Taking control of Invasive Alien Species!

Invasive Alien Species are becoming increasingly widespread and common across the world,  and it is thought that soon, they may take over habitat loss as being the number one cause of ecological destruction. But fear not, scientists and governments are working together to find ways to prevent and eradicate invasions!

Clout & Veitch define two main priorities when trying to minimise further damage to the environment and biodiversity. You can either reduce the risk of new invasions or eradicate the existing invasive populations, both of which are extremely difficult tasks. By either preventing or eradicating Invasive Alien Species (IAS), it can help to increase biodiversity but can also provide economic benefits by removing the causes of agricultural losses for instance. However, the complex dynamic of ecosystems and their species within, make it very hard to successfully do so. 

So how can we successfully eradicate IAS?

There are multiple actions that can be taken to increase the chance of successfully removing an invasive species, as suggested by Pluess et al. For instance, by starting a removal campaign before the infestation gets uncontrollably large or starting to eradicate within the first four years of invasion and by putting focus on IAS that arrive via cultivation. Also, once the removal has begun, ensuring it goes to completion, that species are removed above the rate of reproduction, and the entire population is being accounted for will help to promote success, as explained by Clout & Veitch. 

Invasive Alien Species associated with agriculture are more likely to be eradicated because of economic losses associated when invasions take over, like with the Banana Bunchy Top Virus explored in last weeks post. Also, invasions on islands are more likely to be successfully removed due to the smaller infestation area that is easier to manage. 

EU Regulations

All eradication plans require a lot of cooperation between local people and governments. For instance, on January 1st, 2015, the European Union made a new regulation requiring a list of concerning IAS to be created, prevention methods to be put in place and management schemes set up to quickly eradicate widely spread IAS. It is these large scale plans that improve eradication success by providing larger investments and overall increased efforts although this isn't always enough! 

Issues with Invasive Alien Species eradication!

Despite teams of scientists working to create schemes for eradicating Invasive Alien Species, when they are carried out, it usually doesn't go according to plan.  The outcome of an eradication scheme depends on very special features of both the invading species, the environment surrounding it and fellow inhabiting species. 

 Clout & Veitch explore some of these issues, for instance, eradication success depends on the how the IAS disperses. In plants, for example, if they are spread by wind or birds then their seeds could distribute across a very wide, varying landscape and it is hard to prevent this from happening and fully eradicate certain species.  

Similarly, it is very hard to design eradication techniques that do not harm non-targeted species. On Kapiti Island, brushtail possums (shown to the right) were successfully eradicated, but in the process, 181 birds were also killed in the same traps. This can cause a lot of controversy as members of the public and some organisations, question the ethics of killing a native species in the eradication process of an invasive one. 

However, there is also opposition when it comes to killing the Invasive Alien Species itself.  For instance, the culling of the ruddy duck in England sparked a lot of debate in terms of ethics, as noted by Blackburn et al. Negative responses such as this can jeopardise the progress of eradication schemes and therefore this social aspect also needs to be considered during the planning stage. 

At the end of the day, eradication schemes do involve killing or removing invasive animals, plants or micro-organisms and this is sometimes quite hard to accept. Before exploring Invasive Alien Species throughout this blog, I would have instantly assumed that the eradication of an innocent organism was immoral and avoidable. However, after discovering the major impacts that IAS can have on habitats and their animals within, I've learned that control and elimination can be the lesser of two evils and result in fewer deaths overall. In spite of this, there are steps that we can take to prevent invasions from occurring to prevent lives avoidably being lost. With increasing global transportation and a changing climate, it is our responsibility to reduce the chance of future extinctions and take responsibility for the effects we have.

Do you think its okay to kill entire populations of plants, animals and microorganisms when they may have invaded an area due to humans?

Check out this blog related to marine conservation to see why it is important to prevent more native species loss http://the-turtle-and-the-hare.blogspot.co.uk!

Can we beat the Banana Bunchy Top Virus?!

Banana growing countries across the world are at risk of invasion from the boisterous Banana Bunchy Top Virus!

 

Surprisingly, Invasive Alien Species can come in the form of micro-organisms, like the Banana Bunchy Top Virus. First recorded in Fiji in 1889, it has now invaded more than 120 countries worldwide, and scientists are trying to find a way to control this dangerous disease and prevent further spread in banana plants! 

What does this dreadful disease actually do?

The classic symptoms of infected banana plants include an overall dwarfed effect, bunching up of leaves, lack of fruit production and dark green streaks on the leaves, as reported by Kumar et al. In the image below, the 'In' shows the infected plant compared to the healthy 'He' one. 

The stunted growth and reduced fruit production cause detrimental economic and health effects. Worldwide production of bananas exceeds 100 million tonnes, and it is the 4th most important food crop behind rice, wheat and maize according to Cook et al., making it fundamental to millions of livelihoods. 

What is the main mechanism of invasion?

The Banana Bunchy Top Virus (BBTV) either gets transmitted by the aphid, Pentalonia nigronervosa (as shown by the image to the right) or by infected plants coming into contact with healthy ones. In Hawaii specifically, Almeida et al. believe that the movement of contaminated plant material across and between the islands led to this epidemic destroying large amounts of their crops. 

Almeida et al. describe the human transportation of these plants to new sites, both with and without the aphid being present upon them, as a type of Pathogen Pollution. This invasion of virus' into places outside their native area cause the host (the banana plant in this case) to be at a new risk of infection and hence human activity is causing major spreads of diseases and not just in the banana plant! 

