Molecular identification of phytoplasma vector species.

The correct identification of the insect species involved in phytoplasma transmission is an essential condition for managing phytoplasma diseases and employing control strategies. The taxonomy of leafhoppers, planthoppers, and psyllids traditionally relies on morphological characters. Unfortunately, the identification of the distinctive traits requires skills and experience possessed by only a few specialist entomologists. In this chapter we provide protocols for the molecular identification of phytoplasma-vector species, mainly based on the polymerase chain reaction (PCR) amplification of mitochondrial and ribosomal DNA. Protocols for the application of molecular identification keys to dried specimens stored in insect collections are also provided. The same total DNA preparations can serve as a PCR template for either insect species or phytoplasma identification. The molecular identification methods can be applied not only to males, but also to nymphs and females for which a morphological taxonomic tool is generally unavailable. We suggest that taxonomic databases of planthoppers, leafhoppers, and psyllids should include species-specific DNA sequences as soon as they become available.