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 Preliminary results for the Falkland Islands and South Georgia

Norbert Maczey, Rob Tanner and Richard Shaw

March 2012

Contents

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www.cabi.org

KNOWLEDGE FOR LIFE

Contents.............................................................................................................................1

Project introduction.............................................................................................................2

Biological control of weeds.................................................................................................2

Arthropods..........................................................................................................................3

Adaptation of prioritization tool...........................................................................................4

Preliminary results for the Falkland Islands- Weeds..........................................................5

Preliminary results for the Falkland Islands - Arthropods.................................................11

Preliminary results for South Georgia- Weeds.................................................................13

Preliminary results for South Georgia - Arthropods..........................................................15

Annexes...........................................................................................................................17

Norbert MaczeySenior Ecologist/Entomologist

CABI Bakeham LaneEgham, SurreyTW20 9TYUK

T: +44 (0) 1491 829029E: n.maczey@cabi.org

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Project introduction

Recent reviews of invasive non-native species (INNS) on the South Atlantic UKOTs, revealed that there is a considerable on-going threat by these species to the endemic biodiversity on these islands. Management plans and capacity building efforts to combat invasive plants have already been developed, or are in the process of being developed, by various conservation bodies and other research institutions. However, to-date, there are few plans to include classical biological control in these new schemes despite this management practise having a long history of successful use on islands in the past. We understand that many species including rare, endangered and/or iconic species are negatively impacted upon by introduced invasive plants or invertebrate species and that the reduction of their impact through biological control could bring tangible benefits to biodiversity in these fragile habitats. At present there is little known about the potential of this tool in South Atlantic UKOTs and therefore this feasibility study focuses on the future potential usage of this method.

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, developed initially for Australia, but already proving to be very useful on the islands in the South Pacific. Priority species are selected on the basis of population dynamics, reported impact on biodiversity, impact on livelihoods, costs for on-going control measures other than biological control and others.

In addition, two detailed case studies will evaluate the potential of implementing a biological control programme against priority species for the Falklands and South Georgia more closely. These detailed assessments will 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 associated costs of available control options, we will include a catalogue of recommended strategies for each priority target species aimed to halt the biodiversity loss through invasive plant and invertebrate species more effectively.

Biological control of weeds

A major focus of this study is the assessment of invasive weeds on all South Atlantic UK OTs since they are often the most numerous, widespread and damaging introduced non-native species able significantly to alter whole ecosystems. In comparison to mechanical or chemical control, which often fails to persistently control the target species, and which needs to be repeatedly applied throughout seasons and year on year, biological control is often the only available practical and economically feasible option, which can be applied over a large geographical area. It impacts very little on the environment in contrast to the associated 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 and Bazely 2003, MacFadyen 1998, Hoffmann 1995, Fowler et al. 2000).

Integrated biological control can be regarded as a very safe and cost efficient method provided 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 (International Plant Protection Convention 1996, Food and Agriculture Organization of the United Nations 1997) are followed. Possible non-target effects are quite predictable by the safety-testing that is now routinely carried out (Pemberton 2000).

However, we also recognise that the introduction of a biocontrol agent without considering any conflicts of interest is unwise and ultimately unproductive so we will also assess the general public’s

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opinions on invasive species and biological control as an important part of the detailed feasibility assessments planned for the Falklands Islands and South Georgia. Management plans and capacity building efforts to combat the threat of invasive species have already been developed or are in the process of being developed by various conservation bodies such as RSPB, Kew Gardens and other research institutions (i.e. Glass et al. 2006, Whitehead 2008). However, biological control currently plays only a very small role in any new control schemes and we aim to close this gap through the work in this study.

We have started this project with a desk-based review and results of the recently completed ‘South Atlantic Invasive Species Project’ have already provided detailed baseline information for this. In addition, CABI has collated information on the impacts of non-native plants and invertebrates using literature reviews and current relevant databases and added this to the results of recent surveys and reviews. Based on this non-native species were ranked with the aim to form a list of priority candidate species in urgent need to be targeted in possible future biological control programmes. For this process a recently-developed weed biocontrol prioritisation tool, developed by Paynter et al. (2009) for Australia, was used. This decision tool is currently being applied to the islands of the South Pacific and is proving to be very useful. It ranks many factors associated with weed biocontrol to produce a score to aid decision makers in allocation of limited resources focussing on likely success versus scale of the problem. These 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 a subject of adequately resourced biological control program

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?• What type of is the life cycle needs to be taken into account? • In which way reproduces the target species?• Is it a weed in its native range?• Is it difficult to target multiple forms of weed, or probability of replacement of the weed by forms

or congeners of the target following successful biological control thereby negating benefits?• Is it growing in competitive environment (agricultural vs. environmental)? • Is it a native/valued exotic congener?

ArthropodsIntroduced insects can cause widespread and serious problems on islands from reduced biodiversity and the threat of extinction through reduced agricultural productivity to impacts on human health and quality of life. This was the case with the introduced ensign scale, Orthezia insignis which not only threatened many horticultural plants on St Helena but was severely damaging and in many cases killing the national tree, Commidendrum robustum (Asteraceae). Thankfully a specialist coccinellid beetle had been used successfully against this pest elsewhere in the world and CABI was able to facilitate its introduction in the 1990s. This action is believed to have saved the tree from extinction (see Booth et al. 1995; Fowler 1996). The feasibility for biological control of introduced invasive terrestrial arthropods was assessed in the same way as non-native weeds, and only small adaptation to the selected prioritisation tool were required. Although the in-depth data for many non-native arthropods in the OTs is patchy, a good list exists in most cases. CABI holds an extensive database on previous insect biocontrol activities around the globe and this was used to determine whether any key arthropod pests have been subject to attention in the past. Target species were prioritised based on likely safety and success and the reported scale of the problem.

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Adaptation of prioritization tool In this study we use Paynter et al. (2009) as a tool suitable to estimate the feasibility for biological control of weeds and invertebrates on the South Atlantic OTs. Paynter et al. (2009) use a scoring system widely established in Australia through their Weeds of National Significance system (WoNS). A comparable system for the SAOTs does not yet exist. The scoring system developed by Whitebread (2008) for the Falkland Islands assesses the risk of invasiveness and not the actual impact and can therefore not be used for an accurate adjustment of the Paynter et al. method. Developing impact assessment systems comparable to the WONS in Australia are complex and are based on the input of a large number of data over long time periods by many experts eventually collating substantial background information. As a workable replacement we developed a slightly simplified approach, which still allows the accurate ranking of priority species feasible for biological control. We suggest the following adjustments within the three main modules of this method:

Module 1: Weed importance and desirability of biocontrolBased on the information available from the SAIS project, the JNCC database and additional literature covering reported impacts of relevant species in other countries we suggest the scoring system described in table 1 to estimate weed importance:

Table 1: Questions to determine whether a species is sufficiently widespread/intractable/important to justify investment in biocontrol.

