Kemotaksični odziv parazitskih ogorčic (Rhabditidae) na izbrane sekundarne metabolite ječmena (Hordeum vulgare)

Vidic, Martina (author), Laznik, Žiga (mentor)

V raziskavi smo preučevali kemotaksični odziv treh vrst parazitskih ogorčic polžev (Phasmarhabditis papillosa, Oscheius myriophilus in Oscheius onirici) na hlapne organske spojine (HOS), ki jih izločajo korenine ječmena (Hordeum vulgare L.). V poskus smo vključili štiri spojine: dimetil sulfid (DMS), heksanal (H), 2-pentilfuran (2PF) in (E)-non-2-enal (N2E), ter njihove sintetične mešanice. Poskusi so potekali pri dveh temperaturah (18 °C in 22 °C) na agarnem gojišču, kjer smo spremljali gibanje ogorčic v odziv na posamezne snovi in njihove kombinacije. Rezultati so pokazali značilne razlike med vrstami, spojinami in temperaturnimi obravnavanji. Najmočnejši privabilni učinek sta imela 2-pentilfuran (2PF) in dimetil sulfid (DMS), zlasti pri vrstah O. myriophilus in P. papillosa, kar nakazuje, da ti dve spojini igrata pomembno vlogo pri privabljanju ogorčic. Nasprotno pa sta aldehida heksanal (H) in (E)-non-2-enal (N2E) povzročila šibkejše ali celo odvračilne odzive, kar bi lahko bilo povezano z njuno vlogo pri signalizaciji stresa ali razgradnje rastlinskega tkiva. Pri mešanicah HOS so bili odzivi bolj kompleksni – v nekaterih primerih so kombinacije povečale privlačnost (npr. DMS × 2PF), v drugih pa so povzročile zmanjšano aktivnost, kar kaže na možne antagonistične ali maskirne učinke med spojinami. Temperatura je pomembno vplivala na izraženost kemotaksičnega odziva. Višja temperatura (22 °C) je povečala splošno gibanje in odzivnost ogorčic na posamezne HOS, kar nakazuje, da okoljski dejavniki pomembno vplivajo na njihovo vedenje. Največjo aktivnost je pokazala vrsta O. myriophilus, ki je v vseh obravnavanjih izkazovala najvišjo stopnjo privlačnosti k testiranim spojinam. Skupno rezultati potrjujejo, da so odzivi parazitskih ogorčic vrstno specifični, temperaturno odvisni in pogojeni s sestavo hlapnih signalov, ki jih izločajo rastline. Spoznanja prispevajo k boljšemu razumevanju kemijske ekologije parazitskih ogorčic ter predstavljajo osnovo za razvoj biotičnih pristopov zatiranja polžev, prilagojenih posameznim vrstam ogorčic in okoljskim razmeram.

• Language: Slovenian
• Keywords: kemotaksični odziv, parazitska ogorčica, Oscheius myriophilus, Phasmarhabditis papillosa, Oscheius onirici, sekundarni metaboliti, koncentracija, temperatura, usmerjeno gibanje, način iskanja gostitelja, ječmen
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Year: 2026
• PID: 20.500.12556/RUL-189893
• COBISS.SI-ID: 301443075
• Publication date in RUL: 18.10.2026

Secondary language

• Language: English
• Title: Chemotactic response of parasitic nematodes (Rhabditidae) to selected secondary metabolites of barley (Hordeum vulgare)

Abstract

In this study, we investigated the chemotactic response of three species of slug-parasitic nematodes (Phasmarhabditis papillosa, Oscheius myriophilus, and Oscheius onirici) to volatile organic compounds (VOCs) emitted by barley (Hordeum vulgare L.) roots. Four VOCs were tested: dimethyl sulfide (DMS), hexanal (H), 2-pentylfuran (2PF), and (E)-non-2-enal (N2E), as well as their synthetic mixtures. Experiments were conducted at two temperatures (18 °C and 22 °C) on agar plates, where nematode movement was monitored in response to individual compounds and their combinations. The results revealed significant differences among species, compounds, and temperature treatments. The strongest attraction was recorded for 2-pentylfuran (2PF) and dimethyl sulfide (DMS), particularly for O. myriophilus and P. papillosa, suggesting that these two compounds play an important role in nematode host-searching behavior. In contrast, the aldehydes hexanal (H) and (E)-non-2-enal (N2E) elicited weaker or even repellent responses, which may be related to their function as stress or decay signals in plants. Responses to VOC mixtures were more complex—some combinations (e.g., DMS × 2PF) enhanced attraction, while others reduced chemotactic activity, indicating possible antagonistic or masking effects between compounds. Temperature significantly affected chemotactic behavior. The higher temperature (22 °C) increased overall movement and responsiveness of nematodes to individual VOCs, highlighting the role of environmental conditions in shaping nematode activity. O. myriophilus exhibited the highest activity across all treatments, showing the greatest attraction to the tested compounds. Overall, the results confirm that the responses of slug-parasitic nematodes are species-specific, temperature-dependent, and influenced by the composition of volatile signals released by plants. These findings contribute to a better understanding of the chemical ecology of slug-parasitic nematodes and provide a foundation for developing biocontrol strategies tailored to specific nematode species and environmental conditions.

• Keywords: chemotactic response, parasitic nematode, Oscheius myriophilus, Phasmarhabditis papillosa, Oscheius onirici, secondary metabolites, temperature, concentration, directed movement, barley