Trichogramma parasiticwasps often are cryptic species and can not be distinguished because of theirsmall size and the plasticity of their morphological traits. The species identityof Trichogramma has been based on the morphology of the male genitaliaand flagellar structures, this presents a particular problem for parthenogeneticforms. The objective here was to identify by molecular methods cryptic speciesof Trichogramma occurring in agricultural fields of Mexico. We identifiedthe cryptic species T. pretiosum, T. fuentesi y T. exiguum, andthe non cryptic species T. atopovirilia y T. pintoi. A identificationdichotomous key to species was constructed using as taxonomic characters thesize of the internal transcribed spacer 2 (ITS2) region of ribosomal DNA andthe difference in restriction length polymorphism of species. Also the ITS2regions were sequenced coupled with ITS2 sequences from GenBank and the percentsof similarity and divergence were calculated between species. This moleculartool can solve identification of cryptic species of Trichogramma fromMexico.
