Final report - Defra, UK

Understanding and addressing the impact of invasive non-native species in the UK Overseas Territories in the South Atlantic: A review of the potential for biocontrol DEFRA ref: CR 0492

CABI ref: TR10086

Final report Norbert Maczey, Rob Tanner, Oliver Cheesman and Richard Shaw December 2012

www.cabi.org

KNOWLEDGE FOR LIFE 1

Contents Executive summary ........................................................................................................................................................... 3 1.1

Background ......................................................................................................................................................... 4

1.2

The South Atlantic UKOTs .................................................................................................................................. 4

1.3

Project aims and approach ................................................................................................................................. 7

1.4

Biological control of weeds ................................................................................................................................. 7

1.5

Biological control of invertebrates ....................................................................................................................... 8

2

Methods and project activities ............................................................................................................................. 9

2.1

Literature survey and survey of other publicly available sources, species evaluation and project website ......... 9

2.2

Questionnaire, core contacts and stakeholder consultation ................................................................................ 9

2.3

Workshop, stakeholder meetings and field site visits on the Falklands and Ascension .................................... 10

2.4

Adaptation and implementation of prioritization tool.......................................................................................... 11

3.

Results .............................................................................................................................................................. 14

3.1

Number of assessed species and selection of species for full assessment ...................................................... 14

3.2

Results for individual UKOTs ............................................................................................................................ 20

3.2.1

Falkland Islands- Weeds ................................................................................................................................... 20

3.2.2

Falkland Islands - Invertebrates ........................................................................................................................ 33

3.2.3

South Georgia- Weeds ..................................................................................................................................... 36

3.2.4

South Georgia - Invertebrates ........................................................................................................................... 40

3.2.5

Ascension Island - Weeds ................................................................................................................................ 43

3.2.6

Ascension - Invertebrates ................................................................................................................................. 57

3.2.7

St. Helena - Weeds ........................................................................................................................................... 59

3.2.8

St. Helena - Invertebrates ................................................................................................................................. 81

3.2.9

Tristan da Cunha - Weeds ................................................................................................................................ 88

3.2.10

Tristan da Cunha - Invertebrates .................................................................................................................... 100

Annexes ........................................................................................................................................................................ 105

Norbert Maczey Senior Ecologist/Entomologist CABI Bakeham Lane Egham, Surrey TW20 9TY UK T: +44 (0) 1491 829029 E: [email protected] 2

Executive summary The DEFRA project CR 0492 has evaluated the potential for classical biological control (CBC) of invasive alien species (terrestrial invertebrates and plants) in the South Atlantic UK Overseas Territories (UKOTs). CBC, the introduction of co-evolved, host specific natural enemies from the target species’ native range, has been utilised for the control of non-native species for over 100 years. The project has been conducted by CABI and administered through the JNCC. It builds on the results of previous work, notably the recently completed South Atlantic Invasive Species (SAIS) project led by the RSPB, complementing strategies and recommendations arising from that project. The main project objectives were to: 1.

Assess the potential for CBC of introduced invasive plants on all the South Atlantic UKOTs, using a recently-developed prioritisation tool

2.

Conduct a preliminary review of the potential for CBC of invertebrate species prioritised by the SAIS project, using the arthropod biocontrol database held by CABI

3.

Use the Falkland Islands and South Georgia as the focus for more detailed assessments (case studies) of priority invasive weeds and invertebrates for which CBC is considered feasible. (This more detailed approach was subsequently extended to Ascension Island).

Individual non–native species were assessed using the method developed by Paynter et al. (2009), which was then modified for application to the South Atlantic UKOTs and further adapted for assessment of invertebrate species. The assessments were based on a review of literature and reports from publicly available sources, and additional information provided by stakeholders involved in conservation on the islands included in this study. Preliminary results were refined through stakeholder workshops and field site visits on the Falkland Islands and Ascension, which also allowed stakeholder attitudes to CBC to be assessed in more detail. A major output of the project was the identification of the highest priority species for which CBC is likely to provide a cost effective and sustainable management option. The case studies for the Falklands, South Georgia and Ascension Island indicate that the following high priority species are particularly suitable for CBC, and recommended for further more detailed assessments:

Priority weed species

South Georgia

Falklands

Ascension

-

Berberis microphylla

Prosopis juliflora

Pilosella officinarum

Nicotiana glauca

Ulex europaeus

Argemone mexicana Lantana camara

Priority invertebrate species

-

Forficula auricularia

Icerya purchasi

For St. Helena and Tristan da Cunha, a preliminary evaluation of priorities for both non-native plants and terrestrial invertebrates was made without the benefit of field site visits and detailed stakeholder consultations. Consequently, species for which CBC is feasible and recommended are subject to further consideration. Nonetheless, the uptake of CBC measures is provisionally highly recommended for the fast spreading Asparagus densiflorus on St. Helena and the scale insect Pseudococcus viburni currently threatening the endemic gumwood trees on St. Helena.

