Molecular taxonomy of trichogrammatids

Abstract

Molecular taxonomy of trichogrammatids has made impressive beginning in the last two decades. Several workers have employed RFLP, RAPD, AFLP and PCR techniques. In India, a modest beginning has been made in using the internal transcribed spacer (ITS) region especially ITS-2. By the use of specific primers, it is possible to confirm the identity among thelytokous populations/species, thus overcoming the limitation to use males in conventional taxonomy. Examples of molecular key for Trichogramma species based on PCR product size and response to chosen enzymes (like Eco RI, Mse I, Pvu I and Nru I) are provided. Scope exists for evolving multiplex PCR, involving both species-specific primers and a complementary universal primer for ITS-2 region. Potential for application of molecular techniques exists in quality control for commercial units against contamination by other species. Strain identification is possible with microsatellite markers and ISSR (inter-simple sequence repeat) technique. Enzymatic analysis, especially with EST, MDH and SOD, can be employed as complementary means of distinguishing morphologically close relatives. The targets of analysis include mitochondrial DNA and ribosomal RNA. Analysis and alignments of DNA sequences are also discussed. Software packages providing additional information are also listed.