The polymerase chain reaction method as a tool for identifying members of the Anopheles gambiae complex (Diptera:Culicidae) in northeastern Tanzania.

Polymerase chain reaction (PCR) primers developed at the Centers for Disease Control in Atlanta for the identification of members of the Anopheles (Cellia) gambiae Giles complex were tested on material collected in the Bagamoyo and Muheza districts of northeastern Tanzania. Part of the sample from Bagamoyo was chromosomally identified and correlated with the PCR identifications. This sample contained 170 Anopheles arabiensis, 328 An. gambiae, and 58 Anopheles merus, of which 121, 237, and 54 specimens, respectively, were identified with both PCR and chromosomes. Three specimens identified chromosomally as An. merus gave only the PCR fragment characteristic for Anopheles quadriannulatus, but on retesting gave the correct result. The Muheza sample consisted of 771 An. arabiensis, 852 An. gambiae, 43 An. merus, and 4 specimens producing the fragment characteristic for An. quadriannulatus. Because An. quadriannulatus has never been recorded from mainland Tanzania and due to the high number of specimens that produced no result (193), it is probable that DNA degradation led to misidentification of An. merus specimens as An. quadriannulatus. The overall probability of correct identification by PCR was 99.685% at first testing, which compares favorably with other genetic methods currently in use.