Threat Abatement Plan - Tramp Ants - Department of the Environment

49 Pages·2006·2.28 MB·English

THREAT ABATEMENT PLAN
BACKGROUND DOCUMENT
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BACKGROUND DOCUMENT
for the
THREAT ABATEMENT PLAN
To reduce the impacts of tramp ants on biodiversity in
Australia and its territories
Department of the Environment and Heritage
© Commonwealth of Australia 2006
ISBN 0 642 55246 0
Published 2006
This work is copyright. Apart from any use permitted
under the Copyright Act 1968, no part may be
reproduced by any process without prior written
permission from the Commonwealth. Requests and
inquiries regarding reproduction should be addressed to:
Assistant Secretary
Natural Resource Management Policy Branch
Department of the Environment and Heritage
GPO Box 787
CANBERRA ACT 2601
This publication is available on the internet at: http://
www.deh.gov.au/biodiversity/threatened/publications/tap/
trampants
For additional hard copies, please contact the
Department of the Environment and Heritage,
Community Information Unit at [email protected] or phone
1800 803 772.
This plan should be cited as follows: Commonwealth
of Australia. 2006. Background document for the threat
abatement plan to reduce the impacts of tramp ants on
biodiversity in Australia and its territories, Department of
the Environment and Heritage, Canberra.
Front cover and sequential page photo: Red Imported
Fire Ant (Solenopsis invicta) – Steve Wilson.
Note: This background document to the Threat
abatement plan to reduce the impacts of tramp ants
on biodiversity in Australia and its territories provides
supporting information on a range of issues such
as tramp ant biology, population dynamics, spread,
biodiversity impacts and management measures.
Contents
1. Introduction 1
2. Background and organisation 2
2.1 Background 2
2.2 Organisation 3
3. Characteristics and biology 4
3.1 The threat – tramp ants as invasive alien species 4
3.2 Invasive attributes 5
3.3 Factors predicting invasions 5
3.4 Impacts 6
4. Evaluating current management of the threat 7
4.1 Prevention of entry and spread 7
4.2 Preparedness for response 8
4.3 A general response framework 9
4.3.1 ‘Trigger’ phase 9
4.3.2 Scoping phase 10
4.3.3 Operational response phase 10
5. Developing a national and regional approach to management 12
5.1 Coordination and cooperation in a national approach 12
5.2 Coordination and cooperation within our region 13
5.3 Roles and responsibilities 13
5.4 Stakeholder participation 14
5.5 Building stewardship 14
5.6 Setting priorities 15
6. References 18
7. Glossary and abbreviations 22
8. Acknowledgements 25
9. Tables, Boxed Inserts, Appendices, 26

1. Introduction
Invasive alien tramp ants are The tramp ant threat abatement plan establishes
a diverse group of species a national framework to guide and coordinate
originating from many regions Australia’s response to tramp ants, identifying
of the globe which arrive at the research, management, and other actions
Australia’s doorstep through a necessary to ensure the long-term survival of
variety of transport pathways. native species and ecological communities
They share genetic, behavioural, and affected by tramp ants.
ecological attributes that infl uence their probability
The goal of the plan is to minimise the impact of
of entry, establishment and spread, ecological
invasive tramp ants on biodiversity in Australia
dominance, and high impact.
and its territories by protecting threatened
While their impacts on biodiversity in Australia native species and ecological communities,
are not well quantifi ed, many tramp ants have the and preventing further species and ecological
ability to affect Australia’s native biodiversity. Their communities from becoming threatened.
impacts may be felt directly through predation
The Department of the Environment and Heritage
upon or competition with native animals, or
will convene a National Implementation Team to
indirectly by modifying habitat structure and
assist and advise on the implementation of the
altering ecosystem processes. Most tramp ants
plan. The team will include people with expertise
have multi-sectoral impacts, and can affect plant
in the research and management of tramp ants.
and animal health, social and cultural values, and
It will also include stakeholders such as state and
human health.
territory agencies.
