Post on 10-May-2015
description
December 18th | Brussels
Use of Trichilogaster acaciaelongifoliae for biological control of the invasive plant Acacia longifolia – a safe and cost-effective method
Hélia Marchante(1,2), Elizabete Marchante(1) & Helena Freitas(1)
technical-scientific consultation of John Hoffmann(3)
(1) Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Portugal(2)Department of Environment, Agrarian School, Polytechnic Institute of Coimbra, Portugal(3)University of Cape Town, South Africa
December 18th | Brussels
The problem (1)
Invasion by Acacia longifolia
- Exotic tree, from Australia
- Introduced in the early 20th century for sand stabilisation
- At present: invades extensive areas of coastal dunes and other habitats in Portugal and other MS: Spain, France, Italy
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
The problem (1)
Invasion by Acacia longifolia
- Exotic tree, from Australia
- Introduced in the early 20th century for sand stabilisation
- At present: invades extensive areas of coastal dunes and other habitats in Portugal and other MS: Spain, France, Italy
- Key point: massive seed production – large long-lived seed bank fast re-invasion potential
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
The problem (2)
Invasion by Acacia longifolia
- Major Impacts:
- Decreases biodiversity; threatens protected species & habitats, e.g., Natura 2000 sites and Nature Reserves
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
The problem (2)
Invasion by Acacia longifolia
- Major Impacts:
- Decreases biodiversity; threatens protected species & habitats, e.g., Natura 2000 sites and Nature Reserves
- Changes soil biology and chemistry;
- Decreases forest productivity
December 18th | Brussels
December 18th | Brussels
The problem (2)
Invasion by Acacia longifolia
- Major Impacts:
- Decreases biodiversity; threatens protected species & habitats, e.g., Natura 2000 sites and Nature Reserves
- Changes soil biology and chemistry;
- Decreases forest productivity
- Increases fire hazard
December 18th | Brussels
December 18th | Brussels
The problem (2)
Invasion by Acacia longifolia
- Major Impacts:
- Decreases biodiversity; threatens protected species & habitats, e.g., Natura 2000 sites and Nature Reserves
- Changes soil biology and chemistry;
- Decreases forest productivity
- Increases fire hazard
Economic impacts: >> 1M€ + non-available data
December 18th | Brussels
December 18th | Brussels
• prohibitively expensive • fails to succeed due to copious seed banks
mechanical and chemical control available
The solution?
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
December 18th | Brussels
• prohibitively expensive
Biological control
Sustainable alternatives needed!
• fails to succeed due to copious seed banks
mechanical and chemical control available
The solution?
December 18th | Brussels
• Based on scientifically sound principles and protocols• Cost effective, sustainable & environmentally benign• Key tool for Invasive Alien Species management worldwide (CBD;
EPPO; European Strategy Invasive Alien Species)• Good safety record
Worldwide (for plants)• Since late 1800s, > 400 agents against ca. 150 target plants/
weeds• Many target weeds significantly or permanently controlled
Can biological control be the solution?
December 18th | Brussels
December 18th | Brussels
Can biological control be the solution?Europe:• Over 300 releases of 176 predators/ parasitoids against insects;
e.g., Anaphes inexpectatus against Gonipterus platensis (Eucalyptus globulus) in Portugal
• Only 1 agent against an invasive plant – released in 2010 in the UK: Aphalara itadori to control Fallopia japonica
http://news.bbc.co.uk/2/hi/8555378.stm http://www.guardian.co.uk/environment/2009/jul/23/japanese-knotweed-bug-control
December 18th | Brussels
and Trichilogaster acaciaelongifoliae?
1mm
December 18th | Brussels
• Australian bud-galling wasp (Hymenoptera: Pteromalidae), 3mm
Trichilogaster acaciaelongifoliae
1mm
December 18th | Brussels
• Australian bud-galling wasp (Hymenoptera: Pteromalidae), 3mm
• Mono-specific – affects exclusively A. longifolia
• Annual life cycle:
• 362 days inside galls;
• Emergence of , search for flower (vegetative) buds; ♀
• oviposition and death after 2-3 days
Trichilogaster acaciaelongifoliae
December 18th | Brussels
December 18th | Brussels
• Australian bud-galling wasp (Hymenoptera: Pteromalidae), 3mm
• Mono-specific – affects exclusively A. longifolia
• Annual life cycle:
• 362 days inside galls;
• Emergence of , search for flower (vegetative) buds; ♀
• oviposition and death after 2-3 days
• galls develop instead of flowers – NO SEEDS produced
Trichilogaster acaciaelongifoliae
December 18th | Brussels
Trichilogaster acaciaelongifoliae
Short term effects:
• seed production & dispersal decline;
December 18th | Brussels
December 18th | Brussels
Trichilogaster acaciaelongifoliae
Short term effects:
• seed production & dispersal decline;
• no addition to the seed bank
Long term effects:
• reduction of germination post-control, fire or other disturbances
• physiological stress - plants die as cannot cope with heavy gall
loads
December 18th | Brussels
Host-specificity tests• Conducted from September to December 2005 – 2010• Female wasps obtained from galls (South Africa)• Specificity test
• 40 non-target species tested (different criteria)• Flower & vegetative buds dissected to detect eggs
1 - Non-choice test2 - Paired-choice test3 - Trials on potted plants 4 - Field surveys in South Africa and Australia
December 18th | Brussels
Host-specificity tests
Results:• Oviposition in ONLY 3 non-target species in non-choice tests (Acacia melanoxylon, Vitis vinifera, Cytisus striatis) BUT confinement in cages disrupts normal behavior
Trials on potted plants: • Galls ONLY developed on A. longifolia (able to complete the life
cycle)
Field surveys in South Africa and Australia: • Galls ONLY detected on A. longifolia
December 18th | Brussels
South Africa: detailed long-term studies• Released in 1982• Non-target species were not affected except for negligible galls in
Acacia melanoxylon and Paraserianthes lophanta (invasives)• Significantly reduced seed production (> 85%) and curtails
vegetative growth and area invaded• 1980: A. longifolia top 10 Invasive plants 2013: trivial
Specificity tests in Portugal (additional list of species) • NO GALLS in any non-target species
YES, T. acaciaelongifoliae can be safely used decreases economic and biological impacts of A. longifolia in a
cost-effective, sustainable way, without undesirable effects
Is it safe?
December 18th | Brussels
Future?Ideal conditions to follow up (INVADER-B project - ongoing)• Assess/ follow the distribution of A. longifolia and biocontrol
agent (remote sensing); • Monitoring plan in place to measure T. acaciaelongifoliae
establishment and success;
TO STRESS:• Imported into quarantine facilities; only females that emerge
will be released
Doing nothing is the biggest risk! More species lost, more money spent, more difficult the solution…
December 18th | Brussels
Thank you!