Comparative performance of five hermetic bag brands during on-farm smallholder cowpea (Vigna unguiculata L.Walp) storage

Cowpea (Vigna unguiculata L. Walp) grain is an important source of protein for smallholder farmers in developing countries. However, cowpea grain is highly susceptible to bruchid attack, resulting in high quantitative and qualitative postharvest losses (PHLs). We evaluated the performance of five different hermetic bag brands for cowpea grain storage in two contrasting agro-ecological zones of Zimbabwe (Guruve and Mbire districts) for an 8-month storage period during the 2017/18 and 2018/19 storage seasons. The hermetic bag treatments evaluated included: GrainPro Super Grain bags (SGB) IVR™; PICS bags; AgroZ® Ordinary bags; AgroZ® Plus bags; ZeroFly® hermetic bags. These were compared to untreated grain in a polypropylene bag (negative control) and Actellic Gold Dust® (positive chemical control). All treatments were housed in farmers’ stores and were subjected to natural insect infestation. Hermetic bag treatments were significantly superior (p < 0.001) to non-hermetic storage in limiting grain damage, weight loss and insect population development during storage. However, rodent control is recommended, as rodent attack rendered some hermetic bags less effective. Actellic Gold Dust® was as effective as the hermetic bags. Callosobruchus rhodesianus (Pic.) populations increased within eight weeks of storage commencement, causing high damage and losses in both quality and quantity, with highest losses recorded in the untreated control. Cowpea grain stored in Mbire district sustained significantly higher insect population and damage than Guruve district which is ascribed to differences in environmental conditions. The parasitic wasp, Dinarmus basalis (Rondani) was suppressed by Actellic Gold Dust® and all hermetic treatments. All the hermetic bag brands tested are recommended for smallholder farmer use in reducing PHLs while enhancing environmental and worker safety, and food and nutrition security.     

Low permeability triple-layer plastic bags prevent losses of maize caused by insects in rural on-farm stores

Participatory on-farm trials were conducted to assess effectiveness of Purdue Improved Crop Storage (PICS?) bags for storage of maize in small-scale farmers’ stores in rural villages in eastern Kenya. A PICS bag is a three-layered hermetic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Jute, woven polypropylene or PICS bags were filled with shelled maize grain, purchased from the participating farmers, and the three sets of bags kept in the farmers’ own stores for 35 weeks. Oxygen and carbon dioxide levels in the PICS bags were monitored, as well as the temperature and relative humidity in all the bags. Grain moisture, live insect population, grain damage and weight loss were examined at intervals of seven weeks. Oxygen and carbon dioxide composition demonstrated that PICS bags are capable of sustaining good air-barrier properties under farmer storage conditions. Moreover, moisture content of maize stored in PICS bags did not change throughout the storage period whereas the moisture content of maize stored in polypropylene and jute bags decreased significantly in the final 14 weeks. Maize stored in PICS bags remained free from insect infestation and the weight loss due to insect damage was below 1 %. On the contrary, polypropylene and jute bags permitted profuse build-up of insect populations. At 35 weeks, grain damage reached 77.6 % and 82.3 % corresponding to 41.2 % and 48.5 % weight loss in the polypropylene and jute bags respectively. These findings demonstrate that PICS bags are effective in controlling losses caused by storage pests under farmer storage conditions.     

Effectiveness of grain storage facilities and protectants in controlling stored-maize insect pests in a climate-risk prone area of Shire Valley,Southern Malawi

