Fundamental and translational investigations in vector biology: from competence to control

Integrated vector management is key to controlling vector-borne diseases and reducing the burden of mosquito-borne pathogens worldwide in recent decades. This vector control approach requires a detailed knowledge of which mosquito populations are transmitting a given pathogen in a geographic region, as well as effective tools that consider the biology and ecology of vector species in their implementation. The work described herein aims to address these two requirements as they apply in different aspects of vector-borne disease. During the Zika virus epidemic in the Americas in 2015-16, there was speculation that in addition to Aedes mosquitoes, other species such as Culex quinquefasciatus could be involved in virus. We compared the vector competence of Cx. quinquefasciatus to Ae. aegypti using a validated qRT-PCR approach to detecting virus that considered the requirements for virus transmission by mosquitoes in its interpretation. We found no evidence of Zika virus transmission by Cx. quinquefasciatus, and identified multiple tissue barriers to infection in this mosquito species. However, we also observed persistence of the virus in Cx. quinquefasciatus, which is important to interpretation of future laboratory and field vector competence studies. We investigated the viral invasion dynamics in susceptible and non-susceptible mosquito cells and found evidence that Zika virus infection in Culex mosquitoes may be blocked post-entry, which is highly informative as to the nature of the barrier to virus transmission in Cx. quinquefasciatus mosquitoes. While emerging infections like Zika virus have been the subject of much attention lately, malaria is still the most serious vector-borne disease. We assessed the potential of the Chromobacterium genus for biopesticide development and malaria vector control. Chromobacteria are environmental bacteria sometimes found in close association with mosquitoes. We identified that several Chromobacterium isolates are strongly mosquitocidal against both larval and adult Anopheles gambiae mosquitoes, and can be applied to mosquitoes by a variety of techniques, which would make them a uniquely flexible tool in controlling malaria by targeting different mosquito life stages. Together, these distinct research areas add critical information to our understanding of mosquito-microbe interactions, and represent vital knowledge to effective integrated vector management in vector-borne disease endemic regions