QuestionScore if question is answered with yes

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? 5(0-no, or no data available; 5-yes)

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? 10(0-no; 5-yes)

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? 10(0-no; 10-yes)

Have impacts on human or animal health recorded on the island(s) for this species? 10(0-no; 10-yes)

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Only species scoring at least 20 in the questionnaire above are considered a suitable target for biocontrol and are further assessed. One option would have been to include current control methods in the above approach, something Paynter et al. have suggested themselves as a possibility for their method applied to Australian weeds. However the necessary inclusion of data for each species turned out to be above the scope of this project. It may also be of influence to account for public perception in this tool as it could be that 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 agentsWe kept this this module unchanged. Paynter et al. give a minimum score for each question in this module to accommodate the fact that because of the unique flora of Australia even in cases of successful existing programs in other geographical areas a certain amount of additional testing is required. We most likely can assume this also for the South Atlantic OTs. Due to the unique nature of the indigenous flora on these islands efforts for host plant testing very similar to Australia can be assumed.

Module 3: Predicting the potential impact of biocontrol Again we kept this this module unchanged. There is the possibility to apply a different weighting of questions 9-14. Since the basis of the weighting within Paynter et al. is based on large combined data sets from Australia, South Africa and North America one can assume that no other datasets able to provide similar accuracy exist, which could deliver a better weighting better suited to the flora of the SAOTs.

Adaptation for invasive alien invertebrate speciesWe used a similar approach as for weed species. The only difference being a deletion of questions 9-11 within module 3. These questions are not suitable for invertebrates and no datasets exists to replace these factors with others and to develop an according weighting system. We have however, added one new question: Asking whether biological control programs have been conducted (successful or unsuccessful) for closely related species, which would increase the possibility for any successful control efforts of the relevant species. If no biological control of even related species has been recorded the species will be regarded as currently unsuitable for biological control.

Preliminary results for the Falkland Islands- Weeds

Twenty-nine non-native plant species had an initial impact score of 20 or above and were processed further within the selected prioritisation tool. Preliminary results of this assessment are given in table 2 below. As a cut-off point below we regard BC not to be feasible anymore we have chosen an overall score of 50. However, a high overall score of an individual species does not automatically result in an immediate recommendation to give BC of this species a high priority. This needs to be looked into in more detail through a case-by-case assessment taking other control options and costs versus benefits into account.

Ulex europaeus, Cytisus scoparius and Calluna vulgaris all showed a total score higher than 300, thus suggesting these species are suitable candidates for classical biological control. Indeed, all three species have been the subject of biological control programmes in other geographical regions and therefore ‘off-the-shelf’ biocontrol agents would be available and significantly reduce the costs of implementing classical control programmes against these species on the Falkland Islands. However, Ulex europaeus is regarded as having some benefits to the Falklands by providing natural fencing for farming purposes. In particular with regards to the control of this species aside from a cost-benefit analysis intensive stakeholder consultations are required to determine the relationship between beneficial value and any negative impacts this species has on the local community and local biological diversity.

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Another species where such ‘off the shelf’ solutions are readily available is Senecio jacobea. For this species BC has been very successful in some countries, although in the case of New Zealand BC has turned out to be less efficient. In the case of the Falklands further detailed assessments would be required to predict the efficacy of introduced control agents in more detail.

For some species readily available BC agents have been tested but not proven to be effective or only partially effective. To this group of species, which are generally difficult to control through BC, belong Cirsium vulgare and C. arvense. Some potentially effective control agents are not host specific enough to be released in countries with native thistles, but may turn out to provide suitable options for the Falklands where no native close relatives exists. Equally, research into these two species is still on-going with regards to alternative control agents, which may become available in the near future.

For some species no BC agents have been tested and proven to be effective as yet, but research efforts are on-going as these species cause severe problems in other geographical regions. This group includes Pilosella aurantiaca, Pilosella officinarum and Sonchus asper. For these species suitable agents may become available in the near future. Alternatively, independently funded scoping studies and host range testing could initiated for the Falklands. Such larger scale projects need of course be set in relation to the current or imminent threats these species pose to indigenous species and habitats.

Although scoring relatively low due to the fact that in the past no BC have been undertaken for these species, it may well be worth to look in more detail into the potential of BC for Berberis buxifolia and Berberis microphylla as other species within this genus are currently subject of BC programmes. The lack of closely related species on the Falklands could make these also suitable targets based on the results of these on-going projects. In particular complementary initial scoping studies looking for suitable BC agents can be highly recommended.

Although scoring overall relatively low it may also well be worth to look into the potential of BC for Rumex crispus and Rumex obtusifolius. Both species have been the subject of research into the potential for biological control, given currently unsuccessful. However, with the ease of working in the native range and the low number of closely related species biocontrol may be an option in the future if the impact of the species is considered high.

Ammophila arenaria, Lupinus arboreus and Equisetum arvense belong to a group where no BC has been initiated so far or only insufficient efforts have been conducted in the past. Initiating new control projects would be costly compared to ‘off the shelf’ solutions and need to be justified on a case by case study into the scale of current and expected impacts. We currently regard the impact these species have on the indigenous habitats as too low to justify the implementation of full scale BC projects. However, this preliminary judgement may turn out to be unjustified for some of these species and remains open for reassessment at any time. This is also true for a number of other species (Conium maculatum, Hedera helix, Myosotis discolour, Tussilago farfara, Bellis perennis, Atriplex patula, Sonchus oleraceus, Sedum acre, Senecio squalidus, Plantago major, Senecio sylvaticus). These all have a total score below 50 which does currently not warrant research into biological control.

