and Oomycetes, fungi-like organisms that also infect insects. The results were published in the May issue of Advances in Genetics.

Sap-sucking insects, such as cicadas, are the most frequently attacked by fungi. The researchers believe this is because of the way this order of insect evolved. They have specialized mouth parts for sucking sap making them susceptible to fungi that originally infect plants.

"The fungi may have found a good environment inside the insect and then they would have established in the new host by host-jumping from plants to insects," said Araujo.

Host-jumping occurs when the fungi, in this case, are able to infect new groups of hosts like insects, animals or plants and so jump from one species or groups of hosts to others.

The researchers also discovered that flies are the only order of insects that are infected at all stages of development -- from when they are eggs until they are adults. They believe flies are especially susceptible to infection because they are found all over the world and get their food in a wide variety of ways. Their larvae often occupy a wide range of breeding sites, ranging from ponds to tree trunks. This diversity within the order is a potential explanation for the susceptibility to fungal infections in all stages of flies.

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Fungus Inside Us: A New Health Frontier?

The big, weird world of creatures inside you may be even bigger and weirder than anybody thought.

Fungi are the latest addition to human menagerie, joining bacteria and viruses in forming the teeming, biological kingdom-spanning superorganisms of our bodies.

“We were all fascinated with the diversity and sheer mass of microorganisms that live inside our intestines,” said immunobiologist David Underhill of the Cedars-Sinai Medical Center. “So we started asking: What do we know about fungus in the gut?”

In a June 8 Science study, researchers led by Underhill and postdoctoral student Ilian Iliev link gut fungus to colitis, an inflammatory bowel disease.

While the findings may be presently useful to colitis researchers, the implications are sweeping: Scientists might ask the same questions of internal fungi as they do internal bacteria, the importance of which is now a buzzing research frontier.

In the last decade, researchers have linked resident communities of bacteria — which outnumber human cells in a body by 10 to 1 — to diseases and fundamental processes, from diabetes and heart disease to metabolism and immune system function. Even viruses are in on the act.

Appreciation of this so-called microbiome represents a sea change in awareness of bacteria: No longer are they external entities that sometimes cause disease, but rather an essential, positive component of human health.

Whether fungi also play a part is a question relatively few researchers have asked. A handful of studies have suggested a limited role, primarily in skin and mouth conditions.

Continued:  http://www.wired.com/wiredscience/2012/06/gut-fungus/#more-114693

Attack of the Killer Fungi: Rising Threat Worries Scientists

An unprecedented number of diseases caused by fungi have been causing some of the most severe die-offs and extinctions ever witnessed in wild species and jeopardizing crops to boot, scientists now report.

Fungi are wiping out amphibians on several continents, decimating bats in eastern North America, contributing to the disappearance of bees dubbed colony collapse disorder, and killing corals and sea turtles.

They are even threatening humans, if indirectly, by attacking crops. Fungi and fungilike organisms called oomycetes can cause significant losses to rice, wheat, maize, potatoes and soybeans, according to the researchers who write that the problems "vary regionally but pose a current and growing threat to food security."

To determine if fungi are causing more diseases and extinctions among plants and animals, the team, led by Matthew Fisher at the Imperial College London, combed through years of scientific reports.

Read on:  http://www.livescience.com/19628-fungal-diseases-emerging-threat.html

Bees Self-Medicate To Fight Off Fungus

When they get sick, bees raid their own "medicine cabinet," researchers have found. Specifically, when infected with fungi, they collect loads of antifungal plant extracts and coat their hives with them.

The mix of plant resins and wax that the bees usually use to line their hives, called propolis, have antifungal properties.

The new research could help beekeepers ward off fungal infection in their colonies, Michael Simone-Finstrom of North Carolina State University said in a statement. "Historically, U.S. beekeepers preferred colonies that used less of this resin, because it is sticky and can be difficult to work with," he said. "Now we know that this is a characteristic worth promoting, because it seems to offer the bees some natural defense."

