Chemical composition and insecticidal potential of bioactive fractions from Brucea antidysenteric (abalo) stem bark extract against Sitophilus zeamais

For pest control, the use of botanical insecticides can be an effective alternative to synthetic insecticides. The objective of this study is to analyze the chemical composition and evaluate the insecticidal potential of B. antidysenterica stem bark extract as a natural alternative for controlling maize weevils. A fractionated extract was obtained by macerating and soaking the stem bark powder in n-hexane (1.36 ± 0.81%), chloroform (1.26 ± 0.43%), ethyl acetate (1.03 ± 0.47%), acetone (2.24 ± 0.75%), ethanol (3.01 ± 0.26%), and methanol (2.1 ± 0.9). The experimental tests for the insecticidal potential of each crude extract were conducted at different concentrations (0.025, 0.05, and 0.1 g/mL) on adult maize weevils to investigate the mortality rate, seed damage, and grain weight loss using contact bioassay method. The experiment was conducted in a completely randomized design with three replications. The data were analyzed using two-way ANOVA with the Tukey test for mean comparison. After 72 h, all extracts demonstrated high insect mortality while concurrently reducing grain damage and weight loss. However, ethanolic extract was the most effective at 0.1 g/mL with insect mortality (79 ± 1%), grain damage (18 ± 041%), and weight loss (21.6 ± 11%). GC-MS analysis of the ethanol extract identified forty-one compounds, mainly fatty acid esters, other esters, phenols, alkenes, and terpenoids. The presence of these bioactive compounds contributed to its strong insecticidal activity. Overall, the findings highlight the potential of B. antidysenterica ethanol extract as a promising natural alternative to synthetic insecticides.