Shire Valley is one of Malawi's most vulnerable areas to climate change (CC). In addition to other impacts, CC is expected to affect storage insect pest status, and the efficacy of grain storage facilities and protectants. On-farm grain storage trials were therefore conducted in Shire Valley to assess the performance of storage facilities and grain protectants against storage insect pests. Eight smallholder farmers hosted the trials in Thyolo and Chikwawa districts. Seven grain storage treatments were evaluated for 32 weeks during two storage seasons: Neem leaf powder (NM), Actellic Super dust (ASD), ZeroFly^® bag (ZFB), Purdue Improved Crop Storage bag (PICS), Super Grain Bag (SGB), hermetic metal silo (MS) and untreated grain in a polypropylene bag (PP). Insect pest populations and grain damage increased with storage duration and differed significantly between treatments (p < 0.05). Grain stored in hermetic bags (PICS, SGB) sustained significantly lower (p < 0.05) insect damage and weight loss compared to other treatments across sites and seasons. The hermetic bags also outperformed the other treatments in suppressing insect numbers. However, germination rates of undamaged grains stored in the hermetic storage facilities (MS, PICS, SGB) for 40 weeks were extremely low (<15%) compared to that of undamaged grains from NM treatment (53–58%) and the other treatments (>75%) at both sites. The hermetic MS, ZFB bags, ASD and NM treatments did not effectively protect grain from insect damage. High in-store mean temperature (35.6 °C) and high initial grain moisture content (13.7%) may have negatively affected efficacy of some treatments and seed germination. Tribolium castaneum survival in the MS requires further investigation. The hermetic storage bags (PICS, SGB) can be recommended for long-term maize grain storage (≥32 weeks) by smallholder farmers in Shire Valley and other similar climate change-prone areas in sub-Saharan Africa.     

Quantitative and quality losses caused by rodents in on-farm stored maize: a case study in the low land tropical zone of Kenya

Rodents are one of the major storage pests in on-farm maize storage in the tropics. However, information on actual magnitude of weight and quality losses caused by rodents in maize stores and species of rodent associated with the losses is scarce and if available would help to improve maize postharvest management. Maize stores of small-scale farmers in the lowland tropical zone of Kenya were monitored for actual weight losses caused by rodents and rodent trapping was conducted to determine species and estimate population of the rodents associated with the losses. Moulds and total aflatoxin contamination and nutritional value of rodent-damaged grain and non-damaged grain samples were also compared to evaluate the impact of rodent infestation on grain quality. In a sample of 20 farmers, we found that cumulative weight losses due to rodents ranged from 2.2 to 6.9% in shelled maize grain and from 5.2 to 18.3% in dehusked cobs after storage for 3 months. Rattus rattus was the only rodent species captured over the whole trapping period with a trap success rate of 0.6–10.0%. Total mould count, Fusarium spp. incidence and total aflatoxin contamination were significantly higher in rodent-damaged grains than in the non-damaged ones whereas no significant differences were observed for the incidence of Aspergillus spp. There were also significant decreases in dry-matter, fat, crude protein and fatty acid content in rodent-damaged grain compared to non-damaged grain. These findings show that rodents are a significant cause of postharvest losses in on-farm maize storage and impact negatively on food nutrition and safety. Mitigation strategies for postharvest losses should therefore include rodent control.     

Nutritional deterioration of stored Zea mays L. along supply chain in southwestern Ethiopia: Implication for unseen dietary hunger

Maize plays a key role in household food security in southwestern Ethiopia, but its benefits have been negated by high post-harvest losses. Previous loss assessment and management studies have focused mainly on quantity losses. This study was therefore designed to assess nutritional quality losses of stored maize along the supply chain in Jimma Zone, southwestern Ethiopia. Three districts representing potential maize producers and different agro-ecological regimes for maize production were selected for analyses. Sample collection started at harvest and continued for six months at two-month intervals from 21 selected actors along the supply chain. The experiment was conducted for two seasons, and a total of 72 samples were collected during each season. Both nutritional and anti-nutritional analyses were carried out following the international standards of the Association of Official Analytical Chemists. Data were analysed using SAS software (version 9.2) using a general linear model (GLM). The result revealed that moisture content significantly decreases (P < 0.05) as storage duration increases under different actors and agro-ecological conditions. But, showed increment during the final months under farmers' storage conditions. In addition, moisture content at the loading stage was not optimal for safe storage. Crude protein, crude fat, carbohydrate, and calorific value content significantly decreased (P < 0.05) as the storage duration increased, but fibre, ash, and major mineral (Ca, Zn, and Fe) content increased significantly over the storage period. Phytate and tannin content varied with storage duration and agro-ecological setting. Storing maize under traditional conditions along the supply chain resulted in substantial quality losses. This has great implications for nutrition insecurity and unrecognized undernourishment in the society. Additionally, substantial increases in fibre content above the optimum have important effects on nutrient absorption. There is thus a need to develop and disseminate appropriate storage technologies that minimize quality loss in maize stores.     

