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MOSQUITO CONTROL &
RESEARCH |
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CURRENT RESEARCH INTERESTS
URLs of co-investigators and
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Systematics of Culex pipiens complex The systematics of the members of the Cx. pipiens complex has been investigated for many years and still there is no universal consensus on the genetic relatedness of the primary members of the complex. Confusion arises because the members of the complex behave and interact differently with each other in different parts of the world (reviewed by Cornel et al. 2003) that may or may not be strongly influenced by their interactions with the symbiont Wolbachia pipientis. There is now renewed interest in investigating systematics of this mosquito complex to further understand the transmission and epidemiology of diseases such as West Nile and Rift Valley fever viruses that are vectored by members of this complex. My laboratory is currently focused on developing polytene chromosome maps (South Africa), for the purpose of using them as population genetic tools and in genomic studies to locate specific locations of genes and other DNA fragments. This work is currently funded by the NIH (July 2003 to June 2005). Molecular tools such as microsatellites and mitochondrial DNA sequence variations offer additional tools to conduct detailed population genetic studies on members of this complex and a proposal is being prepared for NIH funding to use these tools for a comprehensive population genetic study. CORNEL A.J., MCABEE R., RASGON, J., STANICH M., SCOTT T., and COETZEE, M. 2003. Differences in extent of genetic introgression between sympatric Culex pipiens and Culex quinquefasciatus in California and South Africa. J. Med. Entomol. 40: 36-51. |
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Insecticide resistance in members of the Cx. pipiens complex and other mosquitoes Colonies of members of the Cx. pipiens complex that are resistant to pyrethroids have been established and these colonies provide material for development of new methods for detecting and monitoring pyrethroid resistance in mosquitoes. New fluorescent substrates that have recently been developed by Professor Bruce Hammock for detection of enzyme mediated metabolism in mammal tissues hold considerable promise for use in mosquitoes (McAbee et al. in press). The main objectives of this project are to evaluate and develop inexpensive yet highly sensitive and selective assays for monitoring enzyme mediated pyrethroid resistance first in Cx. pipiens sensu latu and then in other mosquito species. California state funds were used to develop preliminary data for a substantial NIH grant in collaboration with Professor Hammock and his staff (http://www.biopestlab.ucdavis.edu). Prospects of five years of funding look very positive beginning in January 2004. Our intentions are to grow this research even further to use these assays to 1) conduct molecular studies to isolate and clone esterases and mixed function oxidases responsible for pyrethroid metabolism in mosquitoes and 2) to use these assays to understand linkage between i) disease transmission and insecticide resistance in mosquito vectors and ii) agricultural use of insecticides and selection of resistance genes in mosquito disease vectors in California and in Africa. MCABEE, R., KANG, K-D., STANICH, M., CHRISTIANSEN, J., WHEELOCK, C., INMAN, A., HAMMOCK, B. and CORNEL, A.J. Pyrethroid tolerance in Culex pipiens molestus from Marin County, California. Pest Management Science. A collaboration with Professor Maureen Coetzee (National Health Laboratories, Johannesburg, South Africa [http://www.wits.ac.za/fac/med/entomology/medento.htm]) is currently underway to examine the potential of using the novel fluorescent substrates for detection of enzyme mediated pyrethroid resistance in African malaria vectors. If these substrates work then the project will be expanded to use this technology to monitor resistance and develop resistance mitigating strategies for control of insecticide resistance in African malaria vectors. High level resistance to the insect growth regulator methoprene was detected in California populations of the mosquito Ochlerotatus nigromaculis (Cornel et al. 2000, 2002). Identifying the mechanism/s of resistance to methoprene in this mosquito would be intriguing research and funding options are currently being pursued. However, attempts to colonize this mosquito have thus far failed and from my perspective mechanistic work would be dependant on having available methoprene susceptible and resistant colonies. CORNEL, A.J., STANICH, M., FARLEY, D., MULLIGAN III, F.S., and BYDE, G. 2000. Methoprene tolerance in Aedes nigromaculis (Diptera: Culicidae) in Fresno County in California. Am. Mosq. Control. Assoc.16: 223-228. Cornel, A.J., Stanich, M., McAbee, R., and Mulligan III, S. 2002. Sustained field applications of methoprene induces and selects for high level methoprene resistance in the mosquito Ochlerotatus nigromaculis (Ludlow) in Central California. Pest Management Science. 58:791-798. |
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Identifying oviposition attractants (in collaboration with Professor Walter Leal) Professor Leal is the principal investigator (http://chemecol.ucdavis.edu) who in the past two years has isolated and cloned the odorant binding protein in antennae of female Cx. pipiens quinquefasciatus and Cx. tarsalis (Ishida et al. 2001, 2002). The odorant binding proteins will be used to screen for oviposition attractants. As oviposition attractants are found they will be evaluated by us in the field with the intention that oviposition based traps will one day replace CO2 baited traps that are currently being used to collect mosquitoes for virus surveillance and isolation purposes in California. Oviposition traps in theory should offer a far more sensitive method than host seeking based traps because they should capture older females that have had more opportunity to become infected with virus. ISHIDA, Y., CORNEL, A.J., and LEAL, W. 2002. Identification and cloning of a female antenna-specific odorant-binding protein in the mosquito Culex quinquefasciatus. J. Chem. Ecol. 28: 867-871. ISHIDA, Y., CORNEL, A.J., and LEAL, W. 2003. Odorant-Binding protein from Culex tarsalis, the most important vector of West Nile virus in California. J. Asia-Pacific Entomol. 6: 1-4. |
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Identifying mechanism/s of pyrethroid resistance in the cattle tick Boophilus microplus This project is in collaboration with Dr. Rodrigo Rosario-Cruz (INIFAP-CONACYT) in Mexico and is aimed at identifying mechanisms responsible for pyrethroid resistance in populations of Boophilus microplus in Mexico. Enzyme assays using the novel substrates as discussed above on mosquitoes indicate that esterases may be involved in pyrethroid detoxification and a putative esterase has been cloned. The role of insensitive target site resistance (kdr-type) as a parallel resistant mechanism is now currently under investigation. |
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Population structure of Anopheles gambiae (in collaboration with Professor Gregory Lanzaro) In the past few months my laboratory has set up a collaboration with Professor Lanzaro (http://entomology.ucdavis.edu/faculty/facpage.cfm?id=lanzaro) who is a newly appointed faculty member in our department. He is the principal investigator on an NIH funded grant that has as its objective to examine the population structure of Anopheles gambiae in Africa. My laboratory is responsible for karyotyping polytene chromosomes of An. gambiae with the intention of using inversion frequencies as genetic markers. |
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Integrating GIS in mosquito control operations (in collaboration with Kris Lynn) Technologies offered by Geographic Information Systems (GIS) allow us to develop a GIS based operating system for day to day work by mosquito abatement districts. A GIS based system is currently under development (Lynn et al. 2001) and is being simultaneously evaluated and modified by a mosquito abatement district. So far the system has proved its worthiness for the abatement district by enormously facilitating record keeping, budgetary and personnel issues and has reduced time taken to make decisions about operations that has allowed for personnel cost savings. GIS is also currently being used to assess the effects and linkage of agricultural pesticide usage to development of pesticide resistance in mosquito disease vectors in California. LYNN, K., CORNEL, A.J., FARLEY, D., SAPP, E. ,and MCFEETERS, S. 2001. Integrating geographic information systems in mosquito control in Fresno. Proceedings of the Mosquito and Vector Control Association of California.69: 64-69.
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