Survival of soil organisms is a wake-up call for biosecurity

Tiny creatures in soil that attack plants have shown the ability to survive for at least three years stored in dry conditions in a recent AgResearch study, giving new insights into the biosecurity threats posed by passenger travel and trade between countries. The research article is published in the open access journal Neobiota.

The findings of the study also add to the discussions about how best to detect these creatures, called nematodes, before they cross borders and potentially reduce yields of important crops and pasture.

Nematodes are very small worm-like organisms. They can be extremely hardy and can have both beneficial and detrimental impacts. The harmful ones, the plant parasitic nematodes (PPN) include species that attack plants reducing their growth and survival.

In the study, funded by AgResearch via the Better Border Biosecurity collaboration, soil collected from a native forest and an organic orchard was stored separately in cupboards at room temperature for a period of 36 months.

Samples were then taken at regular intervals to see if any nematodes could be recovered from the soil and, if they could, whether they were able to infect plant hosts.

“In the study we used different methods to detect nematodes — including a water misting technique to draw them out of the soil, and a baiting method — where we grew white clover and ryegrass plants in pots containing a soil sample,” explain the authors.

“One of the PPN we looked at was the root lesion nematode. What we found was that lesion nematodes were able to successfully invade the roots of ryegrass even after 36 months,” says AgResearch nematologist Lee Aalders.

“They were also able to produce offspring at 13 months. Interestingly, no PPN were recovered from soil stored beyond the 13th month using the three-day misting technique.”

This means that given the right conditions, PPN in soil, which is carried on sea freight, footwear or used machinery, and protected from sun or extreme heat, will survive if they end up near a suitable host plant. This is a result that may not be detected using an extraction test like misting.

For quarantine officials around the world, this result is an important find, as it reinforces the risk associated with soil that, even though it may look sterile, unwanted nematodes may be present and undetected until paired with a suitable host plant.

“In the context of biosecurity, we think that the development of a generic test for plant parasitic nematodes – based around a molecular based bioassay — would enhance the probability of detection of PPNs and, therefore, prevent unwanted incursions beyond the border.”

Earlier this year, another AgResearch study into the survival rates of various transported soil organisms and published in Neobiota concluded that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes.

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Original source:

Aalders LT, McNeill MR, Bell NL, Cameron C (2017) Plant parasitic nematode survival and detection to inform biosecurity risk assessment. NeoBiota 36: 1-16. https://doi.org/10.3897/neobiota.36.11418

People can simultaneously give a hand to endangered apes and stay at safe distance

Primates claim the highest proportion of endangered species among all mammals, according to the IUCN Red List. Yet, the substantial conservation interference from humans, which is already in place, could itself lead to even greater losses.

Plenty of studies have proven that while researchers and ecotourists raise vital for ape conservation knowledge and funds, it is actually human presence that compromises primates’ well-being due to extremely similar genetics and, thereby, easily transmittable diseases, ranging from common cold to human tuberculosis and Ebola fever.

In a paper published in the open access journal BioRisk, Rhiannon Schultz, Miami University, seeks the golden mean between giving ape species a hand and keeping safe distance. To showcase the impact human have on primates, the scientist makes example of the Mountain gorilla, an endangered species living in the montane forests of the Democratic Republic of Congo, Uganda and Rwanda.

Simply being in close proximity to primates, humans can easily transmit a wide range of diseases to the animals, including intestinal parasites, hepatitis, tuberculosis, Typhoid fever, Cholera, and Ebola fever. The transmission can occur as easily as having the two species breathing the same air, or the people leaving a banana peel behind.

Furthermore, threats to the gorilla species are also posed by the humans destroying the primates’ habitats. The result is overlapping populations, where a disease is much easier to transmit among the small gorilla populations. For example, normally an ill individual would be put under a ‘natural quarantine’, which is impossible when the habitat has already been reduced.

In the meantime, banning people, both tourists and scientists, from gorilla habitat is not an option, since knowledge about the populations’ dynamics is essential for the conservation of all primate species. On the other hand, ecotourism is what raises a great part of the resources need for conservation work. Income from gorilla trekking is enough to support the Ugandan Wildlife Authority, while also contributing a significant part to the country’s national budget.

The key, Rhiannon Schultz concludes, is to, firstly, promote understanding of the risk for interspecies disease transmission as a conservation threat, and then, improve on current protocols and regulations.

“It may be difficult to ask tourists to wear masks while visiting animals in the wild, and it may be expensive to maintain a veterinary program for wild populations and to improve healthcare systems for local people, but making these improvements could be the key to preventing disease transmission to not only Mountain gorillas but also to other apes,” sums up the scientist.

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Original source:

Schultz R (2016) Killer Conservation: the implications of disease on gorilla conservation.BioRisk 11: 1-11. doi: 10.3897/biorisk.11.9941