Table 2: Preliminary results feasibility for BC for non-native plant species on the Falkland IslandsSPECIES FEASIBILITY OF BIOCONTROL

IMPA

CT

SCO

RE

EFFO

RT

SCO

RE

BIO

CO

NTR

OL

FEA

SIB

ILIT

Y SC

OR

E

TOTA

L SC

OR

E (s

peci

es IM

PAC

T x

Bio

cont

rol x

BC

feas

ible

Ulex europaeusUlex europaeus has a long history of classical biological control mainly from programmes conducted in New Zealand and Australia. The gorse seed weevil Exapion ulicis was the first biological control agent used against U. europaeus. Introduced to New Zealand in 1931, it was widely established by 1935 and has destroyed approximately 35% of the seed

35 5 115 805.0 Y

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SPECIES FEASIBILITY OF BIOCONTROL

IMPA

CT

SCO

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EFFO

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NTR

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FEA

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BC

feas

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crop annually since then. A further six control agents have been introduced to New Zealand. The gorse spider mite, Tetranychus lintearius, the thrips Sericothrips staphylinus was released in New Zealand in 1990 and is spreading slowly. Three foliage-feeding Lepidoptera have been introduced. Agonopterix ulicetella was released in 1990 and although firmly established, no populations have yet reached damaging proportions.Scythris grandipennis was released in 1993 but did not establish and Pempelia genistella was released in 1995 but has established at only two sites to date. The bivoltine seed-feeding moth Cydia succedana was introduced in 1992 to augment the seed predation provided by Exapion ulicis and it has spread rapidly and become abundant in New Zealand. Seed losses to predation by both insects exceed those from E. ulicis alone but the effect on the annual seed crop has yet to be assessed. Exapion ulicis was introduced to the island of Maui, Hawaii, in 1956 and was established on the island of Hawaii in 1984, attacking 78% of seed pods by 1994. The gall-forming weevil Perapion scutellare was released in 1961 and again from 1989 but has not established. Agonopterix ulicetella was released in 1988 but, unlike in New Zealand, this moth has become abundant on the island of Hawaii and larvae destroy a high proportion of growing tips. The rust fungus, Uromyces pisi f.sp. europaei was released in Hawaii but has been recovered only once. Tetranychus lintearius was released on St Helena in 1995, but again appears to be regulated by predatory mites. Exapion ulicis was released in Tasmania, Australia in 1939, but has not prevented the spread of U. europaeus. Tetranychus lintearius and Sericothrips staphylinus have also been released there. E. ulicis, T. lintearius, and Agonopterix ulicetella have been released in Chile. The fungus Fusarium tumidum (Gibberella tumidum) is being developed as a bioherbicide for use against U. europaeus worldwide.Cytisus scopariusBiological control activities targeted at scotch broom started in 1951 in Europe. The twig-mining moth Leucoptera spartifoliella and the weevil Exapion fuscirostre were released in the field in California, USA, in 1960 and 1964, respectively and then widely redistributed. The weevil has been recorded destroying between 60 and 90% of seed produced with attack rates of three weevils per pod. L. spartifoliella initially caused severe damage but was found to be already present in Washington State along with its European parasitoid since at least 1941 and soon failed to maintain the high populations reported regularly in New Zealand. L. spartifoliella was introduced to Australia from New Zealand in 1993, where it has established at several release sites and has reached densities that are starting to stunt growth. The seed beetle Bruchus villosus was released in New Zealand in 1987 and in Australia in 1996. The beetle has established in both countries and, in New Zealand, up to 60% seed loss has been recorded at early release sites. The psyllid Arytainilla spartiophila was first released in 1993 in New Zealand and in 1995 in Australia and is now established in both countries. As well as classical biological control, mycoherbicides are being considered for use against C. scoparius.

30 5 115 690.0 Y

Calluna vulgarisIn New Zealand a biological control programme of heather using the heather beetle (Lochmaea suturalis) was implemented in 1990. While success was initially poor at high altitude sites, by 2009 beetle populations were high and substantial damage was occurring at all release sites. Researchers expect beetle populations will continue to grow and disperse in subsequent years.

25 5 95 475.0 Y

Cirsium vulgareBiological control programmes against C. vulgare have been initiated in North America as a result of its invasiveness and associated economic losses. These include the release of a gall forming fruit fly, Urophora

40 14 115 328.6 Y

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SPECIES FEASIBILITY OF BIOCONTROL

IMPA

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stylata (Tephritidae), and a thistle head weevil, Rhinocyllus conicus (Curculionidae). In Canada, U. stylata was released in 1973 and led to a 65% reduction in achene formation in some areas after three years. This fruit fly is effective in controlling C. vulgare in central and western Europe, but results in North America show that fly dispersal is slow and the agent only survives in dense stands of C. vulgare. Two rosette-feeding weevils, Ceutorhynchus trimaculatus and Trichosirocalus horridus, were released in 1974 to control other carduine thistles in North America and have now spread to C. vulgare. None of these insects have provided adequate control of C. vulgare. In Czechoslovakia, Terellia serratulae and U. stylata were recommended as biocontrol agents for C. vulgare. U. stylata produces galls in the flower heads of C. vulgare causing a reduction in the number of cypselas. T. serratulae does not produce galls but larvae of this species feeding on cypselas decrease seed production of the host plant. Larvae of both species can develop in the same flower head.Senecio jacobeaBiological control is effective in reducing plant density and is recommended for areas where other controls are neither practical nor economical. Several years are required to establish an insect population large enough to reduce a weed population. The three most frequently introduced insects for biological control are Tyria jacobaeae (cinnabar moth), Longitarsus jacobaeae (ragwort flea beetle) and Botanophila seneciella (ragwort seed fly). T. jacobaeae larvae feed on the aerial parts of S. jacobaea. Reviews of biological control strategies for S. jacobaea have been prepared for its introduced distribution, particularly for North America, Australia and New Zealand. The success of such strategies have been mixed, for example, they have been very valuable in controlling S. jacobaea in California and Oregon, Canada and Tasmania but, to date, have proven less useful in New Zealand.

