Bioefficacy of essential and vegetable oils of Zanthoxylum xanthoxyloides seeds against Acanthoscelides obtectus (Say) (Coleoptera: Bruchidae).

Experiments were conducted in the laboratory to evaluate the bioefficacy of essential and vegetable oils of Zanthoxylum xanthoxyloides (Rutaceae) against Acanthoscelides obtectus (Coleoptera: Bruchidae). The chemical composition of the essential oil and the fatty acid composition of the vegetable oil extracted from the seeds of Z. xanthoxyloides were determined. The insecticidal activities of these oils and the associated aromatized clay powder were evaluated against A. obtectus. Both oils were strongly repellent (100% repellency at 0.501 µl/cm² essential oil and 3.144 µl/cm² vegetable oil) and highly toxic (LC50 = 0.118 µl/cm² for essential oil) to this beetle after contact on filter paper. The vapors of the essential oil were highly toxic to adult insects (LC50 = 0.044 µl/cm³), and the aromatized powder made from clay and essential oil was more toxic (LD50 = 0.137 µl/g) than the essential oil alone (LD50 = 0.193 µl/g) after 2 days of exposure on a common bean. Both oils greatly reduced the F1 insect production and bean weight loss and did not adversely affect the bean seed viability. In general, the results obtained indicate that these plant oils can be used for control of A. obtectus in stored beans.

Near infrared spectroscopy for high-throughput characterization of Shea tree (Vitellaria paradoxa) nut fat profiles.

The Shea tree (Vitellaria paradoxa) is a major tree species in African agroforestry systems. Butter extracted from its nuts offers an opportunity for sustainable development in Sudanian countries and an attractive potential for the food and cosmetics industries. The purpose of this study was to develop near-infrared spectroscopy (NIRS) calibrations to characterize Shea nut fat profiles. Powders prepared from nuts collected from 624 trees in five African countries (Senegal, Mali, Burkina Faso, Ghana and Uganda) were analyzed for moisture content, fat content using solvent extraction, and fatty acid profiles using gas chromatography. Results confirmed the differences between East and West African Shea nut fat composition: eastern nuts had significantly higher fat and oleic acid contents. Near infrared reflectance spectra were recorded for each sample. Ten percent of the samples were randomly selected for validation and the remaining samples used for calibration. For each constituent, calibration equations were developed using modified partial least squares (MPLS) regression. The equation performances were evaluated using the ratio performance to deviation (RPD(p)) and R(p)(2) parameters, obtained by comparison of the validation set NIR predictions and corresponding laboratory values. Moisture (RPD(p) = 4.45; R(p)(2) = 0.95) and fat (RPD(p) = 5.6; R(p)(2) = 0.97) calibrations enabled accurate determination of these traits. NIR models for stearic (RPD(p) = 6.26; R(p)(2) = 0.98) and oleic (RPD(p) = 7.91; R(p)(2) = 0.99) acids were highly efficient and enabled sharp characterization of these two major Shea butter fatty acids. This study demonstrated the ability of near-infrared spectroscopy for high-throughput phenotyping of Shea nuts.