A mosquito species that feeds only on non-vertebrate hosts - earthworms and leeches - is reported in a study published this week in Communications Biology. The paper suggests that current methods used for identifying mosquito host species and tracking the transmission of blood-borne pathogens should be updated to include non-vertebrate hosts.
Mosquitoes can transmit pathogens in the blood between hosts. An important part of disease transmission surveillance is tracking the host-use patterns of mosquitoes, in part through analysis of the bloodmeals found in trapped mosquitoes. These analysis methods assume that all bloodmeals come from vertebrate hosts, such as humans, birds or reptiles, because all blood-feeding mosquitoes known to date feed on the blood of vertebrates.
Lawrence Reeves and colleagues observed a species of mosquito from Florida, Uranotaenia sapphirina, feeding on earthworms and leeches. They collected U. sapphirina females that had recently fed and tested them for evidence of vertebrate and annelid (earthworm and leech) DNA. The authors found that all mosquitoes with identifiable host DNA carried annelid blood, but none carried vertebrate blood. In contrast, moquitoes from a related species, U. lowii, showed only evidence of feeding on frogs and toads. Future work is needed to determine whether other species may also feed on annelids or other non-vertebrates.