35 24 100 145.8 Y

Cirsium arvenseSurvey work has identified numerous potential native biological control agents for C. arvense. Biological agents for controlling C. arvense have been reviewed. Widespread adoption of foreign biological control agents is unlikely because of public concern for native thistles and the general lack of effectiveness of currently available biological control agents. The weevil Ceutorhynchus litura severely reduced overwintering survival of below-ground adventitious shoots of C. arvense to as little as 3% of that of uninfested shoots in Canada. In a 3-year study in Montana, 8 to 12% of weevil-infested shoots survived from one year to the next compared with 94 to 99% of uninfested shoots. The insect may have assisted in spreading the rust fungus, Puccinia punctiformis, although this assertion was not substantiated later. C. litura was released 18 times in the USA in California, Colorado, Idaho, Montana, New Jersey, South Dakota, and Washington between 1971 and 1975. In Montana, C. litura spread 9 km in 10 years and the proportion of infested plants increased from 11 to 29% in 1977 to over 80% after 10 years. In Canada, this insect did not greatly or consistently increase mortality of C. arvense shoots. A weevil, Larinus planus, that feeds on seed heads of C. arvense was accidently introduced into the USA, and may be useful for controlling seed production to prevent large areas of infestation from expanding. However, it has been shown to attack a native thistle, Cirsium undulatum var. tracyi in Colorado. Cassida rubiginosa is a fairly effective control agent, and may work well in combination with the effects of competition on C. arvense using plants such as Festuca arundinacea and Coronilla varia. Fungi found on C. arvense have been reviewed

35 21 54 90.0 Y

Ammophila arenariaThere is no history of previous CBC of this species

45 37 60 73.0 N

Pilosella aurantiacaHieracium spp. are not attacked to any noticeable degree by specialized

25 21 54 64.3 Y

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SPECIES FEASIBILITY OF BIOCONTROL

IMPA

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SCO

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BC

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phytophagous insects in New Zealand, and may therefore have a competitive advantage over native rangeland species. Five insect species of European origin were studied and tested and are approved for release in New Zealand. Four of them have the potential to develop on H. aurantiacum: the plume moth Oxyptilus pilosellae, the larvae of which feed on the above-ground plant parts, the cynipid Aulacidea subterminalis which galls the stolon tips of H. pilosella and H. aurantiacum, the syrphid Cheilosia urbana, the larvae of which feed externally on the roots, and Cheilosia psilophthalma, the larvae of which feed in rosette centres, leaf axils and on stolons. H. aurantiacum is not a host plant of the fifth species, the gall midge Macrolabis pilosellae, which galls stolon tips and rosettes.Pilosella officinarumThe rust fungus Puccinia hieracii var. piloselloidarum was chosen as a potential biological control agent. However, during the investigations prior to its introduction, it was detected in the field in New Zealand but further strains may need to be tested and released to inoculate the various biotypes of H. pilosella. Apart from this rust fungus, five herbivorous insects of European origin have been studied as potential biological control agents of H. pilosella and have been approved for release in New Zealand. Four of them, Oxyptilus pilosellae (Lepidoptera, Pterophoridae), Aulacidea subterminalis (Hymenoptera, Cynipidae), Macrolabis pilosellae (Diptera, Cecidomyiidae) and Cheilosia urbana (Diptera, Syrphidae) have already been field released in New Zealand. Releases of the fifth insect, Cheilosia psilophthalma (Hymenoptera, Syrphidae) are planned for 2003/2004.

25 21 54 64.3 Y

Equisetum arvenseThere is no history of previous CBC of this species

25 24 60 62.5 Y

Berberis buxifoliaThere is no history of previous CBC of this speciesB. buxifolia was listed among the top twelve invasive alien plants on the Falkland Islands, categorised as a result of an assessment on the potential of non-native flora to cause land management problems and economic impact. Additionally it achieved a top score of 19 in a risk assessment that categorised non-native flora that scored above 15 as potentially invasive plants because they out-compete local flora species and reduce agricultural productivity (Whitehead (2008) in Otley et al, 2008).There are several management options that have been suggested for the control of B. buxifolia (Belton, 2008). "Do nothing", has been suggested (Belton, 2008) as the species currently affects very few landowners, and thus causes very little perceived annoyance. This option will also contribute very little impact economically in the short term, however it will also allow the problem to increase, and is thus not a long term solution. "Containment" has also been suggested (Belton, 2008). The costs associated with this method are probably very low, however due to the dispersal method of the species, bird dispersal, it will also be very hard and is thus, considered not appropriate. "Site-led management" has been suggested (Belton, 2008). This would involve the identification of B. buxifolia sites and the prioritization of their treatment. Those sites deemed high priority and those where very little resources are required would be treated first, with others treated when resources and funds are available. This method seems appropriate as it would treat large sites, hopefully reducing their potency, as well as stopping sites of little establishment from becoming more infested. "Eradication" is the last method proposed (Belton, 2008). This would be the largest type of operation to be undertaken, however as B. buxifolia is considered to be in a lag phase in only some areas, this type of treatment may only be effective in these areas, not in other areas where growth has become exponential. This method is not deemed appropriate. The responsibility of control is also an issue raised by Belton (2008). Affected and concerned landowners, a lead

30 29 54 55.9 Y

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SPECIES FEASIBILITY OF BIOCONTROL

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government agency, and a charitable trust have all been suggested as possible figureheads to take responsibility of B. buxifolia control. Only the establishment of a charitable trust is considered as an option in Belton's (2008) report. Various steps have been suggested as a sort of plan for the management scheme. 2008 was to include the mapping and abundance of B. buxifolia, the establishment of a Trust of the Falklands and the initiation of control measures on the smallest infected areas. 2009 was to include the acquisition of funding for necessary resources, although the continuation of actual control measures is not mentioned. 2010 is to include further funding acquisition, review of control techniques to establish a best practice. The techniques used in the control are "Cut and paste treatment" (Belton, 2008), which includes the cutting of all stems as close to the ground as possible, and the application of a herbicide called "Vigilant" which is applied as a paste (Belton, 2008). Manual and mechanical removal are also an option, however broken roots often re-sprout, so these methods are not recommended. Foliar spraying of a herbicide is another technique which should be successful. It has not been tested on B. buxifolia itself, however it has been proven as an effective technique on other Berberis sp.Berberis microphyllaThere is no history of previous CBC of this species but for other species within the genus for which research into insects and pathogens as suitable control agents is currently on-going (Smith et al. 2004).

30 29 54 55.9 Y

Lupinus arboreusThere is no history of previous CBC of this species

30 33 60 54.5 Y

Sonchus asperBiological agents are currently being researched as a possibility for managing S. asper and other Sonchus species in Australia.  Preliminary surveys for biological control agents have been made in southern France and northern Europe. Currently the rust fungus Miyagia pseudosphaeria and an unidentified eriophyid mite species are two widespread organisms in Australia with potential for control.

