Hermetic storage technologies reduce maize pest damage in smallholder farming systems in Mexico. (September 2020) - Odjo, Sylvanus
Abstract: In Mexico, smallholder farmers use a variety of technologies to store their maize grain for several months, which may result in high losses in quantity and quality of grain. This work compared the effectiveness of different storage technologies for minimizing losses in smallholder conditions in 109 different locations from 21 to 2816 m above sea level (asl) across different agroecological zones of Mexico, under "controlled" (i.e. managed by researchers), and "non-controlled" conditions (i.e. on-farm managed by extension agents). Depending on the common practice at each site, conventional storage technologies (polypropylene bag with and/or without insecticide) were compared to alternative storage technologies (selected from hermetic metal silos, hermetic bags, recycled plastic containers, silage plastic bags, and inert dusts-micronized and standard lime) during one to 12 months. Data on grain damages were collected at the beginning and end of the storage period. Climatic variables and initial grain infestation with pests influenced the ability of a technology to minimize losses, particularly under tropical conditions. After six months of storage, percentages of insect-damaged grain with polypropylene bags, the most common farmers' practice, were 39.4% and 4.1%, respectively, in lowlands (<500 m asl) and highlands (>2000 m asl). With hermetic metal silos, percentages of insect-damaged grain after six months of storage were 3.8% on average in the highlands and similar in lowlands, with 2.9%. Hermetic technologies, which prevent the introduction of oxygen, were effective in reducing losses under farmers' conditions across agroecological areas, regardless of storage time. Recycled hermetic containers had similar results and were a viable low-cost alternative to more expensive options like hermetic metal silos. With adequate technical support for their appropriate use, hermetic technologies have the potential to reduce grain losses during storage and strengthen food security in Mexico and Latin American countries with similar conditions. Highlights: Postharvest losses during storage in Mexico are mainly caused by insects and fungi. Evaluation of 10 grain storage technologies for maize across agroecological zones. Hermetic silos and hermetic bags minimize losses regardless of storage conditions. Plastic barrels and plastic bottles are effective low-cost storage alternatives. Non-hermetic technologies failed to reduce losses in tropical conditions.