Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology (BIUST), Palapye, Botswana.
School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, United Kingdom of Great Britain and Northern Ireland.
Sci Total Environ. 2020 May 1;715:136952. doi: 10.1016/j.scitotenv.2020.136952. Epub 2020 Jan 25.
Free-range cattle rearing in arid landscapes contributes profoundly to ecosystem degradation. Cattle dung nutrification in aquatic habitats potentially shapes species diversity and abundance due to resource availability. These nutrient-enriched environments may increase oviposition by mosquitoes and influence proliferation of disease vectors. Here, we examined mosquito larval abundance of Culex pipiens pipiens (culicine) and an unidentified Anopheles (anopheline) species across different concentration treatments of nutrient (cattle dung) loadings (T1-T4; 1 g L, 2 g L, 4 g L and 8 g L, respectively) in a randomised outdoor mesocosm experiment. The experiment was run for two weeks post-dung inoculation (Day 7 to 21), with mosquito larvae collected (Day 14 and 21), identified and quantified. Higher dung nutrient concentrations significantly increased mosquito larval abundance relative to dung-free controls. Culicine larvae were 26-times more abundant than anopheline on average. Higher dung concentrations also tended to promote more rapid development in larval mosquitoes. With no colonisation by mosquito larvae in the control treatments, we conclude that the input of dung in aquatic ecosystems promotes vector development and abundance with the potential to increase risk of mosquito-borne infections. We therefore recommend sustainable management policies that tackle likely ecological disservices attributable to free-ranging livestock communities.
干旱景观中的自由放养牛养殖对生态系统退化有深远影响。水生栖息地中的牛粪营养盐会因资源可用性而潜在地影响物种多样性和丰度。这些富含营养的环境可能会增加蚊子的产卵量，并影响疾病传播媒介的增殖。在这里，我们在一个随机户外中观实验中，研究了不同养分（牛粪）负荷浓度处理（T1-T4；分别为 1g/L、2g/L、4g/L 和 8g/L）下，库蚊（Culex pipiens pipiens，库蚊）和一种未识别的按蚊（按蚊）幼虫的丰度。实验在牛粪接种后两周内进行（第 7 天至第 21 天），收集、鉴定和定量了蚊子幼虫。与无粪对照相比，更高的粪便养分浓度显著增加了蚊子幼虫的丰度。库蚊幼虫的平均丰度是按蚊幼虫的 26 倍。更高的粪便浓度也倾向于促进蚊子幼虫更快的发育。在对照处理中没有蚊子幼虫的定殖，我们得出结论，水生态系统中粪肥的输入促进了媒介的发展和丰度增加，从而增加了蚊媒感染的风险。因此，我们建议采取可持续的管理政策，以解决自由放养牲畜社区可能带来的不利生态影响。
