Chironomid fauna (Diptera, Chironomidae) in a filtration plant in Japan.

Massive flights of chironomid midges have been observed frequently, and they have caused some problems in the daily life of residents around water treatment works. The development of physical and biological control strategies against chironomid midges is urgently needed because chemical control is not feasible in slow sand filter beds. In this study, in order to collect basic biological data for controlling the massive flights of chironomid midges, seasonal changes in the abundance and species composition of chironomid midges and larvae were investigated in slow sand filter beds. We identified 21 genera and 49 species belonging to 3 subfamilies. In spring, Cricotopus sylvestris and Rheopelopia maculipennis were the dominant species, whereas Polypedilum nubifer, Cricotopus trifasciatus, Chironomus kiiensis, and Procladius sagitalis were dominant in summer. Tanytarsus mendax and T. volgensis were the dominant species in fall. Polypedilum nubifer, C. sylvestris, and C. kiiensis were the major pest species in Japan. The overall factors influencing the abundance pattern of chironomids supposedly are temperature and the quality and quantity of food in slow sand filter beds.