Green Invasion: Destroying Livelihoods in Africa [Video]

CABI, together with Tmax Productions, have produced a video called the ‘Green Invasion – Destroying Livelihoods in Africa.” The short film (approx. 7mins long) details how invasive weeds are impacting on the lives of rural communities in East Africa.

Although a large number of non-native species have become invasive in the region, this film focusses on four of the most problematic species namely Chromolaena odorata (Devil weed), Parthenium hysterophorus (famine weed), Prosopis juliflora (Mathenge) and Opuntia stricta (erect prickly pear). The excellent footage shows the extent of  weed infestations with accounts from community members on how these invasive plants are destroying the natural resource base on which they depend. It is clear that invasive weeds are destroying traditions, cultures and a way of life for millions of people on the continent.

However, all is not lost. The film notes that if effective management programmes are implemented, including biological control, we can make a difference to many people’s lives.

Although of general interest, the film is intended to raise the profile of invasive species and their impacts on livelihoods amongst donors and governments. We need them to take action and provide support for initiatives to manage one of the biggest threats to economic development on the planet.

Arne Witt
CABI Regional Coordinator, Invasives (Africa & Asia)

Weevil fight them on the waterbodies

Introduced to Britain in the 1980s through the aquatic trade Hydrocotyle ranunculoides, commonly known as floating pennywort, is rapidly spreading through Europe and particularly in the UK, Belgium, Germany, Italy, France and the Netherlands. Originating in Central and South America, this stoloniferous perennial plant is forming dense, impenetrable mats which rapidly dominate water bodies, outcompeting and displacing native species and compromising flood defences, navigation and leisure activities.  Despite its relatively recent introduction, establishment and spread have been exponential thanks largely to its extremely fast growth rate (up to 20cm per day) and its ability to re-generate from small fragments. In 2010, floating pennywort was added to section 14, schedule 9 of the UK’s Wildlife and Countryside Act 1981.  A recent report estimates its cost to Great Britain’s economy as £25.5 million each year through management, disposal, flooding and indirect costs to boating and angling.  News that from 2014 the sale of this plant will be banned is significant and welcomed.

Left - A sheep in a UK river clogged with Hydrocotyle (Credit: Trevor Renals); Right - Distribution map of floating pennywort invasion (Credit: DAISIE)

Left – A sheep in a UK river clogged with Hydrocotyle (Credit: Trevor Renals, Environment Agency)
Right – Distribution map of floating pennywort invasion (Credit: DAISIE)

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CABI welcomes EU action against invasive species

Water fern (Azolla filiculoides) covering a UK pond. Corin Pratt, CABI

Water fern (Azolla filiculoides) covering a UK pond. Corin Pratt, CABI

CABI welcomes action that the EU has recently taken (September 9, 2013) to protect member states against the adverse impacts of Invasive Alien Species (IAS).  The draft Regulation on the prevention and management of the introduction and spread of IAS will help to coordinate management and preventative measures across the whole of the EU, leading to what will effectively be a joint battle against IAS – a problem that costs the EU at least 12 billion Euros each year.

CABI’s initial views on four key areas are summarised below:

A list of invasive alien species of Union concern

Identifying invasive species of European concern is at the core of this Regulation and we are pleased to see that lists of these species will be compiled based on scientific evidence.  However, impact evidence, in the form of scientifically replicated studies, is currently lacking for many IAS across the EU. The lack of such data will inevitably have an impact on the strength of risk assessments for individual species.

Inclusion of chapter IV – Management of IAS that are widely spread

CABI is pleased to see that the draft Regulation highlights the valuable work that has been and continues to be conducted throughout EU member states, and welcomes the consultations to the draft Regulation, including all the steps needed to implement it. The inclusion of chapter IV – Management of IAS that are widely spread – is particularly welcomed, as these species are often overlooked due to the networks, resources and time needed to address them on an EU-wide scale.

Inclusion of all management methods, including biocontrol

CABI also welcomes the inclusion of all management methods into the Regulation (physical, chemical and biological actions), as the control and management of some of the more widespread EU weed species can only realistically be achieved using integrated pest management options, in particular classical biological control. Biological control also plays play an important role in protecting aquatic and riparian habitats, and so helps meet requirements of the EU Water Framework Directive as chemical and mechanical control options are often impractical or prohibitively expensive or taboo in such cases.

