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Promoting smallholding farmers to use improved storage technology is pivotal to enhance the sustainable agri-food system. Studies suggest that hermetic storage technology reduces post-harvest storage losses, improves grain quality, and enhances food security. However, weak causal evidence is prevalent due to confounding and endogeneity issues in such studies. Hence, this study examines the impact of hermetic storage bags through a randomized encouragement design, using the instrumental variable (IV) approach, among 692 smallholding farmers in Nepal, where maize is one of the major food crops. Farmers were encouraged by offers of 100% and 50% subsidies on the price of up to three Purdue Improved Crop Storage (PICS) bags. We found that an additional unit of the hermetic storage bag increased maize storage by 42.84 kg and reduced post-harvest storage losses by 10 kg (32.92% reduction) for the farmers encouraged with a 100% subsidy. It increased maize storage by 39.2 kg for the farmers encouraged with a 50% subsidy, with no significant effect on post-harvest storage losses in this group compared to the control group. Thus, it is essential to encourage farmers to adopt improved storage technologies to increase storage and reduce post-harvest losses. This can contribute to enhancing local food security.

Grain storage loss is a major contributor to post-harvest losses and is one of the main causes of food insecurity for smallholder farmers in developing countries. Thus, the objective of this review is to assess the conventional and emerging grain storage practices for smallholder farmers in developing countries and highlight their most promising features and drawbacks. Smallholder farmers in developing countries use conventional grain storage structures and handling systems such as woven bags or cribs to store grain. However, they are ineffective against mold and insects already present in the grain before storage. Different chemicals are also mixed with grain to improve grain storability. Hermetic storage systems are effective alternatives for grain storage as they have minimal storage losses without using any chemicals. However, hermetic bags are prone to damage and hermetic metal silos are cost-prohibitive to most smallholder farmers in developing countries. Thus, an ideal grain storage system for smallholder farmers should be hermetically sealable, mechanically durable, and cost-effective compared to the conventional storage options. Such a storage system will help reduce grain storage losses, maintain grain quality and contribute to reducing food insecurity for smallholder farmers in developing countries.

The current study assessed the effectiveness of five conventional and three hermetic storage facilities for extended storage of wheat grains under ambient storage conditions during two storage seasons (2023 and 2024). The findings indicated that hermetic storage facilities outperformed conventional ones throughout the six-month storage period. For instance, GrainPro PHB exhibited the minimal increase in grain moisture contents (0.50 and 0.33%), resulting in the least grain damage (2.38 and 2.44%) and weight loss (0.93 and 0.93%) during both years, respectively. Additionally, GrainPro PHB recorded the highest seed germination (90.50 and 90.33%) for both years. Compared to conventional storage methods, GrainPro PHB exhibited a lower number of storage insects. The proximate composition analysis revealed significant nutritional differences between polypropylene bags and GrainPro PHB. GrainPro PHB successfully maintained proximate composition, with minimal decreases in protein (1.03 and 0.71%), fat (16.88 and 14.95%), and starch content (0.8 and 0.5%) and minimal increases in ash (25.00 and 23.33%) and fiber contents (18.33 and 16.80%) in both years. Moreover, results revealed a positive correlation between grain moisture contents and damage parameters, suggesting that the higher moisture contents may aggravate the percent grain damage and weight loss. There were also better rheological properties in flour made from grains stored in GrainPro PHB, like a lower minimum water absorption capacity (WAC), a longer dough development time (DDT), and a maximum dough stability time (DST). Furthermore, texture profile analysis (TPA) of bread made from flour of grains stored in GrainPro PHB showed improved texture, with higher chewiness, cohesiveness, springiness, and resilience, and lower hardness, resulting in superior overall quality compared to bread made from conventionally stored grains. Eventually, these findings underscore the effectiveness of hermetic storage facilities in maintaining grain moisture contents, reducing losses, preserving seed quality, and enhancing food and nutrition security.

