Impact of diazinon on movement and feeding behaviours of the amphipod Gammarus pulex

Abstract

Water ecosystems are receiving increasing concentrations of pesticides due to the increased use of these substances in agricultural activities. However, data regarding lethal and sublethal effects of these chemicals on aquatic biota are limited. This study aimed to investigate locomotion (vertical and horizontal swimming) and feeding responses of the freshwater amphipod Gammarus pulex to the organophosphorothioate pesticide diazinon, its metabolite diazinon oxon and diazinon in a commercial formulation.Horizontal swimming was not effect following 24 exposures to ≤ 100 nM of diazinon. Similarly, no significant change in vertical movement behaviour was observed following 24 h exposure to ≤ 100 nM of diazinon oxon. However, this movement behaviour was significantly reduced following to 24 h of exposure to 25 and 50 nM of diazinon in the test commercial formulation and diazinon, respectively.Feeding activity G. pulex was not affected by 48 h of exposure to ≤ 25 nM of diazinon oxon. Exposure for 24 h ≥ 5 of diazinon in the commercial formulation significantly decreased the feeding activity of G. pulex. However, a higher diazinon concentration (10 nM) took 48 h to induce significant inhibition in feeding activity.In conclusion, behavioural responses of aquatic biota can provide sensitive makers of aquatic pollution and thus can be developed and employed in water quality mentoring programs.