An investigation of nematode fauna and biodiversity in forest areas of Adana, Gaziantep, Hatay, and Osmaniye provinces

This study was conducted to identify the nematode fauna in the forested areas of Adana, Hatay, Gaziantep, and Osmaniye provinces, and to determine the nematode biodiversity and population development at different soil depths in designated areas within the Adana province, specifically in the Sarıçam, Çukurova, Salbaş, Varda, and Pozantı regions. For this purpose, soil sampling was carried out between 2022 and 2024 from forested lands under the jurisdiction of 109 Forest Management Chief Offices in Adana (Feke, Karaisalı, Kozan, Pozantı, Saimbeyli), Osmaniye (Kadirli), Hatay (Antakya, Dörtyol, İskenderun), and Gaziantep. The nematodes extracted from the collected soil samples were identified at the genus and species level, and their densities were determined. A total of 25 nematode species classified within 9 families of the orders Tylenchida, Aphelenchida, and Dorylaimida were identified. In the study conducted to determine the forest nematode faunas, the five most frequently encountered species were identified as Xiphinema malaka, Pratylenchus thornei, Xiphinema pachtaicum, Xiphinema diversicaudatum, and Aphelenchus avenae, with occurrence frequencies of 25.29%, 20.69%, 20.69%, 17.24%, and 13.29%, respectively. Among the identified species, Xiphinema malaka is a new record for the nematode fauna of Turkey. All species identifiedrepresent new records for the nematode fauna of forested areas in Turkey. In order to investigate the nematode biodiversity and the population development of significant plant-parasitic species in Adana province, the nematode species diversity and the distribution of trophic groups were examined from samples taken from six selected sub-regions. Sixteen genera of plant-parasitic nematodes were identified. Bacterivorous nematodes, represented by 16 genera within the free-living fauna, constituted the most diverse group. Omnivorous and predatory groups were represented by 3 genera, while the fungivorous group, also represented by 3 genera, was identified as the two trophic groups with the lowest diversity. The proportion of plant-parasitic nematodes in the fauna was found to be 24%, bacterivores 40%, fungivores 26%, and predators and omnivores 10%. Consistently, higher nematode densities were detected in the 0-30 cm soil depth in each sub-region studied.