Chemical composition and insecticidal activity of the essential oils of Crateva Adansonii dc. Leaf on Sitophilus Zeamais and Callosobrunchus Maculatus
This study was conducted to determine the insecticidal activity of essential oil of Crateva adansonii against adult S. zeamaise and C. maculatus. The essential oil was obtained from the leaves of the plant using a Clevenger apparatus and analyzed by gas chromatography and mass spectrometry (GC/MS). The experimental data generated from the insecticidal assay results were analysed using statistical tool (ANOVA). GC/MS analysis revealed the presence of 52 compounds but with a low total yield of volatile fractions (0.1%). The major constituents of the oil were n-hexadecanoic acid (palmitic acid) (14.68%), Phytol (14.21%), 9,12-octadecanoic acid (Z,Z)- (linoleic acid)(5.81%), linalool (5.75%). Insecticidal bioassays showed that Crateva adansonii oil had a strong insecticidal activity on adult test insects they were exposed to at different concentrations and periods. An increase in the exposure time from 24 h to 72 h caused increase in mortality from 35.5% to 100% in S. zeamais and 31.1% to 100% in C. maculatus, respectively. According to these results, Crateva adansonii essential oil can be useful as an alternative for beans and maize protection against C. maculatus and S. zeamais.
Key words: Insecticidal Bioassays, C. maculatus, S. zeamais, Crateva adansonii, Essential Oil,