Abstract
BackgroundMalaria is often persistent in communities surrounded by mosquito breeding habitats. Anopheles gambiae sensu lato exploit a variety of aquatic habitats, but the biotic determinants of its preferences are poorly understood. This study aimed to identify and quantify macroinvertebrates in different habitat types with determined water physico-chemical parameters to establish those preferred by An. gambiae s.l. larvae as well as their predators and competitors.MethodsA field survey was conducted in Kibuye and Kayonjo villages located in the vicinity of the River Sezibwa, north-eastern Uganda to identify Anopheline larval habitats shared by aquatic insects. Habitats were geo-recorded and as streams, ponds, temporary pools and roadside ditches. From October to December 2017, random microhabitats/quadrats were selected from each habitat type, their water physico-chemical parameters (electrical conductivity, total dissolved solids, temperature and pH) were measured, and they were sampled for macroinvertebrates using standard dippers. All collected arthropod macroinvertebrates were then morphologically identified to family level and enumerated.ResultsPrincipal component analysis showed that the four larval habitat types were characterized by distinct physico-chemical parameter profiles. Ponds and streams had the highest number and diversity of macroinvertebrate insect taxa and sustained few An. gambiae s.l. larvae. Anopheles gambiae s.l. were more common in roadside ditches and particularly abundant in temporary pools which it commonly shared with Dytiscidae (predaceous diving beetles) and Culex spp. Cluster correlation analysis conducted on the abundance of these taxa within quadrats suggested that An. gambiae s.l. and Dytiscidae have the most similar patterns of microhabitat use, followed by Cybaeidae (water spiders). Whilst Culex spp. co-occurred with An. gambiae s.l. in some habitats, there was only partial niche overlap and no clear evidence of competition between the two mosquito taxa.ConclusionsPonds and streams are habitats that host the largest diversity and abundance of aquatic insect taxa. Anopheles gambiae s.l. larvae distinctively preferred temporary pools and roadside ditches, where they were exposed to few predators and no apparent competition by Culex spp. Further studies should aim to test the impact of Dytiscidae and Cybaeidae on An. gambiae s.l. dynamics experimentally.Graphical
Highlights
Malaria is often persistent in communities surrounded by mosquito breeding habitats
Physico‐chemical parameters of aquatic habitat types Overall, there was no significant difference in mean temperature, Potential hydrogen (pH), total dissolved solids (TDS), or electrical conductivity (EC) measured from each larval breeding site in relation to village (Kruskal–Wallis H-test: χ2 < 0.12, df = 1, P > 0.736 in all cases) and month of collections (Kruskal–Wallis H-test: χ2 < 2.73, df = 3, P > 0.257 in all cases)
The results provide the first account of the diversity and abundance of potential predators and competitors of An. gambiae s.l. larvae in the different aquatic habitats in Uganda
Summary
Malaria is often persistent in communities surrounded by mosquito breeding habitats. Anopheles gambiae sensu lato exploit a variety of aquatic habitats, but the biotic determinants of its preferences are poorly understood. IVM programs using LSM would benefit from in-depth knowledge of the mosquito larval ecology and a better understanding of the trophic interactions in larval habitats This could prioritize larval control efforts focusing on habitats that sustain the highest densities of anopheline larvae while protecting habitats rich in natural predators. Assessing larval habitat preferences, the extent of niche overlap and possible competitive interactions between mosquito taxa is relevant to predicting possible changes in mosquito communities and disease transmission in response to vector control interventions. It can help understand the possible consequences of suppressing the malaria mosquito, Anopheles gambiae sensu lato, on aquatic predators and competitors in ecosystems [10]
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