COMPARATIVE STUDY OF THE INSECTICIDAL ACTIVITY OF ESSENTIAL OILS OBTAINED BY HYDRODISTILLATION OF DRIED LEAVES FROM TWO MYRTACEAE SPECIES CALLISTEMON VIMINALIS AND MELALEUCA LEUCADENDRA AGAINST SITOPHILUS ZEAMAIS (MOTSCHULSKY, 1855)
Adama Faye, El Hadji Gorgui Diouf*, Alioune Diouf, Mamadou Latyr Ndour, Toffène Diome, Adama Ndiaye
ABSTRACT
Background: Post-harvest maize storage is threatened by Sitophilus zeamais, a major pest in sub-Saharan Africa, traditionally controlled using synthetic insecticides with recognized toxicological concerns. Aim: This study compared the bioinsecticidal potential of essential oils (EOs) from dried leaves of Callistemon viminalis and Melaleuca leucadendra, obtained by hydrodistillation and characterized by GC/MS. Methods: Insecticidal activity was evaluated against adult S. zeamais at four doses (D1-D4), with corrected mortality monitored over 29 days. Data were analysed using three-factor ANOVA (Plant × Dose × Time) followed by Tukey’s test. Results: EO yield was significantly higher in C. viminalis (5.032 ± 0.014%) than in M. leucadendra (1,684 ± 0,210%). GC/MS revealed contrasting chemical profiles: C. viminalis contained phenylpropanoids (eugenol, meta-eugenol and methyleugenol; 16.94%) and phytol (12.21%), whereas M. leucadendra was dominated by hydrocarbon sesquiterpenes, mainly β-humulene and aromadendrene (53.01%), with no phenylpropanoids detected. C. viminalis produced rapid and pronounced insecticidal activity, reaching 99-100% mortality within 24 h, with an overall mean mortality of 81.00%. In contrast, M. leucadendra showed lower efficacy (40.7%) and a marked dose-dependent response. The difference was highly significant (F = 154.84; p < 0.001). Conclusion: C. viminalis appears more promising for botanical protection of stored maize, potentially due to the combined effects of its major bioactive constituents.
Keywords: Callistemon viminalis, Melaleuca leucadendra, essential oil, Sitophilus zeamais, insecticidal activity, GC/MS.
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