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1.

Introduction

1.1

Background

The UK Overseas Territories (UKOTs) are a diverse and geographically widely-distributed set of small, mostly island, administrations. The two largest regional groupings occur in the Wider Caribbean and the South Atlantic, although UKOTs are also found in the Pacific (Pitcairn Island), the Indian Ocean (British Indian Ocean Territory) and Europe (Gibraltar and the Cyprus Sovereign Base Areas). Collectively, the UKOTs support biodiversity of a much greater global significance than Britain itself, particularly in terms of threatened and endemic taxa (e.g. Pienkowski 2010; Pelembe & Cooper 2011). Despite local capacity constraints, responsibility for environmental policy is largely devolved to UKOT Governments. However, the UK Government is responsible for the UKOTs under international Multilateral Environmental Agreements, such as the Convention on Biological Diversity (CBD), and is committed to supporting environmental protection in the UKOTs, including under a set of bilateral Environment Charters (Defra 2009). Invasive alien species are now widely recognised as one of a group of key, interacting drivers of global biodiversity loss and ecosystem change (e.g. MEA 2005; CBD 2010). Their impacts on the natural environment and human well-being have been particularly severe on islands, and are likely to remain so (e.g. MEA 2005; Wong et al. 2005; CBD 2011). The need to combat invasive species has recently been reinforced under the CBD through the adoption of the Aichi Biodiversity Targets as part of the Strategic Plan for Biodiversity 2011-2020 (e.g. CBD 2011). Aichi Target 9 foresees that: By 2020, invasive alien species and pathways are identified and prioritized, priority species are controlled or eradicated, and measures are in place to manage pathways to prevent their introduction and establishment. Across the UKOTs, invasive species are recognised as a major environmental threat, the management of which poses very serious challenges (e.g. Cheesman et al. 2003; Cheesman & Clubbe 2007; Cheesman & Varnham 2010). Consequently, and given the international commitments noted above, tackling invasive alien species is one of the UK Government’s five strategic priorities for conservation of biodiversity in the UKOTs (Defra 2009). Recently, the relevant information base was greatly enhanced by the collation of records of non-native species of all taxa for the UKOTs, resulting in a report (Varnham 2006) and an accompanying database which was updated in 2009. From a conservation perspective, as on many other islands, much attention in the UKOTs has been devoted to the impact of introduced rodents and other mammalian predators, particularly on bird populations (e.g. Hilton & Cuthbert 2010). Although implementation costs are often high, techniques for the control of such invasive species have been refined in recent years, making eradication of mammalian predators an increasingly realistic proposition. However, different techniques are required for other invasive taxa, including plants and invertebrates. Biological control has a long history of application against agricultural weeds and pests, but is increasingly used against plants and invertebrates that impact primarily on biodiversity and ecosystem function (van Driesche et al. 2010).

1.2

The South Atlantic UKOTs

The South Atlantic UKOTs comprise five islands or island groups, extending southwards from Ascension Island (close to the equator, around latitude 8oS) to South Georgia & the South Sandwich Islands (the latter around latitude 58oS). Further south lies British Antarctic Territory (BAT), comprising the Antarctic Peninsula and associated islands. This area, where activities are governed by the Antarctic Treaty System, is not covered by the current project. However, the presence and potential introduction of non-native species are a matter of considerable concern there (e.g. Chown et al. 2012). Brief accounts of the five South Atlantic UKOTs are given below. All are notable breeding centres for seabirds, with some islands supporting colonies that are amongst the most important in the world (e.g. Hilton & Cuthbert 2010). However, each Territory has its own unique features, in terms of landscape and habitats, species-level biodiversity, and human impacts on the environment. 4