30 25 44 52.8 Y

Conium maculatumThere is no history of previous CBC of this species

25 28 54 48.2 N

Hedera helixThere has been no attempt to identify and introduce biological control agents, and in view of the species' importance in horticulture in the USA, it is extremely unlikely that any such attempts will be made in that country. In view of the species' near immunity to pests and diseases in its native range, prospects for biological control are limited. Prasad (2002) has reported that the use of a bioherbicide in the form of the fungus Chondrostereum purpureum has been applied to H. helix but its efficacy has yet to be ascertained.

25 33 60 45.5 N

Rumex crispusThe possibilities for classical biological control of R. crispus and other weedy Rumex spp. has been investigated in relation to the possibility of importing agents from Europe in the USA and Australia. No introductions are reported for the USA but two sessiid root borers, Bambecia chrysisiformis and Chamaesphecia doryliformis were imported into Australia after host specificity studies and a progamme of releases initiated. The fungi Uromyces rumicis investigated by Frank (1973) and Ramularia rubella investigated by Huber-Meinicke et al. (1989), which were found to be specific to Rumex spp., has been proposed but does not seem to have been followed up.

35 31 38 42.9 N

Rumex obtusifoliusGastrophysa viridula has been suggested as a possible agent of biological control. Although heavy grazing by this beetle reduces leaf area and overall biomass and affects the number and weight of seeds (Bentley et al., 1980), it is unlikely that G. viridula, acting alone, could be an effective

35 31 38 42.9 N

11

SPECIES FEASIBILITY OF BIOCONTROL

IMPA

CT

SCO

RE

EFFO

RT

SCO

RE

BIO

CO

NTR

OL

FEA

SIB

ILIT

Y SC

OR

E

TOTA

L SC

OR

E (s

peci

es IM

PAC

T x

Bio

cont

rol x

BC

feas

ible

control agent for the weed. In Tasmania the clearwing dock moth Chamaesphecia doryliphormis was introduced in 1997 at 2 sites to provide control of R. obtusifolius. However, there is no further information on the establishment and efficacy of this organism. Studies involving fungal pathogens have not developed control methods, though the possibilities have been discussed for Uromyces rumicis and Ramullaria rubella. Hughes et al. (1996) investigated the effects of infection of Armillaria mellea and A. ostoyae, which attack the root system, and reported that the taproots were extensively rotted.Myosotis discolorThere is no history of previous CBC of this species

20 28 54 38.6 N

Tussilago farfaraThere is no history of previous CBC of this species

25 37 55 37.2 N

Rosa caninaThere is no history of previous CBC of this species

20 38 60 31.6 N

Rosa rugosaThe biota of herbivorous arthropods and pathogenic microorganisms associated with R. rugosa in its native and exotic ranges was reviewed by Bruun (2005) as an initial step towards the identification of potential agents for biological control in Europe and North America. Based on the literature, the most promising candidates for biocontrol seem to be the aphids Myzus japonensis and Amphorophora amurensis, the leaf hopper Empoasca ussurica, the tortricid moth Notocelia longispina, the cynipid gall-wasp Diplolepis fukudae, and the rust fungi Phragmidium rosae-rugosae and P. yezoense. A screening programme is suggested, investigating the impact of these organisms on R. rugosa performance, their host specificity and the risk of undesired indirect effects in the ecosystem where agents are released.

20 38 60 31.6 N

Bellis perennisThere is no history of previous CBC of this species

20 37 55 29.7 N

Atriplex patulaThere is no history of previous CBC of this species

20 37 54 29.2 N

Sonchus oleraceusThere is no history of previous CBC of this species

20 37 49 26.5 N

Sedum acreThere is no history of previous CBC of this species

25 47 45 23.9 N

Senecio squalidusThere is no history of previous CBC of this species

30 43 32 22.3 N

Plantago majorThere is no history of previous CBC of this species

25 43 38 22.1 N

Senecio sylvaticusThere is no history of previous CBC of this species

20 43 32 14.9 N

Preliminary results for the Falkland Islands - ArthropodsOnly four non-native arthropod species had an initial impact score of 20 or above and were processed further within the selected prioritisation tool. Preliminary results of this assessment are given in table 3 below. As with weed species we regard BC not to be feasible anymore below a cut-off point of an overall score of 50 and therefore we believe the linyphiid spider Tenuiphantes tenuis is not a suitable target species for biological control. On the other hand, a high overall score of an individual species does not automatically result in an immediate recommendation to give BC of this species a high priority. This needs to be looked into in more detail on a case by case assessment taking other control options and costs versus benefits into account.

12

Currently we regard the European earwig Forficula auricularia a very promising target species. Particularly as chemical sprays are ineffective because of its widespread occurrence and great mobility (Santini & Caroli 1992). Off the shelf solutions using parasitoid tachinid flies are readily available. One of these species Triarthria setipennis has established successfully in Newfoundland and British Columbia (Morris 1984). Studies on the establishment of T. setipennis in Newfoundland indicated a considerable reduction in earwig numbers, which was most probably due to high levels of parasitism in the mid-1970s (Morris 1984). However, since 1978, no further evaluation of parasitoid impact has been undertaken. A second species Ocytata pallipes has been introduced into Canada to control the European earwig during the 1990s (Kuhlman et al. 2001). Maggots were applied singly to about 115 earwigs, and the earwigs and 20 adult flies were later released at one site in Ottawa. Although this ad hoc release programme was useful as a pilot study, the release of such a low number of potentially infected F. auricularia makes success of this introduction unlikely and no follow up monitoring had been conducted. Ocytata pallipes and Triarthria setipennis have also been introduced into the USA and New Zealand. Introductions into the USA had been done as early as the 1920s (Oregon) (Kuhlman et al. 2001). Again little is known about the success of these releases. Risk assessments and host range testing programmes for the introduction of one or both of these tachinid species into the Falklands should be minimal as no closely related invertebrates occur on the Falklands or the nearest other islands. In addition there have been recent observations of an entomopathogenic nematode (Steinernema carpocapsae) as a possible enemy of Forficula auricularia (Hodson et al. 2011). However, this species is currently not considered a possible BC agent.

Biological control of the two greenbottle flies (Protophormia terraenovae and Lucilia sericata) is certainly feasible, as numerous releases of parasitoids over many years have shown. However, by en large these control projects (particularly in Australia, NZ and South Africa) have been only partially successful and never been able to provide a very high degree of control. Therefore, any options for BC on the Falklands would needed to be very carefully set against other viable control methods, currently in place.