The effective and appropriate management of
threats from tramp ants poses a formidable
challenge to Australia, testing the continuum of
biosecurity, from pre-border surveillance through
to pest management. Individual tramp ant species
are at varying stages in the invasion process, so
the nature and scale of management responses
will vary accordingly.
1
2. Background and organisation
2.1 Background control program. In April 2003, the Minister for
the Environment and Heritage approved listing
The Environment Protection and Biodiversity RIFA as a key threatening process and approved
Conservation Act 1999 (EPBC Act) provides a the development of a threat abatement plan
framework and mechanism for the listing of a key to address the key threatening process, and
threatening process that affects biodiversity in tramp ant species more broadly. In April 2005,
Australia and its territories. The process is initiated the Minister approved the listing of ‘Loss of
by a written nomination of a key threatening biodiversity and ecosystem integrity following
process, followed by public comment and invasion by the yellow crazy ant (Anoplolepis
evaluation of the nomination by the Threatened gracilipes) on Christmas Island, Indian Ocean’ as a
Species Scientifi c Committee, a panel of key threatening process.
independent experts who make a recommendation
At the same time as these developments, these
to the Minister for the Environment and Heritage
and other tramp ant species were emerging as
on listing of the nominated key threatening
threats elsewhere in Australia. Management
process.
responses have included eradication programs for
If the Minister approves the listing, the Minister the African big-headed ant (Pheidole megacephala,
then identifi es whether to produce a threat BHA) and tropical fi re ant (Solenopsis geminata,
abatement plan, which provides for research, TFA) in Kakadu National Park and an ongoing
management, and other actions deemed attempt to eradicate a widespread YCA infestation
necessary to reduce the impact of a key in east Arnhem Land. Recent incursions by
threatening process on affected native species or several tramp ant species (eg YCA into northern
ecological communities. New South Wales, Brisbane, and Cairns, and
the Argentine ant (Linepithema humile, AA) in
To satisfy the requirements of the EPBC Act
Brisbane) have been followed by rapid responses
the plan must, among other things, state (i) its
to achieve eradication.
objectives; (ii) criteria against which achievement
is measured; and (iii) actions prescribed to achieve The threat abatement plan focuses on the
the objectives (see Appendix A). production of a coordinated national approach
to management, research, and education that
The red imported fi re ant (Solenopsis invicta,
increases awareness, prevents entry and spread,
hereafter RIFA), discovered in Brisbane in 2001
provides early detection and diagnosis, and
and the target of a national eradication program,
provides rapid response to both incursions and
was nominated in 2002 as a key threatening
established populations of tramp ants.
process under the EPBC Act. In 2003 another
invasive tramp ant, the yellow crazy ant The purpose of a threat abatement plan is to
(Anoplolepis gracilipes, YCA), was nominated as defi ne actions to mitigate the impact of a key
a key threatening process on Christmas Island threatening process on affected native species and
(Indian Ocean), an external territory of Australia, ecological communities. However, because almost
where it is currently the subject of a large-scale all tramp ants have a range of impacts including
2
Figure 1. Stages in the invasion sequence of a species (after Kolar and Lodge 2000)
Prevention Eradication Control
1 2 3 4
Ecological,
Region of Survive in Establish in Spread in
Economic, Social
Origin Pathway New Habitat New Habitat
Impact
Integrated Response Framework
Community Engagement
on plant and animal health, social and cultural Each solid arrow represents a transition to the
values, and human health, it is diffi cult to separate next stage (with an associated probability) and a
actions (especially at early stages in the invasion decision point (1-4) for managers. Management
process) that mitigate their impacts on biodiversity responses are in italics.
from those that affect primary industry and social
The threat abatement plan uses the major stages
values. The plan focuses on actions to reduce the
in the invasion sequence as its organising principle
impacts of tramp ants on native biodiversity and
for identifying and prescribing policy, management
ecological communities, but many, if not all, of
and research, and actions at the transition
these actions are also likely to mitigate impacts on
between stages (eg point 2, between survival in
other sectors that are affected by tramp ants.
