The ion channel ppk301 controls freshwater egg-laying in the mosquito Aedes aegypti

Abstract

Female <i>Aedes aegypti</i> mosquitoes are deadly vectors of arboviral pathogens and breed in containers of freshwater associated with human habitation. Because high salinity is lethal to offspring, correctly evaluating water purity is a crucial parenting decision. We found that the DEG/ENaC channel <i>ppk301</i> and sensory neurons expressing <i>ppk301</i> control egg-laying initiation and choice in <i>Ae. aegypti</i>. Using calcium imaging, we found that <i>ppk301</i>-expressing cells show <i>ppk301</i>-dependent responses to water but, unexpectedly, also respond to salt in a <i>ppk301</i>-independent fashion. This suggests that <i>ppk301</i> is instructive for egg-laying at low-salt concentrations, but that a <i>ppk301-</i>independent pathway is responsible for inhibiting egg-laying at high-salt concentrations. Water is a key resource for insect survival and understanding how mosquitoes interact with water to control different behaviors is an opportunity to study the evolution of chemosensory systems.