Prevalence, identification, and molecular variability of potato cyst nematodes in Algeria.
The aim of the present study was to evaluate the geographical distribution, infestation degree, and diversity of Potato Cysts Nematode (PCN) in Algeria, including the southern regions. Accurate identification of PCN is essential to determine the appropriate control methods to be used in an Integrated Pest Management program. PCNs were found in forty percent (12 out of thirty) of localities sampled. The average population density of PCN was much higher in the southern regions, compared to the northern regions (9.8 cysts per 100 cm3 vs.4.6 cysts per 100 cm3). The southern potato production areas were more infested with PCN than those of the north (7 from 25 fields in North vs. 5 from 5 fields in the South). Globodera pallida occurred predominantly in the northern region of Algeria, whereas G. rostochiensis occurred predominantly in the southern regions. No mixtures of these species were found in any of the positive studied localities. These species were confirmed by the molecular analysis based on PCR with species-specific primers, ITS-rDNA, and cytochrome b of mtDNA. The low molecular diversity and their phylogenetic association with the European populations of PCN suggest that Algerian populations were probably introduced from Europe, probably by infested seed-potato.