The performance of six grain storage technologies for the control of insect pests in maize was evaluated over a 36-week (9-month) storage period. The six technologies used were: two ZeroFly® hermetic bag brands (laminated and non-laminated); Purdue Improved Crop Storage (PICS) bag; non-hermetic ZeroFly® bag; woven polypropylene (PP) bag containing maize grain treated with Actellic Gold® Dust (pirimiphos-methyl 1.6% + thiamethoxam 0.3%) and woven PP bag containing untreated grain. Each bag was filled with 50 kg maize grain and four replicates of each were set up. With the exception of the non-hermetic ZeroFly® bag, 50 live adults of the larger grain borer Prostephanus truncatus and of the maize weevil Sitophilus zeamais, were introduced into all the bags. Insects were not introduced into the non-hermetic ZeroFly® bag to assess its effectiveness in repelling infestation from outside. Parameters recorded were gas composition (oxygen and carbon dioxide) levels inside the bags; weight of flour generated by insect feeding activities; grain moisture level; live adult insect counts; grain damage and weight loss; grain germination rate and aflatoxin level. At termination, the plastic liners of the hermetic bags were examined for perforations. Results show that oxygen depletion and carbon dioxide evolution were faster in ZeroFly® hermetic compared to PICS bags. Throughout the 36-week storage trial, grain damage remained below 4% and weight loss below 3% in all the treatments except in the untreated PP bags in which it increased to 81.1 and 25.5%, respectively. The hermetic PICS, ZeroFly® and Actellic Gold dust-treated PP bags maintained grain germination at 60%, which was lower than the initial 90%, while in untreated control, it reduced to 4.7%. The mean aflatoxin levels fluctuated between 0.39 and 3.56 parts per billion (ppb) during 24 weeks of storage in all the technologies tested, which is below the acceptable maximum level of 10 ppb in maize. Based on the evaluation results, it can be concluded that hermetic PICS and ZeroFly® bags and woven PP bag with Actellic Gold dust-treated grain effectively protected stored maize grain from insect attack and weight losses. Appropriate strategies and mechanisms for the effective and efficient adoption of hermetic storage bag technology at scale would contribute towards global food security.

Loss of stored plant products due to insect infestation is a problem that is likely to increase with global warming. Improved storage under hermetic conditions in oxygen deficiency can prevent or control infestation and preserve product quality. Oxygen levels in hermetic storage decrease due to different factors, one of which is the oxygen consumption of the insects present. Experiments were carried out using varying numbers (25, 50, or 200) of all developmental stages of the grain weevil Sitophilus granarius L. (eggs, larvae, pupae, and adult beetles) caged and placed in sealed 30-L containers containing 22 kg of wheat for at least 21 weeks. Oxygen levels were measured at regular intervals. The oxygen consumption depended on the number of insects and went below the critical threshold of 3% for S. granarius survival in most of the trials. Some surviving beetles were observed at the end of the hermetic experiments and 12 weeks afterwards during control for progeny, when oxygen levels did not fall below the critical threshold or the low level could not be maintained for a sufficient time. Monitoring oxygen levels in hermetic storage is therefore essential to ensure safe storage over long periods.

Modified atmospheres such as hermetic storage are widely used for the control of stored grain insect pests. To improve their effectiveness, there is need to better understand insect responses to low-oxygen environments. Adult Callosobruchus maculatus F. (Coleoptera: Chrysomelidae: Bruchinae) on cowpea and Sitophilus oryzae L. (Coleoptera: Curculionidae) on wheat were exposed to hypoxia treatments consisting of 1, 3, and 5% oxygen levels for 14 d. Acoustic activity was monitored during the experiment, and insect mortality and grain quality were examined immediately after the hypoxia treatments. Adult emergence was assessed 45 d post-treatment. All three hypoxia treatments eliminated acoustic activity of both species within 4 d. There was neither insect survival for both species nor significant grain damage immediately after 14-d exposure to hypoxia treatments. No adult insects emerged 45 d post-exposure on grains maintained at 1% oxygen level for 14 d. However, at 3 and 5% oxygen levels, there were eggs on cowpea, holes in wheat, and emerging adults for both insect species 45 d post-exposure. Although insect activity ceased within 4 d when hypoxia was maintained below 5%, there is need to explore exposure beyond 14 d for 3 and 5% oxygen levels, to ensure to avoid potential adult emergence from eggs and other insect life stages post-treatments. Maintaining 3–5% hypoxia conditions for a longer duration would ensure insufficient oxygen is available for progeny development.

Several postharvest technologies are currently being commercialized to help smallholder farmers in sub-Saharan Africa reduce grain storage losses. We carried out a study in Northern Benin to compare the effectiveness of five technologies being sold to protect stored grain. Maize that had been naturally infested by insects was stored in four hermetic storage technologies (SuperGrainbag™, AgroZ® bag, EVAL™, and Purdue Improved Crop Storage-PICS™ bags), an insecticide impregnated bag (ZeroFly®), and a regular polypropylene (PP) woven bag as control. Oxygen levels in hermetic bags fluctuated between 0.5 ± 0.0 (v/v) and 1.0 ± 0.3 (v/v) percent during the seven months of storage. No weight loss or insect damage was observed in grain stored in any of the hermetic storage bags after seven months. However, grain stored in ZeroFly® and PP woven bags had weight losses of 6.3% and 10.3%, respectively. These results will help farmers and development agencies when making decisions to use and/or promote storage technologies to reduce postharvest grain losses.