Table 3: Preliminary results feasibility for BC for non-native arthropods on the Falkland IslandsSPECIES FEASIBILITY OF BIOCONTROL

IMPA

CT

SCO

RE

EFFO

RT

SCO

RE

BIO

CO

NTR

OL

FEA

SIB

ILIT

Y SC

OR

E

TOTA

L SC

OR

E (s

peci

es IM

PAC

T x

Bio

cont

rol x

1/

Effo

rt)

BC

feas

ible

Forficula auricularia; Dermaptera (Forficulidae)This seems to be a very promising target species for BC. Off the shelf solutions using parasitoids are available. Ocytata pallipes (Dipt., Tachinidae) has been introduced into Canada to control the European earwig; although follow up monitoring has not been conducted these previous efforts are relatively likely to have been successful. Ocytata pallipes & Triarthria setipennis (both Dip. Tachinidae) have also been introduced into USA and New Zealand.

40 12 86 286.7 Y

Protophormia terraenovae; Diptera (Calliphoridae)High priority score, due to the impact on wool quality by this species. Extensive research on BC of Calliphoridae in general has been conducted in the past; despite partial successes in the past BC does not seem to be a widely applied method of control for this taxonomic group. Alysia manducator (Hym. Braconidae), Brachymeria podagrica (Hym. Chalcididae), Nasonia vitripennis (Hym. Pteromalidae) were introduced in 1920s into New Zealand to control Calliphoridae. Previous experiences on islands are mostly related to the control of calliphorid and other flies developing in dung. Based on previous programmes CBC seems feasible to control this species at least to some degree. However, rather costs and efforts involved to select and test the best suitable control agents are currently not likely to be more effective than other applied control methods.

35 12 86 250.8 Y

Lucilia sericata; Diptera (Calliphoridae) 35 12 81 236.3 Y

13

High priority score, due to the impact on wool quality by this species. Extensive research on BC of Calliphoridae in general has been conducted in the past; despite partial successes in the past BC does not seem to be a widely applied method of control for this taxonomic group. Alysia manducator (Hym. Braconidae), Brachymeria podagrica (Hym. Chalcididae), Nasonia vitripennis (Hym. Pteromalidae) were introduced in 1920s into New Zealand to control Calliphoridae (Biocat 2010). Previous experiences on islands are mostly related to the control of calliphorid and other flies developing in dung. Based on previous programmes CBC seems feasible to control this species at least to some degree. However, rather costs and efforts involved to select and test the best suitable control agents are currently not likely to be more effective than other applied control methods.Tenuiphantes tenuis; Arachnida (Linyphiidae)There is no history of previous BC of this species or spiders in general. Development of biological control programs would require a large scale research efforts and efficacy of this methods for this taxonomic group remains speculative. Therefore such efforts can only be justified by accordingly large recorded impacts on native species and habitats, which have not been recorded from the Falklands yet.

20 37 35 18.9 N

Preliminary results for South Georgia- WeedsEight non-native plant species had an initial impact score of 20 or above and were processed further within the selected prioritisation tool. Preliminary results of this assessment are given in table 4 below. Similar to that of the Falklands, a cut-off point below we regard BC not to be feasible anymore we have chosen an overall score of 50. The relatively low scores, compared to those in the Falklands reflects that none of the species listed in the table below have been the subject of a successful biological control programme in the past.

There is still a little confusion with the actual identification of the Cardamine species on South Georgia and if it is the species listed in table 4 (Cardamine glacialis) and not Cardamine flexuosa, classical biological control would need to consider the risk of spreading any control agent introduced to SG to the Falkland Islands where Cardamine glaclalis is native. Currently the Cardamine species on SG is subject to an eradication programme and BC would only become a viable option in case these current control efforts were not successful.

Grass species are always regarded as potentially difficult from a biological control perspective and as such there has been little research into the biological control of this group of species. Poa annua and Poa pratensis both have a score just below the cut of mark of 50. However, due to the invasiveness of Agrostis capillaris syn. tenuis on South Georgia, and in other geographical regions this species has a high impact score and subsequent total score, putting the species in second position. Although difficult BC could still become an option for grasses in case impact on the native ecosystem is seen as severe justifying a more costly full BC control project. Herbivores and pathogens, which are specific to the genera Poa and Agrostis exist and as there are no native congeners on SG biological control may well be feasible.

Similarly, for Taraxacum officinale the lack of closely related species increases the chance to find suitable control agent. This species has been the subject of classical biological control programmes in North America and Canada and may prove to be a suitable target for South Georgia if the impact of the species warrants further control measures.

Table 4: Preliminary results feasibility for BC for non-native weeds on South Georgia

14

SPECIES FEASIBILITY OF BIOCONTROL

IMPA

CT

SCO

RE

EFFO

RT

SCO

RE

BIO

CO

NTR

OL

FEA

SIB

ILIT

Y SC

OR

E

TOTA

L SC

OR

E (s

peci

es IM

PAC

T x

Bio

cont

rol x

1/E

ffort

)

BC

feas

ible

Rumex acetosellaThere is no history of previous CBC of this species

35 24 59 86.0  Y

Agrostis capillaris syn. tenuisThere is no history of previous CBC of this species

40 33 65 78.8  Y

Cardamine glacialisThere is no history of previous CBC of this species

30 24 54 67.5  Y

Taraxacum officinalePhoma exigua and P. herbarum have been isolated from T. officinale complex in Ontario, Canada, and considered as potential biocontrol agents. Controlled-environment studies showed that young T. officinale plants were more susceptible to P. herbarum than older plants. P. taraxaci was considered as a biocontrol agent for T. officinale complex in Sweden. P. taraxaci spread by pycnospores and infected seeds, however, it was extremely variable with respect to its pathogenicity on T. officinale complex and its viability in soil. Von Hofsten (1954) also mentioned an unnamed 'ring-forming fungus' which released a substance that was highly toxic to T. officinale complex and other plants. Sclerotinia species have also been tested as biological control agents for T. officinale complex in Canada and New Zealand. Sclerotinia sclerotiorum and S. minor were evaluated in a controlled environment and in turfgrass swards for their virulence on T. officinale complex. Isolates of both species reduced the dry weight of plants in a controlled environment and reduced the number of plants in turfgrass swards. Heat-killed seeds of perennial ryegrass were suitable as both a growth substrate for Sclerotinia spp. and a delivery system to T. officinale complex. A mycelium-on-wheat preparation has been used for S. sclerotiorum, while either a granular sodium alginate formulation or a mycelium-on-barley preparation has been employed to deliver S. minor. Sclerotinia sclerotiorum caused localized infection on the leaf laminas and created basal necroses of 1-2 cm in length on tap roots of T. officinale complex. These necroses inhibited leaf regrowth from the root after defoliation.

