SYNERGISTIC CONTACT ACTIVITY CONSTITUENTS OF Acorus gramineus AND Rosmarinus officinalis ESSENTIAL OILS AGAINST Sitophilus oryzae

Authors: Bo Kong, Xianhui Zhou
Journal: Journal of Animal and Plant Sciences (JAPS)
ISSN: 1018-7081 (Print), 2309-8694 (Online)
Volume: 37  Issue: 1  
Year: 2027
DOI: https://doi.org/10.36899/JAPS.2027.1.0010
URL: https://doi.org/https://doi.org/10.36899/JAPS.2027.1.0010
Publisher: Pakistan Agricultural Scientists Forum

Abstract:
<h1 style="margin-top: 12pt; text-align: justify; text-indent: 0in; line-height: 1.2;"><span style="font-size: 12pt;"><span style="font-family: 'Times New Roman', serif; color: black; font-weight: normal;">Plant </span><span style="font-family: 'Times New Roman', serif; color: black; font-weight: normal;">essential</span><span style="font-family: 'Times New Roman', serif; color: black; font-weight: normal;"> oils exhibit multiple insecticidal activities and serve as an important source of botanical insecticides. This study evaluated the contact toxicity of 26 plant essential oils, alone and in binary mixtures, against <em style="mso-bidi-font-style: normal;">Sitophilus oryzae</em> (Coleoptera: Curculionidae; Linnaeus, 1763). Essential oils were extracted by steam distillation. The active constituents of the two oils with the strongest individual and combined activities were identified by gas chromatography-mass spectrometery and a&nbsp;<span style="mso-bookmark: OLE_LINK5;">compound-elimination assay</span>. The essential oil of <em style="mso-bidi-font-style: normal;">Acorus gramineus</em> (Acorales: Acoraceae; Aiton, 1789) showed the strongest contact toxicity against <em>Sitophilus oryzae</em>, with an LD<sub>50</sub> value of 4.01 &mu;g/adult. When <em>Acorus</em><em style="mso-bidi-font-style: normal;"> gramineus</em> oil was combined with the other 25 oils, <em style="mso-bidi-font-style: normal;">Rosmarinus officinalis</em> (Lamiales: Lamiaceae; Linnaeus, 1753) oil produced the strongest synergistic effect, with a co-toxicity factor of 60.87. The major constituents of <em>Acorus</em><em style="mso-bidi-font-style: normal;"> gramineus</em> oil were &beta;-asarone (69.94%), isoeugenol methyl ether (14.04%) and aristolone (5.14%), whereas those of <em>Rosmarinus</em><em style="mso-bidi-font-style: normal;"> officinalis</em> oil were patchouli alcohol (64.33%), eucalyptol (8.63%), (+)-2-bornanone (5.56%) and L(-)-borneol (4.49%). The compound-elimination assay identified &beta;-asarone and patchouli alcohol as the principal active constituents of <em>Acorus</em><em style="mso-bidi-font-style: normal;"> gramineus</em> and <em>Rosmarinus</em><em style="mso-bidi-font-style: normal;"> officinalis</em> oils, with LD<sub>50</sub> values of 3.82 and 39.93 &mu;g/adult, respectively. &beta;-Asarone showed stronger contact toxicity than <em>Acorus gramineus</em> essential oil. A mixture of &beta;-asarone and patchouli alcohol at a volume ratio of 1:9 had an LD<sub>50</sub> value of 35.42 &mu;g/adult and a synergistic ratio of 0.58, indicating an additive effect. <em>Acorus</em><em style="mso-bidi-font-style: normal;"> gramineus</em> essential oil showed strong contact toxicity against <em>Sitophilus oryzae</em>. Its combination with <em>Rosmarinus</em><em style="mso-bidi-font-style: normal;"> officinalis</em> oil produced the strongest synergistic effect among the tested oil mixtures. The main active constituents were &beta;-asarone and patchouli alcohol, and their binary mixture showed additive contact toxicity against <em>Sitophilus oryzae</em>.</span></span></h1>

Keywords: β-asarone; patchouli alcohol; Sitophilus oryzae; compound-elimination assay; binary mixture