Ecologically-based Rodent Management Research Articles

Farmers' perception, knowledge, and control attitudes of rodents infesting cereal growing areas in Morocco.

Rodent pests threaten agricultural cropping systems, impacting food security and small-holder farmers' income in cereal-growing areas. This study investigated knowledge, attitude, and practices (KAPs) toward rodents infesting Moroccan cereal crops through a survey of 100 farmers in two regions (Rabat-Sale-Kenitra and Fes-Meknes). A constructive questionnaire about all rodent aspects was created and distributed to the farmers. Rodent infestation is perceived in most fields (80%), with Mus musculus (28%) and Rattus rattus (26%) being the most prevalent species. Farmers perceived rodents negatively (> 90%), considering them as a major threat. Most of the control attitudes against rodent infestation were positive when continuously established and promoted. The farmer profile was shown to influence rodent knowledge and control attitude. Younger, educated, and experienced farmers understood rodent damage trends better and adopted environmental-friendly management practices, while older, inexperienced respondents preferred to use rodenticides instead. The study revealed novel insights into rodent problems in Moroccan cereal fields and urged the need for ecologically-based rodent management (EBRM) practices. © 2024 Society of Chemical Industry.

From problem to progress: Rodent management in agricultural settings of sub-Saharan Africa and calling for an urban perspective

In sub-Saharan Africa, agricultural intensification and urbanization have increased the risk of proliferation of rodents in rural and urban habitats. Management of rodent populations is a challenge in terms of food security and public health. However, conventional efforts to manage rodents are currently reactive and based on the inadequate use of synthetic chemical rodenticides, including first- and second-generation anticoagulants and acute rodenticides. This approach carries substantial environmental and health risks and has yielded limited success in terms of reduction of rodent populations sustainably. In this paper, which is the second part of a diptych, we advocate for a shift towards more sustainable and environmentally friendly approaches, such as Ecologically-Based Rodent Management (EBRM), as a realistic alternative to synthetic rodenticides. This method is based on a good knowledge of habitat use, species diversity and population dynamics of major rodent pests, and involves community-based interventions aimed at reducing rodent abundance to economically and hygienically acceptable levels in the long term. We present for the first time a comprehensive compilation of published and unpublished information derived from observational field studies conducted in Ethiopia, Niger, Nigeria, Benin, Mali, Mauritania and Senegal with the aim to provide an overview of EBRM case studies in these countries of sub-Saharan Africa. This paper intends to serve as a catalyst for change, encouraging the transformation of rodent management practices towards sustainable methods. We aim at stimulating further research and interventions that promote EBRM in Africa, ultimately fostering more environmentally conscious and effective solutions.

Strengthening ecologically based rodent management in the Philippines using maximum entropy (MaxEnt) predictions

Abstract Rattus species pose a significant threat to the Philippines, causing substantial economic losses in agriculture and posing health risks to humans. While Ecologically Based Rodent Management (EBRM) has been developed to mitigate rodent outbreaks, its implementation is challenging, particularly in the face of climate and land use changes. In this study, we aimed to potentially enhance EBRM strategies by utilizing a high-performing modelling approach, MaxEnt, to predict the habitat suitability for Rattus species in the Philippines. This study revealed that forested areas exhibit high suitability for R. tanezumi, R. exulans, and R. everetti, with a notable degree of similarities in their habitat suitability. Furthermore, the model predicted that R. argentiventer, a species with no records in the mainland of Luzon, could potentially find suitable habitats in some areas of these regions, particularly in Central Luzon. Conversely, R. norvegicus was predicted to be highly suitable for areas with high-human population density, such as urban cities. The predictive model deepens our understanding of the interactions between Rattus species and their environments across the Philippines, which is crucial for identifying high-risk areas that require immediate intervention. These results have the potential to enhance the EBRM approach more effectively on a national scale. The EBRM strategy based on the predictive outcomes of the MaxEnt model is not only crucial for the Philippines but also serve as a guiding framework for other regions facing similar challenges with rodent populations.

Reproductive ecology of the black rat (Rattus rattus) in Madagascar: the influence of density-dependent and -independent effects.

