Potato Cyst Nematodes: Geographical Distribution, Phylogenetic Relationships and Integrated Pest Management Outcomes in Portugal

Abstract

The identification and phylogenetic relationships of potato cyst nematodes (PCN) were studied to assess the potential value of geographical distribution information for integrated pest management of potato production in Portugal. This research focused on PCN species, Globodera pallida and Globodera rostochiensis. From 2013 until 2019, 748 soil samples from the rhizosphere of different potato cultivars were surveyed in the Portuguese mainland to detect and identify both species and track their location. PCN are widespread invasive species throughout Portugal. In fact, during the survey period an incidence of 22.5% was estimated for the tested samples. The patterns of infestation vary among regions, increasing from south to north, where PCN were first detected. Currently, both species are present in all potato producing regions of the country, with a greater incidence of G. pallida. Phytosanitary control measures are influencing to the observed results. The use of potato cultivars resistant to G. rostochiensis led to a decrease of this species but had no influence on G. pallida detections, which continues its reproduction freely since there are no effective resistant cultivars for this species. The relationship between the presence, infestation rate, spread and geographical distribution of PCN is discussed in terms of behavioral responses of the potato cultivars and the implications for developing new integrated crop protection measures.

Integrative Morphometric and Molecular Approach to Update the Impact and Distribution of Potato Cyst Nematodes Globodera rostochiensis and Globodera pallida (Tylenchida: Heteroderidae) in Algeria

“…In this regard, only G. pallida or G. rostochiensis alone isolates in different regions (Algiers, Boumerdes, Blida, Tipaza, Béchar and El Oued) were identified by [ 19 ]. Similar investigations carried out in various other countries have shown the presence of alone isolates and mixed isolates of the PCN species [ 13 , 48 , 49 , 50 , 51 , 52 ], which corroborates with these results. In addition, according to [ 48 ], G. pallida and G. rostochiensis rarely occurred as separate species, but more often as a mixture species in the same field.…”

“…Globodera pallida alone isolates are present in 44% of the fields prospected, while G. rostochiensis alone isolates and mixed isolates are present in the rest of the fields with equal proportions (28%), showing the dominance of the G. pallida species in potato fields. This may result from the control of populations of G. rostochiensis through the intensive cultivation of resistant potato cultivars as is occurring in other countries like the Netherlands [ 53 ], United Kingdom [ 54 , 55 , 56 ] and Portugal [ 52 ] since almost all current potato cultivars are resistant or tolerant to this species [ 34 ], unlike with G. pallida species where the number of resistant varieties is limited [ 26 , 34 , 57 , 58 ].…”

Development and Validation of a Loop-Mediated Isothermal Amplification Diagnostic Method to Detect the Quarantine Potato Pale Cyst Nematode, Globodera pallida

“…The sequence alignment of the "3′end18S-ITS1-5.8S-ITS2-5′end28S" region of Portuguese isolates (G. pallida, G. rostochiensis and Globodera n. sp., the three predominant species in Portugal [52]) and several from the GeneBank database for G. pallida, G. rostochiensis, Globodera n. sp., G. mexicana and G. ellingtonae (Supplementary Table S1) was performed.…”

“…The detection of the target species within pools of non-target species was attempted because it was previously demonstrated that G. pallida and G. rostochiensis cohabit in mixed populations in potato fields [52,56]. Samples of pure G. pallida and pure G. rostochiensis were not used since the specificity had been previously demonstrated.…”

“…and G. rostochiensis, based on sequences of Belgian and Netherlands populations [50,51]. The objective of this work is to develop a LAMP assay for G. pallida, to be used in routine analyses, since the analysis of soils sampled in Portuguese potato fields has revealed an increased spread of G. pallida in the country [52]. The rapid identification of the two species is essential to detect their presence in potato fields, to re-evaluate the control measures implemented so far and adopt more effective practices.…”