Grain size and grain depth restrict oxygen movement in leaky hermetic containers and contribute to protective effect

Postharvest insect pests threaten the nutritional and financial security of smallholder farmers in the developing world. Hermetic storage, a technology that protects grain against insects by blocking their supply of oxygen, alleviates the problem of insect-caused losses. PICS (Purdue Improved Crop Storage) bags represent one hermetic technology that improves food availability and incomes of farmers. The polyethylene liners of PICS bags are sometime damaged during use, acquiring small holes or tears. Observations in the laboratory and field suggest that insect development remains localized around the point where the bag is damaged. We hypothesized that the grain within a hermetic container that has minimal localized damage (such as an insect hole), helps retard leakage of oxygen into the bag and contributes to limiting insect damage and to the overall protective effect. To test this hypothesis, we filled 4 cm dia. by 10 cm long PVC pipes with Callosobruchus maculatus (F.) infested cowpeas and sealed them with caps having a single, insect-sized hole in its center. A vertical tube positioned above the cowpea-filled PVC pipe was filled with one of three different grains (sesame, sorghum, and maize) to different depths (0, 5, 15, 30, 50 cm). Seed size and grain barrier depth significantly reduced the level of bruchid damage to the stored cowpea in the PVC container. Smaller sized grains used for the barriers retarded insect development more effectively than larger sized grains, while deeper grain depth was more effective than shallower barriers. The grain held in a hermetic container contributes in a small, but significant, way to the effectiveness of the containers.     

Field effectiveness of improved hermetic storage technologies on maize grain quality in Central Mexico

Maize is the main crop cultivated by small scale farmers (SSF) in Mexico, and its production represents an important goal for local food security. However, SSF very often face severe post-harvest losses in maize, mainly because of insect pests and the lack of suitable storage technology. This study was conducted to compare the field effectiveness in terms of maize quality under on-field conditions of SSF of two improved hermetic storage technologies with the traditional storage. The field experiment was performed on-farm in the highlands of Central Mexico. Maize grains were stored in three storage devices: hermetic plastic bag (sBag), hermetic plastic silo (Bioxilo), or traditional polypropylene sacks. The study considered the quantitative evaluation of storage, physical, nutritional, and industrial qualities of maize after 4, 8 and 12 months of storage. Environmental conditions of storage such as oxygen levels, temperature and humidity were monitored. After 1 year of field storage, compared with traditional sacks, sBag and Bioxilo showed a significant lower losses in storage due to insects. When controlled infested maize by artificial insect infestation methods was used, the improved technologies were also effective in reducing grain losses. Furthermore, both sBag and Bioxilo prevented grain quality detriment in terms of physical, nutritional and industrial (for tortilla and seed) properties (p < 0.01). Additionally, compared with traditional storage, sBag and Bioxilo showed efficient control of the hermetic conditions in terms of oxygen, temperature and humidity, but no significant differences were detected between the two improved technologies. In summary, under on-farm conditions, the successful preservation of maize grain quality was achieved by the improved sBag and Bioxilo in the highlands of Mexico. In the future, positive effects of this storage system will need to be validated under tropical conditions.     

Effect of storage and insect infestation on the chemical composition and nutritive value of grain sorghums

Changes in the nutritional quality of four varieties (148, 3541, CSH-1 and LYJ) of jowar (Sorghum vulgare) grains when stored for prolonged periods under household (Indian) conditions were studied. Storage in a gunny bag or a metal bin for six to ten months at ambient temperature and humidity caused the grains to be infested by the common household pest Tribolium castaneum. The variety LYJ was least infested despite storage for ten months suggesting its resistance to insect attack. A commercial mercury preservative failed to protect the susceptible varieties from insect attack. The protein quality of grains, generally, remained unaffected by moderate insect infestation or storage per se. But high insect infestation (30%) caused a significant decrease in protein quality. Rats fed on diets based exclusively on jowar and small amounts of Bengal gram showed decreased growth of those rats fed grains from the most infested containers, but otherwise appeared normal. Blood haemoglobin, packed cell volume and liver vitamin A concentrations were similar in animals fed different diets. Liver histology was found to be normal in all animals. Insect-infested grains showed significant losses in total fat, mineral matter, thiamin and riboflavin.     

