Biological control of two major weeds affecting crop and livestock production in East Timor

• National University of Timor Loro Sae, East Timor
• Ministry of Agriculture, Forestry and Fisheries, East Timor
• CRC for Australian Weed Management, Australia
• Department of Infrastructure, Planning and Environment, Australia

Agriculture is the main source of food security and income for the majority of people in East Timor. Cropping and livestock productivity are threatened by the encroachment into cropping and pasture lands of two invasive weeds; Chromolaena odorata and Mimosa invisa. Both weeds 'choke' productive lands by forming dense thickets and by spreading rapidly once established in an area.

Chromolaena (also known as Siam weed) rapidly invades grasslands and if left unchecked will completely replace native vegetation. Cattle and goats cannot be left to feed on Siam weed as the presence of pyrrolizidine alkaloids (naturally occurring chemical compounds) in the weed progressively destroy the animals' liver. This results in eventual death. Mimosa invisa is a serious pest and threat to croplands, especially the staple food maize. Livestock grazing on the weed have also been reported to have been poisoned. Both weeds are a serious threat to native plants and biodiversity, including in natural Eucalyptus alba savannas and open grasslands of the Los Palos district.

Biological control agents against both weeds exist and have been proven to be effective elsewhere in Southeast Asia. The stem gall fly, Cecidochares connexa for Siam weed and a sap sucking psyllid Heteropsylla spinulosa for M. invisa will be collected from sites in West Timor and Queensland respectively. Both will then be distributed and monitored with the psyllid first established at the University Agricultural Farm in Hera, prior to release.

The project aims to provide long term control of two serious weeds (Chromolaena odorata and Mimosa invisa). An associated goal is to develop the scientific capacity of MAFF and UNTL staff and students in biological control technologies, and to enhance rural community knowledge and understanding of biological control as a pest management option, by implementing an efficient, low technology method of collecting and disseminating the stem gall fly for Chromolaena and the sap sucking psyllid for M. invisa control.

Training:
Train MAFF and UNTL staff in biological control theory, rearing and maintaining insect colonies, release methods and monitoring techniques.
Training of technician and project coordinators in entomological techniques in East Timor and Australia.
Incorporate theory of biological control of weeds into the UNTL Agronomy curriculum.

Community socialisation/awareness raising:
Awareness raising workshops for local communities on weeds and the problems weeds cause.
Train local farmers in the basic concepts of weeds and biological control.
Distribute posters and leaflets displaying colour pictures of biocontrol agents and weeds to the wider community.
Training of MAFF and UNTL staff in adult education techniques.

Introduction of Stem Gall Fly:
Establish populations of the stem gall fly in permanent plots
Monitor the population of the stem gall fly in permanent plots
Monitor the stem gall fly impacts on Chromolaena in permanent plots.
Release the stem gall fly more widely in Chromolaena infestations.

Introduction of Sap Sucking Psyllid:
Establish an irrigated plot of Mimosa diplotricha at Hera University farm.
Release and establish psyllid in irrigated plot at Hera University farm.
Release the psyllid in M diplotricha infestations.
Monitor impacts of the psyllid in M. diplotricha infestations.

The stem gall fly has successfully established throughout East Timor, where it spread at a faster rate than initially anticipated. The sap-sucking psyllid was introduced in the final stages of the project and has survived in the nursery sites to date.
After initial community resistance and suspicion, farmers are now asking to be included in the project. The project scientists have seen significant change in community attitudes to biological control, from suspicion to outright support and enthusiasm, as evidenced in local farmers protecting release sites from fires. This has been achieved through the extension and socialisation efforts of the MAFF and UNTL teams working together to bring these technologies to communities. Local communities in affected areas now have an appreciation of the benefits of biocontrol, and some people now have a basic understanding of insect life cycles. Farmers themselves are now engaged in collecting and spreading the insects to other areas infested with chromolaena.
Through the project, staff from MAFF and UNTL have developed a good grounding in biological control techniques and have developed the capacity to implement a biological control program with technical support. Students have been actively involved in monitoring and data collection, and this will continue beyond the life of the project as it has been integrated into the curriculum of the agriculture faculty.
The impacts of the project are now evident with galls widespread throughout the Baucau area, and now can be seen at all of the release sites. Further monitoring will be required for the impact on the density and spread of chromolaena infestations to be quantified. Within the next 5-10 years there should be a noticeable decrease in plant density at release sites, an increase in visibly stressed plants, and a reduction in new satellite infestations.
The sap-sucking psyllid has yet to become established in Timor Leste, although indications are that it will establish at its current release sites. Once this has occurred MAFF staff can easily spread it to other suitable sites, thus accelerating its penetration throughout the mimosa infestations.
More agents need to be introduced as they become available from researchers in South Africa, to increase the pressure on chromolaena. Further introductions of the sap-sucking psyllid are needed to ensure establishment of the insects at the nursery sites, which would then provide a reservoir of insects to be harvested for release throughout Timor Leste.
Because the staff of both MAFF and UNTL now have the capacity and skills to maintain insects in a low-technology setting and understand the principles of biocontrol, more work could be done to introduce biocontrol agents that are readily available and tested to control some of the other serious weeds in Timor Leste. Examples are bellyache bush (Jatropha gossypifolia), prosopis and Sida acuta.