The black rat (Rattus rattus) poses a severe threat to food security and public health in Madagascar, where it is a major cause of pre- and post-harvest crop losses and an important reservoir for many zoonotic diseases, including plague. Elsewhere, ecologically based rodent management (EBRM) strategies have been developed using ecological information to inform decisions on where and when to target control. EBRM could deliver improved health and well-being outcomes in Madagascar if adapted to the local ecological context. Using data collected from removal studies, we explored spatio-temporal patterns in the breeding activity of the black rat (R. rattus) in domestic and agricultural habitats across Madagascar and investigated to what extent these trends are influenced by rainfall and rat density. We identified clear spatio-temporal variation in the seasonality of R. rattus reproduction. Reproduction was highly seasonal both inside and outside of houses, but seasonal trends varied between these two habitats. Seasonal trends were explained, in part, by variation in rainfall; however, the effect of rainfall on reproductive rates did itself vary by season and habitat type. A decline in breeding intensity with increasing rat density was recorded outside of houses. This has important implications for control, as populations may compensate for removal through increased reproduction. We recommend that sustained control initiated before the main breeding season, combined with improved hygiene and adequate rodent-proofing in homes and grain stores, could curtail population growth and reduce pre- and post-harvest losses provided that these measures overcome the compensatory response of rodent populations.

Rodents in agriculture and public health in Malawi: Farmers’ knowledge, attitudes, and practices

Given that rodents are responsible for nearly 280 million cases of undernutrition worldwide and that about 400 million people are affected by rodent-associated zoonoses annually, management of rodent populations that are agricultural pests and/or reservoirs of pathogens is a major food security and public health matter. In sub-Saharan Africa, the median crop loss due to rodents is about 16% in the field and around 8% during storage. The impact on public health is not well-established, albeit over 60 zoonotic diseases can be spread to humans via rodents. Therefore, focusing on rodent-related community knowledge, attitudes, and practices is crucial to establishing robust baseline information as a springboard for future targeted studies. The study was conducted in September 2020 in Lilongwe and Nkhata Bay districts in Central and Northern Malawi, respectively. A semi-structured questionnaire, focus group discussions, and interviews with key informants were used. Farmers reported rodents were a major problem for staple crops (maize, rice, and cassava) and the main species responsible were the Natal multimammate mouse (Mastomys natalensis), silver mole-rat (Heliophobius argenteocinereus), and house mouse (Mus musculus domesticus). Awareness of rodent-associated health risks is very low, as exemplified by reports of rodent–human bites, eating rodent-contaminated food, and processing and consumption of wild rodents in poor hygienic conditions, and these practices were flourishing when Malawi was a bubonic plague endemic country. Rodent management is less practiced, and when practiced, it is symptomatic. It is considered a matter of individual households and typically relies on the use of rodenticides and insecticides without proper dosage and user instructions. We recommend rigorous campaigns to create better awareness among the public regarding the impacts of rodents on agriculture and community health and the need for community engagement for effective rodent management. A paradigm shift is needed by adapting and adopting practices of ecologically-based rodent management and reducing dependence on synthetic chemical rodenticides.

Optimizing the capture of neophobic rice field rats in lowland Asian rice ecosystems

BACKGROUNDTrapping is a key method for monitoring small mammals and is also one of a number of methods recommended under an ecologically‐based rodent management program to control rodent pest populations. Live‐traps are widely used globally for studying small mammal populations. In Asia where rodents are major pests of rice, single capture traps typically provide low trap success. We compared the trap success between two types of live‐traps in rice fields in Indonesia and the Philippines.RESULTSMultiple‐capture traps (MCTs) in conjunction with a linear trap barrier were significantly more effective in catching rodent pest species than single‐capture traps (SCTs) in Indonesia and the Philippines. In Indonesia, MCTs captured more individuals with a mean (±SE) percent trap success rate of (15.54 ± 4.29) compared to SCTs (3.88 ± 1.58). In the Philippines, MCTs captured more species of rodents and had a significantly higher recapture rate (1.96 ± 0.79), than SCTs (0.58 ± 0.32).CONCLUSIONMultiple‐capture traps with a linear trap‐barrier were more effective for capturing Rattus argentiventer and Rattus tanezumi in rice field ecosystems compared to single‐capture traps. MCTs captured more species of rodent pests in the Philippines and recaptured more individuals of each species. These results indicate that rodent populations can be more effectively monitored and controlled by using a multi‐capture trap with barrier system than the use of single capture traps on their own. This is the first time these two trap types have been compared for use in rice ecosystems in Asia. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

