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)
@WittArne


New in February 2014 from the ISC

In February 2014 the following datasheets were published on CABI’s Invasive Species Compendium (ISC). You can explore the open-access ISC here: www.cabi.org/isc

Drosophila suzukii - The damage caused by D. suzukii larvae renders fruit unmarketable. In 2008 economic losses (based on maximum reported yield losses) for California, Oregon and Washington were estimated at 40% for blueberries, 50% for caneberries, 33% for cherries and 20% for strawberries. Production in these three states could sustain $511 million in damages annually because of D. suzukii. D. suzukii produces up to five times more hemocytes than D. melanogaster, making it significantly more resistant to wasp parasitism and making it less likely for indigenous specialized parasitoids to shift host onto it.

Drosophila suzukii ISC datasheet

Drosophila suzukii Invasive Species Compendium datasheet

Rattus rattus - R. rattus has directly caused or contributed to the extinction of many species of wildlife including birds, small mammals, reptiles, invertebrates and plants, especially on islands. The primary economic impact of R. rattus relates to agricultural and horticultural damage. It is capable of destroying up to 30% of crops annually. Phylogenetic restructuring of the ‘Rattus rattus complex’ (comprising the oceanic and Asian groups) is on-going. Based on molecular evidence, there are multiple species within what has historically been identified as Rattus rattus.

Leonurus japonicus - L. japonicus is a highly invasive weed widely naturalized in tropical and subtropical ecosystems. It commonly grows as a weed in waste places, disturbed sites and along roadsides and as an ornamental in gardens and yards. L. japonicus also invades pastures and arable land as well as coastal and dry forests. In a recent work, Xiong, et al. (2013) described the chemical composition and the antibacterial activity of essential oils from different parts of L. japonicus. These essential oils showed antibacterial activity against various Gram-positive bacteria.

Other invasive species datasheets recently published include…

Chamaecrista nictitans

Medicago polymorpha

Pantherophis guttatus

Amphisbaena fuliginosa

Datura ferox

Schilbe mystus

Protopterus aethiopicus

Horizon Scanning for Invasive Species

In this, the era of globalisation, increases in international trade, transport and travel have driven an upsurge in the diversity and volume of non-native species introductions to new areas worldwide. Introduced plant, animal and pathogen species may fail to establish in a new range, and where they do establish, may be environmentally benign. However, there is potential for introduced non-native species to become invasive, even after a (sometimes extensive) period of time without apparent negative impacts.

Preventing the introduction and establishment of a species considered to be an invasion risk is key to mitigating its potential impacts in a new area. For this to be done effectively, it is vitally important that countries conduct horizon scanning initiatives to determine the non-native species likely to arrive, to evaluate the threat posed should the organism become established, to determine by which pathway(s) the organism may be introduced and where appropriate, to convey to the competent authority the requirement for rapid response strategies to alert list species. The recent European Union (EU) draft regulation which aims to legislate for the control of invasive non-native species in the EU is likely to be focused on a list of priority non-native species. A significant number of the species on this list are likely to be alert species not yet present in the region, but which will be determined as threats through the horizon scanning and prioritisation process. The outcomes of this horizon scanning process are likely to be of great interest and importance to various concerned parties across the European continent and beyond, and will certainly be subject to close scrutiny.

Horizon -  Norma Desmond, Flickr

Are invasive species on the horizon?
Photo: Norma Desmond, Flickr

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Himalayan Balsam and its impact on UK invertebrates

Himalayan Balsam and its impact on UK Invertebrates - Infographic

Himalayan balsam is one of the UK’s most widespread invasive weed species, colonising river banks, wasteland, damp woodlands, roadways and railways. Research by CABI scientists has shown local invertebrate biodiversity is negatively affected by the presence of Himalayan balsam. This leads to fragmented, destabilised ecosystems, which has serious consequences on processes and functioning, and complicates habitat restoration unless remedial actions are implemented.

Tanner, R.A., Varia, S., Eschen, R., Wood, S., Murphy, S.T. & Gange, A.C. (2013) Impacts of an invasive non-native annual weed, Impatiens glandulifera, on above- and below-ground invertebrate communities in the United Kingdom. PLoS ONE, 8(6): 1-13

Lakes poisoned to halt topmouth gudgeon invasion

Several lakes in Hampshire are being poisoned in a bid to control topmouth gudgeon (Pseudorasbora parva), an invasive non-native fish first introduced to Britain in the 1980s which has become more widespread in recent years.

