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Oviposition site selection by Anopheles gambiae sensu lato (Diptera: Culicidae) at coastal sites in Kenya

Roberts, Sally (2017) Oviposition site selection by Anopheles gambiae sensu lato (Diptera: Culicidae) at coastal sites in Kenya. PhD thesis, Prifysgol Bangor University.

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Abstract

Female gravid mosquitoes’ choice of oviposition site is crucial to larval survival and subsequent mosquito fitness. In order to determine habitat choice in a natural setting, the distribution of Anopheles and culicine larvae in water bodies of fifteen squared kilometres in urban, peri-urban and rural Malindi, in Coastal Kenya, were characterised for physical and chemical parameters. Results showed an association of Anopheles larval presence with ammonium. This led to oviposition field trials to investigate the potential to use two ammonium based fertilisers; ammonium sulphate and ammonium chloride as oviposition lures to divert Anopheles gambiae sensu lato from nearby undisturbed natural habitats. The field experiments were conducted on the river bank of two villages in Coastal Kenya; Jaribuni, in Kilifi district, and Sabaki, in Malindi district. A second field trial at Sabaki involved investigation of an amino acid mixture as an attractant bait. A third field trial at Sabaki was experimentation of four treatments of sodium chloride with the aim to act as a larvicide to anopheline eggs or larvae. A brown plastic circular round basin served as a mimic burrow pit in all experiments. In Jaribuni significantly more An. gambiae sensu lato eggs were laid at the low dose 0.0625 g l-1 of ammonium sulphate than at the high dose 1.18 g l-1. The explanation may have been an overall ammonia volatilisation lure effect. In the amino acid mixture experiment there was no statistical significant difference between the treatment and control. The sodium chloride treatments result was 2392 anopheline larvae with only two eggs in the full strength sea water equivalent of NaCl. It therefore acted as a repellent. The plastic basin mimic burrow pit was extremely effective as an oviposition trap. These findings provide important information on the potential to utilise simple technology to reduce Anopheles larval populations.

Item Type: Thesis (PhD)
Subjects: Degree Thesis
Departments: College of Natural Sciences > School of Biological Sciences
Degree Thesis
Date Deposited: 08 Jun 2017 08:40
Last Modified: 08 Jun 2017 08:40
URI: http://e.bangor.ac.uk/id/eprint/9862
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