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.