title: Stoichiometric Responses to an Agricultural Pesticide Are Modified by Predator Cues.
abstract: Current ecological risk assessment of pesticides fails to protect aquatic ecosystem health. To get better insight in how pesticides may affect aquatic ecosystems, we tested how sublethal pesticide concentrations modify body stoichiometry. Moreover, as interactions with natural stressors may cause underestimates of the impact of pesticides, we also tested whether this pathway depended on the presence of predator cues. Therefore, we exposed damselfly larvae to chlorpyrifos and cues from predatory dragonflies and focused on body stoichiometry and associated explanatory variables (growth rate, RNA:DNA, and energy storage molecules). The way the predator cues modulated the pesticide effects strongly differed between endpoints. Exposure to chlorpyrifos affected the key body stoichiometric ratios: chlorpyrifos consistently increased N:P, while its effects on C:N (decrease with predator cues) and C:P (increase without predator cues) strongly depended upon the presence of the natural stressor. These stoichiometric responses could be explained by associated changes in growth, RNA:DNA, and in C-rich fat and sugars and N-rich proteins. The observed changes in body stoichiometry may affect the damselflies' food quality and have the potential to cascade through the food web and shape nutrient cycling.
authors.affiliation: Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven , Charles Deberiotstraat 32, B-3000 Leuven, Belgium.
authors.forename: Lizanne
authors.identifier: 0000-0001-9126-4682
authors.initials: L
authors.lastname: Janssens
authors.affiliation: Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven , Charles Deberiotstraat 32, B-3000 Leuven, Belgium.
authors.forename: Lin
authors.initials: L
authors.lastname: Op de Beeck
authors.affiliation: Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven , Charles Deberiotstraat 32, B-3000 Leuven, Belgium.
authors.forename: Robby
authors.initials: R
authors.lastname: Stoks
mesh_terms: D000818:Animals; D004390:Chlorpyrifos; D003463:Cues; D007814:Larva; D063191:Odonata; D010575:Pesticides; D011235:Predatory Behavior
chemical_list: D010575:Pesticides; D004390:Chlorpyrifos