In the context of invasive species management, the South Atlantic UKOTs have recently benefitted from a major EU-funded initiative, managed by RSPB - the South Atlantic Invasive Species (SAIS) project (SAISP 2010). As well as advancing practical action against a range of invasive species, and contributing to the capacity building required to underpin invasive species management and biosecurity in the Territories, this project generated an extremely useful body of information and a South Atlantic UKOTs Regional Strategy and Action Plan (Shine & Stringer 2010). Unfortunately, since the SAIS project ended, lack of substantial follow-up funding from the EU or other sources has hampered the continuation of a fully co-ordinated, regional programme of work. However, important activities continue at a Territory level, building on SAIS outputs or earlier management plans (e.g. Glass et al. 2006, Pickup 1999, Whitehead 2008) and supported by various conservation bodies and other research institutions, such as RSPB, Royal Botanic Gardens (RBG) Kew and others. Nonetheless, invasive species are still considered to be among the main threats to biodiversity in all of the South Atlantic UKOTs (Pelembe & Cooper 2011). Despite the considerable efforts and achievements of the SAIS project, relatively little attention was given to the prospects for biological control of invasive species that might provide suitable targets, a gap which the current project aims to fill. Indeed, there are relatively few recent examples of biological control being applied against weeds and pests in the South Atlantic UKOTs, particularly for conservation purposes. Notable exceptions include two projects undertaken by CABI in the 1990s. One led to the successful control of the scale insect Orthezia insignis when it was severely threatening endemic gumwood Commidendrum robustum trees on St Helena (see Section 1.3). The other may have contributed to slowing the spread of Mexican thorn Prosopis juliflora, one of the most pernicious invasive weeds on Ascension Island (see Section 3.2.5). Ascension Island Situated around 1700km from the west coast of Africa in the mid-Atlantic, Ascension Island comprises one main landmass of c.90km2 and a few, small, off-shore islands and stacks. Its relatively recent, volcanic origin is reflected in the “lunar landscape” of the lowland areas, which are naturally barren and punctuated by low hills, lava flows and cinder cones. The main feature at higher altitude is Green Mountain, which is relatively densely vegetated by a mixture of native and non-native plant species. As a relatively young and isolated island, Ascension is not particularly species-rich, but the indigenous flora and fauna support a high proportion of endemic species (e.g. see Ashmole & Ashmole 2000). The island also provides important nesting sites for marine turtles as well as seabirds. The human population of Ascension numbers a just few hundred, mostly local government workers, commercial contractors and military personnel. Nonetheless, there is a very active Conservation Department, and recent conservation successes include the eradication of feral cats as part of an ongoing seabird restoration programme. St Helena Around 1300km to the southeast of Ascension, St Helena comprises a single main island of c.120km2 and a few, small, off-shore islands. Volcanic in origin, but much older than Ascension, St Helena supports a variety of habitats and numerous endemic taxa (e.g. see Ashmole & Ashmole 2000), including around 50 vascular plants and over 400 invertebrates. However, as an important port of call on international trade and other shipping routes for centuries, St Helena has experienced severe habitat degradation (including as a result of non-native species introductions), and many endemic species are under threat. Some 4000 people live on St Helena, a number that has declined in recent years alongside a contraction in the small, local agricultural and horticultural sector. However, the recent approval for construction of an airport may result in a period of relatively rapid development (and increased tourist activity), once access to the island is no longer exclusively by ship.

5

The local government has recently restructured its environmental departments, which work closely with the St Helena National Trust, an NGO which co-ordinates a range of conservation projects. Examples include the Millennium Forest initiative, started in 2000, a habitat restoration project centred on the planting of endemic gumwood trees. Tristan da Cunha Around 2400km south of St Helena, and some 2800km west of South Africa, Tristan da Cunha comprises a very remote, dispersed archipelago of four islands or small island groups: Tristan itself, Nightingale, Inaccessible and Gough (the last two being designated collectively as a World Heritage Site). There are a range of endemic species including, for example, 34 vascular plants and 20 ferns, although some taxa (including many invertebrate groups) are incompletely documented. The population of less than 300 people (one of the most isolated communities in the world) is confined to the c.95km2 main island, which is accessible only by ship. Partly as a consequence of this, smallscale agriculture and horticulture are important local activities. The small local Conservation Department, with support from RSPB in particular, is engaged in a range of environmental monitoring and protection activities. The control of introduced rodents on Gough is increasingly seen as an international conservation priority. Falkland Islands Lying around 600km east of the southern extreme of South America, the Falklands comprise a quite extensive and complex archipelago of two main islands and over 700 smaller islands and islets, covering around 12,000km2 in total. Endemic taxa identified from the islands include 14 vascular plant species. Around 3000 people live on the Falkland Islands, mostly on East Falkland, in the capital (Stanley) or the military base at Mount Pleasant, although others are distributed across various small farming settlements. Livestock rearing is an important aspect of the local economy, alongside fisheries and an expanding tourist sector based on cruise ships. The Falkland Islands Government’s Environmental Planning Department works in partnership with various local NGOs, notably Falklands Conservation, on a range of environmental initiatives. South Georgia & the South Sandwich Islands Located around 1400km east of the Falkland Islands, South Georgia comprises a main island of c.3750km2 and numerous, small off-shore islands. The South Sandwich Islands form an archipelago some 500km further southeast. Once an important centre for whaling, South Georgia has no permanent resident population as such, but is home to a small number of official staff and research scientists, and attracts visits from tourists undertaking Antarctic cruises. Half of the main island is under permanent ice and snow cover, and the local flora is dominated by bryophytes and lichens. The Government of South Georgia & the South Sandwich Islands is based in the Falkland Islands. An Environmental Officer works with NGOs, notably the South Georgia Heritage Trust, on a range of environmental initiatives. These currently include measures to eliminate all non-native vertebrates (including rats and reindeer) from South Georgia. All consignments of goods entering South Georgia must pass through a recently constructed biosecurity facility.

