Background: The role of water in the maintenance of an aquatic ecosystem is indispensable. In this study, aquatic insect biodiversity and the physico-chemical parameters of Aahoo stream, in southwestern Nigeria, were investigated from March to August 2017. Seven physico-chemical parameters were examined in six study sites. Results: There were significant effects (p < 0.0001) of flow rate (F 5, 12 = 2221.9), electrical conductivity (F 5, 12 = 276.3), air temperature (F 5, 12 = 110.3), water temperature (F 5, 12 = 55.5) and pH (F 5, 12 = 31.45) on the quantity of aquatic insects at the study sites in Aahoo stream. Dissolved oxygen (F 2, 12 = 7.82) also had a significant impact (p = 0.002) on the quantity of aquatic insects at the stream. Three aquatic insect orders, Diptera (most dominant), Odonata (median dominant) and Hemiptera (least dominant)], nine families and 12 genera were found occurring in the stream. Chironomus sp. (Chronomidae, 55.29%), Brachithemis sp. and Orthetrum sp. (Libellulidae, 21.84%) which are usually associated with polluted water showed the highest occurrence in the stream. Low values of diversity indices were observed across the six study sites, which suggest that the six sites were in unstable conditions. Site 5 has the richest (Simpson 1-D 0.77, Shannon H 1.81, Margalef 1.91) and best taxa distribution (Equitability J: 0.73), while site 3 was the poorest (Simpson 1-D 0.52 and Shannon H 1.31) and the least in taxa distribution (Equitability J 0.55). Conclusion: This study has provided information on the assemblage and copiousness of various aquatic insects as well as the physico-chemical parameters of Aahoo stream. It could therefore be concluded that the stream could be somewhat polluted and unsafe for human consumption without being properly treated.

Despite the growing awareness in freshwater conservation, and the sociocultural significance of the Osun River in the designation of the Osun‐Osogbo Sacred Grove as a UNESCO World Heritage Site, there is dearth of information on the biological water quality and conservation value of the river. In this study, the conservation value and biological water quality of the river which defines a UNESCO protected environment are assessed. Benthic macroinvertebrates and physicochemical water condition were studied quarterly from June 2015 to March 2016. The river's naturalness was also measured based on habitat alteration, land use and hydrological modifications. A total of 27 macroinvertebrate taxa were recorded, and the fauna was dominated by the Ephemeroptera, Odonata and Trichoptera (EOT) group. Taxa richness and/or abundance of macroinvertebrates showed a significant inverse response to vegetation removal, farming, total suspended solids, flow velocity, nitrate and phosphate. There is a notable occurrence of Margaritifera margaritifera which is considered a flagship and umbrella species in the river. This study further reveals the natural property of the sacred grove in addition to its cultural property as a WHS; hence, it may be re‐considered as a WHS based on mixed properties.

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Background Mosquitoes are key vectors for the transmission of several diseases. Anopheles gambiae is known to transmit pathogens of malaria and filariasis. Due to several anthropogenic factors such as climate change and population growth leading to diverse land use, their distribution and disease spreading pattern may change. This study estimated the potential distribution and climatic suitability of An. gambiae under the present-day and future conditions across Southwest Nigeria using Ecological Niche Modelling (ENM). The future scenarios assessed were based on two general circulation models (GCMs), namely community climate system model 4 (CCSM4) and geophysical fluid dynamics laboratory-climate model 3 (GFDL-CM3), in two representative concentration pathways (RCP 2.6 and RCP 8.5). Methodology The occurrence data were obtained from literatures that have reported the presence of An. gambiae mosquito species in locations within the study area. Ecological niche modelling data were processed and analysed using maximum entropy algorithm implemented in MaxEnt. Result Fifty-five (55) unique occurrences of An. gambiae were used in the model calibration after data cleaning. Data analysis for the present-day habitat suitability shows that more than two-thirds (81.71%) of the study area was observed to be suitable for An. gambiae population. However, the two future GCMs showed contrasting results. The CCSM4 models indicated a slight increase in both RCPs with 2.5 and 8.5 having 81.77 and 82.34% suitability, respectively. The reverse was the case for the GFDL-CM3 models as RCPs 2.5 and 8.5 had 78.86 and 76.86%. Conclusion This study revealed that the study area is climatically suitable for An. gambiae and will continue to be so in the future irrespective of the contrasting results from the GCMs used. Since vector population is often linked with their disease transmission capacity, proper measures must be put in place to mitigate disease incidences associated with the activities of An. gambiae.