Rats have long been the most important pests of rice in Southeast Asia. The innovative use of a barrier and traps system (TBS) to catch rats attracted to a lure crop was first developed in Malaysia. Use of the 'halo effect' (reduced rat damage to crops surrounding the TBS) to justify investment in a TBS means that the uptake of this technology will be less than socially optimal if managed by individual decision-makers acting in isolation. Management of the TBS as a common property resource (i.e. at a community level) may provide a means to overcome this problem.

We selected Samrong and Lvea Communes as the two study sites because they are close and similar in land use. Eighteen groups of farmers in Samrong implemented rodent pest management using the TBS technology for the dry season rice crop from November 2001 to April 2002. Each group made their own social arrangement to establish and maintain a TBS as a common property resource.

Low levels of damage caused by rats were recorded throughout the two sites. The maximum damage recorded in a ricefield was 1.8% (Samrong) and 3.3% (Lvea) of hills with 50% or more tillers cut by rats. It was not possible to demonstrate the protective effect of TBS on rice crops when there was virtually no damage caused by rats at both sites.

The project team reviewed data collection techniques in an effort to learn from the problems encountered in the first round. The yield loss caused by rats was measured as the difference between potential yield and the actual yield. The potential yield was based on the yield from undamaged hills found in the field. The choice of undamaged hills allowed for subjectivity in sampling and the amount of bias for larger hills (higher yield) in the results was unsatisfactory. To overcome this problem, we will measure the yield loss caused by rats directly in the next cropping season. This is measured by the difference in yields between a rodent proof exclusion plot and an adjacent "at risk" plot.

The core ecological objective of the project is to determine the relationship between the abundance of rodents and the damage caused by rodents, and, between damage and yield losses caused by rodents. These relationships will help us develop simple monitoring indexes for farmers to make decisions and evaluate rodent management options. We have already developed simple, robust index methods:
the relative abundance of rodents is measured by the number of sets of foot prints on a 10 m long bund with moist mud tracking surface over three consecutive nights;
damage is measured by the number of tillers cut by rats in a 10m x 10m area adjacent to the tracking surface.

After trialing TBS on the dry-season crop in 2002, the farmers were firmly committed to the second round of TBS for the wet-season crop. This indicated that the TBS was perceived as an improvement in rodent control strategies, although the test for sustainability was yet to occur.

There was a tendency for free-riding behaviour in the community, placing the burden of the cost of the TBS on the persons who owned the lure crop for the TBS. Nonetheless,

Progress against the Project Objectives has been good. Four crop cycles have now been studied. Some farmers are now confident in selecting sites and constructing TBS by themselves. Farmers have a good understanding of the ecological, technical and socio-economic constraints of the TBS technology. The leader of the TBS group plays a strong role in the success of the TBS within the village.
An extra activity that has been conducted is trailing the TBS in combination with fish aquiculture. While this activity will yield some interesting results, it is important not to direct too many resources away from the core research of the FARMERS project.
The project has gone a long way in testing the TBS at the main treatment site (Samrong) in a short period of time. Evaluation of the success has been through numbers of rats captured, damage to crops (yield loss), yield, costs of control, reduction in use of rodenticides and through the social aspects, looking at how the community works together and improved living standards. All the participants in the project identified benefits and some of the problems of the TBS technology.
A significant flow on of study was the work conducted by OAE at O Riang Ov District and plans were underway for another site (Chan Karloeu) through support of CAAEP2.
Social: The social impacts of the project are strong. Farmers see the benefits of using TBS by working together as groups. Some activities were shared amongst members of the group. The cycles of adaptive management are improving the social impact. CARDI and OAE staff are working well together and with farmers.
Economic: Data to determine the economic impact of the study has been routinely collected through the project, but there was not a good synthesis or analysis conducted to date. Because there is no control (untreated) site, they are limited in what comparisons can be made (also no replication). The analyses are limited to before and after.
Environmental: There are some concerns about disposal of used plastic fencing material and fate of non-target animals captured in TBS traps. This is not a significant issue.
Capacity building impacts: It was clear that project staff had increased their knowledge of rodent management and social sciences. Some continued support is required to maintain and improve the capacity of CARDI and OAE staff. There is little capacity within the Plant Protection Group. Because of staff changes at the beginning of the project, the remaining staff were not fully aware of some data collection issues. These issues were being resolved.
Scientific impacts: So far there have been 13 publications resulting from the project, including extension material, a Cambodian Agriculture Journal article, abstracts, spoken papers and posters at the 2nd International Conference on Rodent Biology and Management. Also some staff attended the annual project coordination meeting for ACIAR project AS1/98/36 (Management of rodent pests in SE Asia) in Hanoi, September 2001. Plans are in place to continue to publish material.

