Comparative Study of Cowpea Storage Technologies in the Sahel Region of Niger

SIMPLE SUMMARY: Cowpea farmers in the West Africa lose a significant portion of their crop during storage due to insects (cowpea weevil). To help farmers deal with this issue, we tested several storage technologies including hermetic (SuperGrainbag(TM), AgroZ(®) bag, EVAL(TM), and Purdue Improved Crop Storage-PICS(TM) bags), an insecticide-treated woven bag (ZeroFly(®)), and a polypropylene (PP) woven bag. After 8 months of storage, we observed that all hermetic bags were effective at maintain the quality of cowpea. No further damage and weight loss was observed in grain stored in hermetic bags; germination decreased modestly, by a maximum of 16%. However, grain stored in ZeroFly(®) and woven bags continued to deteriorate during the storage period due to continued insect population growth, resulting in weight loss of about 25%. Loss in germination was more serious in cowpea stored in the ZeroFly(®) (37.0%) and woven bags (28.8%) than in hermetic bags. Farmers and development agencies in the West Africa (particularly in the Sahel) can use and/or recommend these hermetic technologies to greatly reduce cowpea storage losses due to insects. ABSTRACT: Cowpea stored on smallholders’ farms suffers serious losses to insect pests. A study conducted in Niger compared five postharvest technologies marketed in sub-Saharan Africa to protect stored grain. Naturally-infested cowpea stored for eight months showed adult Callosobruchus maculatus (F.) mortality of 97% to 100% in the hermetic bags (PICS(TM), SuperGrainbag(TM), AgroZ(®), EVAL™, and ZeroFly(®) bags). There was no change in grain damage and weight loss of cowpea stored in hermetic bags. There was, however, a loss of up to 10 to 16% in germination when the grain was stored in hermetic bags. Results observed for grain stored in ZeroFly(®) bags impregnated with deltamethrin were substantial and similar to those in control woven bags. In both ZeroFly(®) and woven bags, (1) adult C. maculatus population augmented by 35.7% and 78.6%, (2) increased weight losses of 27.3% and 25.2%, and (3) reduced germination of 37.0% and 28.8%, respectively. After opening the bags, abrasions were noted on the liners of hermetic bags, potential damage that could limit their reuse if they only have a single liner. Smallholder farmers in the Sahel can safely store their cowpea in all the hermetic bags tested. However, further research is needed to mitigate insect damage on liners of hermetic bags to improve their performance and reusability.