English

Two experiments were conducted, first was to estimate maize seedling damage in farmers’ fields and a simulation experiment. This study aim to investigate the impact of rodent pest species, damage to maize crop in semi-arid areas at pre-harvest, with a view to provide farmers with appropriate information on rodent pest management interventions. In farmers’ fields, damage assessment was done by counting the number of damaged or removed seedlings at each planting hole while yield loss was determined from simulation experiment at five damage levels, viz; 0, 10, 25, 50, and 75% by removing seedlings per plot. Variation of damaged maize seedlings was compared between soil type and fields. The fields with black clay soils had higher damage of maize seedling (mean = 59.201±1.714) as compared to sandy loam soils (means = 49.742±1.714). The damage ranged from 30.17 to 71.91% in different fields. However, no effect was observed between interactions of maize fields and soil types. Results from simulation experiment showed no significant difference (p = 0.2357) among maize damage levels, although relatively higher yield losses were observed at 75%, while lowest yield losses in the control (0%). The increased seedling damage has an impact on final harvest; therefore, ecologically-based rodent management strategies appear to be good solution for reducing crop damage and should be encouraged to improve food security for smallholder farmers. Key words: Damage, habitats, M. natalensis, rodent pest, semi-arid.

Farmers’ Knowledge, Attitudes, and Control Practices of Rodents in an Agricultural Area of Taiwan

Rodents threaten agricultural industries and food security on a global scale. Rodent management practices routinely involve the use of chemical products, mainly anticoagulant rodenticides (ARs). An understanding of farmer rodent control behaviors is crucial in order to implement management changes to more environmentally friendly practices. In this study, we surveyed farmers in an agricultural area of northwestern Taiwan on their knowledge, attitudes, and control practices for rodent pests. From our survey sample of 126 farmers, rodents were perceived to be the most problematic for vegetable crops, followed by rice, and then fruit. Farmers in the oldest age group and those that perceived rodents to cause extensive damage to their crops were found to have the most negative attitudes toward the pests. One-third of the farmers in our survey stated they currently use rodenticides, with crop type, perceived problems caused by rodents, and attitudes toward rodents found to be important explanatory variables. Our results indicate that the use of rodenticides is reactive; farmers are more likely to apply the chemical products if they perceive rodents to cause damage. Additionally, cost–benefit assessments are likely important in governing rodent control behaviors; farmers may be more inclined to use control products that are subsidized by the government, which include ARs, when they observe damage to their crops inflicted by rodents. We also describe how ecologically based rodent management (EBRM) practices could be feasible and sustainable alternatives to rodenticide use.

Agricultural Biodiversity and Coastal Food Systems: A Socio-ecological and Trans-ecosystem Case Study in Aurora Province, Philippines

This paper presents a ridge-to-reef case study on Philippine biodiversity conservation that focused on reducing agricultural chemicals as a contribution to development goals of optimized food security, improving water quality, and mitigating maternal malnutrition. Building upon an earlier study that engaged participants and jurisdictions, farmers were oriented on biodiversity considerations and engaged in ecologically-based rodent management that was extended across the province of Aurora through the Office of the Provincial Agriculturist. Subsequently, a Participatory Action Research and Learning (PARL) cycle was conducted among 14 farmer participants to support biodiversity-friendly agriculture. Developed with local farmers, a biodiversity assessment demonstrated that organic approaches in rice farms increased arthropod biodiversity and reduced the number of key insect pests. The organizational results from this biodiversity study further indicated that local government participation can promote positive change by helping overcome the disconnect between communities and sustainability research. The approach to biodiversity-friendly agriculture reached a milestone through the collaborative development of an agricultural protected area supported by drafting a municipal ordinance to encourage the continued expansion of biodiversity-friendly agriculture and reductions in the chemical load of a key Aurora watershed. This paper discusses the biodiversity analysis and organizational results within the context of trans-ecosystem knowledge management and the goal of improving chronic maternal malnutrition that has been identified in coastal settlements of Aurora.

