Dominance Structure of the Fauna of Parasitic Nematodes of Vegetable Crops in the Fergana Valley, Uzbekistan

The present study investigates the species composition, morphological characteristics, and distribution patterns of parasitic nematodes infesting vegetable crops in the Fergana Valley, Uzbekistan. A total of 283 soil and root samples were collected from tomato (Solanum lycopersicum), bell pepper (Capsicum annuum), and eggplant (Solanum melongena) cultivated under protected ground conditions across the Andijan, Fergana, and Namangan regions. Nematode extraction was performed using the Baermann funnel method, soil washing analysis, and root incubation techniques. A total of 177 temporary and 72 permanent microscopic preparations were produced for morphological and morphometric analysis. Thirteen parasitic nematode species belonging to the order Tylenchida were identified: Meloidogyne arenaria, M. incognita, M. javanica, M. hapla, Pratylenchus pratensis, P. penetrans, P. thornei, P. tumidiceps, Helicotylenchus multicinctus, H. digitiformis, H. dihystera, Ditylenchus dipsaci, and D. destructor. Dominance analysis based on the scale proposed by V.F. Paliy revealed that root-knot nematodes of the genus Meloidogyne are absolutely dominant in the regional nematode fauna, collectively comprising more than 84% of the total species abundance. Meloidogyne incognita recorded the highest dominance index (37.25%), followed by M. arenaria (30.85%) and M. javanica (15.87%), all classified as eudominant species. The high prevalence of thermophilic Meloidogyne species is attributed to the favorable soil-climatic conditions of the Fergana Valley, characterized by warm temperatures, intensive irrigation, and an extended growing season. The Andijan region demonstrated the greatest species richness, whereas the Namangan region yielded rare and previously unrecorded species.

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