Development of methodology and extension material and training material
A working draft of the methodology training course was developed and refined by conducting a training course based on the draft. A training course/workshop was conducted on Participatory Research and Extension by project team members from Australia in Cambodia in March and April, with 11 trainees from the Cambodian Agricultural Research and Development (CARDI), the Office of Agricultural Extension (OAE) and the NGO, CHE (Community Health Education) attending.
The training followed an action learning approach and covered participatory community engagement, participatory methods of learning and exploring issues with communities and participatory evaluation. Training focussed on participation with an emphasis on how to engage the community on rodent management issues. From this training course a manual and complementary CD are being developed for use by trainers in Cambodia for use in participatory research and extension techniques.
Drafts of technical extension material for the use of the Trap Barrier System (TBS), specifically for Cambodian conditions, have been completed for publication as extension material by CARDI. The materials developed by this project will be made available to other agricultural agencies within Cambodia.
Monitoring of the treatment site
During the past 12 months the project team has been continuing with monitoring of the treatment site where farmers have continued to trial the TBS technology without monetary support from the project. Technical data was collected for the 2003 wet season (ending in September) to continue evaluation of the effectiveness of the TBS method for rat management. Project team members are also continuing to monitor and document the adaptation of the technology and certain socio-economic aspects surrounding the technology and rat management.
Socio-economic analysis in the reporting period has concentrated on the management of rodent pests as a common property resource management problem. This work has been conducted primarily during field work at Samrong and L'vea Communes, leading to a close relationship with the farming community and greater understanding of how the communities organise other aspects of community life involving groups. This field work has also contributed to understanding of how the TBS fits into the farming system in the study area.
The team conducted a participatory evaluation of the level of participation as perceived by the farmers involved with the project. One of the overall intentions of the project was to have community involvement in all stages of the project. This evaluation helped the project team to understand what level of participation had been achieved and what impact this has had on the community. The evaluation considered the distribution of the work load within the project and the distribution of project benefits. Farmers considered that project costs and labour were shared and showed an appreciation of research findings as project benefits falling to the farmers as well as scientists. Farmer meetings and supporting visits by OAE and CARDI staff have maintained interest in the project, despite the lack of financial support for TBS construction. Farmers at L'vea Commune were not willing to participate in TBS activities without financial support for materials. Despite this initial reaction, there has been a level of interest and activity at L'vea and limited continued TBS operation in Samrong Commune.

To facilitate the transformation of advances in understanding rodent ecology into development outcomes, ACIAR has funded this project to investigate factors affecting the adoption of the community TBS in Kampong Cham Province in Cambodia. The key findings of this project indicate that the adoption of the technology is limited because the cost of establishing and maintaining the community TBS is justified if rodent damage to crops is high. A community TBS must be implemented in the rice field at the transplanting stage so that a lure crop is planted inside the TBS. However, farmers cannot make a timely decision whether or not to implement a community TBS because it is too early to forecast rodent damage to crops at the transplanting stage. However, a number of farmers at the project site have adopted and improved the community TBS in areas where high rodent damage occurs each year. The financial support from the project (e.g., supply of trap and fence materials) for the community TBS has been gradually phased out from 40% of total cost in 2003 to 0% in 2004. The number of TBS groups, the number of participating farmers, and the quality of TBS construction and maintenance did not decline over this period, indicating that the community TBS is self sustainable.

