Developing effective rat control for rural Madagascar landscapes: using individual based modelling to inform strategies

在整个发展中世界，粮食不安全问题在小农占主导地位的农村地区最为严重。提高这类农场的生产力对生计有重要的积极影响，对全球战胜饥饿至关重要。制定有效的管理战略以减少农业有害生物造成的作物损失，需要了解有害生物种群在人口和农业景观规模上对控制的反应。鼠害是造成粮食不安全的重要因素。在全球范围内，啮齿动物每年吃掉和破坏的谷物足以养活发展中国家约2.8亿人。它们也是一系列牲畜和人类疾病的重要宿主。在亚洲和非洲的一些国家，对导致啮齿动物丰度变化的过程的了解增加，导致了基于生态的啮齿动物管理（EBRM）的成功发展。EBRM在一年中的关键时间针对特定地点的社区行动，可以显著减少损失。虽然传统上大多数行动的目的是减少有害生物的生存（例如陷阱屏障系统），但人们对避孕饵的兴趣日益增加。在马达加斯加，营养不良仍然是一个普遍的问题。小农占主导地位，大米是主食。黑鼠是主要的啮齿动物，在从森林到耕地和村庄的所有生境中都有发现。此外，该物种是可传播给人类和/或牲畜的疾病（如鼠疫、钩端螺旋体病）的宿主。马达加斯加目前尚未实行EBRM，有机会制定改善粮食安全和人类和牲畜健康的战略。以往的研究为黑鼠种群生态学以及几种啮齿动物相关疾病的流行病学提供了良好的基础知识。然而，迫切需要预测人口和疾病在景观一级对替代控制战略的反应。例如，通过诱捕或毒杀来转移个体可能有利于增加动物从非控制地区的扩散，可能完全抵消控制带来的任何好处，并助长疾病传播。这个跨学科项目将使用现有的啮齿动物捕获数据和系统建模方法来探索管理方案。利用最近开发的基于个体的建模平台RangeShifter，该平台整合了种群动态、扩散行为和遗传学，可用于模拟空间显性景观的场景，该项目将(1)比较不同栖息地和不同季节的目标鼠控制效果；使用一个以现有捕获数据和土地覆盖图为参数化的模型，(2)将个体疾病状况纳入RangeShifter，并调查控制对不同病原体（包括鼠疫和钩端螺旋体病）的景观流行病学的影响；(3)根据对照试验的现场数据检验模型预测。

Across the developing world, food insecurity is greatest in rural areas, where smallholder farms predominate. Increased productivity of such farms has important positive effects on livelihoods and is essential for the global fight against hunger. The development of effective management strategies to reduce crop losses from agricultural pests requires an understanding of how pest populations will respond to control, at both the population and agricultural landscape scale. Rodent pests contribute significantly to food insecurity. Globally, rodents annually eat and spoil cereals that could feed ~280 million people in developing countries alone. They are also important reservoirs for a range of livestock and human diseases. In some countries in Asia and Africa, increased understanding of processes contributing to variation in rodent abundance has led to the successful development of Ecologically Based Rodent Management (EBRM). EBRM targeting community actions at key times of year in specific locations can significantly reduce losses. Although traditionally most actions aim to reduce pest survival (e.g. trap barrier systems), there is increasing interest in contraceptive baits. In Madagascar, undernourishment remains a prevalent problem. Smallholders predominate and rice is the staple food. The black rat, the major rodent pest, is found in all habitats from forest to cultivated areas and villages. Moreover, this species is a reservoir for diseases that can be transmitted to humans and/or livestock (e.g. plague, leptospirosis). EBRM is not presently practiced in Madagascar and there is an opportunity to develop strategies that improve both food security and human and livestock health. Previous studies provide a good base knowledge of the population ecology of the black rat, as well as the epidemiology of several rodent associated diseases. However, there is an urgent need to predict landscape-level responses of populations and diseases to alternative control strategies. For example, removal of individuals through trapping or poisoning may favour increased dispersal of animals from non-control areas, possibly completely negating any benefits from control and also contributing to disease spread. This interdisciplinary project will use existing rodent trapping data and a systems modelling approach to explore management options. Using a recently developed individual-based modelling platform, RangeShifter, which integrates population dynamics, dispersal behaviour and genetics, and can be used to simulate scenarios on spatially explicit landscapes, this project will (1) compare the effectiveness of targeting rat control in different habitats and different seasons, using a model parameterised with existing trapping data and landcover maps,(2) incorporate individual disease status into RangeShifter and investigate the impact of control on the landscape epidemiology of different pathogens, including plague and leptospirosis and (3) test model predictions against field data from control trials.