Physical quality of maize grain harvested and stored by smallholder farmers in the Northern highlands of Tanzania: Effects of harvesting and pre-storage handling practices in two marginally contrasting agro-locations

On-farm trials were conducted to investigate the effects of maize harvesting and handling practices of smallholder farmers on the quality of the produce before, and during storage in two contrasting agro-locations. Farmers harvested and prepared the crop according to local practices, and stored it in ordinary woven polypropylene bags for 30 weeks. Grain moisture, insect populations, insect-damage, moldy/diseased/discolored grain, rodent-damage, shriveled grain, broken grains, non-consumable grains, impurities, and overall losses were monitored. Moisture of the pre-stored grain ranged between 11.0 and 23.7% while the overall physical damage was 16.9 ± 6.2%. Late harvesting increased moldy/diseased/discolored grain two-fold while de-husking and drying practices increased the levels in early-harvested grain by factor of 2–3. Insect populations were >10 times higher in the cooler agro-location, and handling practices increased them by factor of 2–10. The interaction of agro-location, harvesting time and drying influenced the amount of grain that was unfit for human consumption. Pre-storage losses of 3.6–11.2% were determined, mainly as grade-outs. With storage, the quality of early-and late-harvested maize did not differ. However, the majority of examined parameters were distinct by agro-location. Moreover, secondary pests and the levels of shriveled and broken grain levels were also distinct by drying method, while moldy/diseased/discolored grain, non-consumable grain, and overall losses were distinct depending on whether the harvested cobs were de-husked or not de-husked before drying. The high levels of grade-outs at the pre-storage stage suggest that sorting should be emphasized for quality improvement at the farm gate not only for the market but also household nutrition. Cultivation of varieties with superior maturing and post-harvest traits would lower the sorting losses. Agro-location and farmer practices influenced grain quality and magnitude of losses during storage. These findings should inform choice of intervention steps right from the pre-storage stage.     

农村农户储粮损失对比试验

针对我国农村粮食产后数量损失巨大、质量损失明显的重大技术问题,开展农户储粮损失调查,其主要目的是了解我国农村储粮的现状,掌握玉米等粮食的收获情况、主要储存方式、储粮用具的主要类型、储粮损失情况等信息,帮助农村农户解决储粮损失问题。     

Predicting Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) populations and associated grain damage in smallholder farmers’ maize stores: A machine learning approach

Prostephanus truncatus is a notorious pest of stored-maize grain and its spread throughout sub-Saharan Africa has led to increased levels of grain storage losses. The current study developed models to predict the level of P. truncatus infestation and associated damage of maize grain in smallholder farmer stores. Data were gathered from grain storage trials conducted in Hwedza and Mbire districts of Zimbabwe and correlated with weather data for each site. Insect counts of P. truncatus and other common stored grain insect pests had a strong correlation with time of year with highest recorded numbers from January to May. Correlation analysis showed insect-generated grain dust from boring and feeding activity to be the best indicator of P. truncatus presence in stores (r = 0.70), while a moderate correlation (r = 0.48) was found between P. truncatus numbers and storage insect parasitic wasps, and grain damage levels significantly correlated with the presence of Tribolium castaneum (r = 0.60). Models were developed for predicting P. truncatus infestation and grain damage using parameter selection algorithms and decision-tree machine learning algorithms with 10-fold cross-validation. The P. truncatus population size prediction model performance was weak (r = 0.43) due to the complicated sampling and detection of the pest and eight-week long period between sampling events. The grain damage prediction model had a stronger correlation coefficient (r = 0.93) and is a good estimator for in situ stored grain insect damage. The models were developed for use under southern African climatic conditions and can be improved with more input data to create more precise models for building decision-support tools for smallholder maize-based production systems.     

