Widely used mosquito repellent proves lethal to larval salamanders: new study
Insect repellents containing picaridin can be lethal to salamanders. So reports a new study published today in Biology Letters that investigated how exposure to two common insect repellents influenced the survival of aquatic salamander and mosquito larvae.
Insect repellents are a defense against mosquito bites and mosquito-borne diseases like dengue, chikungunya, Zika, and West Nile virus. Salamanders provide natural mosquito control.
During their aquatic juvenile phase, they forage on mosquito larvae, keeping populations of these nuisance insects in check.
Emma Rosi, a freshwater ecologist at Cary Institute of Ecosystem Studies and a co-author on the paper explains, “Use of insect repellents is on the rise globally.
Chemicals in repellents enter aquatic ecosystems through sewage effluent and are now common in surface waters. We set out to understand the impact of repellent pollution on both larval mosquitoes and the larval salamanders that prey on them.”
The paper is the first to suggest that environmentally realistic concentrations of picaridin-containing repellents in surface waters may increase the abundance of adult mosquitoes due to a decrease in predation pressure on mosquitoes at the larval stages.
The research team tested the effects of two of the most widely used insect repellents -- DEET (Repel 100 Insect Repellent) and picaridin (Sawyer Premium Insect Repellent) -- on larval salamanders and mosquitoes. In a lab, they exposed mosquito larvae and just-hatched spotted salamander larvae to three environmentally relevant concentrations of these chemicals, as well as a control treatment.