30 24 54 67.5  Y

Ranunculus repensThere is no history of previous CBC of this species

35 43 65 53.0  Y

Poa annuaThere is no history of previous CBC of this species

25 33 65 49.2  N

Poa pratensisThere is no history of previous CBC of this species

25 33 65 49.2  N

Cerastium fontanumThere is no history of previous CBC of this species

20 33 54 32.7  N

Preliminary results for South Georgia - ArthropodsOnly six non-native arthropod species had an initial impact score of 20 or above and were processed further within the selected prioritisation tool. Preliminary results of this assessment are given in table 5 below. As with weed species we regard BC not to be feasible anymore below a cut-off point of an overall score of 50. However, a high overall score of an individual species does not automatically result in an immediate recommendation to give BC of this species a high priority. This needs to be looked into in more detail on a case by case assessment taking other control options and costs versus benefits into account.

Based on this we currently regard only one arthropod species, the greenbottle fly Calliphora vicina a possible target for classical BC. Biological control of calliphorid flies has been attempted during

15

numerous projects releasing parasitoids over many years. However, by en large these control projects (particularly in Australia, NZ and South Africa) have been only partially successful and never been able to provide a very high degree of control. Therefore any options for BC on South Georgia would needed to be very carefully set against current or expected impact Calliphora vicina has on indigenous ecosystems.

We believe that none of the other non-native arthropods is a suitable target for biological control. The main reason for this is that for the majority of these species no previous experiences in BC exist but also not for any other species belonging to the same family. One exception would be Aptinothrips stylifer for which we could see the possible development of a biological control programme. However, we regards the impact this species currently has on native habitats not sufficiently high enough to justify the development of such a relatively large programme, which would not benefit from already available ‘off the shelf’ solutions.

Table 5: Preliminary results feasibility for BC for non-native arthropods on South Georgia

SPECIES FEASIBILITY OF BIOCONTROL

IMPA

CT

SCO

RE

EFFO

RT

SCO

RE

BIO

CO

NTR

OL

FEA

SIB

ILIT

Y SC

OR

E

TOTA

L SC

OR

E (s

peci

es IM

PAC

T x

Bio

cont

rol x

1/

Effo

rt)

BC

feas

ible

Calliphora vicina; Diptera (Calliphoridae)Extensive research on BC of Calliphoridae in general has been conducted in the past; despite partial successes in the past BC does not seem to be a widely applied method of control for this taxonomic group. Alysia manducator (Hym. Braconidae), Brachymeria podagrica (Hym. Chalcididae), Nasonia vitripennis (Hym. Pteromalidae) were introduced in 1920s into New Zealand to control Calliphoridae (Biocat 2010). Previous experiences on islands are mostly related to the control of calliphorid and other flies developing in dung. Based on previous programmes CBC seems feasible to control this species at least to some degree. However, rather costs and efforts involved to select and test the best suitable control agents are currently not likely to be more effective than other applied control methods.

30 12 34 85.0 Y

Dendrodrilus rubidus; Oligochaeta (Lumbricidea)There is no history of previous BC of Lumbricidae or earthworms in general. Development of biological control programs would require a large scale research efforts and efficacy of this methods for this taxonomic group remains speculative. Therefore such efforts can only be justified by accordingly large recorded impacts on native species and habitats, which have not been recorded from SG yet.

20 28 66 47.1 N

Trechisibus antarcticus; Coleoptera (Carabidae)There is no history of previous BC of Carabidae in contrast of using carabid beetles for BC of pests themselves. Development of biological control programs would require a large scale research efforts and efficacy of this methods for this taxonomic group remains speculative. Therefore such efforts can only be justified by accordingly large recorded impacts on native species and habitats. However, despite indications of negative impacts by carabids on SG evidence showing long term loss of native species and severe habitat alterations has not been recorded yet.

25 29 34 29.3 N

Scatopse notate; Diptera (Scatopsidae)There is no history of previous BC ofScatopsidae. Development of biological control programs would require a large scale research efforts and efficacy of this methods for this taxonomic group remains speculative. Therefore such efforts can only be justified by accordingly large recorded impacts on native species and habitats, which have not been recorded from SG yet.

20 28 37 26.4 N

Oopterus soledadinus; Coleoptera (Carabidae)There is no history of previous BC of Carabidae in contrast of using carabid beetles for BC of pests themselves. Development of biological

20 29 34 23.4 N

16

SPECIES FEASIBILITY OF BIOCONTROL

IMPA

CT

SCO

RE

EFFO

RT

SCO

RE

BIO

CO

NTR

OL

FEA

SIB

ILIT

Y SC

OR

E

TOTA

L SC

OR

E (s

peci

es IM

PAC

T x

Bio

cont

rol x

1/

Effo

rt)

BC

feas

ible

control programs would require a large scale research efforts and efficacy of this methods for this taxonomic group remains speculative. Therefore such efforts can only be justified by accordingly large recorded impacts on native species and habitats. However, despite indications of negative impacts by carabids on SG evidence showing long term loss of native species and severe habitat alterations has not been recorded yet.Aptinothrips stylifer; Thysanoptera (Thripidae)There exist numerous examples of biological control of species in the same family; however these programs concern exclusively horticultural pests and regard predominantly augmentative BC in greenhouses (mostly without the need to conduct specific host range testing). Development of a biological control program for Aptinothrips stylifer seems feasible, but would still require larger research efforts. Such efforts can only be justified by accordingly large recorded impacts on native species and habitats, which have not been recorded from SG yet.

