Characterization of Native Entomopathogenic Nematode Isolates from Bilecik, Türkiye: Heat Tolerance, Dispersal, and Pathogenicity

Abstract

This study aimed to evaluate the biological and ecological characteristics of entomopathogenic nematode isolates collected from soil samples in Bilecik, Türkiye, to assess their potential for use in biological pest control. The isolates were tested for their dispersal ability in olfactometers, pathogenicity against greater wax moth larvae, and tolerance to elevated temperatures. A commercial strain and a hybrid strain were included as references for comparison. The experiments revealed significant variability among the isolates. One local isolate exhibited strong dispersal capacity and heat tolerance, outperforming the reference strains in some parameters. Conversely, certain isolates showed lower levels of virulence, indicating limited pest control potential. Lethal dose assays demonstrated that pathogenicity varied substantially, with some local isolates matching or exceeding the performance of commercial strains under laboratory conditions. Mortality assessments across increasing temperature levels revealed that sensitivity to heat stress was not uniform and differed considerably among isolates. The findings confirm that biological performance is highly isolate-dependent and influenced by multiple interacting traits. While some local isolates showed promise in one or more evaluated traits, no single isolate combined superior performance in all parameters. Therefore, the results provide a valuable foundation for further characterization studies involving additional traits such as reproductive capacity, storage potential, and field efficacy. Overall, this study emphasizes the importance of locally adapted isolates in developing effective and environmentally sustainable pest management strategies. Selecting and improving such isolates may contribute to the broader adoption of biological control practices and reduce dependency on chemical pesticides.

Keywords

• Biological control
• Heterorhabditis
• pest
• Steinernema

References

1. 1. Campos-Herrera R, Vicente-Díez I, Blanco-Pérez R, Chelkha M, González-Trujillo MDM, Puelles M, Čepulitė R, Pou A. Positioning entomopathogenic nematodes for the future viticulture: Exploring their use against biotic threats and as bioindicators of soil health. Turk J Zool. (2021);45 (Special issue 1):335–346. https://doi. org/10.3906/ZOO-2106-40
2. 2. Manochaya S, Udikeri S, Srinath BS, Sairam M, Bandlamori SV, Ramakrishna K. In vivo culturing of entomopathogenic nematodes for biological control of insect pests: A review. J Nat Pest Res (2022);1:100005. https://doi.org/10.1016/j.napere.2022.100005
3. 3. Koppenhöfer AM, Shapiro-Ilan DI, Hiltpold I. Entomopathogenic nematodes in sustainable food production. Front Sustain Food Syst. (2020);4(125):1–14. https://doi.org/10.3389/fsufs.2020.00125
4. 4. Poinar GO, Grewal P. History of entomopathogenic nematology. J Nematol. (2012);44(2):153–61. PMID: 23482453
5. 5. Kaya HK, Gaugler R. Entomopathogenic nematodes. Ann Rev Entomol. (1993);38(1):181–206. https://doi. org/10.1146/annurev.en.38.010193.001145
6. 6. Peters A. The natural host range of Steinernema and Heterorhabditis spp. and their impact on insect populations. Biocontrol Sci Techn. (1996);6(3):389–402. https://doi.org/10.1080/09583159631361
7. 7. Ehlers R-U. Mass production of entomopathogenic nematodes for plant protection. Appl Microbiol Biotechnol. (2001);56(5–6):623–633. https://doi. org/10.1007/s002530100711
8. 8. Shapiro-Ilan DI, Han R, Dolinksi C. Entomopathogenic nematode production and application technology. J Nematol. (2012);44(2):206–217. PMID: 23482883

