Abstract
Terpenoids play a crucial role in plant–insect interactions and are the most significant group of natural plant compounds, functioning as attractants, feeding deterrents, and toxins. This study analyzed the phytochemical composition of healthy leaves (HL) and galled leaves (GL) of Milicia excelsa that were 32 and 64 weeks old using standard techniques and Gas Chromatography-Mass Spectrometry. Gas Chromatography-Mass Spectrometry was used to evaluate phytochemical contents in extracts of GLs and HLs. The data were examined using descriptive statistics, and means were compared using analysis of variance (ANOVA) with a significance level of p=.05. Alkaloid levels were elevated in GL (2.44 ± 0.02%) and reduced in HL (2.12 ± 0.03%) by week 32. The concentrations of saponins, terpenoids, tannins, and flavonoids fell from 0.09 ± 2.08 mg/g, 0.55 ± 0.01 mg/g, 0.44 ± 0.45 mg/g, and 0.49 ± 0.08 mg/g in HL to 0.01 ± 0.01 mg/g, 0.16 ± 0.07 mg/g, 0.23 ± 0.06 mg/g, and 0.23 ± 0.06 mg/g in GL by week 32. By week 64, GL had higher levels of saponins (0.25 ± 0.16 mg/g) and alkaloids (6.30 ± 0.14%) compared to HL, which had lower levels of saponins (0.17 ± 2.08 mg/g) and alkaloids (3.78 ± 0.13%). Healthy leaf had higher levels of terpenoids (0.70 ± 0.31 mg/g),
tannins (0.84 ± 0.85 mg/g), and flavonoids (0.73 ± 0.39 mg/g) compared to GL, which had lower levels of terpenoids (0.54 ± 0.43 mg/g), tannins (0.57 ± 0.65 mg/g), and flavonoids (0.50 ± 0.19 mg/g). Terpenoids found in HL were not detected in GL at week 64. The high concentration of terpenoids in the HL of M. excelsa may suggest its appeal to Phytolyma fusca.
Cite this article as: Olorunnibe, V. N., Omoloye, A. A., & Alabi, O. Y. (2025). Abundance of terpenoids in Milicia excelsa as an indicator of attractants to the gall bug, Phytolyma fusca walker. Forestist, 75, 0018, doi: 10.5152/ forestist.2025.24018.