Seasonality and locality affect the diversity of Anopheles gambiae and Anopheles coluzzii midgut microbiota from Ghana.

Symbiotic bacteria can have important implications in the development and competence of disease vectors. In Anopheles mosquitoes, the composition of the midgut microbiota is largely influenced by the larval breeding site, but the exact factors shaping this composition are currently unknown. Here, we examined whether the proximity to urban areas and seasons have an impact on the midgut microbial community of the two major malaria vectors in Africa, An. coluzzii and An. gambiae. Larvae and pupae were collected from selected habitats in two districts of Ghana during the dry and rainy season periods. The midgut microbiota of adults that emerged from these collections was determined by 454-pyrosequencing of the 16S ribosomal DNA. We show that in both mosquito species, Shewanellaceae constituted on average of 54% and 73% of the midgut microbiota from each site in the dry and rainy season, respectively. Enterobacteriaceae was found in comparatively low abundance below 1% in 22/30 samples in the dry season, and in 25/38 samples in the rainy season. Our data indicate that seasonality and locality significantly affect both the diversity of microbiota and the relative abundance of bacterial families with a positive impact of dry season and peri-urban settings.

共生细菌对病媒生物的发育与媒介效能具有重要影响。按蚊属（Anopheles）蚊子的中肠微生物群组成在很大程度上受幼虫孳生地的影响，但目前尚不明确决定该组成的确切因素。本研究以非洲两大主要疟疾媒介——科氏按蚊（An. coluzzii）与冈比亚按蚊（An. gambiae）为研究对象，探究了采样点与城区的邻近程度以及季节变化是否会对成蚊中肠微生物群落产生影响。研究人员于旱季与雨季，在加纳两个行政区的选定孳生地采集了幼虫与蛹，并对由此羽化的成蚊中肠微生物群进行了检测：通过对16S核糖体DNA（16S ribosomal DNA）开展454焦磷酸测序（454-pyrosequencing）完成菌群分析。结果显示，在两种按蚊中，旱季与雨季各采样点的希瓦氏菌科（Shewanellaceae）平均占中肠微生物群的54%与73%；肠杆菌科（Enterobacteriaceae）的丰度则相对较低，旱季22/30份样本中其占比不足1%，雨季25/38份样本中亦是如此。本研究数据表明，季节周期性与采样地点显著影响了微生物群的多样性以及细菌科的相对丰度，其中旱季与城郊环境可产生正向调控作用。