the transport pathway and establishment in the
new habitat). A species invasion can be seen as
a series of distinct phases, beginning with the
2.2 Organisation of response
transfer of a source population and ending with a
species becoming established in an environment
An integrated framework for preparing for and
to which it is alien. This new environment could be
responding to invasive tramp ants must include
at any geographic scale (eg a national park, a water
actions at several stages, and be consistent with
catchment, a state, a country, or a region).
generic frameworks for exotic pest incursions
where management runs along a continuum from Actions taken at a given stage in the invasion
pre-border preventative measures to eradication sequence aim to reduce the transition probability
or control of established invaders, to monitoring as far as possible. Actions can be divided into
and evaluating control activities (Figure 1). Key (i) measures to prevent entry and to prepare
elements in this integrated framework include: in advance for incursions; and (ii) responses to
eradicate or control incursions and limit their
(cid:129) identifi cation and assessment of risks
spread so as to mitigate impacts. Research and
(cid:129) risk mitigation strategies
development, coordination and cooperation
(cid:129) surveillance and diagnostic strategies among stakeholders, and community engagement
(cid:129) response procedures, with defi ned roles and including key stakeholders and the public, underpin
responsibilities the success of management responses at any and
(cid:129) follow-up monitoring and evaluation. all of these stages.
3
3. Characteristics and biology
Invasive tramp ants threaten values seed dispersers, scavengers), and act as
– environmental, economic, social, cultural, and ecosystem engineers to shape the structure
health – that underpin Australian society. of some ecosystems. From temperate forests
A special challenge to natural resource managers, to the arid zone to the rainforest canopy, they
tramp ants are a diverse group of ant species can dominate ecological communities, helping
derived from many regions. They share common determine their structure, biodiversity and function
genetic, behavioural, and ecological attributes that (Davidson et al. 2003, Andersen 2004). Like most
infl uence their probability of entry, establishment animal groups, the ants have diversifi ed in relative
and spread, ecological dominance, and high levels isolation on different continents where they are
of impact in Australia and its territories. often restricted to that continent. Nowhere is this
better illustrated than in Australia, which has a rich
Tramp ants routinely test Australian border
native ant fauna comprising over 100 genera and
defences through their occurrence in a variety
at least 1300 species, most of which are endemic
of transport pathways and in their association
(ie found only in Australia), with only a minority
with a diverse range of commodities. There are
of species shared with neighbouring regions
many examples of the complexity and range
(Shattuck 1998).
of circumstances in which rapid and ongoing
Ants are also the exemplar of invaders.
management responses are needed. These
Globalisation of trade and commerce has
include the recent incursion of RIFA in suburban
accelerated exchange of a subset of the ants,
Brisbane (Vanderwoude et al. 2003), the rapid
perhaps more than 200 species to date, among
spread and catastrophic impact of supercolonies
previously isolated biogeographic regions
of YCA in Christmas Island National Park (O’Dowd
(McGlynn 1999). Although many of these
et al. 2003), and the detection of the BHA in
transported ants continue to fail to establish in
the World Heritage listed Kakadu National Park
areas of introduction, a subset of approximately
(Hoffmann and O’Connor 2004) and Great Barrier
35–40 species referred to as ‘tramp ants’ have
Reef islands (Hoffmann et al. 2004). Invasive
established widely beyond their areas of origin,
tramp ants present a challenge at every phase in
usually in close association with humans (Holway
the quarantine continuum.
et al. 2002). At least 12 of these species, from
three major subfamilies, appear to be highly
invasive (see Table 1).
