Evolution of the Merchantability during Storage of Cowpeas (Vigna unguiculata L Walp) Bagged Pics Containing a Biopesticide (Lippia multiflora Moldenke)

Aims: This study was undertaken to evaluate the merchantability of bagged PICS cowpea (Vigna unguiculata L Walp) containing a biopesticide (leaves of Lippia multiflora Moldenke) during storage.

Study Design: Cowpea grains were collected from April to May 2015 in the Southwest of Côte d’Ivoire and the fresh leaves of Lippia multiflora were dried in sunlight for 7 days and chopped before using as biopesticide. The storage bags used were from Purdue Improved Cowpea Storage (PICS) developed by Purdue University for storing cowpeas from Niger.

Place and Duration of the Study: This study was carried out during June 2015 to February 2016 in the Laboratory of Biochemistry and Food Science, Félix Houphouët-Boigny University, Côte d’Ivoire.

Methodology: For the storage of cowpea seeds, 6 lots (1 control polypropylene bag, 1 control PICS bag, and 4 lots in PICS bags with biopesticide) were used. The 4 lots in PICS bags were filled with different proportions of biopesticides (0.7%, 2.5%, 4.3% and 5% of chopped dried leaves per bag). The filling of the bags (50 kg) was done in stratum, alternating cowpea seeds and leaves of Lippia multiflora. Changes in moisture, weight losses and damages caused by insects were then evaluated after 0, 1, 2, 4.5, 7 and 8 months.

Results: Moisture content, weight losses and damages of the control without PICS (polypropylene bags) were respectively 14.67 ± 0.15%, 22.03 ± 0.25% and 43.14 ± 2.79%, respectively at 4.5 months. For the control PICS bag without biopesticide, the values of moisture content, weight losses and damages were 14.10 ± 0.11%, 19.20 ± 1.74% and 37.77 ± 3.27% after 8 months of storage, respectively. The moisture values, weight losses and damages in PICS bags of cowpeas treated with biopesticides were low and less than, 12.10 ± 0.10%, 4.03 ± 0.27% 11.18 ± 0.01%.

Conclusion: Adding Lipppia multiflora leaves in PICS bags for storage allows a good preservation and merchantability of cowpeas grains after 8 months.