The Genus Pratylenchus (Nematoda: Pratylenchidae) in Israel: From Taxonomy to Control Practices

Abstract

Due to Israel's successful agricultural production and diverse climatic conditions, plant-parasitic nematodes are flourishing. The occurrence of new, previously unidentified species in Israel or of suggested new species worldwide is a consequence of the continuous withdrawal of efficient nematicides. Among plant-parasitic nematodes, migratory endoparasitic species of the genus Pratylenchus are widely distributed in vegetable and crop fields in Israel and are associated with major reductions in quality and yield. This review focuses on the occurrence, distribution, diagnosis, pathogenicity, and phylogeny of all Pratylenchus species recorded over the last few decades on different crops grown throughout Israel-covering early information from nematologists to recent reports involving the use of molecular phylogenetic methodologies. We explore the accepted distinction between Pratylenchus thornei and Pratylenchus mediterraneus isolated from Israel's northern Negev region, and address the confusion concerning the findings related to these Pratylenchus species. Our recent sampling from the northern Negev revealed the occurrence of both P. thornei and P. mediterraneus on the basis of molecular identification, indicating P. mediterraneus as a sister species of P. thornei and their potential occurrence in a mixed infection. Finally, the efficiencies of common control measures taken to reduce Pratylenchus' devastating damage in protected crops and field crops is discussed.

Keywords: Pratylenchus; control management practices; distribution; molecular phylogeny; pathogenicity; root lesion nematode; taxonomy.

Figure 1

Map of the known distribution of Pratylenchus species recorded in Israel’s farming regions. Only recorded infested regions are indicated for each Pratylenchus species.

Figure 2

Symptoms caused by Pratylenchus capsici. (A) Pepper plant decline in the Arava Rift Valley characterized by stunted growth and wilting. (B) Heavily infected roots, with pronounced lesions along primary and secondary roots. (C) Photograph of developed root lesion taken under a dissecting microscope.

Figure 3

Weed distribution and function as a reservoir for Pratylenchus capsici during and in between growing seasons. (A) Weeds emerging early after pepper seedling planting, and (B) throughout the pepper-growing season. (C) Lesions caused by P. capsici on Chenopodium album growing alongside the pepper plants.

Figure 4

Bayesian 50% majority rule consensus tree inferred on concatenated sequences of 28S; asterisks indicate species that were only identified by morphology. The dataset was aligned by MAFFT v. 7.205 [70] using the G-INS-i algorithm. The phylogeny was reconstructed by maximum likelihood (ML) and Bayesian inference (BI) using RAxML v.8.1.11 [71] and MrBayes 3.2.3. [72]. Branch support is indicated in the following order: posterior probability (PP) value from BI analysis/bootstrap (BS) value from ML analysis. Red marked species indicate local Israeli isolates.

Figure 5

Integrated nematode management. Protocol used in practice to control migratory or sedentary plant-parasitic nematodes. (A) Destruction of previous crop’s roots before removal to reduce primary inoculum. (B) Root removal, tilling, and soil preparation for fumigation and solarization requirements. (C) Soil-disinfection approaches using different soil fumigants in combination with soil solarization for at least 4 weeks during the summer. (D) Planting of seedlings and reinstallation of shade net.