3.1 The threat – tramp ants as invasive
alien species The issues involved in tramp ant invasions can be
illustrated by focusing on six key tramp ant species
Ants are among the most ecologically successful – the red imported fi re ant (Solenopsis invicta,
groups of animals (Wilson 1992). Worldwide, RIFA), the tropical fi re ant (S. geminata, TFA), the
these social insects comprise at least 15 000 little fi re ant (Wasmannia auropunctata, LFA), the
species, occupy most terrestrial habitats and African big-headed ant (Pheidole megacephala,
adaptive zones, fi ll a diversity of key functional BHA), the yellow crazy ant (Anoplolepis gracilipes,
roles (eg as predators, herbivores, seed eaters, YCA) and the Argentine ant (Linepithema humile,
4
AA) (Box 1). All except S. geminata are listed increase colony production and size. Their broad
among the world’s 100 worst invaders by the diets may allow a greater variety of resources to
Invasive Species Specialist Group of the World be harvested, also increasing colony productivity.
Conservation Union (ISSG 2004a). These six tramp Numerical superiority may simply mean that these
ant species have signifi cant impacts on biodiversity ants can rapidly mobilise to monopolise resources,
and ecological communities elsewhere and which increases population size and hence,
represent major threats to Australian biodiversity, impact.
agriculture, the economy, social values, and human
Invasiveness is also shaped by the attributes
health. Some species, like RIFA and AA, have been
of the recipient community (Lodge 1993). This
the focus of intensive research and management
may be related to both biotic factors (eg absence
efforts internationally (and in Australia), so their
of predators, parasites and pathogens, or the
biologies are relatively well known, and actions
presence of mutualists (species that benefi t
for their eradication or control are relatively well
from the ants) in the area of introduction) and
developed and tested.
environmental factors (eg high levels of climatic
and habitat matching, and disturbance in the
area of introduction). For example, in areas of
3.2 Invasive attributes
introduction, these ants may have far fewer
natural enemies (and perhaps competitors) than
Most of these tramp ant species share a
in their area of origin, allowing them to achieve
number of characteristics that help explain their
higher population sizes, and perhaps even broader
invasiveness, ecological dominance, and impact in
distributions. Most tramp ants are associated with
areas of introduction. These include unicoloniality,
disturbed habitats in their area of origin and human
low levels of intra-species aggression, polygyny
disturbance may facilitate their establishment and
(many-queened nests), generalised nesting
spread in areas of introduction (Suarez et al. 1998,
habits and frequent nest relocation, broad
Holway et al. 2002). Similar climate and habitat in
diets, and well-developed mutualisms (mutually
the area of introduction and the area of origin may
benefi cial relationships) with honeydew-secreting
assist successful establishment and invasion.
Homoptera (Bach 1991, Passera 1994, Holway et
al. 2002, Helms and Vinson 2002).
3.3 Factors predicting invasions
Some of these attributes characterise these ants
in their areas of origin, but others are probably a
Much research on the genetics, behaviour, and
consequence of genetic bottlenecks and founder
ecology of tramp ants remains to be done before
effects following human-mediated dispersal
we are able to accurately predict their probabilities
(Tsutsui and Case 2001, Tsutsui and Suarez
of invasion and the severity of their impact. Their
2003). Some attributes (eg generalised nesting
invasive attributes (see Section 3.2 above) are
habits, polygyny, and association with disturbed
likely to improve their chance of moving between
habitats) may increase the probability that tramp
different stages in the invasion process (Figure 1)
ants move into and survive in human-mediated
and help to explain why they are such effective
transport pathways to reach and establish in new
and signifi cant invaders. Nevertheless, the most
areas. Others, including unicoloniality, low levels
robust generalisations for predicting the success
of within-species aggression, high levels of inter-
of biological invaders involve three factors
species aggression, and omnivorous (broad) diets
(Lonsdale 1999):
may be directly related to the ability of these tramp
ants to reach high, sustained densities in areas of (cid:129) Invasion history. If the species has a history of
invasion (Tsutsui and Suarez 2003). For example, successfully invading elsewhere, its probability
unicolonial tramp ants do not defend territories of invading here is increased. The worldwide
against conspecifi cs (ants of the same species) distribution records for each of these six
so may allocate workers to other tasks that tramp ant species show that each has invaded
5