Rodent management and cereal production in Asia: Balancing food security and conservation.

Rodents present a major problem for food security in Asia where smallholder farming families are particularly vulnerable. We review here recent developments in the biology and management of rodent pests in cereal cropping systems in Asia. The past decade has seen a strong focus on ecologically-based rodent management (EBRM), its adoption in field studies significantly increased rice yields (6-15%) and income (>15%) in seven Asian countries. EBRM principles have also been successfully applied to maize in China. We provide case studies on EBRM in Cambodia, on interactions between rodent pests and weeds, and on the importance of modified wetlands for biodiversity and rodent pest management. Knowledge on post-harvest impacts of rodents is increasing. One research gap is the assessment of human health impacts from a reduction of rodent densities in and around houses. We identify 10 challenges for the next decade. For example, the need for population modelling, a valuable tool missing from our toolbox to manage rodent pests in cereal systems. We also need to understand better the interactive effects of cropping intensification, conservation agriculture and climate change. Finally, new management approaches such as fertility control are on the horizon and need to be considered in the context of smallholder cereal farming systems and mitigating health risks from zoonotic diseases associated with rodents. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Small mammal communities, associated damage to rice and damage prevention in smallholder rice storage facilities in Sri Lanka

Several rodent species damage rice crops and commensal rodents cause damage to stored produce and infrastructure, hygienic problems and they can transmit zoonotic pathogens. In the first such study in Sri Lanka, we identified the main rodent and shrew species and the extent of post-harvest damage caused in rice storage facilities of smallholder farmers. Netting of rice bags was trialled as a new measure of protection. Field experiments were performed in the three main agro-ecological zones of Sri Lanka.Five rodent species and one shrew species were captured in storage facilities. Rattus rattus, Bandicota indica and Suncus murinus were the dominant species in storage facilities. The small mammal composition was more related to season than to region. In storage, depending on region, 3.2–9.1% (mean 7.6%) of rice was lost to rodents when rice was stored indoors in unprotected polyethylene bags. Netting around bags reduced damage by 89% - equivalent to the annual rice consumption of one person per storage facility, reduced the presence of rodent droppings by 92% and the bag area damaged by rodents by 96%.Our findings clearly show the considerable amount of damage caused by rodents to rice post-harvest across three agro-ecological zones of Sri Lanka and indicate that netting bags considerably reduces damage and contamination. This netting can be used to aid the development of an ecologically-based rodent management (EBRM) program tailored to local conditions. More detailed studies are needed to fully understand the population and breeding ecology of the relevant rodent pest species in relation to damage patterns to optimize management beyond individual structural measures.

Tailor-made solutions to tackle rodent pests of rice through community-based management approaches in Cambodia

Rodents are a major pest of rice throughout Southeast Asia, causing both pre- and post-harvest losses. In Cambodia, where 90% of the cultivated land is used for rice production, rodent damage to rice can cause significant impacts to smallholder farmers’ livelihoods and to food security. To help smallholder farmers minimize yield losses from rodent pests, adaptive research experiments were established in two villages in Takeo province. In each village, three replicate 5-ha sites were selected for treatment and three for control. In each treatment site, groups of farmers implemented ecologically-based rodent management (EBRM) methods over two rice cropping seasons. The management methods were adapted based on the local situation and preferred practices of farmers and included maintaining basic hygiene in field margins, synchronous planting of rice crops, community rat hunts, no electric fencing and the implementation of a Community Trap Barrier System (CTBS) along with a Linear Trap Barrier System (LTBS) in an area of intensive rice monoculture, and a LTBS with targeted and limited bromadiolone rodenticide in an area growing recession rice on lake margins. Over 130 rats were caught at each treatment site per season and rodent damage levels were reduced from a mean of 22–34% per site and season in the non-treatment sites to less than 6% in the treatment sites. Following the implementation of EBRM, rice yields were, on average, 20–32% higher in the treatment sites than in the non-treatment sites, giving a 53–169% increase in net income and a benefit-cost ratio ranging from 3:1 to 11:1 per season. We show that rodent damage to rice in Cambodia and the associated yield loss can be significantly reduced following the implementation of cost-efficient EBRM approaches that were locally adapted to village-specific agro-ecological and social conditions. We conclude by discussing incentives that support the adoption of these practices by smallholder farming communities.

