Clashing in Murky Waters: On Amphibian Mosquito Suppression

Mosquito-borne diseases are on the rise globally due to the shifting distribution of key disease vector species. Due to increased global trade and travel and increasing temperatures and changing precipitation patterns, the spread of mosquitoes and the increasing burden of their accompanying diseases like malaria, yellow fever, and dengue persist. Seeking sustainable control measures, there's growing interest in natural control, particularly through predators like amphibians, a globally threatened vertebrate group. However, the effectiveness of different natural predators and their role in an ecological context remains poorly understood. This study compares the predator efficiency of common European amphibian species to common aquatic insect mosquito predators. Focusing on the cosmopolitan mosquito Culex pipiens s.l., known for transmitting pathogens like West Nile virus, we assessed predator rates, sex-specific efficiency in amphibians, and the impact of predator presence on mosquito oviposition behavior. Amphibians proved to be more effective mosquito predators than aquatic insects, consuming up to 4-8 times as many larvae per individual compared to the aquatic insects. No difference was detected between the two amphibian species, nor their sexes or the levels of eutrophication. Predator cues deterred oviposition behavior across the entire experimental setup, thus suggesting the ability of mosquitoes to react to a (purported) landscape of fear. The combined effect of deterring egg laying and lowering mosquito survival highlights the potential of natural predation, and particularly that of amphibian species as natural larval control agents, thus emphasizing the importance of conserving these threatened species and facilitating them in urban and rural environments.