Current research interests

• Population structure of Culex pipiens complex
• Insecticide resistance in Cx. pipiens s.l. in California
• Chemo reception in mosquitoes
• Population biology and genetics of Anopheles gambiae sensu lato
• Role of Afrotropical mosquitoes in transmission of malaria and other pathogens affecting birds

Population structure of Culex pipiens complex

The systematics of the members of the Culex 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 do not behave and genetically interact consistently where they occur in sympatry in various parts of the World (see Cornel et al. 2003).

We developed a polytene chromosome map for one of the members of the complex namely, Culex quinquefasciatus from (South Africa) called the Johannes burg strain (Mcbee e tal. 2003).  The full genome of this mosquito strain was completed and published in 2010 (see Arensburger et al. 2010). Unfortunately the polytenization of the chromosome and hence production of readable spreads for all members of the complex and even strains of the same species is not consistent which precludes their usefulness for detailed population genetic studies. We are currently engaged in studies using microsatellites (Edillo et al. 2007) and single nucleotide polymorphisms as genetic markers to investigate in various environs the extent of gene flow and degree of relatedness/differentiation of populations of members of this complex in California.  Identification and resolution of Cx. pipiens s.l. in California still needs considerable research and we expect that this laboratory will continue to work on this complex for many years to come. This work is currently funded by Marin Sonoma and Consolidated Mosquito Abatements districts.

Edillo, F. E., Tripet, F., McAbee, R. D., Foppa, I, M., Lanzaro, G. C., Cornel, A. J. and Spielman, A. A set of broadly applicable microsatellite markers for analyzing the structure of Culex pipiens s.l. (Diptera: Culicidae) populations. J. Med. Entomol. 44:145-149. 2007.

Peter Arensburger,^1* et al. Sequencing of Culex quinquefasciatus establishes a platform for  mosquito comparative genomics. Sequencing of Culex quinquefasciatus establishes a platform for mosquito comparative genomics. Science 333: 86-88. 2010.

Cornel, A. J., McAbee, R., Rasgon, J., Stanich,  M., Scott, T. W. & Coetzee, M.  Differences in extent of genetic introgression between sympatric Culex pipiens and Culex quinquefasciatus in California and South Africa. J. Med. Entomol.40: 36-51.2003

Insecticide resistance in Cx. pipiens s.l. in California

Since we discovered a population of Cx. pipiens s.l. resistant to pyrethroids (Cornel et al 2000) we have followed up with ad hoc susceptibility testing. Most of our tracking efforts have focused on populations in Fresno County and resistance is quite widespread due to combined roles of kdr resistance and enzyme mediated detoxification (Waite et al. 2005, Inceoglu et al. 2009). ULV field trials in Fresno County are currently underway and studies thus far confirm that resistance to pyrethroids compromise efficacy of adulticides. Resistance management strategies are now required to be developed and used in earnest for effective control of this important vector complex .  This work is financially supported by California Mosguito Abatement Districts.

Cornel, A. J., Stanich, M., McAbee, R. & Mulligan III. F. S. High level methoprene resistance in the mosquito Ochlerotatus nigromaculis (Ludlow) in Central California. Pest Management Science. 58: 791-798. 2002

Inceoglu, A. B., Waite, T. D., Christiansen, J. A., McAbee, R. D., Kamita, S. G., Hammock, B. D. and Cornel, A. J. A rapid luminescent assay for measuring cytochrome P450 activity in individual larval Culex pipiens complex mosquitoes (Diptera:Culicidae). J. Med Entomol. 46 (1): 83-92. 2009.

Waite, T.D., H. Huang, B. Inceoglu, J.S. Christiansen, R.D. McAbee, B.D. Hammock and A.J. Cornel.  Improved methods for identifying elevated enzyme activities in pyrethroid-resistant mosquitoes.  Proceedings of the 2005 Annual Mosquito and Vector Control Association of California Conference. Vol. 73: 131-136. 2005.

Chemo reception in mosquitoes

Work is ongoing with Professor Leal (http://chemecol.ucdavis.edu) as the PI and expert in chemo reception to tease apart the mechanisms (genetic and biochemicals) of chemo receptive pathways that mosquitoes have evolved to detect hosts for blood meal engorgement and to select sites to lay eggs in several mosquito disease vectors. Noteworthy accomplishments include a comparative examination of Odorant binding proteins in the major malaria vector Anopheles funestus Xu et al. 2010), development of an effective oviposition attractant for the West Nile virus vector Culex quinquefasciatus (Leal et al. 2008) and development of methods for chemo reception studies (Pelletier et al. 2010).