Natural bait additives improve trapping success of common voles, Microtus arvalis

Common voles are serious pests in European agriculture, damaging cereals, rapeseed and other crops and causing substantial losses per outbreak. Not only might the usual approach of applying rodenticides for population management have disadvantages for non-target species, these rodenticides also cannot be used in organic farming. An alternative solution could be an approach related to the concept of ecologically-based rodent management combining environmentally sustainable methods based on knowledge about the target species. Such a method inhibits the dispersal of common voles from field margins to crop habitats via a trap-barrier system. However, little is known about attractants, which could increase the trapping success of common voles. We screened 22 natural substances in T-maze trials. The three most successful substances were further tested during enclosure trials under semi-natural conditions. Bisabolol, eugenol and maltol attracted six of eight voles during the T-maze trials and were mixed into grain pellet bait. Bait containing maltol caught significantly more common voles in enclosures than plain control bait or bait containing bisabolol or eugenol. Of all individuals, 21% chose exclusively baits with maltol. Generalized Linear Mixed Model (GLMM) indicated that every individual would be trapped once in 6 h with this bait type and GLMM predicted that 63% of females and 56% of males would choose this bait over plain control bait. Maltol bait could help either by more efficiently trapping common voles in a trap-barrier system or improving bait acceptance when rodenticides are applied.

Effects of American Kestrel Nest Boxes on Small Mammal Prey in Cherry Orchards

In order to potentially reduce use of environmentally damaging rodenticides, integrated Pest Management (IPM) for rodents, or Ecologically Based Rodent Management (EBRM), proposes a more sustainable management approach using strategies informed by an increased understanding of rodent population and community ecology, including interactions with important predators, such as raptors. Nest boxes and perches can encourage raptor presence in agricultural areas and potentially enhance the regulatory ecosystem services provided by raptor predation of agricultural pests. To assess this idea, we studied American kestrels (widespread, generalist predators that readily use nest boxes) in a fruit-growing region of northwestern Michigan. The most common mammal prey in the diets of these kestrels from 2013 through 2016 were voles, which are considered the most important rodent pests in temperate fruit orchards. We utilized live trapping to measure small mammal abundances and activity during the summer at sites with and without active kestrel nest boxes; furthermore, we utilized camera trapping to measure small mammal presence during the winter, when damage to trees is most likely. As predicted, small mammal abundance and activity was lower at orchards with active kestrel boxes and at orchards that had been more recently mowed; however, these differences did not carry over as differences in winter presence in orchards. Our sampling demonstrated that voles were absent from orchards during both summer and winter, which suggests that orchards offer insufficient cover except under certain conditions, such as sustained snow cover. Instead, mice were the most abundant small mammals in most orchards during the summer and were also present during the winter. More evidence is therefore needed to determine the extent of orchard damage attributable to Peromyscus spp. and whether indirect effects of kestrels on Peromyscus spp. may reduce damage. We provide recommendations for future research on the effects of raptor predation in orchards.

Evaluation of habitat requirements of small rodents and effectiveness of an ecologically-based management in a hantavirus-endemic natural protected area in Argentina.

