Scientists warn of emerging fungal peril

Apr 13, 2012 By Tom Marshall
Scientists warn of emerging fungal peril
Little brown bats showing signs of white nose syndrome.

Fungal diseases are a major threat not just to wild plants and animals, but to us.

A new Nature paper shows we're already heading for huge fungal damage to vital and ecosystems over the coming decades. If we don't do more to stop these diseases' spread, their impact could be devastating.

already destroy at least 125 million tonnes a year of rice, , and and soybeans, worth $60 billion. Researchers estimate that in 2009-10, this lost food could have fed some 8.5 per cent of the world's people. And this is just the result of persistent low-level infection; simultaneous epidemics in several major crops could mean billions starve.

But the threat has gained a new urgency lately, and crops aren't the only thing at risk. More and more of these killer fungi are appearing, and they're increasingly attacking animals.

Emerging fungal epidemics already account for 72 per cent of extinctions from disease – more than bacteria and viruses put together. For instance, amphibians are being wiped out at an unprecedented rate by a deadly chytrid fungus that's been spread by the global animal trade; at least 500 species are thought to be at risk. Likewise, bats are being struck down by so-called White Nose Syndrome, which has spread all over North America since it was first spotted in 2006.

"We've known for a long time about fungal pathogens like Dutch elm disease and potato blight," says Dr. Mat Fisher, an expert in fungal infections at Imperial College London and one of the paper's authors. "But we're seeing more and more of these pathogens, and they are starting to affect animals in a way we've never seen before. The chytrid fungus has wiped out 40 per cent of amphibian species in some parts of Central America in just a few years, and we don't know what the knock-on effects will be."

New fungal diseases keep appearing, affecting organisms from bees and corals to sea otters. If we don't do more to control them, we could see species wiped out all over the planet.

In many cases there are direct consequences for humans. For example, bats eat insects that would otherwise attack crops; studies suggest White Nose Syndrome could end up costing farmers some $3.7 billion a year. But even organisms that aren't obviously useful to us will have unpleasant consequences somewhere down the line if they disappear.

"Ultimately you can't separate ecosystem health from human health – eventually, these birds will come home to roost," Fisher says, adding that the less diverse become, the less they can stand up to sudden changes.

are even making climate change worse; scientists estimate that the trees they've killed or damaged would otherwise have absorbed 230-580 megatonnes of CO2 – around 0.07 per cent of the total in the atmosphere.

Unfortunately it's almost impossible to eradicate fungal disease once it's loose in a wild population. But by tightening rules on the transport of plants and animals around the world, we could limit these pathogens' spread into new areas.

Why have fungi become so deadly? Many have tough, long-lived spores, so they can survive without a host for much longer than most bacteria or viruses. Combined with our unprecedented levels of global trade and travel, this makes it easy for fungi to reach new areas. And environmental change may be helping them thrive once they've arrived.

Moreover, many fungi – particularly those that target animals – can infect several species. If a pathogen affects just one victim and it wipes it out, it has doomed itself too. So most single-species infections reach equilibrium with their host population, and never kill it off entirely.

But diseases that jump between species work differently. They aren't tied to one species, so there's no reason to avoid wiping a host out. And some species will be more vulnerable than others. The more resistant ones can carry the fungus without serious harm, so they can spread it about, infecting even isolated pockets of their more vulnerable cousins. For instance, in the UK the invading North American signal crayfish is wiping out the native white-clawed crayfish with the help of a fungus-like disease that the invader tolerates but that's deadly to its indigenous rival.

Finally, fungi are adept at swapping genes between themselves, so when we bring different species into contact, dangerously virulent combinations can result.

Fisher says we need to start taking biosecurity far more seriously – cutting down the amount of living material we transport around the world, quarantining what we do transport far more rigorously, and doing more to stop the illegal trade in plants and animals. Eventually, breakthroughs in genetic diagnostic technology may make it possible to screen for fungus or spores. But in the meantime, we need to do more to prevent outbreaks, and move quickly to control those that do happen before they get out of hand.

He adds that we also need to train more mycologists to analyse these emerging threats - the subject has itself come dangerously close to in recent years. And mycologists need to communicate their work more effectively to policy-makers and the public.

Explore further: Stanford researchers rethink 'natural' habitat for wildlife

More information: MC Fisher et al. Emerging fungal threats to animal, plant and ecosystem health. Nature, 12 April 2012. DOI 10.1038/nature10947

Journal reference: Nature search and more info website

Provided by PlanetEarth Online search and more info website

5 /5 (6 votes)
add to favorites email to friend print save as pdf

Related Stories

Frog trade link to killer fungus revealed

Nov 08, 2011

The global trade in frogs, toads and other amphibians may have accidentally helped create and spread the deadly fungal disease, chytridiomycosis, which has devastated amphibian populations worldwide.

Mold fungi can cure plants

Nov 01, 2011

We know them from our garden, from damp cellars or from the fridge - mold fungi can be found almost everywhere. Their success is due to their remarkable versatility:  depending on external conditions, ...

Culling can't control deadly bat disease

Feb 14, 2011

Culling will not stop the spread of a deadly fungus that is threatening to wipe out hibernating bats in North America, according to a new mathematical model.

Recommended for you

Plants with dormant seeds give rise to more species

5 hours ago

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Scientists tether lionfish to Cayman reefs

15 hours ago

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

5 / 5 (1) Apr 13, 2012
An acquaintance returning from a trip told me of sitting next to an elderly doctor on the plan who spent the entire trip railing against anti-aging efforts because, according to him, we'd all just end up being slowly eaten alive by one or more forms of fungi as our immune systems irreversibly declined with age. The descriptions were rather grotesque.
2 / 5 (1) Apr 13, 2012
Ecologies are almost never in equilibrium. They are inherently dynamic, a consideration that continually drives evolution. For each species that is thriving and diversifying, there is probably one, maybe more, that is fading and dying.
Dynamic equilibrium can only exist in the simplest closed systems.

More news stories

Researchers successfully clone adult human stem cells

( —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Plants with dormant seeds give rise to more species

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers develop new model of cellular movement

( —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Male monkey filmed caring for dying mate (w/ Video)

( —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Treating depression in Parkinson's patients

A group of scientists from the University of Kentucky College of Medicine and the Sanders-Brown Center on Aging has found interesting new information in a study on depression and neuropsychological function in Parkinson's ...