Developing effective rat control for rural Madagascar landscapes: using hierarchical modelling approaches to inform rodent management strategies.
Supervisor
Dr Sandra Telfer (Reader & Wellcome Trust Senior Researcher), School of Biological Sciences, Zoology Building, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ.
Abstract
Invasive rodent species, including Rattus rattus, R. norvegicus, and Mus musculus, pose significant ecological, economic, and public health challenges, particularly in lower-middle-income countries (LMICs). In Madagascar, these rodents exacerbate food insecurity and spread zoonotic diseases like leptospirosis and plague. This study investigates the interactions between rodent abundance, land use, and disease risk, focusing on R. rattus and its role in transmitting Leptospira borgpetersenii, L. interrogans, and Anjozorobe virus (ANJZV). We used landscape- and local-scale metrics to assess rodent population dynamics, infection patterns, and the impact of continuous rodent control in Madagascar.
Our findings show that habitat features, particularly irrigated rice systems, influenced rodent abundance and disease risk. R. rattus populations were lower in rice dominated areas but exhibited higher infection rates for L. borgpetersenii. Native forests had lower rodent densities and infection rates, though forest fragmentation increased disease risk by creating favourable microhabitats and facilitating invasive-native species interactions. Seasonal variations affected rodent abundance, peaking in the dry season and declining post-harvest. Adult male R. rattus had higher infection risks during the wet season due to increased movement linked to mating.
Control interventions, including trapping and removal, altered population dynamics and disease risks. Removal of dominant males increased subordinate activity and infection rates, elevating disease transmission risks. Higher-density areas showed increased infection risks for younger rodents. Interspecies interactions were key; R. rattus suppressed M. musculus populations and reduced their infection risks, indicating competitive exclusion between species. Continuous control reduced R. rattus occupancy in treatment villages, while M. musculus occupancy inversely increased. Structural features, such as softer ceilings and nearby vegetation, were linked to higher rodent occupancy, especially for mice.
This study highlights the need for tailored Ecologically-Based Rodent Management (EBRM) strategies that consider local conditions, reduce rodent populations, and minimize disease transmission risks. These insights are crucial for improving rodent management in Madagascar and similar LMICs.
Data Chapters
- Chapter One – Effect of land-use, host density and previous host removal on the prevalence of Leptospira and Hantavirus in invasive rodents of Madagascar.
- Chapter Two – Invasive Rat Spatial-Temporal Patterns in Abundance: Habitat, Landscape, and Season in Rural Madagascar.
- Chapter Three – Rodent management strategies: occupancy models evaluating the effectiveness of rodent control and species interactions.
Publications
Appear once published.