Hantavirus pulmonary syndrome is a severe cardio pulmonary disease transmitted to humans by sylvan rodents found in natural and rural environments. Disease transmission is closely linked to the ecology of animal reservoirs and abiotic factors such as habitat characteristics, season or climatic conditions. The main goals of this research were: to determine the biotic and abiotic factors affecting richness and abundance of rodent species at different spatial scales, to evaluate different methodologies for studying population of small rodents, and to describe and analyze an ecologically-based rodent management experience in a highly touristic area. A 4-year study of small rodent ecology was conducted between April 2007 and August 2011 in the most relevant habitats of El Palmar National Park, Argentina. Management involved a wide range of control and prevention measures, including poisoning, culling and habitat modification. A total of 172 individuals of 5 species were captured with a trapping effort of 13 860 traps-nights (1.24 individuals/100 traps-nights). Five rodent species were captured, including 2 hantavirus-host species, Oligoryzomys nigripes and Akodon azarae. Oligoryzomys nigripes, host of a hantavirus that is pathogenic in humans, was the most abundant species and the only one found in all the studied habitats. Our results are inconsistent with the dilution effect hypothesis. The present study demonstrates that sylvan rodent species, including the hantavirus-host species, have distinct local habitat selection and temporal variation patterns in abundance, which may influence the risk of human exposure to hantavirus and may have practical implications for disease transmission as well as for reservoir management.

Yield and Income Effects of Ecologically-based Rodent Management in Mekong River Delta, Vietnam

Regression-based strategies along with propensity score matching (PSM) were used to assess the farm-level economic impact of community action (CA) strategies associated with ecologically based rodent management (EBRM). The paddy yield and real net income of rice farmer beneficiaries of the EBRM approach in An Giang Province, Mekong River Delta, Vietnam, were analyzed using panel data from 151 rice farmers. PSM along with the difference-indifference framework using the fixed-effect approach were found to be the most appropriate methods to evaluate the farm-level economic impact of the adoption of the CA strategies. The EBRM through CA did not replace what the farmers were doing, but rather built on their practices and incorporated a scientific basis by encouraging farmers to work together at key times of a cropping season. In terms of labor use for rodent control, CA only entailed an additional 0.3 man-days/ha for every CA. Normally, for a 40-hectare (ha) rice field, around 30 persons participated in each CA including men, women, and children. With two to three times done in a season, a total of 1 man-day/ha is as an additional labor for the whole season. The adoption of the EBRM through CA had a significant and positive impact on paddy yield and real net income of rice farmers. The mean paddy yield increased by 0.43-0.45 ton per ha and real net income of the beneficiaries increased by VND1.16–1.19 million/ha (approximately USD65-67/ha). These findings imply that the adoption of the CA strategies in rodent pest management as part of EBRM may not only have partly contributed to food security and increased household income of the rice farmer-beneficiaries but also to environmental improvement in these communities.

Plant Secondary Metabolites as Rodent Repellents: a Systematic Review.

The vast number of plant secondary metabolites (PSMs) produced by higher plants has generated many efforts to exploit their potential for pest control. We performed a systematic literature search to retrieve relevant publications, and we evaluated these according to PSM groups to derive information about the potential for developing plant-derived rodent repellents. We screened a total of 54 publications where different compounds or plants were tested regarding rodent behavior/metabolism. In the search for widely applicable products, we recommend multi-species systematic screening of PSMs, especially from the essential oil and terpenoid group, as laboratory experiments have uniformly shown the strongest effects across species. Other groups of compounds might be more suitable for the management of species-specific or sex-specific issues, as the effects of some compounds on particular rodent target species or sex might not be present in non-target species or in both sexes. Although plant metabolites have potential as a tool for ecologically-based rodent management, this review demonstrates inconsistent success across laboratory, enclosure, and field studies, which ultimately has lead to a small number of currently registered PSM-based rodent repellents.

Integrated rodent management in outbreak-prone upland rice growing areas of Northern Laos