Topmouth gudgeon (Pseudorasbora parva)

Topmouth gudgeon (Pseudorasbora parva)
(Photo credit: Melania, Wikimedia Commons)

The fish, native to Asia, has spread across much of Europe in recent decades, travelling along waterways and facilitated by illegal fish stocking. Its impacts are significant and include predation on native and farmed fish eggs, resource competition and the ability to host and transmit the rosette agent (Sphaerothecum destruens), a fish parasite that is particularly devastating to Salmonid species such as trout and salmon

The piscicide, Rotenone, is to be applied to the lakes following the removal of native fish in an effort to eradicate topmouth gudgeon whilst limiting non-target impacts. The method has been used by the Environment Agency at a number of sites over the last decade as part of a wider strategy to eradicate topmouth gudgeon from England and Wales. Rotenone breaks down over several weeks, after which the site can be re-stocked with native and/or farmed fish species. Whilst the intervention is fairly drastic, it is considered necessary to prevent the further spread of topmouth gudgeon and limit its likely environmental and economic impacts.

Find out more about the topmouth gudgeon and hundreds of other invasive species at CABI’s open access Invasive Species Compendium.


Dr Paul Fisher
Communications Manager, CABI

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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The advance of the Asian hornet creates a buzz in the UK media

Some of the species that are included in our open-access Invasive Species Compendium are well known to the general public, for example Japanese Knotweed. Others are more obscure, and I had never heard of the Asian Hornet, Vespa velutina, until I edited the datasheet about it earlier this year. I was therefore interested to hear an item about it a few days ago on the Today programme, one of the best-known programmes on BBC radio (you can listen to the item here).

Picture: ©Muséum de Toulouse/Didier Descouens-2013. CC BY-SA 3.0

The species originates from eastern Asia and was accidentally introduced to southern France about 10 years ago in a consignment of terracotta pots from China. It spread rapidly through France, soon reaching the stage where eradication was impossible, and into neighbouring countries. As it is a predator of honey bees, it is of serious concern to the beekeeping industry (where it is native, bees have some ability to kill hornets by surrounding them with a ball of bees and heating them to death, but European bees are much less effective at this). It can sting people badly too, although European populations are generally not very aggressive.

It is considered very likely that V. velutina will spread to the UK, either through accidental transport by humans or by flying across the English Channel (see here for a risk assessment). Eradication will only be possible if it is spotted promptly, and long-term management will also require knowledge of where it is present, so the public (especially beekeepers) are being asked by the Department for Environment, Food and Rural Affairs to look out for it and report any sightings to alert_nonnative@ceh.ac.uk. This request has been picked up by several parts of the UK media, including the Independent, the Daily Mail and even the local newspaper here in south Oxfordshire.

An information sheet describing how to recognise the species is available here; August and September are the peak months for V. velutina activity, so if you live in the southern part of the UK, or indeed anywhere else in western Europe, please look out for it!

Mark Palmer
Content Editor
CABI

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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Invasive species catch a wave

Over two years have now passed since the Tohoku earthquake rent the seafloor 40 miles off the coast of Japan. The 9.03 magnitude quake – the largest in Japan’s history – triggered a staggeringly destructive tsunami which cost the lives of over 15,000 people.

Aside from the human tragedy of the disaster, the tsunami has had another, quite unexpected, effect: the transport of invasive species across the globe.  Plants and animals from the north-west Pacific are now washing up over 8000 miles away on North American beaches, sparking fears that a wave of ecological invasions could be threatening coastal environments the length of the continent.

How have these organisms managed to travel so far? Such was the force of the tsunami as it tore into docks, boats and buildings on the Japanese coast that an estimated 1.5 million tons of debris was washed out to sea. This was not just the usual plastic waste that pollutes the Pacific Ocean; individual blocks of steel and concrete weighing over 100 tons have been sighted drifting off the coast of Hawaii and North America. Flotsam this large provides a substrate for sedentary coastal life and can shield species from the worst of oceanic conditions. Individual species regularly make similar transits attached to the hulls of boats.

However, what has surprised ecologists in this instance is the number of species that are washing up after 15 months adrift. Whilst whole communities are not turning up on American shores – larger and more mobile animals in particular have long since been washed away – species are certainly arriving en masse in North America. For example, a pier from Misawa port in Japan was harbouring over 100 species when it beached in Oregon in June 2012.

A 66' long concrete dock in Oregon USA, debris from the 2011 tsunami in Japan

A pier from Misawa port, covered in non-native kelp, that washed up in Oregon in June 2012.
Source: Oregon Parks and Recreation Department

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