A recently published review paper in Nature draws attention to the dangers of globalisation and international trade which facilitate spreading of fungal diseases. The authors collected data from all over the world and showed that fungal infections had increased, caused extinction of several species and even contributed to climate change in the last few decades. They claim that immediate action is needed to prevent devastating impacts of the spreading of fungal diseases mainly by more research and better implementation of science into policy and practice.
The scientists looked at the problem holistically and pointed out some unusual links. They state for example that fungal diseases can contribute to climate change through killing or damaging trees that otherwise would have absorbed significant amount of CO2. They also highlight that biodiversity loss is accelerated by fungal pathogens. Due to small population effects and decreased ecosystem diversity, a fungal disease can wipe out entire species as it is seen in the case of amphibians. In case of animal species, fungal infections already account for 72% of infection-related extinctions which is more than viral and bacterial caused extinctions altogether.
Fungal pathogens can even facilitate invaders’ success. In the well known case of the North American signal crayfish in the UK a fungus-like disease (Crayfish Plague) helps the invader. The signal crayfish is tolerant to the infection which is lethal to the indigenous white-clawed crayfish. By spreading the disease around and wiping out the native crayfish the invader can occupy more and more habitats.
Food security is also in danger. Fungal infections of our five main food crops (rice, wheat, maize, potatoes and soybeans) are already causing serious problems and destroy a significant amount of the yield each year. Newly emerging fungal diseases can affect agriculture directly while new pathogens affecting animals can also have an indirect effect on crop production. Estimations suggest that White Nose Syndrome which decreases bat populations in North America can cause huge extra costs ($3.7 billion) to agriculture through the lack of bat control on insect pests.
The authors point out that human behaviour (international travel and trade) is the major cause of the recently recognised expansion of fungal diseases. Therefore, they call for stronger international biosecurity by strengthening international trade regulations, quarantining more rigorously and tackling illegal trade more effectively through trade control organisations. They also emphasise that integrated research on identifying, monitoring and mitigating the impacts of these diseases is much needed to get ahead of fungal epidemics.
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The original paper: MC Fisher et al. Emerging fungal threats to animal, plant and ecosystem health. Nature, 12 April 2012. DOI 10.1038/nature10947