Bioassay of Chironomid Larvae (Diptera: Chironomidae) Using Chlorine Dioxide Solution

ABSTRACT The recent detection of Chironomid larvae in tap water has raised concerns about the reliability of existing disinfection processes in drinking water treatment. This study investigated the efficacy of chlorine dioxide as a control agent for Chironomid larvae and eggs, compared its performance with sodium hypochlorite, and assessed its behavior within a pilot‐scale water treatment system. Laboratory bioassays were conducted using two Chironomid species and a wild community across a range of concentrations and temperatures. Chlorine dioxide exhibited significantly higher larvicidal activity than sodium hypochlorite, achieving complete mortality at lower concentrations and shorter exposure times. Temperature‐dependent toxicity tests showed accelerated mortality rates at higher temperatures. Chlorine dioxide also suppressed egg hatching, reducing the hatching rate to 0% at 1.0 mg/L. Comparative analysis of five commercial chlorine dioxide formulations revealed no significant differences in toxicity, indicating consistent performance regardless of product type. In pilot‐scale trials, chlorine dioxide injected at 7‐ to 10‐mg/L effectively reduced larvae and was consistently detected at safe residual levels (< 0.8 mg/L) after treatment stages. These findings demonstrate that chlorine dioxide is a practical and scalable alternative for integrated Chironomid control in water treatment systems. The study provides a comprehensive dataset for evaluating concentration, exposure time, and environmental conditions necessary for its effective application.