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General Morphology

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Genera and Species Identification

Genera and species identification can be performed by standard entomological aspects based on anatomy. Further and newer techniques include biochemical techniques such as enzyme electrophoresis and gas chromatography, DNA probes and monoclonal antibodies.

Standard entomological techniques

Females and males can be distinguished by the naked eye. In females, the end of the abdomen appears blunt. The abdomen is narrow immediately after hatching, inflated and reddish after the first blood meal, brown to black after digestion and markedly thicker with a yellowish shade during egg development. The male abdomen resembles that of unfed females or even thinner and ends in paired appendages, appearing like small spines to the naked eye (Perfil'ev, 1968).

In general, the identification of sand flies is based to a large extent on anatomy. Females of the genera Phlebotomus and Sergentomyia and males of the genus Sergentomyia are identified by anatomical characters. Identification of males of the genus Phlebotomus is based on the morphology of the terminalia (Perfil'ev, 1968).

For further details on anatomy see Perfil'ev, (1968). New techniques (see below) are being introduced to resolve problems of identification, especially when epidemiologically significant females cannot be differentiated (WHO, 1990).

Isoenzyme electrophoresis

A technique used successfully to distinguish species in the Old and the New World. Principal enzymes that vary within and between species are glucose phosphate isomerase, hexokinase, malate dehydrogenase NAD+, malate dehydrogenase NADP+ and phosphoglucomutase (WHO, 1990).

Gas chromatography

It is used for the examination of cuticular hydrcarbon extracts (cuticular lipids – Peters, 1992) and has proved to be very useful to distinguish species in which the females were inseparable. It has also been used to highlight geographic variation in other species (WHO, 1990).

DNA probes

Highly specific DNA probes have been developed and offer an ideal tool in epidemiological studies. Sand flies are squashed onto special membranes and sequentially hybridised with probes against the suspected vector and parasite species.

Monoclonal antibodies

They as well are used for identification of sand flies.

   

References

  • Perfil'ev, P.P.: Fauna of U.S.S.R. Diptera. Phlebotomidae (sandflies). Acad. Sci. U.S.S.R. Zool. Inst. New Ser. No. 93, Vol. 3 No. 2, Israel Program for Scientific Translations, Jerusalem, 1968
  • WHO: Control of the leishmaniases. Report of a WHO Expert Committee, Tech. Rep. Ser. No. 793, WHO, Geneva, 1990

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