The most commonly used rodent control method in Southeast Asia has been and will continue to be the application of zinc phosphide bait. This is because the bait has been the most affordable technology for rice farmers. Laying zinc phosphide bait is also the most commonly used method for the control of mouse plagues in Australia. A group of key farmers designed and implemented bait trials to develop improved methods of zinc phosphide baiting. They found that bait uptake and palatability was improved by replacing maize with rice as the bait base. They also learnt to manufacture wax block bait with technical inputs from the project. They prefer to use wax block bait because they are weather resistant and not palatable to non-target species such as chickens, dogs and other domestic animals.

The participating farmers have improved both the TBS and zinc phosphide baiting technologies. They played the role as trainers in workshops to teach other farmers to use these technologies. Although the primary aim of these workshops was to field test the extension material developed by the project, the workshops did achieve extension of the technologies to farmers from nearby communes. However, the success of the extension was limited geographically because only farmers near the project site could attend the workshops. The project was not designed to extend the technologies.

Extension material for community TBS have been developed and used for training workshop and general distribution through the government network. The extension material is currently being updated because of the continuing improvements made by the participating farmers of the project. Extension material for zinc phosphide baiting technologies is being developed and will be available in by the end of 2005. The extension material has been drafted in Khmer and will be finalised and distributed to researchers and extension workers in Cambodia through the government network by the end of 2005.

To facilitate the transformation of advances in understanding rodent ecology into development outcomes, ACIAR has funded this project to facilitate the adoption of the community based Trap and Barrier System (TBS) and other rice field rodent pest control methods in Kampong Cham Province in Cambodia. The following extension material for community TBS have been developed and used for training workshop and general distribution through the government network: (1) a 36-page booklet entitled "TBS for field rat management"; (2) a 4-page pamphlet "Wax block baiting technique to control rice field rat"; (3) a 95-page book "Rice field rats: biology, management, and case study in lowland field"; and (4) a 58-page book "Participatory research and extensions manual for trainers and trainees". The extension material is in Khmer and has been distributed to a number of researchers and extension workers in Cambodia through the government network.

A total of 33 community based TBS's were implemented by 240 farmers during the project. The key findings of this study indicate that the adoption of the technology is limited because the cost of establishing and maintaining the community TBS is justified if rodent damage to crops is high and predictable. The community TBS must be implemented in the rice field at the transplanting stage so that a lure crop to attract rats is planted inside the TBS. Farmers cannot make a decision at the planting stage whether or not to implement a community TBS because it is too early to forecast rodent damage to crops at the transplanting stage. However, a number of farmers at the project site have adopted and improved the community TBS in areas where high rodent damage occurs regularly each year. The financial support from the project (e.g., supply of trap and fence materials) for the community TBS has been gradually phased out from 40% of total cost in 2003 to 0% in 2004. The number of TBS groups, the number of participating farmers, and the quality of TBS construction and maintenance did not decline over this period, indicating that the community TBS is self sustainable.

The most commonly used method to control rice field rodents in Southeast Asia has been and will continue to be the application of rodenticide bait. This is because the bait has been the most affordable technology for rice farmers. Laying rodenticide bait is also the most commonly used method for the control of mouse plagues in Australia. Our project has conducted an experiment to demonstrate that bait uptake and palatability is improved by 65% by replacing maize with rice as the bait base. The farmers also learnt to make wax block bait with technical inputs from the project. They prefer to use wax block bait because they are weather resistant and not palatable to non-target species such as chickens, dogs and other domestic animals.

The participating farmers have improved both the TBS and zinc phosphide baiting technologies. They played the role as trainers in workshops to teach other farmers to use these technologies. Although the primary aim of these workshops was to field test the extension material developed by the project, the workshops did achieve extension of the technologies to farmers from nearby communes. However, the success of the extension was limited geographically because only farmers near the project site could attend the workshops. The project was not designed to extend the technologies beyond the study site.