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1.3

Project aims and approach

A major component of this study is a desk-based review assessing the impact of non-native plant and invertebrate species in the South Atlantic UKOTs. We rank the need and suitability for biological control of individual invasive species, from high to low, using a recently-developed weed biocontrol prioritisation tool (Paynter et al 2009), developed initially for Australia, but already proving to be very useful on the islands in the South Pacific (Paynter 2010). Priority species are selected based on their population dynamics, reported impact on biodiversity, impact on livelihoods, the costs of on-going control by other means, and other criteria. At the outset of the project, it was planned that two detailed case studies would evaluate the potential of implementing a biological control programme against priority species for the Falklands and South Georgia in particular. An additional stopover visit, including field site visits and stakeholder consultations, allowed this approach to be extended to include Ascension Island as well. These detailed assessments combine all current information about the target pest species, including information on their native range, areas of introduction and recorded natural enemies in their areas of origin. Ranked in order of priority, and underpinned with the more detailed information from the case studies, detailed recommendations are given for each priority target species. During field site visits to the Falkland Islands and Ascension Island, dialogue with stakeholders allowed local attitudes towards biological control to be assessed. We hoped to underpin this part of the feasibility study through a questionnaire completed by stakeholders, including on the Territories that were not featured in the detailed case studies. However, the response to this approach was disappointing, and direct dialogue quickly turned out to be a far better way to assess stakeholder’s attitudes. In addition, the need for pilot projects to demonstrate the benefits of effective weed management on associated trophic levels were assessed for the Falkland Islands, South Georgia and Ascension Island. This included appraisal of needs for information and training materials amongst land managers, particularly with respect to actions required to restore habitats after successful biological control of target species.

1.4

Biological control of weeds

A major focus of this study is the assessment of invasive weeds on all South Atlantic UKOTs, as these are often the most numerous, widespread and damaging introduced non-native species, with the potential significantly to alter whole ecosystems. Mechanical or chemical methods often fail to effect persistent control (needing to be repeatedly applied throughout seasons and year-on-year), and may not be feasible owing to the extent or location of populations of the target species. Consequently, biological control is often the only available practical and economically feasible option. It can be applied over a large geographical area, and impacts very little on the environment, in contrast to the disturbance caused by manual or other mechanical clearing, or the application of herbicides. When successful, biological control is permanent and self-sustaining (Wittenberg & Cock 2001). On average, more than 75% of target weeds have been significantly or permanently controlled using biocontrol in the past century. Success rates range from 50% to 87% depending heavily on the amount of effort and funding applied to required research (Myers & Bazely 2003, McFadyen 1998, Hoffmann 1995, Fowler et al. 2000). A recent meta-analysis has demonstrated the positive impacts of classical biocontrol and, in particular, its positive impact on the re-establishment of native plants in a broad range of systems (Clewley et al., in press). Integrated biological control can be regarded as a very safe and cost efficient method, provided that adequate risk assessment procedures and current protocols such as the International Plant Protection Convention's Code of Conduct for the Import and Release of Exotic Biological Control Agents (IPPC 1996, 2006) are followed. Possible non-target effects are predictable and can be avoided by application of the safety-testing methods that are now routinely carried out under biological control programmes (Pemberton 2000). However, we also recognise that the introduction of a biocontrol agent without considering potential conflicts of interest is unwise and ultimately unproductive. Hence the consideration of attitudes to 7

