Sub-lethal effects of Roundup™ on tadpole anti-predator responses

• Roundup is the most widely used agricultural pesticide in the world
• While it is generally non-toxic to mammals, it appears highly toxic to tadpoles
• Here we show that sub-lethal exposure impairs tadpole anti-predator responses
• The likely cause of impairment is the loss of function of alarm cues
• This loss has negative ecological and survival consequences for amphibians

Roundup™ is a commonly used pesticide applied to agriculture and forest habitats. These areas are generally ideal for amphibians due to the presence of small, ephemeral water bodies. While Roundup™ has been shown to have lethal effects on many species of amphibians, effects on behaviour and sensory perception have yet to be considered. Here, we exposed wood frog tadpoles to a sub-lethal concentration of Roundup™ and showed that the ability of tadpoles to respond to injured conspecific cues, an important source of information regarding local predation risk, was impaired. Subsequent experiments revealed that impaired responses likely result from a chemical reaction between the Roundup™ and the cues and that tadpoles chronically exposed to Roundup™ had reduced basal movement rates compared with unexposed tadpoles. Our data demonstrate that environmentally-relevant concentrations of Roundup™ can drastically alter movement and anti-predator responses of tadpoles, with potential negative consequences for the population.