Xu, W., Cornel, A.J, Leal, W. S. Odorant binding proteins of the malaria vector Anopheles funestus sensu stricto. PLOS One 5: (10): e15403. doi:101371/journal.pone.0015403. 2010

Leal, W. S., Barbosa, R.M.R., Xu, W., Ishida, Y., Syad, Z., Chen, A. M., Morgan, T.I., Cornel, A. J., Furtado, A. Reverse and conventional chemical ecology approaches for the development of oviposition attractants for Culex mosquitoes. PLoS One, 3(8) :e3045.2008.

Pelletier, J., Guidolin, A., Syed, Z., Cornel, A. J., Leal, W.S. Knockdown of a mosquito odorant-binding protein involved in the sensitive detection of oviposition attractants. J. Chem. Ecol. 36:245-248, 2010.

Population biology and genetics of Anopheles gambiae sensu lato

Several projects are currently in progress with Prof Gregory Lanzaro (http://faculty.vetmed.ucdavis.edu/faculty/gclanzaro/lab/) who runs the vector genetics laboratory at UC Davis.  Malaria still causes the highest mortality and morbidity of all vector borne diseases worldwide. Much still has to be learnt about the population structure and ecology and behavior of the major African malaria vectors. Our more recent investigations have discovered a third form (Forest M form) of Anopheles gambiae (Slotman et al. 2007, Lee et al. 2009) and studies are underway to figure out the distributions and degrees of gene flow between this new and the other forms of Anopheles gambiae. Studies to examine the ecological genetics of important behaviors such as blood feeding propensities, exophily and endophily of another major malaria vector Anopheles arabiensis will be starting in 2011 in Tanzania.
Investigating genetic factors affecting susceptibility of Anopheles gambiae forms is an area of much interest these days which Profs Lanzaro, Shirley Luckhart in the Medical School (http://www.ucdmc.ucdavis.edu/medmicro/staff/luckhart.html) and myself are investigating (Horton et al. 2010).  All this work on malaria vectors is funded by several NIH grants.

Slotman, M. A., Tripet, F., Cornel, A. J., Meneses, C. R., Lee, Y., Reimer, L. J., Thieman, L. J., Fondjo, E., Fofana, A., Traore, S. F. and Lanzaro, G. C. Evidence for subdivision within the M molecular form of Anopheles gambiae. Mol. Ecology 16:639-649. 2007.

Lee, Y., Cornel, A. J., Meneses, C., Fofana, A., Andrianarivo, A. G., McAbee, R. D., Fondjo, E., Traoré S. F., and Lanzaro, G. C. Ecological and genetic relationships of the Forest-M form among chromosomal and molecular forms of the malaria vector Anopheles gambiae sensu stricto. Malaria Journal 8: 75 doi:10.1186/1475-2875-8-75 2009.

Horton, A., Lee, Y., Coulibaly, C., Rashbrook, V., Cornel, A. J., Lanzaro, G., Luckhart, S. Identification of three single nucleotide polymoprhisms in Anopheles gambiae  immune signaling genes that are associated with natural Plasmodium falciparum infection. Malaria journal 9: 160. doi: 10.1186/1475-2875-9-160.2010.

Role of Afrotropical mosquitoes in transmission of malaria and other pathogens affecting birds

Well over 500 species of mosquitoes occur in tropical and temperate regions of Africa and we know almost nothing about the feeding and breeding behaviors of 95% of them.  Many of these mosquito species are obligatory or more opportunistic bird feeders and are efficient vectors of avian Plasmodium and other disease that affect birds. In 2008 I began studies in collaboration with Senior researchers at UCLA Institute of the Environment and Sustainability (IoES) (http://www.ioe.ucla.edu/ctr/people.html) to investigate the role of mosquitoes in transmission of avian pathogens in pristine and disturbed forest environments in Cameroon. We have only touched the tip of the iceberg in this area of research as the diversity of these lesser known mosquitoes and pathogens is enormous. So far we have identified numerous avian malaria mosquito vector species (Njabo et al 2009, Njabo et al. 2010, Njabo et al. 2011) and there will undoubtedly be more to discover as we spread our investigations to other environs in Africa such as the savanna and temperate forest regions. This work is funded by the Rufford Foundation small grants foundation.   

Njabo, KY., Cornel, A. J., Sehgal, R. N. M., Loiseau, C., Buermann, W., Harigan, R., Pollinger, J., Valki?nas, G, and Smith, T. B. Coquillettidia (Culicidae, Diptera) mosquitoes as new natural vectors of avian malaria in Africa. Malaria Journal 103 (11). 1127-1138. 2009.

Njabo, K.Y., Cornel, A. J., Bonneaud, C., Toffelmier, E., Sehgal, R. N. M., Valki?nas, G., Smith, T. B. Isolations of Plasmodium  from field-collected mosquitoes (Diptera:Culicidae) in the low land