Comparative Efficacy of Four Hermetic Bag Brands Against Prostephanus truncatus (Coleoptera: Bostrichidae) in Stored Maize Grain

The Fall Armyworm and Larger Grain Borer Pest Invasions in Africa: Drivers, Impacts and Implications for Food Systems

Invasive alien species (IAS) are a major biosecurity threat affecting globalisation and the international trade of agricultural products and natural ecosystems. In recent decades, for example, field crop and postharvest grain insect pests have independently accounted for a significant decline in food quantity and quality. Nevertheless, how their interaction and cumulative effects along the ever-evolving field production to postharvest continuum contribute towards food insecurity remain scant in the literature. To address this within the context of Africa, we focus on the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), and the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), two of the most important field and postharvest IAS, respectively, that have invaded Africa. Both insect pests have shown high invasion success, managing to establish themselves in >50% of the African continent within a decade post-introduction. The successive and summative nature of field and postharvest damage by invasive insect pests on the same crop along its value chain results in exacerbated food losses. This systematic review assesses the drivers, impacts and management of the fall armyworm and larger grain borer and their effects on food systems in Africa. Interrogating these issues is important in early warning systems, holistic management of IAS, maintenance of integral food systems in Africa and the development of effective management strategies.

Hermetic SuperGrain bags for controlling storage losses caused by Callosobruchus maculatus Fabricius (Coleoptera: Bruchinae) in stored mung bean (Vigna radiata)

Mung bean is highly susceptible to insect attack during storage. Hermetic storage is an effective technique to control insect damage. This study investigated the potential of the hermetic SuperGrain bag (SGB) for controlling bruchids during storage. The dry samples were packed in SGB infested with adult bruchids (SGB-I), SGB natural field infested (SGB-N), woven polypropylene bags (WPP-I and WPP-N) and kept at room temperature for 180 days. Oxygen (O₂) and carbon dioxide (CO₂) concentrations were measured at 15 days intervals. Moisture content, infestation level, seed damage and weight loss were determined at 60 days intervals. Seed colour, hardness, crude protein and fat contents were analysed before and after storage. The O₂ level decreased to 10.09%, whereas the CO₂ level increased to 8.87% in both SGB-I and SGB-N treatments. The moisture content of mung bean was maintained as onset storage in both SGB-N and SGB-I treatments, whereas reduced in WPP-N (9.26% db) and WPP-I (9.21% db). In SGB treatments, no significant bruchids were detected, but they increased drastically in WPP-N (52 ± 9) and WPP-I (377 ± 14). Seed damage (2-3%) and weight loss (0.8-1.0%) were recorded in both SGB-N and SGB-I. Conversely, seed damage reached 26.67 and 54.17%, corresponding to weight losses of 12.33 and 20.82% in WPP-N and WPP-I, respectively. Seed colour, hardness, crude protein and fat contents in SGBs showed no significant changes than in the WPP bags. The study illustrated that the SGB is an efficient hermetic device in protecting mung beans against bruchids attacks compared to the WPP bags.

Effect of Storage Technologies on Postharvest Insect Pest Control and Seed Germination in Mexican Maize Landraces

Smallholder farmers who grow maize landraces face important challenges to preserve their seed biodiversity from one season to another. This study was carried out in the central highlands of Mexico to compare the effectiveness of two seed storage practices-specifically, polypropylene woven bags (farmers' conventional practice) vs. hermetic containers-for minimizing seed losses and maintaining germination. Four Mexican landraces were stored for three and six months. Data on moisture content and kernel damage were collected at the beginning and the end of the storage period. Pest-free samples collected were also analyzed for seed germination. Moisture content was below 13% overall and was not significantly affected by storage technology or storage time. Samples from the polypropylene woven bags suffered significant damage from Sitophilus zeamais and Prostephanus truncatus, with the percentages of insect damage and weight loss reaching 61.4% and 23.4%, respectively. Losses were minimal in seed stored in hermetic containers, with a maximum insect damage of 4.1% and weight loss of 2.2%. Overall, the germination rate of samples stored in these airtight containers was greater than 90%. This study provides additional evidence on the effectiveness of hermetic containers at maintaining Mexican landraces' seed quantity and quality during storage in smallholder conditions in central Mexico.

Estimation of nutritional postharvest losses along food value chains: A case study of three key food security commodities in sub-Saharan Africa

Postharvest losses (PHLs) amplify food insecurity and reduce the amount of nutrients available to vulnerable populations, especially in the world's Low and Middle Income Countries (LMICs). However, little is known about nutrient loss at the various postharvest stages. The objective of our study was to develop a methodology and a tool to estimate nutritional postharvest losses (NPHLs) along food value chains for three distinct food commodities in sub-Saharan Africa. The study used a combination of literature, laboratory and field data to investigate NPHLs caused by both changes in quantity and quality of food material (quantitative and qualitative NPHLs, respectively). The method can be expanded to various other food value chains. A user-friendly predictive tool was developed for case studies involving maize and cowpea in Zimbabwe, and for sweet potato in Uganda. Quantitative and qualitative NPHLs were combined and converted into predicted nutrient loss and nutritional requirement lost due to postharvest losses. The number of people who may not meet their daily nutritional needs, as a result of the food and nutrient losses at country level, was estimated. The estimates consider nutritionally vulnerable groups such as children under five years and pregnant women. The nutrient density of the harvested food material, the level of food production, the postharvest stages along the food value chain, the levels of pest damage along the value chain, and the susceptibility of the nutrients to degradation e.g. during storage, are all important factors that affect NPHLs. Our modelling work suggests that reducing PHLs along food value chains could significantly improve access to nutritious food for populations in LMICs.

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.

Performance of Five Postharvest Storage Methods for Maize Preservation in Northern Benin

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.