9. 9. Dunn MD, Belur PD, Malan AP. A review of the in vitro liquid mass culture of entomopathogenic nematodes. Biocontrol Sci Techn. (2021);31(1):1–21. https://doi.org /10.1080/09583157.2020.1837072
10. 10. Erdoğan H, Ünal H, Susurluk İA, Lewis EE. Precision application of the entomopathogenic nematode Heterorhabditis bacteriophora as a biological control agent through the Nemabot. Crop Prot. (2023);174:106429. https://doi.org/10.1016/j.cropro.2023.106429
11. 11. Metwally HMS, Saleh MME, Abonaem M. Formulation for foliar and soil application of entomopathogenic nematodes for controlling the onion thrips Thrips tabaci Lindeman (Thysanoptera: Thripidae). Egypt J Biological Pest Cont. (2025);35(1):4. https://doi.org/10.1186/ s41938-025-00841-8
12. 12. Askary TH, Abd-Elgawad MMM. Opportunities and challenges of entomopathogenic nematodes as biocontrol agents in their tripartite interactions. Egypt J Biological Pest Cont. (2021);31(1):42. https://doi.org/10.1186/ s41938-021-00391-9
13. 13. Peters A. Application and commercialization of nematodes. Appl Microbiol Biotechnol. (2013);97(14):6181–6188. https://doi.org/10.1007/s00253-013-4941-7
14. 14. Kapranas A, Malone B, Quinn S, O’Tuama P, Peters A, Griffin CT. Optimizing the application method of entomopathogenic nematode suspension for biological control of large pine weevil Hylobius abietis. BioControl. (2017);62(5):659–667. https://doi.org/10.1007/s10526- 017-9824-x
15. 15. Nxitywa A, Malan AP. Formulation of Steinernema yirgalemense in gel for long-term storage at room temperature. J Plant Dis Prot. (2023);130(4):809–816. https://doi.org/10.1007/s41348-023-00764-2
16. 16. Lalitha K, Nithya K, Bharathi BG, Venkatesan S, Shivakumar MS. Long-term storage does not affect the infectivity of entomopathogenic nematodes on insect hosts. Appl Microbiol Biotechnol. (2022);107(1):419- 431. https://doi.org/10.1007/s00253-022-12309-y.
17. 17. Flores P, Alvarado A, Lankin G, Lax P, Prodan S, Aballay E. Morphological, molecular and ecological characterization of a native isolate of Steinernema feltiae (Rhabditida: Steinernematidae) from southern Chile. Parasites and Vectors. (2021);14(1):45. https://doi. org/10.1186/s13071-020-04548-7
18. 18. Bruno P, Machado RAR, Glauser G, Köhler A, CamposHerrera R, Bernal J, Toepfer S, Erb M, Robert CAM, Arce CCM, Turlings TCJ. Entomopathogenic nematodes from Mexico that can overcome the resistance mechanisms of the western corn rootworm. Sci Rep. (2020);10(1):8257. https://doi.org/10.1038/s41598-020-64945-x
19. 19. Susurluk A, Dix I, Stackebrandt E, Strauch O, Wyss U, Ehlers RU. Identification and ecological characterisation of three entomopathogenic nematode-bacterium complexes from Turkey. Nematology. (2001);3(8):833– 841. https://doi.org/10.1163/156854101753625326
20. 20. Hsieh FC, Tzeng CY, Tseng JT, Tsai YS, Meng M, Kao SS. Isolation and characterization of the native entomopathogenic nematode, Heterorhabditis brevicaudis, and its symbiotic bacteria from Taiwan. Curr Microbiol. (2009);58(6):564–570. https://doi. org/10.1007/s00284-009-9371-5
21. 21. Morton A, García-del-Pino F. Ecological characterization of entomopathogenic nematodes isolated in stone fruit orchard soils of Mediterranean areas. J Invertebr Pathol. (2009);102(3):203–213. https://doi.org/10.1016/j. jip.2009.08.002
22. 22. Yuksel E, Canhilal R. Isolation, identification, and pathogenicity of entomopathogenic nematodes occurring in Cappadocia region, central Turkey. Egypt J Biological Pest Cont. (2019);29(1):1–7. https://doi.org/10.1186/ s41938-019-0141-9
23. 23. Levy N, Faigenboim A, Salame L, Molina C, Ehlers RU, Glazer I, Ment D. Characterization of the phenotypic and genotypic tolerance to abiotic stresses of natural populations of Heterorhabditis bacteriophora. Sci Rep. (2020);10(1):1–16. https://doi.org/10.1038/s41598-020- 67097-0
24. 24. Raja RK, Sivaramakrishnan S, Hazir S. Ecological characterisation of Steinernema siamkayai (Rhabditida: Steinernematidae), a warm-adapted entomopathogenic nematode isolate from India. BioControl. (2011);56(5):789–798. https://doi.org/10.1007/s10526- 011-9345-y
25. 25. Glazer I, Salame L. Osmotic survival of the entomopathogenic nematode Steinernema carpocapsae. Biological Cont. (2000);18(3):251–257. https://doi. org/10.1006/bcon.2000.0814