With the world's population size continuing to grow rapidly, the demand for food is ever increasing meaning that more banana plantation sites are being formed. The set-up of theses farms requires the transfer of crops from previous areas, and this is where the cross-contamination occurs. Also, as mentioned in another blog post, improved transportation efficiency is allowing plants, animals and micro-organisms to spread to new invade-able areas meaning that diseases like BBTV can spread even more easily thanks to our increased trading and travels. Bananas generate both an income and a food source for people all over the world and so the management and control of diseases that destroy them is highly important, but how is it done? 

Methods of management?

The Cooperative Extension Service of the University of Hawaii says there are two ways of controlling such a disease either by killing the aphid's that carry the disease of removing all the infected banana plants from a particular site. 

For the Banana Bunchy Top Virus in Australia, Cook et al. predicted the amount of area that would be affected by BBTV if no management strategy was enforced (Nil Management) vs, a plan of Active Containment. This Active Containment plan involved destroying any previously infected crops and as soon as the infection was detected locally, to stop further spread. As the graph to the left shows, the Active Containment reduces the amount of land diseased drastically, with the variance shown being due to the risk of re-emergence and eradication is not 100% effective. 

However, these plans and policies are very effective in theory but when it comes to practising them, it is never as successful. For instance, in 1993 in Australia a five-year programme was carried out to eradicate Banana Bunchy Top Virus but did not fully work and by the end, not all of the disease was removed and so spreading began again. 

In sub-Saharan Africa BBTV is also widespread but due to different socioeconomic conditions, long-term, wide-scale programmes like done is Australia are as suitable, even if they did become entirely effective. As a result, Kumar et al. proposed some new ideas on how to control BBTV in sub-Saharan Africa:

• Educate farmers on how to efficiently destroy diseased crops 
• Supply clean, BBTV free planting material to farmers 
• Improve monitoring schemes 
• Deploy rapid removal responses to the detection of the disease 

The schemes suggested are not mutually exclusive but can be used together to detect, destroy and prevent re-infection in plantations efficiently. Such epidemics require cooperation between the governments, local authorities and the farmers themselves in order stand any chance of effective control.

 Do you do think the consumer has any responsibility for making sure they buy bananas from farms that actively try to reduce the spread of BBTV? Should this information be made available?

Whatever your view,  next time you buy a banana, just remember how lucky you are that that one escaped the grasp of the famous Banana Bunchy Top Virus!! 

Climate - the game changer?

'Climate change' is a phrase thrown about by the media and scientists, commonly used to explain the weird and wonderful things that are happening on Earth today. But what affect is it having on Invasive Alien Species?

What does 'climate change' mean?

According to the Metoffice, climate change is:

"A large-scale, long-term shift in the planet's weather patterns or average temperatures."

and the results of this can be seen across the world. For instance, since 1901 there has been a 0.89 degree Celsius rise in the average surface temperature, global sea levels have risen 19cm since the 1900's, rainfall patterns are changing with a major increase in the mid-latitudes of the Northern Hemisphere and Arctic sea ice has reduced 4% since the 1970's.
These telltale signs of climate change, amongst many others, have major impacts on all organisms. But what affect is it having on Invasive Alien Species? Hellmann et al. defined five key consequences that climate change is already having or is expected to have in the future. 

1. Altered transport and introduction methods: 

As previously mentioned in my blog 'Transport and Trade of Invasive Alien Species', how Invasive Alien Species get to new areas is really important. Not only is it changing due to increased transport efficiencies but rises in sea levels mean previous unconnected areas are being joined by water. Also, melting of sea ice means that new shipping routes are becoming available and shipping seasons are being extended meaning more opportunity for pesky species to hitch a ride. 

2. New Invasive Alien Species: 

Non-native species that were not previously unsuccessful at invading, may be able to inhabit new areas that now have climates more suitable to them. Also, Invasive Aliens Species are known to be able to be able to survive in changing environments, where are native species are not as good. With longer dispersal ranges, more tolerances and a shorter juvenile period they are more likely to survive when the going gets tough! 

3. Altered impact of the previous Invasive Alien Species:

The impact an Invasive Alien Species can have, once fully established in an area, is commonly restricted by environmental factors such as temperature and water. For instance, a temperature constraint set by the extreme cold may mean an Invasive Alien Species is unable to survive in winter, allowing the native species to recover and spread. However, with temperature increases, the growing season may be extended, reducing the recovery time of the native species and could result in their extinction. 

4. Altered distribution of the previous Invasive Alien Species:

With changes in climate, the landscapes also change, and the spread of Invasive Alien Species responds to this. Bellard et al. for example, predict that species are likely to move away from lower latitudes due to the already extreme climatic conditions that are likely to become unbearable. This is expected to lead to a loss of tropical Invasive Alien Species but a movement to more temperate mixed forest areas in the Northern Hemisphere. Its already being seen with a reported 76% increase in the number of Invasive Alien Species in Europe in the last 30 years. 

5. Change to the effectiveness of control strategies: 

Check back soon to find out more about this and how scientists and governments are trying to combat the issue of Invasive Aliens Species through control, such as the chemical spraying shown to the right. 

So why is all this climate change occurring? Click the link to find out some more information: http://www.metoffice.gov.uk/climate-guide/climate-change/why

Also, to find out how climate is affecting human health, check out this other blog https://unhealthyplanet.blogspot.co.uk!