Integrative diagnosis, biological observations, and histopathology of the fig cyst nematode Heterodera fici Kirjanova (1954) associated with Ficus carica L. in southern Italy

Abstract

Morpho-biological notes and histopathology, based on LM and SEM observations, of the fig cyst nematode Heteroderafici isolated from Ficuscarica roots, collected in home and public gardens of Apulia region, southern Italy, are described and illustrated. Seventy-five localities throughout the Apulia region were sampled and one-quarter of the sampled localities had fig roots infested with H.fici, with population densities ranging from 44 to 180 cysts/100 ml of soil. All attempts to detect H.fici on ornamental Ficus spp. as well as on imported bonsai in Italy were unsuccessful. Morphometric characters of the Italian population conform to those of the type and re-description populations reported for H.fici. Molecular analysis using ITS, D2–D3 expansion domains of the 28S rRNA, and the partial 18S rRNA sequences of H.fici newly obtained in this study matched well with the corresponding sequences of H.fici present in the GenBank database. Phylogenetic trees confirmed and supported the grouping of H.fici in the Humuli group. Heteroderafici completes its embryogenic development in 14–16 days at 25 °C. Post-invasion development and maturity in the roots of F.carica seedlings is completed in 64–68 days at 25–28 °C with juveniles and adults showing different parasitic habits, being endoparasitic and semi-endoparasitic respectively. The establishment of permanent feeding sites that consist of the formation of large syncytia causes anatomical modification of vascular elements and general disorder in the root stelar structures. Syncytia structures associated with mature females showed different degrees of vacuolisation, numbers of syncytial cells, and contained nuclei and nucleoli which were constantly hypertrophied.