Ingestion of an avian blood parasite (Haemoproteus sp.) reduces survivorship of the West Nile vector Culex quinquefasciatus

Abstract

Arthropod vectors are frequently exposed to a diverse assemblage of parasites, but the consequence of these infections on their biology and behavior are poorly understood. Given vector survivorship is a key parameter of vectorial capacity, we experimentally evaluated whether the ingestion of a common protozoan parasite of avian hosts (Haemoproteus spp.) impacted the survivorship of Culex quinquefasciatus, one of the most widespread mosquito vectors of zoonotic pathogens. Blood was isolated from wild northern cardinals (Cardinalis cardinalis) in College Station, Texas and screened for the presence of Haemoproteus spp. parasites using microscopic and molecular methods. Experimental groups of Cx. quinquefasciatus mosquitoes were offered Haemoproteus-positive cardinal blood through an artificial feeding apparatus, while control groups received Haemoproteus-negative cardinal blood or domestic canary (Serinus canaria domestica) blood. Culex quinquefasciatus mosquitoes exposed to Haemoproteus infected cardinal blood (N=69) survived significantly fewer days than mosquitoes that ingested Haemoproteus-negative cardinal blood (N=31) (p < .0001). The survival of mosquitoes fed on positive cardinal blood had a median survival time of 18 days post-exposure and the survival of mosquitoes fed on negative cardinal blood exceeded 50% across the 30 day observation period. Additionally, mosquitoes that fed on canary controls (N=47) survived significantly fewer days than cardinal negative controls with canary control mosquitoes having a median survival time of 17 days (p < .0001).This study further supports prior observations that Haemoproteus parasites can be pathogenic to bird-biting mosquitoes, and suggests that Haemoproteus parasites may indirectly suppress the transmission of co-circulating vector-borne pathogens by modulating vector survivorship. Our results also suggest that even in the absence of parasite infection, bloodmeals from different bird species can influence mosquito survivorship which could influence pathogen transmission.