Title: Synergistic effects between pesticide stress and predator cues: conflicting results from life history and physiology in the damselfly Enallagma cyathigerum
Authors: Janssens, Lizanne ×
Stoks, Robby #
Issue Date: May-2013
Publisher: Elsevier/North Holland Biomedical Press
Series Title: Aquatic Toxicology vol:132-133 pages:92-99
Abstract: There is increasing awareness that the negative effects of anthropogenic stressors may be magnified in the presence of natural stressors. Very few of these studies included physiology, yet this may learn about the mechanistic base of such synergisms at the life history level and identify synergistic interactions not translated in life history traits. We studied in Enallagma cyathigerum damselfly larvae potential synergistic effects between exposure to the pesticide glyphosate and predator cues on a key life history trait, growth rate, its associated behavioral trait, food intake, and three types of physiological traits known to be affected by both stressors in isolation: the stress protein Hsp70, energy storage and variables related to oxidative stress and damage. The pesticide and predator cues reduced growth rate in an additive way. Food intake increased under pesticide exposure and was not affected by the predator cues, indicating physiological mediation of the growth reduction. One potential physiological mechanism was that both stressors additively increased Hsp70 levels, this may also have contributed to the reduced levels of total carbohydrates when exposed to predator cues. Chronic exposure to predator cues reduced oxygen consumption, possibly to avoid too high costs of an increased metabolic rate. This reduction did not occur in the presence of the pesticide, reflecting the need for energetic expensive defense mechanisms (such as Hsp70 upregulation). When both stressors were combined, there was a reduction of the antioxidant enzyme superoxide dismutase (SOD) and an associated increase of oxidative damage in lipids. While synergistic interactions were not present for growth rate and food intake, they were identified for antioxidant defense and oxidative damage. This novel type of “hidden” synergistic interactions may have profound fitness implications, and when ignored will lead to underestimations of the impact of pollutants in natural populations where predators are omnipresent.
ISSN: 0166-445X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Department of Biology - miscellaneous
Ecology, Evolution and Biodiversity Conservation Section
× corresponding author
# (joint) last author

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