Identification of dipteran vectors of human diseases (e.g. malaria and river blindness)

Some problems in controlling diseases such as malaria and riverblindness are caused by the fact that the vector species that transmit the parasite to man (Anopheles spp., and Simulium spp., respectively) are member of 'sibling-species' complexes. These vector species complexes consist of a number of morphologically almost-identical species that are very closely related. However, problems arise for control programmes in that not all members of the complex are medically important- some might for example bite animals in preference to man. Therefore it is important to use taxonomic techniques such as polytene chromosome banding patterns and allozyme, DNA differences to distinguish the species. Once this first step has been taken, information can be provided about breeding grounds of these vectors which can then be subjected to various control methods. 

Selected publications

Charalambous, M, Arzube, M, Lowell, S, Cytogenetic analysis of a new subcomplex of Simulium exiguum (Diptera :Simuliidae) in Amazonian Ecuador, Bull Entomol Res, 1998, Vol: 88, Pages: 247 - 255

Charalambous, M, Lowry, CA, Lowell, S, et al , The value of the larval head pattern for differentiating Simulium exiguum s l and S-gonzalezi (Diptera: Simuliidae) in the onchocerciasis focus of Ecuador, Bull Entomol Res, 1997, Vol: 87, Pages: 19 - 24

Charalambous, M, Shelley, AJ, Herzog, MM, et al , Four new cytotypes of the onchocerciasis vector blackfly Simulium guianense in Brazil., Med Vet Entomol, 1996, Vol: 10, Pages: 111 - 120

CHARALAMBOUS, M, SHELLEY, AJ, GRACIO, AJD, et al , Cytogenetical analysis of the Simuolium damnosum complex (DIPTERA,SIMULIUM) in Guinea- Bissau, Med Vet Entomol, 1995, Vol: 9, Pages: 330 - 330

Population Genetics of dipteran vectors of human diseases (e.g. malaria and river blindness)

Once genetic markers that distinguish the members of the species complex have been obtained, we can start to investigate the population structure of the vectors. These studies are important to understand how gene flow varies among the populations. In Ecuador, we found that populations of Cayapa cytospecies of the vector Simulium exiguum do not exchange migrants equally; instead the poulations were 'isolated by distance' so that gene flow occurred more between close geographic populations. For mosquitoes and malaria, these sorts of studies will yield valuable information for future control programs which aim to release transgenic mosquitoes into the wild. The fate of the transgenes through time and the efficacy of such programs will be dependent on the population structuring of the vector.

Selected publications

Charalambous, M, Lowell, S, Arzube, M, et al , Isolation by distance and a chromosomal cline in the Cayapa cytospecies of Simulium exiguum, the vector of human onchocerciasis in Ecuador. , Genetica, 2005, Vol: 124, Pages: 41 - 59

Charalambous, M, Townson, H, Harbach, RE, et al , Electrophoretic and DNA identification of Anopheles bwambae and A-gambiae (Diptera : Culicidae) in western Uganda , Bull Entomol Res, 1999, Vol: 89, Pages: 111 - 117                                               

Sexual selection on insect mate recognition systems

Courtship signals between potential mates, be they visual, acoustic, chemical, are a source of great evolutionary wonder: How have they evolved? Are they costly to produce? What information do they give? Can they separate the good from the bad? Are they involved in speciation? The list is endless...

My interest, ever since PhD days, is in the songs of grasshoppers. If we take the Chorthippus biguttulus group that occurs in Europe, again we see that they are morphologically very similar (sibling species). However if you listen to the calling/courtship songs that the male sings to the female, they are radically different in structure. In fact, the songs serve to isolate the species where they occur together: the males and females of the different species do not recognise each other's songs in the wild and so do not mate. However, viable offspring are produced when they different species are when brought into the lab and 'forced' to mate. This demonstrates that pre-mating isolation is stronger than post-mating isolation. If females are choosing to mate with males who show a particular song trait value, as demonstrated in C. brunneus, then this potentially allows the signal -receiver systems to evolve very rapidly, and might even drive population differentiation and speciation.

Current projects

• The effect of parasite burden on mate choice in Chorthippus brunneus.
• Sexual selection and the effect of B chromosomes (selfish genetic elements) in the grasshopper Myrmeleotettix maculatus
• Do females of the bug Oncopeltus faciatus prefer to mate with ageing lotharios or young bucks,and what are the fitness implications?
• Pheromones, mate choice and learning in the cricket Gryllus bimaculatus
• Assortative mating for condition in the cricket Gryllus bimaculatus
• How are alternate male reproductive morphs of the bulb mite Rhizoglyphus robini maintained? - in collaboration with Isabel Smallgange

Selected publications

Smallegange IM, Thorne N, Charalambous M, Fitness trade-offs and the maintenance of alternative male morphs in the bulb mite (Rhizoglyphus robini)., J Evol Biol, 2012, Vol:25, Pages:972-980

Charalambous, M, Butlin, RK, Hewitt, GM, Genetic variation in male song and female song preference in the grasshopper Chorthippus brunneus (Orthoptera, Acrididae), Anim Behav, 1994, Vol: 47, Pages: 399 - 411