Browsing by Author "Mahenge, Herieth"

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Common predators and factors influencing their abundance in Anopheles funestus aquatic habitats in rural south-eastern Tanzania
(PLOS ONE, 2023-06-26) Mahenge, Herieth; Muyaga, Letus; Nkya, Joel; Kifungo, Khamis; Kahamba, Najat; Ngowo, Halfan; Kaindoa, Emmanuel
Background The role of larval predators in regulating the Anopheles funestus population in various malaria-endemic countries remains relatively unknown. This study aimed to investigate the common predators that co-exist with Anopheles funestus group larvae and evaluate factors that influence their abundance in rural south-eastern Tanzania. Methods Mosquito larvae and predators were sampled concurrently using standard dipper (350 ml) or 10 L bucket in previously identified aquatic habitats in selected villages in southern Tan zania. Predators and mosquito larvae were identified using standard identification keys. All positive habitats were geo-located and their physical features characterized. Water physico chemical parameters such as dissolved oxygen (DO), pH, electrical conductivity (EC), total dissolved solids (TDS) and temperature were also recorded. Results A total of 85 previously identified An. funestus aquatic habitats in nine villages were sampled for larvae and potential predators. A total of 8,295 predators were sampled. Of these Coena grionidae 57.7% (n = 4785), Corixidae 12.8% (n = 1,060), Notonectidae 9.9% (n = 822), Aeshnidae 4.9% (n = 405), Amphibian 4.5% (n = 370), Dytiscidae 3.8% (n = 313) were com mon. A total of 5,260 mosquito larvae were sampled, whereby Anopheles funestus group were 60.3% (n = 3,170), Culex spp. 24.3% (n = 1,279), An. gambie s.l. 8.3% (n = 438) and other anophelines 7.1% (n = 373). Permanent and aquatic habitats larger than 100m2 were positively associated with An. funestus group larvae (P<0.05) and predator abundance(P<0.05). Habitats with submerged vegetation were negatively associated with An. funestus group larvae (P<0.05). Only dissolved oxygen (DO) was positively and significantly affect the abundance of An. funestus group larvae (P<0.05). While predators’ abundance was not impacted by all physicochemical parameters. Conclusion Six potential predator families were common in aquatic habitats of An. funestus group lar vae. Additional studies are needed to demonstrate the efficacy of different predators on lar val density and adult fitness traits. Interventions leveraging the interaction between mosquitoes and predators can be established to disrupt the transmission potential and sur vival of the An. funestus mosquitoes
Predation efficacy of anopheles funfests larvae by Aquatic predators in rural South Eastern –Tanzania
(NM-AIST, 2023-08) Mahenge, Herieth
The study aimed to examine the impact of 3 common predator on Anopheles funestus larvae. Specifically, (a) The impact of predator on larval and adult density (b) The impact of aquatic predation on fitness traits of Anopheles funestus mosquitoes (wing size, larval and adult survivals) in the semi-field system. Three selected predator families (Aeshnidae, Coenagriondae and Notonectidae) and Anopheles funestus group larvae were collected from the natural aquatic habitats in rural south eastern Tanzania and transferred to the semi-field system (Mosquito city) at Ifakara Health Institute. Anopheles funestus larvae were exposed to artificial habitats with predators. The number of surviving Anopheles funestus larvae were counted after 24 hours. Remaining larvae were monitored until all they are consumed or developed into pupae stage. An emerged trap was placed at the top of artificial habitats to capture an emerging mosquito. Emerged mosquitoes were provided 10% glucose solution- soakes cotton wool and their 24 hours mortality were recorded. Wings of died female mosquitoes were measured and used as a proxy for their body sizes. All predators were significantly reduced the Anopheles funestus density, affect the survival and wing sizes of emerged mosquitoes. Coenagrionidae were most efficient predators followed by Notonectidae while Aeshinidae were least efficient predators on Anopheles funestus larvae. The current study suggest that these aquatic predators may play an important role as complementary tool in reducing Anopheles funestus larval population and hence contribute to the reduction of the malaria vectors in Southern eastern Tanzania. Further investigations should be done in a real natural aquatic habitat