Research

Research direction

Mosquito-pathogen interactions facilitate the transmission of medically important arboviruses, such as dengue virus and West Nile virus, which represent a serious threat to more than half of the world’s population. Characterizing these interactions is a major research priority that will facilitate the development of new tools and techniques to control mosquito-transmitted disease.

However, there is a third player in this story: the mosquito microbiome. A wide range of microorganisms including, bacteria, fungi, algae and viruses associate with mosquitoes, forming complex and variable communities, and we are still learning about the ways that they impact mosquito biology.

There is a growing body of evidence demonstrating that some of these microorganisms can enhance or restrict a mosquito’s potential for transmitting certain medically-important pathogens.

Notable amongst these is Wolbachia pipientis, a bacterial endosymbiont that forms an intricate relationship with its host, modifying many aspects of its biology, and inhibiting infection with many major arboviruses. Consequently, Wolbachia-infected mosquitoes are currently being used in disease control programs around the world.

Wolbachia and other mosquito-associated microorganisms rely on their host to obtain the nutritional resources they need to survive, and can greatly perturb host metabolism. Likewise, arbovirus infection is heavily dependent on mosquito metabolism, and is tied to mosquito lipids, insulin, and essential micronutrients, amongst others.

Host-microbe metabolic interactions can directly influence mosquito immunity and pathogen transmission, but crucially, they remain poorly understood. My laboratory’s research aim is to improve understanding of the relationships between mosquitoes, microorganisms and arboviruses, particularly as they relate to host metabolism and immunity.

Specific research aims

A. Characterize the microbiota of mosquitoes in Florida and examine the role of key microbes in mosquito biology.

Florida is a hotspot for mosquito biodiversity in the United States, with more than 80 species present. This includes major vectors of arboviruses that cause disease important disease in people, both native and invasive, and numerous exotic and understudied mosquito species. In our location at the Florida Medical Entomology Laboratory, we are well situated to study wild populations of these species, and to characterize their microbiomes.

We aim to understand how the composition of the mosquito microbial community changes between different populations, between species, and due to different environmental factors, including human-driven environmental factors. Broadly, we also aim to understand the functional roles that specific bacteria and fungi play in mosquito biology, and how diversity amongst the microbiota impacts mosquito biology. This research aim will serve as the basis for future projects in the lab, as identifying which microorganisms are associated with which mosquito populations under different conditions is the first step to understanding the roles of specific microorganisms in mosquito biology.

B. Determine how changes to mosquito diet impact the microbiome.

In nature, mosquito larvae feed on the biological material found in their aquatic habitat, which includes decaying plant matter and microorganisms, with the content varying greatly between habitats. Adult females feed on blood for egg production, and can also carbohydrate sources like nectar, while males are restricted to nectar.

All of these nutritional inputs are biochemically complex, and can vary greatly across mosquito habitats. Differences in dietary input influence the metabolic environment of mosquito tissues, particularly the gut, where the majority of the microbiota dwell. As different microorganisms have distinct metabolic needs this could shape the composition of the microbiota.

We aim to understand how and why changing the composition of mosquito diet can lead certain mosquito-associated bacteria to prosper or struggle within the gut of major mosquito vectors, both under laboratory and semi-field conditions.

C. Elucidate the role of mosquito metabolism in mosquito-microbe-arbovirus interactions

Mosquitoes possess vast networks of metabolic pathways that underwrite numerous physiological processes from blood digestion to egg development. Many of these are also intrinsically linked to the mosquito immune system, and therefore can play a coordinating role in interactions between a mosquito and microorganisms, including bacteria, fungi and arboviruses.

Recent evidence has highlighted the importance of certain host lipids and micronutrients like iron to arboviral infection in mosquitoes. We aim to build on these data and improve our understanding of metabolic-immune networks that underlie mosquito-microbe-arbovirus interactions using molecular genetics techniques to activate or suppress key mosquito metabolic pathways, and gauge the impact on the host, its microbiota and medically-important arboviruses.

D. Identify biological commonalities in mosquitoes that are naturally infected by Wolbachia

Native Wolbachia infections, like those in the key mosquito vectors Aedes albopictus and Culex quinquefasciatus, have long-established relationships with their host species. Like the artificial transinfections useful to mosquito control, native infections impact mosquito reproductive biology. They also have an attenuated effect on other aspects of host biology as a result of long-term co-adaptation. Interestingly, evidence suggests they still invoke a residual immune response, alter host metabolism and nucleic acid processes, and can impact susceptibility to pathogen infection.

We aim to learn more about the impact of native Wolbachia on mosquito biology by exploring similarities and differences across multiple infected mosquito species. We are interested in understanding impacts on host physiology, metabolism, and whether these infections play a role in modulating host-pathogen interactions in the lab and in nature.

Data from these experiments will help us to understand plasticity in Wolbachia-host relationships, and this is directly relevant to the use of Wolbachia for controlling Aedes aegypti, as Wolbachia-host relationships are hypothesized to become more benign, and more similar to a native Wolbachia infection over time.

Current projects

As of August 2021.

Characterization of the microbiomes of mosquitoes in the Oslo Riverfront Conservation Area (ORCA). The aim of this project is to characterize the microbiome of the different mosquito species (including disease vectors) that dwell in this 508-acre field site, which is adjacent to FMEL and also a local conservation area.

Investigate functional niches of bacteria and fungi in mosquito biology. The project aims to understand the roles that microorganisms play in mosquito biology and vector competence.

Evaluate the potential of microorganisms in helping mosquitoes adapt to environmental change. The aim of this project is to examine whether microorganisms associated with specific environmental conditions can help mosquito larvae to adapt to physicochemical changes in their environment.

If you would like to know more, or are interested in joining the lab, please contact Eric: e.caragata@ufl.edu.