Paratanytarsus grimmii (Chironomidae) Larvae in Drinking Water Distribution Systems: Impairment or Disaster?

Abstract

The occurrence and mass development of macroinvertebrates in drinking water networks is a challenge for drinking water pipe management. A current problem is the development of larvae of the chironomid Paratanytarsus grimmii (mosquito), a so-called pest organism that can have severe impacts on water quality due to mass accumulation from parthenogenic reproduction, biofouling and other aesthetic reasons. The aim of this study was to develop a new practical method for determining larvae size classes and analyzing the growth of the larvae. Knowledge of the dimensions, life cycle and fertility of these larvae within drinking water networks is essential for any risk analysis and the development of P. grimmii pest-control strategies. A two-year study of P. grimmii in a drinking water distribution system in Northern Germany was conducted, and P. grimmii population dynamics are presented. The parthenogenetic reproduction of P. grimmii without any pharate females (facultative flying stage) within the drinking water distribution system was proofed. In 2020 and 2021, five generations of P. grimmii were observed per year, with a maximum abundance of 6350 ind. m−3. Mass accumulation occurred in the late-summer/autumn period.