INVASIVE WEEDS MANAGEMENT
IN VANUATU.
BIOLOGICAL CONTROL WORKSHOP
16 – 18th November 2009
Auckland, New Zealand.
Compiled by Sylverio Bule
Plant protection officer
1- INVASIVE WEEDS MANAGEMENT.
Targeted weed species
• Sida acuta (broom weed)
• Eichorneae crassipes (water hyacinth)
• Pistia stratiotes (water lettuce)
All the three weeds were controlled through the biological control in line with the
guidelines stipulated in ISPM no 3.
Pest Risk Analysis (PRA) were drafted and submitted to the relevant authorities for
approval of the import of biological control agents.
Importation of bio-control agents
Rearing in the Post Entry Quarantine facility into the first generation
Mass breeding of the agents (in the pools for water hyacinth and water lettuce)
Field releases into the infested sites
Monitoring and evaluation.
In country locations where the targeted weeds are present and their bio-control agents were released.
• Sida acuta widely present in all islands of
Vanuatu. Calligrapha is also widely distributed
in all islands.
• Water hyacinth only present on
Efate,Santo,Malekula and Tanna. The
neochetina eichorrneae have been released on
these infested islands
• Water lettuce is only present on Efate, Santo
and Malekula. Neohydronomus affinis have
been released in these infested islands.
1.1- SIDA ACUTA (Broom weed)
Sida acuta is a perrenial, invasive weeds
which is commonly found in paddocks and
along side of tracks.
A paddock on Efate, infested with sida acuta
Young sida plant
Sida acuta biological control agent
Calligrapha pantherina
C.pantherina were imported from Fiji.
Scarabeidae beetle greenish in color feeds
on the sida leaves, leaving the plants ‘’naked’’
Life cycle
Egg mass
5 days after 1st instar
larvea emerge
4th instar larvae
took 9 days
10 days for
newly emerged
adult is
brownish
3 days after sexually
matured adults are
ready to make new
babies
It takes about 24
days from egg to
adults to a complete
life cycle of the agent
First impact of the beetle on sida plants in one
of the release sites.
Field release, monitoring and
evaluation.
To date, the agents have been released in
most of the islands of Vanuatu.
Field data collection and physical assessment
of the impact of the beetles on sida plants
Data collection in one of the released sites
One of the release site on Efate in 2005 Same location in 2008
1.2 – Eichorrneae crassipes (water hyacinth)
Water hyacinth is perennial, herbaceous aquatic weed in the
family of ponterderiaceae, which the leaves are comprised of
smooth, glossy, circular to kidney-shaped lamina and a
swollen , spongy petiole.
In a nutrient
rich
environment,
the plant can
reach this
size.
Young water
hyacinth
plant
Part of a lake infested with water hyacinth plants
Water hyacint bio-control agent
Neochetina eichorrneae imported from Fiji.
Adults are 4-5mm and brownish to grey in
color
N.Eichorrnea life cycle
Eggs laid
under
leaves
7 day after larvae
emerges
Pupae for 23 days
Adults sexually
matured ready to make
new babies
Water starts to open up as the result
of the weevils heavy feeding.
It takes about 70 – 80
days for the n.eichorrneae
from egg to adult
Field release of agents, monitoring
and evaluation
To date, the weevils have been released most of
islands infested with water hyacinth.
Field data collection and physical assessment of
the impact of the beetles on sida plants
Collection of the weevils in the pools
Data collection on the infested lakes.
Results of the activity.
Successfully control of the weed.
Infested lake before the release of Same lake in 2008 after the release of n. eichorrneae
neochetina eichorrneae in 2005
1.3 – Pistia stratiotes (water lettuce)
P.stratiotes is a floating herbaceous weed.
Water lettuce bio-control agent
Neohydronomus affinis collected from Papua New
Guinea (Kimbe, Bulolo and Lae) and brought into
Vanuatu.
N.affinis is small, stout weevil (1.5 – 2.4mm long)
with loosely covered scales. It feeds on the plants
leaves.
N.affinis mass reared in the pools before field releases
Field release, monitoring and evaluation
Most of islands infested with the weed have n.affinis released.
Data collection are currently carried out to evaluate the impact of
the weevils on the weed.
Measuring of the 2nd
youngest leaf length and
width.
Counting of the damaged leaves
Result of the bio-control activity.
Successful results are now visible. Some of the infested lakes are already
cleared from the weed.
One of the lakes before the release of n.affinis in
2005Same lake in 2008 after the release of n.affinis
Other biological control work carried in Vanuatu.
-Biological control work on spiralling white fly (aleurodecus dispersus)
Bio-control agents introduced from Fiji (SPC laboratory)
- Nephaspis oculatus
- Nephaspis bicolor
Future biological control activities.
- Mimosa diplotricha
- Micania micrantha
- Erythrina gall wasps
- Coconut leaf minor (promeccotheca opacicolis)
All the three weeds species are now under control in released sites.
All the acknowledgment is forwarded to SPC/European Union for
funding these activities. The acknowledgment is also extended to Warea
Orapa and the SPC team for all their inputs for the success of these
activities.
Thank you for your attention.