Towards a molecular understanding of mosquito host detection

Mosquitoes obtain blood-meals from vertebrate hosts to enable egg production. Blood is not the only source of nourishment for mosquitoes. Both male and female mosquitoes seek nectar sources from plant hosts. Since males male do not bite, nectar is their principle energy source.  Mosquitoes gain access to these nutrients by sensing volatile chemicals in their environment. Olfactory cues such as body odor, carbon dioxide, and nectar volatiles are sufficient to enable mosquito attraction. Understanding how mosquitoes sense their hosts is the focus of the DeGennaro lab. Using a molecular genetic analysis of mosquito behavior, we seek to identify the odors and olfactory receptors that are necessary for mosquito host detection.

Aedes aegypti female feeding on a human host.

Aedes aegypti female feeding on a human host.

 

Previous work

My post-doctoral research in Leslie Vosshall's laboratory at Rockefeller University established techniques to edit the genome of mosquitoes. Using this approach, I demonstrated that the mosquitoes use the OR/ORCO olfactory receptor pathway to respond to human odors and nectar volatiles. My work implicated the Ionotropic Receptor (IR) family of olfactory receptors in mosquito host-seeking. In addition, I showed that DEET repels mosquitoes in two distinct ways: through ORCO-dependent olfaction and a yet to be identified taste receptor. My laboratory at Florida International University is expanding on this work in three main areas presented below.

 

Current Projects

Testing the response of female Aedes aegypti to a human host using an olfactometer.

Testing the response of female Aedes aegypti to a human host using an olfactometer.

Identifying the mosquito receptors for human odor

          The goal of this project is to identify olfactory receptors that enable the dengue fever mosquito, Aedes aegypti, to be attracted to humans. The proposed research promises to (1) provide insight into the genetic basis of mosquito attraction to humans and (2) provide specific information useful for preventing the spread of human disease by mosquitoes. Our hypothesis is that the ionotropic receptor (IR) pathway that is retained in orco mutants is essential for mosquito attraction to humans. By combining loss-of-function behavioral studies with an IR expression map, we will identify IRs that are candidate human odor receptors. These candidate odor-selective IRs and their cognate IRCOs will be screened using human odor components. Identifying behaviorally relevant mosquito receptors and the human odors that activate them will provide molecular insights that can be used to make mosquito behavior less harmful.


Aedes albopictus male caught in the act of nectar-seeking.

Aedes albopictus male caught in the act of nectar-seeking.

Genetic analysis of mosquito nectar-seeking

          Identifying the receptors that enable mosquito nectar-seeking behavior is one of our interests. We know that the olfactory receptor co-receptor, ORCO is necessary for both male and female mosquitoes to respond to nectar volatiles. The ORs that provide the odor-ligand specificity are unknown. In this project, we seek to identify receptors using a combination of loss-of-function behavioral studies and cell-based assays. In addition, the first meal a female mosquito ingests consists of nectar not blood. We are interested in learning more about the molecular basis of this switch from nectar-seeking to human host-seeking behavior. This research could set the stage for a novel approach to lock female mosquitoes in a behavioral state where they never become interested in human hosts.

Female Aedes aegypti in a 2-port olfactometer-based choice assay

Female Aedes aegypti in a 2-port olfactometer-based choice assay

Vector ecology of Aedes aegypti in South Florida

          Our lab is located in a region where Aedes aegypti is prevalent and local transmission of the dengue virus is once again occurring. We are developing projects to understand the vector ecology of mosquito host interactions in south Florida. In particular, we are interested in dengue virus prevalence in wild populations and the role of mosquitoes in pollination.

 
 
 

 

The lab will be looking for undergraduate researchers to start in the summer of 2017, email if you are interested in joining.

The DeGennaro lab (March 2016)

The DeGennaro lab (March 2016)

Here is a link to the FIU Biology Ph.D. application requirements.

Header mosquito photo by Alex Wild.