Inclusion of habitat restoration post control

It is encouraging  to see the inclusion of habitat restoration post control, though it will be difficult to implement from a practical point of view due to cost and the highly disturbed nature of many of the habitats invaded by IAS.

Dr Dick Shaw, CABI’s Global Director of Invasive Species Management says:

“It’s great to see this initiative come so far and that Member States may soon have to do something about invasive species that can and do wreak havoc to biodiversity and their environments.  There will be a lot of horse trading to come but I believe the will is there to make a change in the face of such a major and cross-cutting threat.”

Use them and lose

Is promoting the utilisation of invasive non-native species for commercial or other uses e.g. as a feed for livestock, use as a fuel or to produce biogas, a help or a hindrance to their control?

A view from Arne Witt, CABI Regional Coordinator, Invasives (Africa & Asia):

Promoting the utilization of any invasive non-native species (INNS) has largely contributed to their spread, especially in most developing countries which don’t have the capacity to develop and implement effective integrated management strategies.  Utilization as a control can only be effective if it forms part of an integrated management plan – on its own it merely exacerbates the problem.  There are many examples of where INNS have been intentionally spread by individuals because they have been led to believe that they can enrich themselves by growing and then utilizing an INNS – at low densities many INNS are beneficial, but it does not stay that way for very long – short-term benefits but long-term costs.

One needs to remember that utilization works from “inside out” whereas “control or management” works from “outside-in”.  In other words, the most cost-effective way to utilize an INNS is at the largest and densest infestations. As such you would build your biogas plant or sawmill in an area where the costs with regard to transport are lowest. In addition, you would not “eradicate” any of the plants you utilize – it is expensive and time-consuming to do so and why would you want to anyway, you want a renewable resource, so getting the plants to coppice, so that you can use them again in the future, is exactly what you want.  This is largely what is happening in Africa – those utilizing prosopis for charcoal do not apply herbicide to the cut stumps or dig out the rootstock – they want the plants to coppice. The same happens in India with regard to the utilization of lantana – communities don’t kill the lantana, they allow it to coppice. In addition, it does not make economic sense to utilize plants growing individually or in small pockets away from these dense infestations, especially in developing countries where we have poor infrastructure.  For a control/management strategy to be effective we need to work from the “outside-in”, removing individual plants or small isolated stands first before moving onto the dense stands – utilization works in the opposite way which is why it is ineffective as a management strategy on its own.

African landscape dominated by prosopis

African landscape dominated by prosopis (Arne Witt, CABI)

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Getting swamped: Australian swamp stonecrop (Crassula helmsii) in the UK

In January this year, large parts of southern Australia were ablaze with fierce bush fires, while most of the UK was covered in snow. Half a world away from each other, and at one point nearly 40ºC apart, there aren’t too many similarities to be drawn between the two locations. And yet, there is a water weed, Crassula helmsii, that survives happily in both extremes – and in the UK, where it has been introduced, this adaptability is proving extremely problematic.

 Crassula helmsii, also known as Australian swamp stonecrop or New Zealand pygmyweed, is a small semi-aquatic plant in the Crassulaceae family. As its common name implies, this low-growing succulent originates from the antipodes, but was introduced to Britain from Tasmania almost 100 years ago. Initially sold by garden and aquatic centres as an oxygenating plant, by the 1950s it had established in the wild, and from there it has spread to numerous ponds, lakes and waterways throughout the UK.

A mat of Crassula helmsii in flower

A mat of Crassula helmsii in flower

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Rusty Solutions for a Prickly Problem

The state of Queensland has got an alien thorny invader: Prickly acacia, or in scientific terms Acacia nilotica subspecies nilotica.

Prickly acacia - Kunjithapatham Dhileepan

Prickly acacia invasion, north Queensland, Australia, Photo: Kunjithapatham Dhileepan, DEEDI, Australia