invasive species and biological control as an important part of the detailed feasibility assessments conducted for the Falklands Islands, South Georgia and Ascension. This project started with a desk-based review, for which results of the recently completed, EU-funded South Atlantic Invasive Species Project (SAISP 2010) provided particularly useful baseline information. In addition, CABI has collated information on the impacts of non-native plants and invertebrates using literature reviews and current relevant databases and combined this with the results of other recent surveys and reviews. Based on this information, non-native species recorded from the South Atlantic UKOTs were ranked, to form a list of potential priorities for future biological control programmes using the weed biocontrol prioritisation tool developed by Paynter et al. (2009). This incorporates many factors associated with weed biocontrol, and produces an overall prioritisation score to aid decision makers in the allocation of limited resources, based on the scale of the species’ impacts and the likelihood of achieving successful management of the problem through a biological control programme. Such factors include: • • • • • • • • • •

Is opposition to biological control likely? Does the weed species have socioeconomic value? Is the weed sufficiently widespread/intractable/important to justify investment in biological control? Has the weed been/is it the subject of adequately resourced biological control programmes elsewhere? What is the accessibility and ease of working in its native range? Is literature available regarding natural enemies; is it well known/accessible? How closely related to indigenous/valued plants is the target weed? Which habitats are invaded? Is it growing in competitive environment (agricultural vs. environmental)? Is it a native/valued exotic congener?

After eradication of an invasive plant, habitat management is essential to aid restoration of the area to its former state. Invasive plants can impact on the soil microbial community, including by adversely affecting fungi beneficial to native species. As a result, native plant species can struggle to recolonise invaded areas. To address this aspect of weed control, where appropriate, CABI included the potential for integrated approaches into recommendations for the control of individual species for the Falkland Islands, South Georgia and Ascension. This can, in some cases, include future efforts to evaluate the ecology of native and introduced plants in trial sites, in order to deliver the best management practices and remedial actions to support native plant restoration.

1.5

Biological control of invertebrates

Introduced invertebrates can cause widespread and serious problems on islands, including threats to indigenous biodiversity, reduced agricultural productivity, and direct impacts on human health and quality of life. For example, on St Helena, the introduced ensign scale Orthezia insignis not only threatened many horticultural plants but was severely damaging (and in many cases killing) the national tree, the endemic gumwood Commidendrum robustum (Asteraceae). Thankfully, the specialist coccinellid beetle Hyperaspis pantherina had been used successfully against this pest elsewhere in the world and CABI was able to facilitate its introduction to St Helena in the 1990s. This action is believed to have saved the tree from extinction (Booth et al. 1995, 2001; Fowler 1996, 2004). Under the current project, the feasibility of biological control against introduced invasive terrestrial invertebrates was assessed in the same way as for non-native weeds, and only small adaptations to the prioritisation tool were required. Although the in-depth data for many non-native invertebrates in the UKOTs is patchy, a good preliminary list exists in most cases. Also, CABI holds an extensive database (BIOCAT 2010) on previous insect biocontrol activities around the globe, and this was used to determine whether key invertebrate pests in the South Atlantic UKOTs had historically been subject to attention elsewhere. Target species were again prioritised based on the severity of their impacts and the likelihood of successful management using biological control.

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2

Methods and project activities

2.1

Literature survey and survey of other publicly available sources, species evaluation and project website

The available literature and reports from publicly available sources (as well as a number of unpublished documents) have been reviewed, and a full list of references is given in Annex 4. The surveyed literature has provided the required background data, against which an evaluation of the environmental impacts of target species has been conducted. Aside from some recent action plans and risk assessments, two particularly important sources of information on the current status of nonnative species in the South Atlantic UKOTs have been included. These are the ’2009 UKOT/CD nonnative database’ compiled by Karen Varnham (initially in 2005, then updated in 2009) and made available on-line by JNCC, and the various annexes to the recent report of the SAIS Project (SAISP 2010) kindly provided by RSPB. In addition to new data collected through field surveys under the SAIS Project, these resources draw together an extensive body of information from previous publications. Major sources of information on the current status of biological control of the species assessed have been the ‘CABI Invasive Species Compendium’ (CABI ISC 2012) and the ‘Global Invasive Species Database’ (GISD 2012), both publicly available online resources. Another important source of information has been the so far unpublished ‘BIOCAT’ database (2010) held by CABI, which includes extensive historical information on previous and on-going biocontrol projects using invertebrates.

