Understanding how fine-scale environmental heterogeneities in bloodmeal resources affect the geographical distribution, sibling species composition, host-seeking behaviours and insecticide resistance traits of malaria mosquitoes within the Anopheles gambiae complex
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Date
2025-10-03
Authors
Kavishe, Deogratius
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Publisher
University College Cork
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Abstract
This thesis examines how fine-scale environmental heterogeneities influence the ecology, control and relevant heritable traits of malaria vectors within the Anopheles gambiae complex in southern Tanzania. It explores how host availability, habitat integrity, and human activities shape mosquito behaviour, persistence and insecticide resistance traits, with the aim of informing either ubiquitously robust or locally adapted control strategies. The first research chapter establishes a methodological innovation by introducing a self-cooling, self-humidifying backpack for transporting live mosquitoes on foot across otherwise impassable remote landscapes. This new technique overcomes logistical barriers to field entomology, enabling reliable ecological and phenotypic analyses of live-caught mosquitoes and their progeny. The second chapter compares the relative attraction of adult Anopheles arabiensis and Anopheles quadriannulatus to humans across diverse habitats based on the level of enrichment of the latter relative to the former when human-baited capture methods are compared with larval samples and un-baited adult trapping. It demonstrates how local environmental variation in the availability of different mammalian host species creates distinct ecological niches for these different sibling species within the Anopheles gambiae complex, based on their distinctive species-specific host-seeking behaviours, also providing insights into anthropophagy as a driver of transmission heterogeneity. The third chapter documents sparse but persistent populations of the most strictly anthropophagic sibling species within the An. gambiae complex, namely nominate Anopheles gambiae sensu stricto, in fishing camps and frontier settlements in or alongside a community-based Wildlife Management Area. These populations are sustained by locally common nocturnal livelihoods, particularly fishing and crop guarding, which create ecological refugia for this vector population by rendering nighttime use of insecticidal bed nets impractical. The final chapter describes the development of a modest but important extension of a generic schema underpinning an established mosquito database platform that enabled an informatically robust assessment of heritable variation in pyrethroid resistance among An. arabiensis across an environmental gradient of natural ecosystem integrity, with high fidelity of data linkage and sample tracing across complex workflows distributed across several discrete assay procedures implemented by different teams in different places. Collectively, these studies advance understanding of how environmental heterogeneity influences mosquito survival, behaviour, persistence, and resistance, while offering practical new techniques for studying these biological phenomena and informing the design of malaria control strategies that are either tailored to local contexts or robust to environmental variations between them.
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Keywords
Anopheles gambiae complex , Environmental heterogeneity , Malaria vector ecology , Host-seeking behaviour , Insecticide resistance , Entomological surveillance
Citation
Kavishe, D. R. 2025. Understanding how fine-scale environmental heterogeneities in bloodmeal resources affect the geographical distribution, sibling species composition, host-seeking behaviours and insecticide resistance traits of malaria mosquitoes within the Anopheles gambiae complex. PhD Thesis, University College Cork.