Acute Toxicity and Sublethal Locomotor Impairment Induced by the Pyrethroid Tau-fluvalinate in Chironomus riparius (Diptera: Chironomidae)

As pesticides negatively affect non-target organisms, their excessive and indiscriminate use poses a threat to the environment and aquatic ecosystems. In this study, it was aimed to examine the lethal and sublethal effects of tau-fluvalinate, a pyrethroid pesticide, on the non-target organism Chironomus riparius. For this aim, acute toxicity of tau-fluvalinate was evaluated through a 96-h mortality test, and changes in the locomotor activity of C. riparius were examined after 72- and 144-h exposures to different sublethal concentrations. Mortality tests indicated that both concentration (F9, 240 = 133,80; P<0.0001; ηp2 = 0.83) and exposure duration (F3, 240 = 18,93; P<0.0001; ηp2 = 0.19) had statistically significant effects on mortality. In locomotor activity tests conducted at sublethal concentrations (2.75, 5.5, 11, and 22 µg/L) selected based on the calculated 96-h median lethal concentration (44.53 µg/L), concentration (F4, 60 = 236,7; P<0.0001; ηp2 = 0.94), exposure duration (F1, 60 = 35,48; P<0.0001; ηp2 = 0.37) and their interaction (F4, 60 = 3,629; P = 0.0103; ηp2 = 0.19) were found to have statistically significant effects on locomotor activity. As the first study to evaluate the effects of tau-fluvalinate on the non-target organism C. riparius, our findings demonstrate that tau-fluvalinate poses a considerable risk to C. riparius populations, largely due to its environmental persistence, and that its prolonged presence in aquatic ecosystems constitutes an environmental hazard.