author(s)
Amusan Babatunde

abstract
Paraquat dichloride is an organic salt that is widely used to control weeds in many agricultural and non-agricultural areas. However, this and other pesticides have been identified as critical sources of pollution in aquatic ecosystems. This study investigated the acute toxicological effects of the various concentrations of paraquat on whirligig beetles (Orectogyrus sp) with the aim of determining the potential lethal effects of the chemical on the organisms. The test substance (paraquat dichloride) was found to have lethal effects on the test organism (Orectogyrus sp) as it altered the behavioural patterns and eventually caused death of the test organisms. The 72hr and 96hr LC50 was estimated to be 42.03mg/L and 51.47mg/L respectively. The mortality trend in the test organisms followed a linear pattern with the highest mortality recorded in the highest concentration. Abnormalities in the behaviour of the organisms was attributed to oxidative stress and disruption of their nervous coordination.