Acute and chronic sublethal chemical pollution affects activity, learning and memory in mosquito larvae

Freshwater ecosystems play a critical role in supporting biodiversity and providing essential environmental services. However, these ecosystems are increasingly threatened by human activities, including habitat loss, pollution, and climate change. Traditional assessment methods focus on water properties, but biomonitoring approaches, particularly those examining behaviour and cognition, provide valuable insights into the ecological effects of pollutants. This study examines the effects of three common pollutants (glyphosate, atrazine, and paracetamol) on the cognitive abilities of Aedes aegypti mosquito larvae, a vector for several diseases. We used an automated bioassay to study habituation learning and the effects of the three pollutants alone or in mixtures, at sub-lethal doses ranging from field-realistic to commercial-recommended levels. Our results show that the three compounds modulate individual spontaneous activity, impair habituation and memory retention. These changes may alter the perception or the behavioural response of mosquito larvae to signals of their environment, as the presence of conspecifics or predators, and suggest that other organisms living in freshwater ecosystems may also be affected. Incorporating behavioural and cognitive assessments in ecotoxicological studies provides a more comprehensive understanding of the ecological effects of pollutants which is needed to address economic challenges in fragile ecosystems.