Hypoxia, hyperoxia and exposure to potassium dichromate or fenitrothion alter the energy metabolism in Chironomus riparius Mg. (Diptera: Chironomidae) larvae.

Short-term (24 h) effects of four stressors (hypoxia, hyperoxia, potassium dichromate, fenitrothion) on the activity of the electron transport system (ETS) and total lipid, glycogen and protein contents were assessed in 4th instar larvae of Chironomus riparius. Hypoxia and hyperoxia caused an increase in ETS activity and protein content. Glycogen content decreased when larvae were placed under hypoxic conditions. ETS activity increased following exposure to 2 microg x l(-1) of fenitrothion. It decreased in larvae exposed to 20 microg x l(-1) of this insecticide. A decrease in lipid and glycogen contents was observed in larvae exposed to potassium dichromate or fenitrothion. Changes in ETS activity and lipid and glycogen contents may be related to the activation of the respiratory chain due to an increase in energy cost associated with homeostatic phenomena, such as detoxification processes. These results suggest that some parameters related to energy metabolism, such as ETS activity and lipid and glycogen contents, may be used as biomarkers of environmental disturbance in Chironomus riparius larvae.