'Candidatus Tisiphia' is a widespread Rickettsiaceae symbiont in the mosquito Anopheles plumbeus (Diptera: Culicidae)

Abstract

Symbiotic bacteria alter host biology in numerous ways, including the ability to reproduce or vector disease. Deployment of symbiont control of vector borne disease has focused on Wolbachia interactions with Aedes and is hampered in Anopheles by a lack of compatible symbioses. Previous screening found the symbiont Ca. Tisiphia in Anopheles plumbeus, an aggressive biter and potential secondary vector of malaria parasites and West Nile virus. We screen An. plumbeus samples collected over a ten-year period across Germany and use climate databases to assess environmental influence on incidence. We find a 95% infection rate that does not fluctuate with broad environmental factors. Microscopy suggests the infection is maternally inherited based on strong localisation throughout the ovaries. Finally, we assemble a high-quality draft genome of Ca. Tisiphia to explore its phylogeny and potential metabolism. This strain is closely related to those found in Culicoides midges and shows similar patterns of metabolic potential. An. plumbeus provides a viable avenue of symbiosis research in anopheline mosquitoes, which to date have one other proven infection of a heritable symbiont. Additionally, it provides future opportunity to study the impacts of Ca. Tisiphia on natural and transinfected hosts, especially in relation to reproductive fitness and vector efficiency.