Effects of storage methods, storage time and different agro-ecological zones on chemical components of stored sorghum grain in Hararghe, Ethiopia

Sorghum grain stored in traditional underground pits was sampled from seven districts of Hararghe, eastern Ethiopia, representing lowland, intermediate and highland zones, from February to August 2001, and was analysed at the International Livestock Research Institute (ILRI) for changes in chemical composition over time. Samples were also taken from a replicated aboveground bin and pit storage experiment at Alemaya University campus at 2-month intervals from March 2000 to August 2001 and analysed in a similar manner. The effect of geographic location on chemical composition was significant, but there were differences in the sorghum varieties grown. The organic matter (OM) content of grain samples from pits in the lowlands was lower than those from the highlands. The crude protein (CP) and OM contents of samples from the seven districts did not change in 7–9 storage months. The OM content decreased and the CP slightly increased over time in samples from soil pits without any lining material on Alemaya University campus. The OM content decreased from 97.8 to 91.6%; and CP increased from 10.1 to 11.2% in these samples over a 17-month period. Soluble carbohydrate (SCHO) content significantly decreased over time in samples from the districts (from 2.4 to 1.2% by 7 months) and in samples from soil pits on campus (from 2.4 to 1.9% after 7 months and to 0.97% after 17 months). There was no significant change in the organic matter, CP and SCHO contents in samples taken from the cemented aboveground bin, cement- and dung-lined pits at the Alemaya campus, all of which were lined with polythene sheeting. From these data, we conclude that the combination of storage methods, storage period, geographic location and/or sorghum variety affected grain quality. Grain storage in traditional underground pits for long periods does lead to grain deterioration. The use of improved grain storage structures maintains the grain quality and nutritional value of sorghum for a reasonably long period.     

The importance of store hygiene for reducing post-harvest losses in smallholder farmers’ stores: Evidence from a maize-based farming system in Kenya

Knowledge of the role of hygiene in reducing food loss in farm stores is limited among extensionists, researchers, and farmers. Store hygiene practices during post-harvest handling and storage of maize were assessed using a cross-sectional survey of 342 farmers, with regular follow-up of 40 farmers’ stores over seven months to measure losses caused by insects, and to score the hygiene levels using a standard checklist. Fractional Response Model was used to evaluate the associations between hygiene practices and the losses. Farmers stored their produce in sacks (98.2%) kept in outside granaries (60.1%), or rooms in dwelling houses (39.9%). Co-storage with other items — stover or animal feed (29%), old storage containers (41%), farm implements (30%), other crops (65%) and recycling of old storage bags (40%) were common practices. Nine out of ten farmers cleaned their stores before introducing the new harvest, but only half cleaned their stores during the course of storage. High hygiene scores correlated significantly with lower losses. Storing in the bedroom or living room correlated with lower losses by 2.8 and 4.6 percentage points, respectively, compared to storing it in granaries, while storage in the kitchen correlated with higher losses by 19 percentage points margin. Co-storage was associated with higher losses by 2.8 percentage points. Repairing or disinfesting the store before introducing a new harvest did not significantly reduce losses. Training in grain storage did not have a significant effect either, while maize farming experience and younger age were associated with lower losses by 2.8 and 5.9 percentage points, respectively. Stores where majority of the post-harvest handling decisions were made by women had lower losses by 2.8 percent points. These findings are pointers for the need to strengthen education and mechanisms that enable farmers to put knowledge into practice for effective integrated pest management in farm stores.     

Diversity and community structure of insect pests developing in stored sorghum in the Northern-Sudan ecological zone of Burkina Faso

Stored insect pests often create major problems for farmers worldwide. Comprehensive data of insect pests of stored sorghum in Burkina Faso are scarce. Understanding the population structure of insect fauna infesting stored sorghum is important for development of management strategy. Sorghum panicles were collected from January to September 2011 in farmers' granaries in the Northern-Sudanian ecological zone of Burkina Faso to determine the diversity of insect pests and their importance in post-harvest losses. A total of 14 species of insect pests were recorded, including twelve coleopteran and two lepidopteran species. Species diversity peaked between May and September. The highest insect diversity was recorded in sorghum stored in straw granaries and on red coloured grains when compared with that of sorghum stored in mud granaries and on white coloured grains. Rhyzopertha dominica (Fabricius) appears to be the primary insect pest followed by secondary pests including Oryzaephilus mercator (Fauvel), Cryptolestes ferrugineus (Stephens) and Sitophilus zeamais (Motschulsky). The distribution pattern of the pests in granaries corresponds to the Mandelbrot model in which colonization of species in an environment depends on the physical conditions of that environment and on the species currently present, which suggest a progressive colonization occurs in waves with stocks of grain.     

