Over the years, the potato has become an increasingly important staple crop in Indonesia. Since the production rate of potatoes is increasing, problems with pests like the potato cyst nematode Globodera rostochiensis are increasing as well.
G. rostochiensis was identified for the first time in Indonesia relatively recently, in 2003. The exact moment the pathogen was introduced, however, is unknown. Here we performed phylogenetic analysis on fourteen G. rostochiensis field populations sampled on Java and Sumatra. Our dataset of 1.4 million unique variants suggests that this potato cyst nematode species was introduced on Java not too long after the introduction of the potato in the middle of the 18th century. After its introduction, the pathogen spread to Sumatra, where it started to diversify independently.