An integrated rodent management program was tested in outbreak-prone areas in three provinces of the Northern uplands of Laos (Luangprabang, Phongsaly, Houaphanh). In each province, it was replicated in six villages and associated upland rice fields; six neighboring villages served as negative controls. The program started end of 2010 and aimed at protecting the wet season rice harvest of 2011 against rodent damage. Rodent control techniques included sustained trapping, rodent-proofing of grain stores, rodent hunts and village sanitation campaigns, and biological rodent control using the protozoan parasite Sarcocystis singaporensis. The measures were embedded in a community approach, which was coordinated by provincial and district agricultural officers. Compared to the control villages, which showed on average 10.9% rat damage to ripening upland rice before harvest in 2011, and to the situation of the previous year (12.8%), rat damage was significantly reduced to an average of 4.3% in rice fields of the treatment villages. The incidence of rat-infested rice storage huts dropped significantly from an average of 86% in 2010 to 3.5% in 2011 in the treatment villages. Villagers from Houaphanh culled a total of 73,088 rodents over a period of about nine months, which included mainly black rats (Rattus rattus). Because the program phased out before harvest in 2011, potential losses due to rodents were predicted based on yield-damage relationships of the crop year 2010. The predicted average reduction of yield loss for 2011 was 55%, or 417.6 kg ha−1, in the treatment villages when compared to the controls. The program implemented principles of ecologically-based rodent management (EBRM), the components of which are discussed. In conclusion, EBRM could be helpful in stemming as what was observed as high chronic rodent populations in the uplands of Laos. True outbreaks will require development of a suitable forecast system.

Adoption and Impacts of Ecologically-Based Rodent Management in the Mekong Delta Region

Since 1995, the Australian Center for International Agricultural Research has funded eight ecologically-based rodent management (EBRM) projects to address rodent problems in three countries in Mekong Delta Region, namely: Vietnam, Lao PDR, and Cambodia. This paper aims to analyze the adoption and impacts of EBRM among rice farmers in Cambodia, Lao PDR, and Vietnam; the facilitating and constraining factors in its adoption, and lessons learned that could guide EBRM implementation in the future. The study utilized more of a qualitative approach anchored on an impact pathway framework. Data were gathered through focused group discussions among farmers from 19 villages, key informant interviews among key cooperators from collaborating agencies, and review of project documents and scientific papers published from the projects in the three countries. The ACIAR rodent control projects have brought about widespread adoption and significant impacts- economic, environmental, and socio-cultural- of EBRM in Vietnam but were limited in Lao PDR and Cambodia. The interplay of political, socio-cultural, historical, and economic factors is critical in the adoption of EBRM, and therefore, must be considered in promoting EBRM.

Population ecology of the Asian house rat (Rattus tanezumi) in complex lowland agroecosystems in the Philippines

Context Rattus tanezumi (the Asian house rat) is the principal rodent pest of rice and coconut crops in the Philippines. Little is known about the population and breeding ecology of R. tanezumi in complex agroecosystems; thus, current methods of rodent control may be inappropriate or poorly implemented. Aims To investigate the habitat use, population dynamics and breeding biology of R. tanezumi in complex lowland agroecosystems of the Sierra Madre Biodiversity Corridor, Luzon, and to develop ecologically based rodent management (EBRM) strategies that will target specific habitats at specific times to improve cost-efficiency and minimise non-target risks. Methods An 18-month trapping study was conducted in rice monoculture, rice adjacent to coconut, coconut groves, coconut-based agroforest and forest habitats. Trapped animals were measured, marked and assessed for breeding condition. Key results Five species of rodent were captured across all habitats with R. tanezumi the major pest species in both the rice and coconut crops. The stage of the rice crop was a major factor influencing the habitat use and breeding biology of R. tanezumi. In rice fields, R. tanezumi abundance was highest during the tillering to ripening stages of the rice crop and lowest during the seedling stage, whereas in coconut groves abundance was highest from the seedling to tillering stage of nearby rice crops. Peaks in breeding activity occurred from the booting stage of the rice crop until just after harvest, but >10% of females were in breeding condition at each month of the year. Conclusions In contrast with the practices applied by rice farmers in the study region, the most effective time for lethal management based on the breeding ecology of R. tanezumi is likely to be during the early stages of the rice crop, before the booting stage. Farmers generally apply control actions as individuals. We recommend coordinated community action. Continuous breeding throughout the year may necessitate two community campaigns per rice cropping season. To limit population growth, the most effective time to reduce nesting habitat is from the booting stage until harvest. Implications By adopting EBRM strategies, we expect a reduction in costs associated with rodent control, as well as improved yield and reduced risk to non-target species.