Fumigated dry common beans (Phaseolus vulgaris L.) that were artificially infested with Acanthoscelides obtectus Say, and others that were not artificially infested, were stored in hermetic triple-layer PICS (Lela Agro, Kano, Nigeria) or woven polypropylene (PP) bags for 6mo at ambient laboratory temperature conditions of 22.6 ± 1.9°C and 60.1 ± 4.3% relative humidity. In an additional trial, beans contained in PP bags were treated with Actellic Super dust before introducing A. obtectus. Moisture content, number of live adult A. obtectus, seed damage, weight loss, and seed germination were determined at monthly intervals. At 6 mo, beans stored in PICS bags retained higher moisture than those stored in PP bags, but in all treatments the moisture level remained below that recommended for safe storage of beans. In the PICS bags, proliferation of A. obtectus did not proceed and at 6 mo, beans stored in these bags did not have insect-inflicted seed damage or weight loss. In contrast, seed damage and weight loss in PP bags exceeded economic threshold after 1mo in the absence of Actellic Super dust (Syngenta Crop protection AG, Basle, Switzerland), and after 2mo in the presence of it. Germination of beans stored in PP bags decreased greatly whereas the beans stored in PICS bags did not show reduced germination. Chemical free storage of common beans in PICS bags protects them against damage by A. obtectus. Les haricots (Phaseolus vulgaris L.) fumigés puis artificiellement infestés avec Acanthoscelides obtectus Say, et non-infestes étaient stockés dans les sacs (PICS) à triple fonds ou dans les sacs nylons polypropylène (PP) pendant six mois dans les conditions ambiantes de laboratoire (température: 22.6 ± 1.9°C et humiditérelative: 60.1 ± 4.3%). Dans un autre essai, les haricots stockés dans les sacs nylons étaient traités avec la poudre d'Actellic Super avant d'introduire les insectes (A. obtectus). L'humidité des graines, le nombre d'insectes adultes vivants, les graines endommagées, la perte de poids, et la germination étaient mesurés mensuellement. Apres six mois de stockage, les haricots stockés dans les sacs PICS ont maintenu une humiditéélevée comparée à ceux stockés dans les sacs PP. Cependant, tous les traitements ont maintenu leur l'humiditédes grains en dessous du niveau recommandépour un bon stockage. Les sacs PICS ont arrêtéla prolifération de A. obtectus, les dommages des graines, et la perte de poids. En revanche, le dommage des graines et pertes en poids dans les sacs PP ont dépasséle seuil économique aprè s un mois sans traitement et deux mois avec traitement à l'Actellic Super. La germination des graines stockées dans les sacs PP a sensiblement diminuétandis que la germination des graines stockées dans les sacs PICS n'a pas étéréduite. Le stockage sans produit chimique des grains d'haricots dans les sacs PICS les protège contre les pertes post-récolte causées par A. obtectus.

Hermetic storage is of interest to farmers and warehouse managers as a method to control insect pests in small storage facilities. To develop improved understanding of effects of hermetic storage on insect pest activity and mortality over time, oxygen levels, acoustic signals, and observations of visual movement were recorded from replicates of 25, 50, and 100 adult Sitophilus oryzae (L.) (Coleoptera: Curculionidae) hermetically sealed in 500- and 1,000-ml glass jars. Recordings were done for 28 d; twice daily for the first 6 d and twice weekly thereafter. Insect sounds were analyzed as short bursts (trains) of impulses with spectra that matched average spectra (profiles) of previously verified insect sound impulses. Oxygen consumption was highest in treatments of 100 insects/500-ml jar and lowest in 25/1000-ml jars. The rates of bursts per insect, number of impulses per burst, and rates of burst impulses per insect decreased as the residual oxygen levels decreased in each treatment. Activity rates <0.02 bursts s–1, the acoustic detection threshold, typically occurred as oxygen fell below 5%. Mortality was observed at 2% levels. The time to obtain these levels of insect activity and oxygen depletion ranged from 3–14 d depending on initial infestation levels. Acoustic detection made it possible to estimate the duration required for reduction of insect activity to levels resulting in negligible damage to the stored product under hermetic conditions. Such information is of value to farmers and warehouse managers attempting to reduce pest damage in stored crops.

Seed storage life in tropical areas is shortened by high humidity and temperature and the general inaccessibility to dehumidifying and refrigeration systems, resulting in rapid decreases in seed viability in storage as well as a high incidence of fungal and insect infestations. The dry chain, based on rapid and deep drying of seeds after harvest followed by packaging in moisture-proof containers, has been proposed as an effective method to maintain seed quality during medium-term storage in humid climates, even without refrigeration. In addition, seed drying with zeolite drying beads can be more effective and economical than sun or heated-air drying under these warm, humid conditions. In this paper, we review recent published literature regarding the dry chain, considering different crop species, storage environments and seed traits. In addition, we provide new original data on the application of dry chain methods and their implementation at larger scales in South Asia, Latin America and Pacific Island Countries. The clear conclusion is that the combination of reusable drying beads and waterproof storage containers enables the implementation of the dry chain in tropical climates, enhancing seed viability and quality in storage of many crop species. The dry chain approach can therefore significantly enhance seed security for farmers in many tropical countries. Finally, we propose actions and strategies that could guide further scaling-up implementation of this technology.