(186s) Influence of Surfactants in Water On the Behavior of Water-Striders (Gerridae Eurygerris Fuscinervis)

Impact of contaminants in water and its influence on biological systems is a subject of great interest. Though water modifications affect metabolic characteristics of many species for some insects the consequences are directly on their locomotion behavior. This is the case of water strider (gerridae) which lives on the surface of clean waters. The main focus of this work is on the study of changes of behavior patterns when water striders are placed in a non-pure water environment. Two population's samples from the family Gerridae were collected from Colombian region of Boyacá and studied throughout 2 months. One of the samples was merely observed for 2 weeks in surfactant-free water without any additional experimentation. Specimens were taken to the scanning electron microscope (SEM) for morphological identification based on previous works. Different insect groups of the second sample were placed in 5 sodium lauryl sulfate (SLS) modified waters with surface tensions values between 72-30 dynes/cm. In order to study the effect of surfactant concentration in water-striders mobility a high resolution laser distance sensor was employed and the changes of water level after experimental perturbations were registered. Different energy transfer modes were founded and empirical parameters from height-time diagrams were obtained for comparison purposes. The results indicate that under certain conditions water striders could be used as local contamination bioindicators.