The utility of internally transcribed spacer 2 DNA sequences of the nuclear ribosomal gene for distinguishing sibling species of Trichogramma

The usefulness of the internally transcribed spacer 2 (ITS2) of the nuclear ribosomal gene complex is tested for providing taxonomic characters to ide ntify Trichogramma species. The ITS2 sequences of a group of sibling specie s of the T. deion/T. pretiosum complexes were determined. A simple and prec ise identification key to the species of these assemblages was constructed using as taxonomic characters the size of the ITS2 and the difference in re striction length polymorphism of species with similarly sized ITS2. Individ ual wasps can be identified by amplification of their ITS2 with general pri mers, determining the size of the PCR product using standard agarose electr ophoresis, followed in some species by a DNA-digestion with a restriction e nzyme. Because this system works well for a number of closely related speci es we are hopeful that similar PCR-based identification can be extended to all species of the genus once their ITS2 sequences have been determined. Th e advantage of this identification system over the morphology-based system is that non-specialists are able to quickly and cheaply identify individual specimens. In addition, species specific primers were tested for the two m ost common species of these groups (i.e. T. pretiosum and T. deion). These primers can be used either as a direct identification tool or as a method t o confirm the identification using the general key. The phylogeny of this g roup of wasps was also analyzed based on the ITS2 sequence.