Prickly acacia is a shrub or small tree which belongs to the plant family Leguminosae, subfamily Mimosoideae, a family which also accommodates the sensitive plant Mimosa pudica, well-known as a curiosity house plant. The prickly invader A. nilotica is native to Africa, the Middle East and the Indian subcontinent and was introduced from India into Australia in the late 1890s. Originally imported as an ornamental, A. nilotica ssp. indica was later widely used as a shade and fodder tree for sheep. But what was initially a valued addition to the Australian flora soon became a menace. When the grazing regime in Australia changed from predominantly sheep to cows and the country also experienced a number of successive wet years, the balance swung in the favour of prickly acacia. The thorny shrub spread quickly and has now invaded around six million hectares of arid and semi-arid land in the State of Queensland. Acacia nilotica ssp. indica is also present in the Northern Territory as well as in Western Australia. Due to its substantial impact on the environment as well as on the economy, particularly on the livestock industry, prickly acacia was initially declared a noxious weed in Queensland in 1957. Subsequently the plant has also been listed as a “Weed of National Significance” for the whole of Australia. And Australians have every reason to be worried, as the prickly invader has got the potential to spread throughout the arid regions of the whole of northern Australia.

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Alien Battlefield

Recent articles in Science, the NY Times and Nature have suggested that we should embrace invasive species and the resultant “novel ecosystems” and that those that do battle with such species are verging on xenophobic. This is a common cycle in many fields and I’m told that a discussion thread is considered closed once a poster has been described as xeonophobic or worse, if so this discussion could be over before it even begins. Nevertheless, a group of scientists and practitioners wrote a response which can be found on the ISSG website. The issues are certainly complex. It is true that preserving pristine ecosystems is a lost goal and there are probably none in existence anymore, but to do nothing and indeed to try to argue that the new system is one worth accepting suggests that the authors have either given up in the face of too difficult a task, or have seen an opportunity to publish something controversial. There are certainly “profits” of doom to be had on both sides. In order to get your invasive management project funded it is necessary to take the public with you and when engaging with the media evocative negative language can appear in print. On the other side it is easier to stand out from fellow authors if you challenge an accepted paradigm. In the case of weeds, it is generally understood that monocultures of the new plant are less biodiverse but more productive than the flora they replace and depending on your priorities their arrival could be a good or a bad thing. If we accept that biodiversity is a priority there are few arguments to be had for introducing new invasive exotic species except for biocontrol where the excellent paper by Van Driesche and many co-authors shows the potential benefits. It is this tool that was notably overlooked in the discussions despite choosing the Galapagos as a case study where there are excellent targets for weed biocontrol yet no funding has materialised despite the vast sums spent on vertebrate eradications.

Lantana on the Galápagos - a major invasive for which all hope is not lost

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3D modelling: Not just for Hollywood, now for invasive species

An easily overlooked but vitally important component of invasive species management is accurate identification. Picture the scene: It’s Australia, it’s a Friday afternoon, a comprehensive fire ant management strategy has been drawn up, baits have been acquisitioned and an eager team of volunteers is ready to deal with this invasive foe and escape for the weekend. There are plenty of ants around… but nobody knows if they’ve found the right ones because the pesky little critters all look so similar! Scientists in Australia believe they have a solution – a database of 3D images of known species against which 2D photographs of organisms taken and uploaded in the field are compared, giving an estimate of their likely invasive or native status.

Fire Ant - Leo Blanchette

3D Ant – by Leo Blanchette, flickr

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The Nagoya protocol and biological control by Matthew Cock

Since 2009, I have worked with the Global Commission on Biological Control and Access & Benefit Sharing of the International Organisation for Biological Control to raise awareness of the issues relating to biological control which may be affected under the Convention on Biological Diversity’s access and benefit sharing protocol which was finally agreed at COP10 in Nagoya, Japan, in October last year1.

The IOBC Commission attended various background meetings, produced a report for the Global Commission on Genetic Resources for Food and Agriculture2, followed by a Forum Paper in the journal BioControl3 and various news items culminating in a World View page in Nature4 the month before the Nagoya meeting. Basically, we put the case that biological control is a public good, that countries that supply biological control agents are also importers of biological control agents, that the best way forward would be to continue the 100+ years history of free multi-lateral exchange of biological control agents between countries as non-commercial research under any future access and benefit sharing protocol, and that benefit-sharing should be based on shared research activities.

Matthew Cock - Nature

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Blowing our trumpet

A well-balanced article about the biological control of Japanese knotweed was published today in a British newspaper. Most articles about the release of the Japanese knotweed psyllid (Aphalara itadori, pictured) that appeared last year were either dismissive of the idea of releasing a non-native insect to combat another non-native species, often on the grounds that the selected agents will also damage native species. Or the articles just copied bits of press statements.

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