26. 26. Hunt DJ, Nguyen KB. Tabular keys to species of Steinernema and Heterorhabditis. In: Hunt DJ, Nguyen KB, editors. Advances in Entomopathogenic Nematode Taxonomy and Phylogeny. (2017).p. 59–109. Leiden, The Netherlands: Brill. https://doi. org/10.1163/9789004285347. ISBN: 978-90-04-28534-7
27. 27. Susurluk IA, Ulu TC, Kongu Y. Tolerances of hybridized entomopathogenic nematode Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) strains to heat and desiccation. Turk J Entomol. (2013);37(2):221– 228. https://doi.org/10.16970/ted.96639
28. 28. White GF. A method for obtaining infective nematode larvae from cultures. Science. (1927);66(1709):302–303. https://doi.org/10.1126/science.66.1709.302.b
29. 29. Rasmann S, Turlings TC. First insights into specificity of belowground tritrophic interactions. Oikos. (2008);117(3):362–369. https://doi.org/10.1111/ j.2007.0030-1299.16204.x
30. 30. Kour S, Khurma U, Brodie G. Ecological Characterisation of Native Isolates of Heterorhabditis indica from Viti Levu, Fiji Islands. J Nematol. (2021);53(1):1–20. https:// doi.org/10.21307/jofnem-2021-085
31. 31. Ulu TC, Susurluk IA. In vitro liquid culture production and post-production pathogenicity of the hybrid Heterorhabditis bacteriophora HBH strain. Crop Prot. (2024);175(106443):1–7. https://doi.org/10.1016/j. cropro.2023.106443
32. 32. Yamanaka S, Tanabe H, Takeuchi K. Vertical Dispersal and Infectivity of Steinernema glaseri, S. anomali and S. kushidai (Nematoda: Steinernematidae). Nematol Res (Jap J Nematol). (1995);25(1):24–32. https://doi. org/10.3725/jjn1993.25.1_24
33. 33. Bal HK, Michel AP, Grewal PS. Genetic selection of the ambush foraging entomopathogenic nematode, Steinernema carpocapsae for enhanced dispersal and its associated trade-offs. Evolutionary Ecology. (2014); 28(5):923–939. https://doi.org/10.1007/s10682-014- 9706-y
34. 34. Wu S-Y, Duncan LW. Entomopathogenic nematode species combinations alter rates of dispersal, host encounter and insecticidal efficiency. J Pest Sci. (2022); 95(3):1111–1119. https://doi.org/10.1007/s10340-021- 01475-z
35. 35. Bal HK, Grewal PS. Lateral Dispersal and Foraging Behavior of Entomopathogenic Nematodes in the Absence and Presence of Mobile and Non-Mobile Hosts. PLOS ONE. (2015); 10(6):e0129887. https://doi.org/10.1371/ journal.pone.0129887
36. 36. Rolston AN, Griffin CT, Downes MJ. Emergence and Dispersal Patterns of Two Isolates of the Entomopathogenic Nematode Steinernema feltiae. J Nematol. (2006); 38(2):221–228. PMID: 19259450
37. 37. Ulu TC, Susurluk IA. Heat and desiccation tolerances of Heterorhabditis bacteriophora strains and relationships between their tolerances and some bioecological characteristics. Invertebr Surv J. (2014); 11(1):4–10. https://www.isj.unimore.it/index.php/ISJ/article/ view/300/214. ISSN 1824-307X
38. 38. Fallet P, De Gianni L, Machado RAR, Bruno P, Bernal JS, Karangwa P, Kajuga J, Waweru B, Bazagwira D, Degen T, Toepfer S, Turlings TCJ. Comparative Screening of Mexican, Rwandan and Commercial Entomopathogenic Nematodes to Be Used against Invasive Fall Armyworm, Spodoptera frugiperda. Insects. (2022); 13(2):205. https:// doi.org/10.3390/insects13020205
39. 39. Odendaal D, Addison MF, Malan AP. Entomopathogenic nematodes for the control of the codling moth (Cydia pomonella L.) in field and laboratory trials. J Helminth. (2016); 90(5):615–623. https://doi.org/10.1017/ S0022149X15000887
40. 40. Ferreira T, Malan AP. Potential of entomopathogenic nematodes for the control of the banded fruit weevil, Phlyctinus callosus (Schönherr) (Coleoptera: Curculionidae). J Helminth. (2014); 88(3):293–301. https://doi.org/10.1017/S0022149X13000175
41. 41. Susurluk IA, Kumral NA, Peters A, Bilgili U, Açıkgöz E. Pathogenicity, reproduction and foraging behaviours of some entomopathogenic nematodes on a new turf pest, Dorcadion pseudopreissi (Coleoptera: Cerambycidae). Biocontrol Sci Techn. (2009); 19(6):585–594. https://doi. org/10.1080/09583150902957348
42. 42. Özdemir E, Bayram Ş, Susurluk İA. First record of the entomopathogenic nematode Steinernema litorale (filipjev) (Rhabditida: Steinernematidae) and its symbiotic bacterium from Turkey, and its efficacy capability. Insects. (2020); 11(3):144. https://doi.org/10.3390/ insects11030144
43. 43. Wang J, Cao L, Huang Z, Gu X, Cui Y, Li J, Li Y, Xu C, Han R. Influence of the ascarosides on the recovery, yield and dispersal of entomopathogenic nematodes. J Invertebr Pathol. (2022); 188:107717. https://doi.org/10.1016/j. jip.2022.107717