2.2

Questionnaire, core contacts and stakeholder consultation

At the outset of the project, a group of 23 core contacts was identified, encompassing relevant parties (environmental officers, etc.) within the governments of the five South Atlantic UKOTs, key local and international NGOs, cross-Territory bodies and individual specialists. An introductory e-mail was sent to each of these contacts, explaining the aims and approach of the project, seeking their engagement and inviting participation in on-going discussions. In particular, contacts were encouraged to distribute information about the project to other interested parties within their respective organisations, local communities and stakeholders on the islands in question (where contacts were based in-Territory) and to the wider scientific community. Dialogue was maintained with core contacts who responded directly to the introductory e-mail. In addition, regular project updates were disseminated via meetings of the Southern Oceans Working Group (SOWG) of the UK Overseas Territories Conservation Forum (UKOTCF) during 2011 and 2012. Core contacts and/or other representatives of their respective organisations are members of this Group, which also encompasses a wider set of contacts with interests in conservation in the South Atlantic UKOTs. To provide a focus for broader awareness-raising of the project, a dedicated webpage was established (http://www.cabi.org/Default.aspx?site=170&page=4330). This outlined the rationale for exploring the potential of biological control against invasive species in the South Atlantic UKOTs, detailed the aims and approach of the project, and provided contact details for those wishing to engage with the project team. In order to seek views on invasive species issues as they affected the five South Atlantic UKOTs, and (in particular) to examine attitudes to biological control, an on-line questionnaire was established on the Surveymonkey platform. Core contacts were asked to raise awareness of the questionnaire, particularly within the UKOTs concerned, resulting in announcements being distributed through local media, e.g. Penguin News (Falkland Islands) and The St Helena Independent. A link to the questionnaire was made available on the project webpage. Unfortunately, despite these efforts, the number of completed returns was low. This is not unusual when attempting to gather views using a questionnaire-based approach, and some useful information was obtained nonetheless (see below).

9

In order to compensate for the low rate of questionnaire returns, telephone interviews were considered. However, while evaluating the logistics of telephone interviews with stakeholders, it was decided that a better approach would be to hold these interviews in person during site visit to the Falklands and Ascension in March 2012 (see Section 2.3). This enabled engagement not only with local conservation scientists and officials, but also with land managers who were directly affected by invasive plant and invertebrate species. In addition, in the Falklands, face-to-face interviews were conducted with a number of Stanley residents regarding the impact of the European earwig. In total, five specific questionnaire responses were received from the Falkland Islands, one from Tristan da Cunha, two from St Helena and two where the respondent referred to more than one UKOT. With such low return rates, feedback cannot be regarded as representative of the collective views of stakeholders or the wider community within or across Territories. However, all of the questionnaire respondents considered that invasive non-native species were having a direct negative impact on the UKOTs concerned. Impacts spanned across all sectors, including agriculture, conservation, tourism and local infrastructure. The majority of the specific information provided on invasive species locally came from representatives of relevant government departments and NGOs working within the Territories. Most of the questionnaire respondents acknowledged the potential of biological control as a management tool for invasive weeds and invertebrates, and agreed that it should be considered as part of an integrated approach to invasive species management. However, most highlighted that further information would be beneficial, to aid decision making. Potentially, as with other information on invasive species, a straightforward introduction to biological control, alongside a more detailed analysis of the costs and benefits of this approach in particular cases, could be disseminated via government departments and NGOs to a wide audience.

2.3

Workshop, stakeholder meetings and field site visits on the Falklands and Ascension

Falklands The CABI team (Rob Tanner, Norbert Maczey) visited the Falkland Islands from the 17th to the 27th of March 2012. Amongst others, Nick Rendell (Environmental Officer, Environmental Planning Department, FIG), Martin Collins (Chief Executive & Director of Fisheries, GoSG) and Richard McKee (Executive Officer GoSG) were particular helpful with co-ordination during the run-up to this visit, and in providing logistic support during the visit. A one day workshop was held at the Chamber of Commerce meeting room in Stanley on the 20th of March 2012. Stakeholders with a known interest in the uptake of biological control in the Falklands or South Georgia were invited directly via e-mail, and provided with background information including preliminary results of the study. In addition, an open invitation was published in the local Stanley newspaper Penguin News. Sixteen people attended the workshop itself and additional meetings with stakeholders unable to attend on the 20th were held in the days after the workshop. The workshop programme covered a range of objectives: •

To provide an introduction to biological control

•

To emphasise the importance of stakeholder acceptance

•

To explain methods used to assess feasibility of individual species for biological control

