Do Sustainable Drainage Systems favour mosquito proliferation in cities compared to stormwater networks?

With the recent emergence of dangerous mosquito species in cities, Sustainable Drainage Systems used to manage stormwater are sometimes suspected to favour their development. In the metropolis of Lyon, the density of mosquitoes were studied in 15 retention, detention and/or infiltration sites, two green roofs, seven swales and 20 gully pots in traditional sewer networks. None of the swales retained water long enough to be sampled. No larvae were detected in the green roofs. Four classical species were found in the retention/detention basins (Culex pipiens, Culex hortensis, Anopheles maculipennis sl and Culiseta longiareolata). They appeared in May, mainly in the artificial habitats (e.g. concrete parts). Gully pots were colonized by Culex pipiens, Culiseta longiareolata during summer and by Aedes albopictus, ‘tiger mosquito’ in autumn. Vegetated systems where water was drained rapidly (i.e. green roofs, infiltration basins or swales) were not significant breeding sites compared to more artificial sites.