Effects of glyphosate-based herbicide on oxidative stress and neurotoxicity parameters in newt (Triturus ivanbureschi) larvae under temperature changes predicted by future climate scenarios

The alarming decline of amphibian populations can largely be attributed to extent use of pesticide and global warming process. Special concerns were raised over the glyphosate-based formulations, one of the most commonly applied herbicides worldwide, due to their potentially detrimental effects on different animal groups. However, researches on the effects of glyphosate in newt species are still scarce. The present study assessed the effects of environmentally realistic concentrations of commercial herbicide product (22,5 µg/L glyphosate) on antioxidative defense system, oxidative damage to lipids and proteins and the activity of acetylcholinesterase (AChE) in larvae of the Balkan crested newt (T. ivanbureschi) under optimal (19 °C) and increased (23 °C) temperatures after 14 days of treatment. The results showed that even though larvae exposed to glyphosate at 19 °C did not exhibit any differences in the antioxidative defense system, they suffered from increase in protein carbonylation compared to ones from control group. On the other hand, increased temperature in combination with glyphosate led to the significant induction of CAT, GST, and GR activities and an increase in GSH concentration. This response of the antioxidative defence system seems to be sufficient to prevent oxidative damage to lipids and proteins. Glyphosate at elevated temperature also inhibited AChE activity suggesting significant neurotoxic effect. Different response of crested newts emphasize the need to assess the potentially harmful effects of glyphosate in various ecological contexts, particularly in light of the predicted increase in average temperatures by several degrees in the coming decades.