•

To present preliminarily results of the study for Falklands and South Georgia

•

To compare the outputs of the prioritization analysis to the actual experience of stakeholders on the islands

•

To discuss future research on priority species for biological control

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During a number of smaller meetings at the government facilities of the Falklands and South Georgia, including a short presentation to a meeting of the ‘Environment Committee’, biological control options for invasive species based on the results of the workshops were discussed in more detail. The outcomes of the workshop were also presented during two short interviews for Falkland Islands TV (FITV) and the Stanley radio station. Field site visits to areas worst impacted by invasive weeds included a visit to Port Stephens (infestation with Pilosella officinalis) and Port Sussex (infestation of Berberis microphylla). The overall benefits of the visit to the Falkland Islands can be divided into two broad areas. Firstly, during evidence-based discussions, a substantial degree of scepticism could be addressed and stakeholders became more receptive to the idea of future biological control projects. As a direct consequence of this, the process of putting forward a package of more detailed information on the prospects for control of European earwigs and Calafate has been initiated, with the intention of developing full project proposals. In addition, a collaboration looking into the possibilities of biological control of Mouse-eared Hawkweed has been established between the FIG, Kew and CABI. The second area where the field site visits and stakeholder consultation proved to be absolutely vital was in the updating of information on individual invasive species. This allowed preliminary results from the ‘Paynter’ tool analysis (based on publications and grey literature) to be refined, leading to adjustments of the initial priority setting, as reflected in the results for the Falklands and South Georgia presented below. Ascension Island In collaboration with the Ascension Island Government (AIG) Conservation Office, a stopover visit to Ascension was arranged for the 27th – 30th March 2012, on the return journey from the Falklands. Particular thanks are due to Stedson Stroud (AIG Conservation Officer) and Jolene Sim (AIG Assistant Conservation Officer) for their support in making this possible. The programme for the visit included introductory meetings with Stedson Stroud, Miles Miller (AIG Director of Operations) and Colin Wells (Ascension Island Administrator). These were followed by a meeting with stakeholders from local organisations (AIG, CSR [Computer Sciences Raytheon], Babcock, IDL [Interserve Defence Limited], Serco, CSO [Composite Signals Organisation], C&W [Cable & Wireless]), to address the same objectives as the stakeholder meeting in the Falklands. In addition, a presentation was given and discussions held on the subject of invasive species and the principles of biological control at the local school in Two Boats village. After the stakeholder meeting, field site visits were conducted to areas worst impacted by invasive weeds, including to observe any on-going biological control (Prosopis, Opuntia). Benefits of the visit to Ascension Island were similar to those arising from the visit to the Falklands. Again, evidence-based discussions were able to dispel much scepticism over biological control. As a direct consequence, concepts for the enhanced control of Mexican Thorn and the control of Wild Tobacco were developed and forwarded to the AIG for consideration. In addition, an article on future biological control on Ascension based on this visit was published in Ascension Island Conservation Quarterly Issue 38 (http://www.conservation-ascension-island.gov.ac/conservation-quarterly-issue-38). Also as in the Falklands, the visit allowed for refinement of preliminary results from the desk-based study, in particular via the updating of information on individual invasive species, both through stakeholder discussions and field site visits. This refinement is reflected in the results for Ascension presented further below.

2.4

Adaptation and implementation of prioritization tool

In this study, we use Paynter et al. (2009) as a tool to assess the feasibility for biological control of weeds and invertebrates on the South Atlantic UKOTs. An example of the assessment framework, 11

based on three component modules, is given in Annex 1. Paynter et al. (2009) use a scoring system widely established in Australia through their Weeds of National Significance (WoNS) system. A comparable system for the UKOTs does not yet exist. The scoring system developed by Whitebread (2008) for the Falkland Islands assesses the risk of invasiveness but not the actual impact, and therefore cannot be used for an accurate adjustment of the Paynter method. The development of impact assessment systems comparable to WoNS in Australia is complex and relies on the accumulation of a large body of data by many experts over a long period, to establish the necessary background information. As a workable substitute, we developed a slightly simplified approach, which still allows the accurate ranking of priority species feasible for biological control, based on the following adjustments within the three main modules of the Paynter tool: Module 1: Weed importance and desirability of biocontrol Based on the information available from the SAIS project, the JNCC database and additional literature covering reported impacts of relevant species in other countries, we adopted the scoring system described in Table 1 to estimate weed importance under Question 6: Table 1: Factors determining whether a species is sufficiently widespread/intractable/important to justify investment in biocontrol. Score if question is answered with yes

Question Is the species only recently introduced/recorded on the island(s)?

