Molecular-based approach to the differentiation of mealybug (Hemiptera: Pseudococcidae) species.

The rDNA internal transcribed spacer (ITS) region of 4 mealybug species, Pseudococcus viburni (Signoret), P. longispinus (Targiono-Tozzetti), P. calceolariae (Maskell), and P. similans (Lidgett), was isolated by polymerase chain reaction (PCR) amplification, cloned, and sequenced. In this region of the genome there were numerous differences, including nucleotide substitutions, insertions, or deletions between P. viburni, P. longispinus, and P. calceolariae, whereas P. calceolariae and P. similans were very similar. Based on sequence differences between the ITS regions, we designed PCR primers that were able to differentiate the 4 mealybug species and that correlated with morphological differences found between adult females of these species. The PCR amplification by using the species-specific primers enabled the differentiation of not only adult females but also eggs, juveniles, and adult males, which was not previously possible by using conventional identification methods.