The project will comprise three biocontrol research
sub-programs, focussing on”
·
Bellyache bush (Jatropha gossypiifolia )
·
Cat's claw creeper (Macfadyena unguis-cati )
·
Prickly acacia (Acacia nilotica )
Bellyache bush, prickly acacia and cat’s claw creeper have
been considered as the major target species in this biological
control project as they are priority widespread and high impact
weeds in Queensland. Bellyache bush and cat’s claw creeper
have the capacity to expand their distributions and impact
significantly and are identified as promising targets for
biological control, due to a lack of close relatives in Australia.
Prickly acacia has been a longer standing and more challenging
biocontrol target with limited, localised success to-date. However,
recent genetic analysis and climate matching modelling (CLIMEX)
suggests that additional exploration opportunities exist in
India.
Biological control is one management option that can deliver
reductions in the long-term impacts of widespread woody weeds. This
project will support research that will facilitate the release of
new biocontrol agents with the introduction, testing and mass
rearing of agents for bellyache bush and cat’s claw creeper.
The project will also facilitate the establishment of international
partnerships for exploration for biocontrol agents, in particular
exploration activities in India for prickly acacia agents and in
Central and South America for bellyache bush agents.
Prickly acacia biological control
Prickly acacia, Acacia nilotica subsp. indica
, is a thorny shrub or small tree growing 4-5m high, occasionally
to 10m. It was introduced into pastoral Australia from the Asia as
a shade and fodder plant in the 1890’s and was deliberately
planted until the 1960s and was declared a noxious weed in
Australia in 1957. It can now be found throughout the state, with
widespread infestations in areas of north-western and
central-western Queensland. In 1996, seven million hectares of the
Mitchell grass plains were infested with prickly acacia. It is very
invasive and proliferates rapidly in good seasons.
Biological agents that have been released have been damaging in
the wetter areas of prickly acacia’s range, but have had
little success in areas with a long, dry season. Further
exploration in India for potentially suitable agents is considered
desirable and the proposed research provides some funding to
support this.
Bellyache bush biological control
Bellyache bush, Jatropha gossypiifolia is a serious and
expanding weed of northern Queensland. It invades rangeland,
particularly in riparian zones, forming dense thickets that reduce
productivity and biodiversity. All parts of the plant especially
the seeds are toxic and there have been several instances where the
death of grazing animals has been attributed to bellyache bush. In
the Weeds of National Significance prioritising exercise, bellyache
bush was rated as number 21. The species is a declared target for
biological control. It is considered to be a good prospect for
biological control as there is a moderately large suite of natural
enemies attacking the plant in the native range, and no closely
related plant species occur naturally, or are economically
important, in Australia.
One biological control agent (the jewel bug, Agonosoma
trilineatum ) has been released for bellyache bush in
Queensland to date. Despite the release of large numbers of this
insect at some sites, there is still no evidence of field
establishment of this biocontrol agent. Other potential agents have
been identified in exploratory surveys and could be considered with
recommencement of a biological control program for bellyache bush.
There is now increasing community requests for recommencement of a
biocontrol program on bellyache bush whish is now spreading to
isolated regions of Cape York, the Gulf of Carpentaria, Lake Eyre
Basin, the Northern Territory and the Kimberly region of Western
Australia. Having an effective biocontrol agent is considered
necessary to halt its spread and reduce its impact and the research
proposed will support the recommencement of a biological control
program for bellyache bush.
Cats claw creeper biological control: mass rearing and
release program support
Cat’s claw creeper, Macfadyena unguis-cati is a
major environmental weed in coastal and sub-coastal areas of
Queensland and NSW, affecting riparian, woodland and rainforest
ecosystems. CLIMEX modelling of the potential distribution suggests
that this invasive species is capable of expanding throughout much
greater areas of Queensland, potentially affecting inland areas
significantly. Control of this weed by non-biological means is both
difficult and expensive, and biocontrol appears the most suitable
method. The proposed research will support mass-rearing and release
programs for two agents where approval for release is anticipated.
If approved, these promising agents will be field released in
partnership with community and catchment groups and their
establishment and effectiveness monitored.
Project update:
Prickly acacia biocontrol:
·
Contracts with collaborating research agencies (Arid Forest
Research Institute and the Institute of Forest Genetics & Tree
Breeding) for the prickly acacia biocontrol project have been
signed and the project was initiated in India in March 2008.
·
A prickly acacia simulated herbivory trial has been completed,
which suggests that a combination of shoot tip and leaf-feeding
agents would be most effective.
Bellyache bush biocontrol:
·
A bellyache bush biocontrol project was initiated in Nov/Dec 2007
and staff selection for the project completed with the appointment
of a scientist and an experimentalist.
·
An application was lodged to import two insects as potential
biological control agents from Mexico. Import permits for the
agents have been obtained from Department of Environment, Water,
Heritage and the Arts (DEWHA) and Australian Quarantine &
Inspection Service/Biosecurity Australia.
·
A stem boring insect from Mexico was imported into quarantine.
Studies are in progress to standardise its rearing methods for host
specificity tests.
·
A new test plant list is being compiled in consultation with CSIRO,
and all necessary test plants have been procured.
·
A student from QUT has commenced her honours research on responses
of various bellyache bush phenotypes to simulated herbivory.
Cat’s claw creeper biocontrol:
·
The cat’s claw creeper biocontrol agents, leaf-sucking bug
(Carvalhotingis visenda) and the leaf-tying moth
(Hypocosmia pyrochroma) are being released from Mackay in
the north to northern NSW in the south. In the majority of the
release sites, the leaf-sucking bug has become established.
·
Several landcare and community groups are involved in the rearing
and release program.
·
Temperature tolerance studies suggest that the leaf-sucking bug has
wide temperature tolerance and hence is suitable for field release
in both coastal and inland areas.
Studies by a summer-research student from the Queensland
University of Technology (QUT) on the abundance of subterranean
tubers across five cat’s claw creeper infestations in
southeast Queensland suggest that the majority of plants have only
one tuber and appear to have originated from seeds. The research
suggests that a pod/seed feeding insect has the potential to reduce
tuber density by reducing seed output in areas with free standing
infestations.
Key references
National Weed
Strategy