title: Additive effects of predator cues and dimethoate on different levels of biological organisation in the non-biting midge Chironomus riparius.
abstract: The combined effects of a pesticide and predation risk on sublethal endpoints in the midge Chironomus riparius were investigated using a combination of predator-release kairomones from common carp (Cyprinus carpio) and alarm substances from conspecifics together with the pesticide dimethoate. Midge larvae were exposed for 30 days to three sublethal dimethoate concentrations (0.01, 0.1 and 0.25 mg L(-1)) in the presence or absence of predator cues. Sublethal endpoints were analysed at different levels of biological organisation. Available energy reserves, enzyme biomarkers, feeding rate and life history endpoints were investigated. Three endpoints were significantly affected by the two highest dimethoate concentrations, i.e. AChE activity, age at emergence and emergence success, with a significant decrease in response after exposure to 0.25, 0.1 and 0.01 mg L(-1) dimethoate, respectively. Four sublethal endpoints were significantly affected by predator stress: Total protein content, GST activity and biomass decreased only in the presence of the predation risk, while AChE activity further decreased significantly in the presence of predation cues and effects on AChE of combined exposure were additive. From this study we can conclude that sublethal life history characteristics should be included in ecotoxicity testing as well as natural environmental stressors such as predator stress, which might act additively with pollutants on fitness related endpoints.
authors: Department of Biology, Systemic Physiological and Ecotoxicological Research (SPHERE), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
authors: Nander
authors: N
authors: Van Praet
authors: Department of Biology, Systemic Physiological and Ecotoxicological Research (SPHERE), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium. Electronic address: maarten.dejonge@uantwerpen.be.
authors: Maarten
authors: M
authors: De Jonge
authors: Department of Biology, Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven, Ch. Deberiotstraat 32, 3000 Leuven, Belgium.
authors: Robby
authors: R
authors: Stoks
authors: Department of Biology, Systemic Physiological and Ecotoxicological Research (SPHERE), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
authors: Lieven
authors: L
authors: Bervoets
mesh_terms: D000818:Animals; D002347:Carps / Q000502:physiology*; D002683:Chironomidae / Q000187:drug effects*; D004117:Dimethoate / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D007306:Insecticides / Q000008:administration & dosage / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects*; D008297:Male; D011235:Predatory Behavior / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D007306:Insecticides; D014874:Water Pollutants, Chemical; D004117:Dimethoate
keywords: Chironomus riparius; Dimethoate; Pesticide; Predation stress; Sublethal endpoints