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Root lesion nematodes (RLNs) (Pratylenchusspp.) are one of the most economically important plant parasitic nematodes (PPNs) and are considered one of the leading causative agents of apple diseases that severely decrease yield and quality in apple (Malus domesticaBorkh.) orchards. Occurrence, identification, and diversity of PPNs in apple orchards in central Anatolia region of Türkiye have not been well understood. Therefore, in this study, a field survey was conducted in this region to reveal the occurrence, distribution, and diversity of mainly RLNs. The primary analysis of soil and root samples based on morphology revealed that 8 PPN species were present in sampled areas, the most prevalent of which was RLNs. As a result of morphological, morphometric, and molecular studies, a total of 5 species of RLNs [Pratylenchus crenatusLoof, 1960; Pratylenchus neglectus(Rensch, 1924) Filipjev & Schuurmans-Stekhoven, 1941; Pratylenchus penetrans(Cobb, 1917) Filipjev & Schuurmans-Stekhoven, 1941; Pratylenchus thorneiSher & Allen, 1953 and Pratylenchus vulnusAllen & Jensen, 1951] were identified. Phylogenetic analysis with the D2–D3 domain of LSU-rDNA sequences further confirmed the identification. The results indicated that P. thorneiwas the predominant species in surveyed areas, followed by P. neglectus. The results confirmed the host status of apples for RLNs and demonstrated that RLNs were the most threatening PPNs in the surveyed apple orchards. The necessity of determining the damage caused by plant parasitic nematodes to apple production emerges as an important factor to be done as a future study.

Background: Entomopathogenic nematodes (EPNs) (Steinernematidae and Heterorhabditidae) and their symbiotic bacteria are pathogenic for a wide range of insect pests and have been used successfully as a biological control agent. Although EPNs are well studied against many agricultural insect pests, the efficacy of their symbiotic bacteria still remains unclear for many insect pests of agricultural importance. In the present study, the virulence of native EPN isolates and their cell-free supernatants of symbiotic bacteria were tested against the 3rd and 4th larval instars of Agrotis segetum(Denis & Schiffermüller) (Lepidoptera: Noctuidae) under laboratory conditions (25 ± 1 °C and R.H. 60%). Results: The 4th instar larvae were more susceptible to infective juveniles (IJs) and mortalities over (95%) were achieved by all tested EPN isolates at the concentration of 100 IJs/cm2after 72 hrs of exposure. The cell-free supernatants were more effective against the 3rd instar larvae and the highest mortalities were recorded as 42 and 60% in the contact and leaf disc bioassays, respectively. Conclusion: The results indicated that the cell-free supernatants can be an ideal application for young larval stages of A. segetum. However, further studies are required to test the effectiveness of both EPNs and the cell-free supernatants of their symbiotic bacteria in field conditions.

The present study was carried out in the agricultural areas of Northwestern Turkey with the purpose to assess the occurrence of Pasteuriaspp. bacteria on plant-parasitic nematodes. The soil samples were collected from olive, cherry, peach, pear, almond, walnut, apple orchards, vineyards, vegetable, and sunflower fields, analyzed and the bacterium was detected on 30 nematode species belonging to 31 families. Nematode individuals from Rotylenchus, Helicotylenchus, Pratylenchus, Tylenchorrhynchus, and Geocenamusspp. were most frequently infected while the average height and width of the spore core and endospore ranged between 3.70-4.90 and 1.40-2.37 μm, respectively. The results indicated that Helicotylenchus digonicus, Pratylenchus thornei, P. neglectus, Geocenamus brevidens, Tylenchhorhynchus cylindricus, Rotylenchus cypriensis, Meloidogyne javanica, and M.incognitaindividuals were the most parasitized by the bacterium.