The use and profitability of hermetic technologies for grain storage among smallholder farmers in eastern Kenya

Hermetic storage technologies (HSTs) have been disseminated in Sub-Saharan Africa (including Kenya) to reduce grain storage losses among farmers. We carried out a study in three counties in eastern Kenya to assess the use and profitability of HSTs among farmers. Data were collected from 613 farmers using a semi-structured questionnaire and Kobo Toolbox via android tablets. Results showed an increase in use of HSTs among farmers from 53.7% in 2015 to 91.2% in 2017. PICS was the most used hermetic bags by farmers (84%) in 2017. Majority of farmers (73.5%) received training in the use of HSTs from extension agents and agro-dealers. About 40% of respondents purchased additional (one to five) bags after their first experience using them. The quantity of grain produced made up about half of the farmer’s decision to store. The primary reason (87%) farmers used hermetic bags was the need to manage insect pests. Maize and beans were the most produced and most stored crops; but maize was the most stored in HST. Grain price seasonality showed a near doubling effect between the lean and harvest seasons. Estimates of the return on investments (ROI) ranged between 13 and 80% for all crops and maize stored in hermetic bags had the highest ROI. Awareness and trainings are key in increasing adoption and proper use of HSTs.     

Assessing drivers of maize storage losses in south west Benin using a fractional response model

An assessment of drivers of maize storage losses was undertaken in south west Benin applying the Fractional Response Model on information collected from 400 smallholder maize farmers. The mean loss of maize during the storage period reported by farmers was estimated at 10.25 percent of the total harvest. The average marginal effect obtained from the fitted Fractional Response Model revealed that storage technologies, farmers’ post-harvest attitudes, insect damage, weather conditions and infrastructures play a significant role in storage losses maize farmers experience in south west Benin. The findings revealed that farmers who used bags and plastic containers respectively reduced storage losses by 6.7 and 7.8 percentage points compared to farmers who used woven granary baskets. The results also indicated that applying ash, neem leaves, pepper or lemon increased the storage loss by 4.11 percentage points compared to storing without protectant. Drying after harvesting decreased the storage loss by 1.9 percentage point. In contrast, the storage loss increased by 5.1 percentage points for respondents who reported insects as predators of their stored maize, and by 2.1 percentage points when it rains at the time of maize harvest. A one-degree increase in temperature was associated with an increase in storage losses of 4.4 percentage points and farmers who live at less than 26.09 km to market reduced storage losses by 0.17 percentage point. Effective policies for a sustainable reduction of storage losses among maize farmers in the area should consider the need to raise awareness about the loss issue that represents the use of woven granary basket, ash, neem leaves, pepper and lemon as storage technologies. Farmers should be informed to avoid harvesting during times of rain, encouraged to properly dry their produce after harvesting and sustainable hermetic equipment robust against insect growth during storage should be promoted.     

Effect of storage conditions on nutritional quality and color characteristics of quinoa varieties

To maintain grain quality and prevent loss, effective storage systems are required. The aim of this study was to evaluate the effects of storage duration (0, 60, 120, 180, 240, 300, 360 days) and temperature (4, 10, and 25 °C) on proximate and nutritional components, and color properties of Mint Vanilla and Titicaca quinoa varieties. The results showed that the increase in storage duration and temperature leads to changes in the grain moisture, protein and ash contents, nutritional component and color properties. There was an increase in ash content at 25 °C, moisture content at 10 and 25 °C, and protein content at 4 °C in the stored grains compared with the grains on the initial of storage for Mint vailla variety. Whereas, there was an decrease in ash and protein content for all the temperature at the end of 360 days storage for Titicaca variety. Overall, there was a decrease (except Fe, Zn, Co, Ni, Cd and Pb) in the nutritional component of both quinoa varieties. L1, H° and WI values decreased, and a1, b1 and C1 values increased as a function of storage duration and temperature and showed some temperature-dependent degradation for both quinoa varieties.     

