Generation and use of species-specific DNA probes for insect vector identification

Abstract

Many insect vectors are members of complexes composed of morphologically identical sibling species. The identification of individual species, a requirement of epidemiological studies and control programmes, has traditionally relied upon techniques such as chromosomal analysis or isoenzyme typing. Due to the limitations of these techniques, the last few years have seen many developments in DNA-based technologies for identification. DNA-based protocols have advantages over the other techniques utilized in that they may identify all insect stages of both sexes using alcohol preserved, dried, fresh or frozen specimens. The methods ultimately rely upon either DNA probe hybridization or the polymerase chain reaction (PCR). This chapter describes the development and use of DNA probes for the identification of insect vector specimens. The aim has been to produce a methodology that is cheap, accurate and easy to use. In this chapter, the DNA probe-based techniques, which have been developed for the identification of Anopheles gambiae complex mosquitoes, are used to illustrate the power of these methods, although the technology is directly applicable to many other mosquito or insect vectors. In addition, the methods discussed may be utilized for generating additional epidemiological data such as identification of parasites within the vector or origin of the blood meal.