5

(0-no, or no data available; 5-yes) Does the species currently have a widespread recorded distribution on the island(s)?

5

(0-no, or no data available; 5-yes) Is the species currently expanding its range on the island(s)?

5

(0-no, or no data available; 5-yes) Is the species known to be invasive in other geographical regions?

5

(0-no, or no data available; 5-yes) Is the species known to have negative impacts on biodiversity in other geographical regions?

5

(0-no, or no data available; 5-yes) Is the species known to cause economic damage in other geographical regions?

5

(0-no, or no data available; 5-yes) Is the species known to cause threats to human or animal health in other geographical regions? (0-no, or no data available; 5-yes)

5

Are habitats on the island(s) which can potentially be invaded of conservation importance?

5

(0-no, or no data available; 5-yes) Does the SAIS assessment suggest a likely negative impact on biodiversity, agriculture or health? (0-no; 5-yes)

5

Have ecological impacts been recorded on the island(s) for this species?

10

(0-no; 10-yes) Have economic impacts (agriculture and others) been recorded on the island(s) for this species? (0-no; 10-yes)

10

Have impacts on human or animal health recorded on the island(s) for this species?

10

(0-no; 10-yes)

Only species scoring at least 20 using this modified assessment were considered suitable targets for biocontrol and further assessed. One additional option would have been to consider aspects of current

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control methods in the above, something that Paynter et al. (2009) have suggested themselves as a possible refinement of their method as applied to Australian weeds. However, the acquisition of such information for each species turned out to be beyond the scope of this project. It may also have been appropriate to place greater emphasis on public perception, as a nuisance species might have more support for biocontrol than one actually causing economic or ecological harm. Module 2: Effort required to obtain and host-range test biocontrol agents We kept this this module unchanged. Paynter et al. (2009) give a minimum score for each question in this module, because (even where successful biological control programmes against a weed exist elsewhere) the unique flora of Australia means that a certain amount of additional testing is required. We most likely can assume this also for the South Atlantic UKOTs. Due to their unique indigenous flora, similar efforts for host-range testing to those required in Australia can be assumed. Module 3: Predicting the potential impact of biocontrol Again, we kept this this module unchanged. There was the option to apply different weightings for Questions 9-14. Since the weightings within Paynter et al. (2009) are based on large combined data sets from Australia, South Africa and North America, one can assume that no other, better datasets exist, which could provide weightings more suited to the flora of the South Atlantic UKOTs. Adaptation for invasive alien invertebrate species We used a similar approach as for weed species. The only difference being the deletion of Questions 9-11 within Module 3. These questions are not suitable for invertebrates, and no datasets exists to provide equivalent questions with a corresponding weighting system. We did, however, add one new question: Asking whether biological control programmes have been conducted (successfully or unsuccessfully) for closely related species. Information derived from such programmes might increase the probability of successful control efforts against the species being assessed. If no biological control of even related species had been recorded, then the species was regarded as currently unsuitable for biological control.

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3.

Results

3.1 Number of assessed species and selection of species for full assessment According to the available sources of information, the following numbers of weed and invertebrate species have been recorded at some stage as introduced and naturalized (or at least showing a high potential for spread beyond deliberate cultivation) on the five target islands/island groups: • • • • •

Falklands: South Georgia: St Helena: Ascension: Tristan:

invertebrates (15); invertebrates (30); invertebrates (175); invertebrates (68); invertebrates (111);

plants (261) plants (36) plants (392) plants (414) plants (138)

All these non-native species were put through Module 1 of the evaluation process, to assess their current level of impact and the desirability of biological control. Only species scoring at least 20 were considered further, with an assessment of the feasibility of biological control conducted using Modules 2 and 3. The proportion of species scoring at least 20 owing to their impact is given for each UKOT in Figures 1 and 2 below. A summary and a list of individual species scoring at least 20 is given for each Territory in Tables 2 and 3.

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Weeds on South Georgia

Weeds on Falklands

32;  12%

8; 22%

229; 88%

28; 78%

Weeds on Ascension

Weeds on St Helena

42; 9%

61; 15%

335; 85%

403; 91%

Weeds on Tristan number of recorded alien plant species with impact score cost of control/detrimental impacts

Go to question 2.

i. species valuable as control agent of introduced other non-native species b. Yes, but cost-benefit analysis data does not exist c. Yes and value of species demonstrably