20 47 48 20.4 N

17

Annexes

Annex 1: Evaluation tool (adjusted from Paynter et al. 2009)SPECIES IMPORTANCE & DESIRABILITY OF

BIOCONTROL OUTCOME Prosopis juliflora

1. Is the species native or at least possibly native?a. Yes and in its natural range Biological control is undesirable

b. Yes, but occurring outside its natural rangeBiological control may be ecologically feasible, go to question 2.

c. No, but possibly colonised island(s) naturally Biological control is undesirable

d. No Go to question 2. Y2. Is opposition to biocontrol likely? Does the species have socioeconomic valuea. Yes and value of species demonstrably >cost of control/detrimental impacts Biological control is undesirablei. species valuable as control agent of introduced other non-native species Biological control is undesirable

b. Yes, but cost-benefit analysis data does not exist

Cost-benefit data is likely to be required for biocontrol to proceed, delaying biocontrol, adding to cost & uncertainty of success

c. Yes and value of species demonstrably <cost of control/detrimental impacts Go to question 3.d. No, the species has no documented redeeming features Go to question 3. Y3. Is the species currently established on the island?a. No, only records of single specimen(s) or doubtful records Biological control is unfeasible

b. No, no recent records Biological control is unfeasible

c. Establishment unknown Biological control is unfeasible

d. Yes Go to question 4. Y4. Has the species already been subject of biological control on the island(s)a. Yes, successful control achieved Further biological control is of low priorityb. Yes, but control insufficient or success not sufficiently monitored Go to question 5. Y

c. No Go to question 5.5. Has eradication recently recommended as suitable control methoda. Eradication has been recommended and only small populations locally restricted exist Biological control is undesirableb. Eradication has not been recommended but the occurance and life history of the species does not warrant biological control measures Biological control is undesirablec. Eradication has been suggested as control method but species is already widespread Go to question 6.d. Eradication has not been recommended as as suitable control method Go to question 6. Y

18

6. Is the species sufficiently widespread/intractable/important to justify investment in biocontrol?

Question

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

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

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

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

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

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

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

(0-no, or no data avaliable; 5-yes) 0Are habitats on the island(s) which can potentially be invaded of conservation importance?

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

(0-no; 5-yes) 5Have ecological impacts been recorded on the island(s) for this species?

(0-no; 10-yes) 5Have economic impacts (agriculture and others) been recorded on the island(s) for this species?

(0-no; 10-yes) 5Have impacts on human or animal health recorded on the island(s) for this species?

(0-no; 10-yes) 0

species IMPACT SCORE 45

References records, impact and invasiveness in other geographical regions

Ashmole & Ashmole 2000; Belton 2008; Lambdon et al. 2009; Varnham 2009; CABI ISC 2011, GISD 2011

19

7. Is impact score equal or above 20 if yes, go to next questiona. No Biological control is undesirable

b. Yes Go to next set of questions Y

EFFORT REQUIRED TO OBTAIN & HOST-RANGE TEST BIOCONTROL AGENTS

8. Has the species been/is it a subject of adequately resourced biocontrol program elsewhere?

a. Yes, successful program

If specific agents are already known & host-range testing has already been conducted overseas, then programme is likely to be cheaper 1 1

b. Yes, unsuccessful program

Law of diminishing returns - if current known suite of agents is ineffective, finding new ones will be harder 15

c. Current target/too early/insufficient data to assess success elsewhere or variable success elswhere

Potential for cost savings, but uncertainty factored into score 8

d No, never 20

9. Accessibility and ease of working in native range

a. Difficult 5

b. Moderate 3

c. Easy 2

d. Not applicable (if repeat programme) 1 1

10. Literature regarding natural enemies well known/accessible

a. Yes 1 1

b. No

Formal identification of candidate agents (required for import/release permits) may be time consuming, delaying a program 5

11. Phylogeny: How closely related to indigenous/valued species is the target species?

a. None in same familyCheaper no-choice tests may be sufficient, larget pool of candidate agents 1

b. Same Family 10 10

c. Same Genus

More extensive host-range testing may be required, more species may require testing before a sufficiently specific species is identified 20

EFFORT SCORE 13

20

PREDICTING THE POTENTIAL IMPACT OF BIOCONTROL

12. Has the species been a subject of adequately resourced biocontrol programme overseas?a. Yes, successful target overseas 1 or more occasions

Maximum score: do not go to next set of questions 100

b. Yes, only one example or with varying degrees of success or partial successi. Reason for variable success known (e.g. agent only attacks certain forms of species, or is restricted to certain habitats/climates) and considered unlikely to be a problem Do not go to next set of questions 80 80

ii. Reason for variable success unknown Do not go to next set of questions 60iii. Reason for variable success known and considered likely to be a problem Do not go to next set of questions 40

c. Unsuccessful target overseas only once 30d. Unsuccessful target overseas more than once 20e. Not a target elsewhere or too early to assess success of overseas program Go to next set of questions 1

13. Habitat

Aquatic/wetland Higher probability of success 35

Terrestrial Lower probability of success 14

14. Life cycle

Predominantly temperate annual 3

Predominantly tropical/sub tropical annual 5

Biennial/perennial 5

15. ReproductionVegetative (+/- seed/spore) 25

Seed/spore only 10

16. Weed in native rangea. Yes Lower probability of success 3b. No Higher probability of success 1017. Difficulty targetting multiple forms of weed, or probability of replacement of the weed by forms or congeners of the target following successful biological control thereby negating benefitsa. Likely Lower probability of success 0b. Unlikely Higher probability of success 5

c. Unknown 2

18. Occurring in competitive environment (agricultural vs environmental)a. Predominantly agricultural Lower probability of success 1

b. Predominatly environmental Higher probability of success 5

c. Unknown/both equally 3

19. Native/valued exotic congener

a. Yes 0

b. No 15References for efforts, potential impact and on BC in other geographical areas

Belton 2008; CABI ISC 2011, GISD 2011

BIOCONTROL FEASIBILITY SCORE 80TOTAL SCORE (species IMPACT x Biocontrol x 1/Effort) 276.92Comments Several biological control programmes using species of seed-feeding bruchid

beetles have been developed and implemented. The advantage with bruchids is their observed host specificity, with many species found to feed only on Prosopis, and some only on a single species. Other insect species known to have a deleterious effect on native and exotic Prosopis in the Americas, mainly twig girdlers and psyllids, have also been suggested as possible biological control

21

agents. The twig girdler Oncideres limpida attacks P. pallida in Brazil (Lima, 1994), whereas Oncideres rhodostricta is seen as a serious pest of P. glandulosa in the USA (Polk and Ueckert, 1973). Psyllids are known to severely affect the growth of Prosopis (Hodkinson, 1991) and have been suggested for use in controlling invasions. The same two bruchid species were also introduced to Ascension Island in an attempt to control P. juliflora which is present on 80% of the island, often in dense thickets. Two other species, one a psyllid and the other a mirid, were identified as attacking P. juliflora on Ascension Island and were thought to have been introduced accidentally from the Caribbean. The mirid Rhinocloa sp. causes widespread damage and is thought to lead to substantial mortality of trees (Fowler, 1998) [extract from CABI ISC 2011].

22

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