Mapping of maize storage losses due to insect pests in central Mexico

Postharvest grain storage are a major problem in Mexico, influencing the economy, livelihoods, and food security of most farmers. At present, very limited information is available on postharvest maize losses and the associated insect pests in Mexico. Therefore, the objective of this study was to quantify and map maize storage losses in Central Mexico (State of Mexico) to analyze the effects of major pests in the different regions and to provide useful data to policymakers and local stakeholders. The study was conducted with 120 farmers dispersed across all regions of maize production in the State of Mexico. Storage losses were quantified using standardized maize samples that harvest, stored for a year, and sampled periodically. These data, together with geographic coordinates, were integrated into a geographic information system (GIS) to generate maps of maize storage damage and weight losses. The resulting maps show that in the southern region of the State of Mexico the standardized samples exhibited the highest maize losses after a one-year storage period, with an average of 76% loss and 100% grain damage, followed by the northern region, with an average of 18% loss and 52% damage. The eastern region reported 10% loss and 16% damage, whereas the Central region showed 5% loss and 14% damage. The main storage pests identified displayed localized geographic distributions, with the maize weevil, Sitophilus zeamais, being mainly localized in the South, the larger grain borer, Prostephanus truncatu, in the East and North, and the angoumois grain moth, Sitotroga cerealella, in the Northeast and Central regions. Thus, these maps are robust tools that will help towards improving storage facilities and increasing food security for small-scale farmers.     

Effects of using eolic exhausters as a complement to conventional aeration on the quality of rice stored in metal silos

The aim of this study was to evaluate the effects of utilizing an eolic exhauster on reducing the qualitative losses of rice stored in silos. Paddy rice was stored for a nine-month period, in triplicate, in metal silos with a 550-ton capacity that were or were not equipped with an exhauster system and were analyzed every three months. To evaluate the effects of complementary eolic aeration, the energy consumed for aeration and the physical properties of the grain, as well as the thermal and pasting properties of rice, were analyzed. Using the exhauster system in the rice storage silo reduced the loss of dry matter, the energy required for aeration maintenance over a 9-month period, grain hardening, the development of grain staining defects and the darkening of the grain, while preserving the conclusion temperature of gelatinization and the enthalpy, the final viscosity and the head rice yield and not affecting the onset temperature or the peak temperature of gelatinization. Increasing the duration of storage reduced the aeration maintenance requirement, changed the cooking time, the hardness of the grains, the conclusion temperature and the enthalpy, the peak viscosity and final viscosity, the head rice yield, the development of grain staining and the darkening of rice grains, but with less intensity when the rice was stored in silos that used an exhauster system, without affecting the onset and peak temperatures of gelatinization.     

An assessment of the magnitudes and factors associated with postharvest losses in off-farm grain stores in Kenya

Off-farm grain storage is an important postharvest undertaking by government, traders and processors in Kenya. A survey was conducted in 2014/2015 to assess the kinds and magnitudes of perceived losses experienced in off-farm stores, and the factors associated with them. Store supervisors or key personnel charged with grain storage in 39 public and 74 private stores, spread across the six maize growing agro-ecological zones, were interviewed using a structured questionnaire. Total perceived losses averaged 17.6± 2.3%, and were attributed to insects (7.2± 1.0%), molds (5.7± 2.1%), moisture loss (3.4± 0.5%), rodents (2.0± 0.5%), spillage (0.50 ± 0.0%) and birds (0.10± 0.0%). Total losses experienced in public and privately owned stores were not significantly different. The losses attributed to insect and the vertebrate pests, moisture loss and spillage, were also not significantly different in the two storage systems. However, losses due to molds were significantly higher in the private stores. From regression analysis, higher losses were associated with the use of residual insecticides, purchasing low quality maize for storage, reuse of storage bags, untimely control of storage pests, and the agro-climatic conditions of the moist transitional, moist mid-altitude and dry mid-altitude zones. Relying on infestation reports to initiate pest control had the highest marginal effect (21.7%). Lower loss magnitudes were associated with cleaning and drying grain before storage, early pest control and storage periods shorter than two months. These findings provide important reasons for appraising current off-farm storage techniques with a view to taking possible actions for improvements. It is recommended that innovations to mitigate maize postharvest losses should also target off-farm storage, as the losses incurred are significant.