Biopesticidal value of Senecio glaucus subsp. coronopifolius essential oil against pathogenic fungi, nematodes, and mites

Essential oils are widely investigated as an alternative or complementary approach to broad-spectrum synthetic pesticides. In the present study, essential oil of Senecio glaucus subsp. coronopifolius was screened for its antifungal, nematicidal, acaricidal and repellent activities against the phytopathogens Botrytis cinerea, Meloidogyne javanica and Tetranychus urticae Koch under laboratory conditions. The volatile phase method (VF) and poisoned food method (PF) were adopted to test the antifungal activity of the essential oil. The oil gave 83% inhibition at 16 μL/ml using the PF method. VF method showed 86% inhibition of mycelial growth of B. cinerea at 0.8 μL/ml air. To check the nematicidal activity of the essential oil, two bioassays targeted the mortality of second stage juvenile (J2) and hatch inhibition of M. javanica eggs. 95% immobility of J2 and 92% inhibition of egg hatch were recorded at 16,000 ppm. The effect exerted by the oil was nematostatic. In the case of mites, a leaf dip bioassay revealed 100% mortality of T. urticae adults, and repellency of 24% after exposure to the oil at 80% concentration. Chemical profile of S. glaucus essential oil was obtained using GC–MS. Terpenic compounds, such as indicated α-pinene (26.2%), myrcene (11.4%), p-cymene (9.9%), β-pinene (7.7%), γ-muurolene (4%), deoxynivalenol (3.1%) and α-phellandrene (2.7%) were identified as the major components. The findings indicated that S. glaucus essential oil has the potential for management of these pathogens.