Evolutionary Genetics of Vector and Parasite Populations
Malaria and Anopheles gambiae
We continue our work aimed at understanding patterns of genetic and ecological diversification between and within populations of the main vector of malaria in Africa, the mosquitoes of the Anopheles gambiae complex. The overall aim of the projects are to achieve a better understanding of the population biology of the vector to control the disease it transmits. Work in this area includes 1) understanding patterns and process of spatial genetic differentiation between island and continental populations, 2) identifying genes controlling the innate immune response in mosquitoes that are infected with the malaria parasite, Plasmodium falciparum, 3) using museum samples to detect the geographic origin of an accidental introduction of An. gambiae in Brazil in the last century, 4) using DNA markers to detect the gut content of Anopheles larvae, to understand the process and patterns of spread
of genes involved in insecticides resistance. These projects are in collaboration with Jeffrey Powell, Michael Reddy (Graduate Student, EPH), Erika Schielke (Graduate Student, EEB), and past post-docs Michel Slotman, Nikos Poulakakis, Jonathan Marshall (Southern Utah University), Aris Parmakelis (Un. of Athens), Michael Russello, many other US and international scientists, and several Yale Undergarduates.
Erika Schielke, EEB graduate student, sampling mosquito larvae to detect predation on mosquito larvae using DNA extracts from known or potential invertebrate predators.
Evolutionary genetics of Anopheles mosquito vectors in Equatorial Guinea Michael Reddy, EPH Graduate student
Michael's main research interests include malaria and arthropode-borne disease ecology; mosquito vector population dynamics; and anti-vector intervention design and implementation. Mike is presently involved in a multi-agency collaborative effort with officials from the Equatorial Guinea Ministry of Health, the Marathon Oil Corporation and Medical Care Development International. Mike’s current research projects address two issues of paramount importance to the sustainability of ongoing and anticipated anti-vector intervention activities on Bioko Island and mainland regions of Equatorial Guinea, Central Africa. 1) The goal of the primary project is to elucidate how the ecology, population structure, host-seeking and resting behaviors of Anopeheles melas, a potentially important malaria vector may determine its susceptibility to mosquito suppression activities in Equatorial Guinea. 2) The second research endeavor seeks to describe the spatio-temporal distribution of insecticide resistance alleles among An. gambiae mosquito vectors in order to develop mathematical models for predicting the efficacy of insecticide-based interventions against these vectors. Such models will provide useful guidelines for the rational selection and use of pyrethroid and carbamate insecticides for the suppression of vector populations. The inferences drawn from the proposed research activities will serve to inform intervention activities aimed at diminishing the force of malaria transmission in Equatorial Guinea and beyond. Ultimately, Mr. Reddy wishes to contribute to a more detailed understanding of the eco-epidemiological determinants of mosquito-borne disease transmission in domestic and international settings.
Surveying for Anopheles spp. mosquito larvae, Bata, Equatorial Guinea
Show casing UV-LED light trap designed by Lee Cohnstaedt, EPH Graduate Student, sold by Bioquip
New World sand fly phylogenetics and population structure
Lee Cohnstaed (EPH graduate student)
Lee is interested in elucidating the evolutionary relationships of isomorphic Phlebotomine sand flies for the reliable identification of species and clarification their role in Leishmania transmission. He is using population genetics to determine sand fly abundance, distribution and migration rates, aids public health departments in disrupting the disease vectors transmission cycles.
Lee during a collection trip in Peru’. The hazards of collecting in the jungle!
Evolutionary genetics of tsetse flies, its parasites and symbionts
Human African Trypanosomiasis (HAT) (a.k.a. African sleeping sickness) kills thousands of people each year in sub-Saharan Africa. The disease is caused by African trypanosomes transmitted by the tsetse fly. HAT transmission is complex; it requires mammalian and invertebrate hosts and involves domestic and wild reservoirs. A paratransgenic strategy has been developed which exploits the unique biology of tsetse and its maternally inherited bacterial symbionts. In this strategy, tsetse’s symbiont Sodalis is harnessed to express trypanocidal molecules in tsetse’s midgut to impair trypanosome transmission. Our focus is on the understanding of the patterns of genetic differentiation of the three players in the paratransgenic approach: the tsetse vector, Glossina fuscipes, the Trypanosoma parasite, and the maternally inherited symbionts, Wolbachia, Sodalis, and Wigglesworthia.
Current members of the lab working on this project: Jon Beadell (postdoc EEB) and Chaz Hyseni (Research Assistant, EEB).
Past members of the lab involved in the project: Michel Slotman, Oliver Balmer, and Kirtin Dion (EEB).
This project is in collaboration with Yale EPH professors Serap Aksoy and Alison Galvani, and Loyce Okedi and Patrick Abila from the Livestock Health Research Institute LIRI, Uganda.
Jon Beadell, postdoctoral fellow in EEB-EPH, on a collecting trip with locals in Uganda and preparing traps with Serap Aksoy.
Jon back in the lab colledcting data.
Yellow fever, Dengue fever and Aedes aegypti
The focus of this project is the so-called yellow fever mosquito, Aedes aegypti. Presently, on a global scale, it is a major health concern as the most important vector of dengue fever viruses. Two billion people worldwide are at risk for dengue disease, some forms of which are fatal. We started to gather preliminary data for a project intended to understand the worldwide genetic structure of this important vector. This genetic variation will be related to variation in the species’ ability to transmit flaviviruses. This project is in collaboration with Jeffrey Powell and many other US and international scientists.
Publication: Slotman, M.A., N. B. Kelly, L. C. Harrington, S. Kitthawee, J. W. Jones, T. W. Scott, A. Caccone, and J.R. Powell. 2006. Polymorphic microsatellites markers for studies of Aedes aegypti (Diptera Culicidae), the vector of dengue and yellow fever. Molecular Ecology Notes, 7: 168-171.
Blood meal analysis of ticks carrying Lyme Disease in the Eastern United States
Determination of critical components of pathogen transmission is essential in the development of effective interventions against important tick-borne infectious disease threats such as Lyme disease. Accordingly, we seek to identify the larval host of the tick Ixodes scapularis, the principal vector of Borrelia burgdorferi, the causative agent of Lyme's Disease in the northeastern United States. To achieve this goal, we are currently developing PCR-based techniques for the identification of the reservoir host blood-meal in Ix. scapularis nymphal ticks based on amplification of small species-specific fragments of the ctyb mtDNA gene. This project is in
collaboration with Deborah Lanterbecq, Michael Reddy (Graduate Student, EPH), Nicole Ayache (Undergraduate student), and Durland Fish (EPH Vector Epidemiology Laboratory).