Heritable microbes – viruses, bacteria and protists that pass from a female insect to her progeny – are common in insects, and biologically important. Carrying a heritable microbe may allow a blood feeding vector to live on a blood diet alone and may modify its ability to transmit pathogens. Research on these symbionts has largely focussed on Wolbachia/mosquito interactions, which has developed into a tool for controlling vector borne diseases (mainly dengue). This project will examine symbiotic interactions in sandflies, and their potential to modify vector competence for Leishmania transmission. We will a) establish the diversity of endosymbionts in sandfly vectors in Colombia and Kenya, and b) evaluate the impact they have on the vector competence of their insect host. Our work will concentrate on two microbes: Wolbachia and Rickettsia. Through the project, we will develop a wider understanding of the symbionts of vectors, their potential biological effects, and their potential utility in control of vector borne infections that impact the health and wellbeing of people in Lower and Middle income countries.biting midges, noting their ubiquitous presence in 38% of Culicoides species tested. We have since detected this symbiont in UK Simulium blackflies and Cimex bedbugs. Further, metagenomics data from Lutzomyia sandflies from the USA (Reeves et al. 2008, doi:10.2987/5745.1) indicate the presence of closely related rickettsial infections in a range of vector species. Rickettsia infections were present in midge ovaries, and thus represent heritable symbiont infections rather than vector transmitted infections themselves. However, the inability to colonize UK midges has thus far limited the understanding of the biological significance of these rickettsial symbionts, although analysis of torix Rickettsia genomes indicates it is unlikely to be vitamin provisioning. This project will document the incidence of Rickettsia symbionts in vector species from sub-Saharan Africa and Colombia and ascertain their biological impacts on their invertebrate hosts and associated vector-borne disease (Leishmania, phleboviruses) coinfection rates.