The researchers studied 23 colonies, 12 of which had hives coated with "natural" amounts of resin, and 11 with the low amounts normally used in beekeeping. They then challenged the colonies with fungal and bacterial infections, and analyzed how many bees went out to fetch resin for the propolis in each hive, to see if the hive was sending out more foragers to get resin.

Red on:  http://www.livescience.com/19409-bee-medicate-fungal-infection.html

Fungi-filled forests are critical for endangered orchids

Older forests with just the right fungi may be secret to saving vulnerable plants.

When it comes to conserving the world's orchids, not all forests are equal. In a paper to be published Jan. 25 in the journal Molecular Ecology, Smithsonian ecologists revealed that an orchid's fate hinges on two factors: a forest's age and its fungi.

Roughly 10 percent of all plant species are orchids, making them the largest plant family on Earth. But habitat loss has rendered many threatened or endangered. This is partly due to their intimate relationship with the soil.

Orchids depend entirely on microscopic fungi in the early stages of their lives. Without the nutrients orchids obtain by digesting these host fungi, their seeds often will not germinate and baby orchids will not grow. While researchers have known about the orchid–fungus relationship for years, very little is known about what the fungi need to survive.

Biologists based at the Smithsonian Environmental Research Center launched the first study to find out what helps the fungi flourish and what that means for orchids. Led by Melissa McCormick, the researchers looked at three orchid species, all endangered in one or more U.S. states.

After planting orchid seeds in dozens of experimental plots, they also added particular host fungi needed by each orchid to half the plots. Then they followed the fate of the orchids and fungi in six study sites: three in younger forests (50 to 70 years old) and three in older forests (120 to 150 years old).

After four years they discovered orchid seeds germinated only where the fungi they needed were abundant—not merely present.

In the case of one species, Liparis liliifolia (lily-leaved twayblade), seeds germinated only in plots where the team had added fungi. This suggests that this particular orchid could survive in many places, but the fungi they need do not exist in most areas of the forest.

Meanwhile, the fungi displayed a strong preference for older forests.

Soil samples taken from older forest plots had host fungi that were five to 12 times more abundant compared to younger forests, even where the research team had not added them. They were more diverse as well. More mature plots averaged 3.6 different Tulasnella fungi species per soil sample (a group of fungi beneficial to these orchids), while the younger ones averaged only 1.3.

Host fungi were also more abundant in plots where rotting wood was added. These host fungi, which are primarily decomposers, may grow better in places where decomposing wood or leaves are plentiful.

All this implies that to save endangered orchids, planting new forests may not be enough. If the forests are not old enough or do not have enough of the right fungi, lost orchids may take decades to return, if they return at all.

"This study, for the first time, ties orchid performance firmly to the abundance of their fungi," McCormick said. "It reveals the way to determine what conditions host fungi need, so we can support recovery of the fungi needed by threatened and endangered orchids."

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The University of Alaska Fairbanks and Purdue University also contributed to this study. The abstract will be available here: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2012.05468.x/abstract.

http://www.eurekalert.org/pub_releases/2012-01/s-ffa012412.php

Invisible fungi crucial for rainforest diversity

A complex network of fungi in the lower canopy could be one reason tropical rainforests are home to so many different types of insects, spiders and centipedes, say scientists.

They found that nearly half of these creatures – called arthropods – are largely dependent on an almost-invisible network of fungi that traps dead leaves that have fallen from the upper canopy.

When the researchers removed the fungi, both the numbers and diversity of arthropods dropped dramatically.

The findings could help conservationists figure out how to retain some level of arthropod diversity in managed landscapes like oil palm plantations, or logged forest.

The fungi branch through the lower canopy extending from the forest floor up to around 30 metres high, catching falling leaves wherever their strands go.

'These fungi are everywhere, and form a messy tangle in the forest understory. You can't really see it until you look for it. You're always looking past it, moving it out of the way as you walk through the forest,' explains Dr Jake Snaddon from the University of Oxford, lead author of the study.

This could be why, up until now, its importance was almost entirely overlooked.


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