Food security challenges in Sub-Saharan Africa: The potential contribution of postharvest skills, science and technology in closing the gap

More than half of global population growth between 2013 and 2050 is expected to occur in Africa and is projected to more than double from 1.1 billion to 2.4 billion people by 2050. Estimates suggest that globally, sustainable food production will need to increase by 70%. It is essential that postharvest loss (PHL) reduction occurs alongside this increase in sustainable food production and access to meet the enormous food demand. The paper examines the grain PHL levels in Sub-Saharan Africa (SSA) and their implications. The PHL reduction strategies, their merits and limitations are analysed in terms of appropriateness to smallholder farmers, who form the majority of the farming community in Africa. The paper further identifies emerging postharvest research and development issues and the implications at various levels. The need to consolidate the understanding, approaches and metrics of PHL is highlighted. This will enable losses to be measured more quickly, objectively and comparably across commodities and geographical locations in Africa and beyond, and to assist in decision-making and measuring the impact of different initiatives. That PHL reduction is now an aspiration of many high-level development plans across SSA is a significant step forward. However, the challenge still remains of converting this attention into meaningful practical actions and increased knowledge and skills at the scale required to enhance food security across the region

Ergonomic evaluation of manually-operated peanut butter mills

A JASSA evaluation of manually-operated peanut butter mills in Zimbabwe.Previous studies showed that the manually-operated peanut butter mills available on the market had technical problems related to the design and operation of the machines. One such problem was that the mills were too heavy for women to operate, resulting in limited operational time and ultimately, low total output. An ergonomic study of the original and modified versions of the mills was conducted at the University of Zimbabwe to verify the previously identified problems and develop appropriate and lighter mills for manual operation. A body discomfort assessment and heart rate measurement were used to determine stress endured by 12 women, as a result of operating the mills. Medium to high levels of discomfort were experienced in the lower back, neck, chest, lower arm, upper arm and shoulder. The heart rate readings showed that the mills currently available on the market were highly stressful (138 beats/minute), exceeding guidelines for safe manual operations. The modified mills, incorporating variable feed control devices, can be adjusted to ensure that stress levels are within recommended levels. The ergonomic study also established that for feed rates of 1.1 and . 1.5kg/hour, the mills produce peanut butter of acceptable fineness to the subjects, in one pass without over stressing the operator. In a separate field experiment using the same subjects, extremely high stress levels ( 150 beats/minute) were recorded with the traditional stone-mill

FARMER PERCEPTIONS ON CLIMATE CHANGE AND VARIABILITY IN SEMI-ARID ZIMBABWE IN RELATION TO CLIMATOLOGY EVIDENCE

Farmers in semi-arid Zimbabwe prioritise climate variability as their major agricultural productivity-reducing problem. This paper raises the importance of considering local farmers\u2019 perceptions on climate risk, as this greatly influences on-farm investments and decision-making in agricultural management and production in semiarid Zimbabwe. A study was conducted in two districts of semi-arid Zimbabwe using participatory research techniques, to investigate farmers\u2019 perceptions of climate variability and whether these perceptions correspond with historical climatic data. The study showed that farmers perceived climatic and weather patterns to have changed over the past decade or two, as indicated by erratic rainfall patterns, decreased rainfall and temperature increases, leading to crop productivity decline and increased livestock morbidity and mortality. Majority of respondents (75%; n=81) were highly risk-averse, perceiving that most of the seasons in any ten given years could be poor. The climatic data show no evidence that corroborates the farmers\u2019 perceptions, with only temperature showing a clear signal, indicating the influence of other non-climatic factors. The climate data show rainfall variability to be a normal characteristic of the study sites, with deviations from the climatic rainfall means (or the poor seasons) being cyclical and occurring once in every three seasons over the past 40 years. The study highlights strategies that farmers could implement to enhance agricultural productivity in the semi-arid areas to adapt to climate change and variability.Les fermiers des r\ue9gions semi-arides du Zimbabwe mettent en priorit\ue9 variabilit\ue9 climatique comme facteur majeur de la r\ue9duction de la productivit\ue9 agricole. Cet article \ue9voque l\u2019importance des perceptions paysannes eu \ue9gard au risque climatique \ue9tant donn\ue9 son influence sur les investissements agricoles et la prise des d\ue9cisions dans la gestion agricole et la production dans les milieux semi aride du Zimbabwe. Une recherche \ue9tait conduite dans deux districts semi arides du Zimbabwe afin de faire \ue9tat de perceptions paysannes sur la variabilit\ue9 climatique et ses liens avec les donn\ue9es climatiques historiques. Une technique de recherche participative \ue9tait utilis\ue9e pour cette fin. Les r\ue9sultats de cette \ue9tude ont montr\ue9 que les paysans per\ue7oivent que les scenarios climatiques ont chang\ue9 au cours d\u2019une ou deux derni\ue8res d\ue9cennies comme cela s\u2019est manifest\ue9 \ue0 travers les pluies erratiques, la diminution des pluies et \ue9l\ue9vation de la temp\ue9rature avec pour cons\ue9quences la diminution de la productivit\ue9 des cultures l\u2019augmentation de la morbidit\ue9 et la mortalit\ue9 du b\ue9tail. La majorit\ue9 des r\ue9pondants (75% ; n=81) \ue9tait sous risque, percevant que la plupart des saisons pourrait \ueatre pauvre dans dix ans. Les donn\ue9es climatiques ne montrent aucune \ue9vidence qui confirme les perceptions paysannes, avec seule la temp\ue9rature ayant un signal claire indiquant l\u2019influence d\u2019autres facteurs non climatiques. Les donn\ue9es climatiques montrent que la variabilit\ue9 pluviom\ue9trique dans les sites d\u2019\ue9tude pr\ue9sente une caract\ue9ristique normale, avec des d\ue9viations cycliques des moyennes des pr\ue9cipitations (les saisons pauvres) apparaissant une fois toutes les trois saisons au cours de 40 ans. L\u2019\ue9tude met en \ue9vidence les strat\ue9gies auxquelles les paysans pourraient recourir pour am\ue9liorer la productivit\ue9 des cultures en milieux semi arides pour l\u2019adaptation au changement climatique et sa variabilit\ue9

Evaluation of pesticidal plants for smallholder grain protection

Widespread and indiscriminate use of synthetic pesticides for storage pest control can cause serious problems including: pest resistance build-up, pest resurgence, environmental and health concerns. Pesticidal plants can be an effective alternative for resource-poor farmers because of their local availability, ease of use and minimal cost. Knowledge of application methods, safety and efficacy of these pesticidal plants based on scientific evidence is scanty even though farmers are already using the materials. The insecticidal properties of different pesticidal plants used as grain protectants by smallholder farmers in Zimbabwe were evaluated against maize, cowpeas and beans storage insect pests to validate, improve and optimize the efficacy of the plants. In a series of experiments, eight local plants already being used by smallholder farmers were tested separately as leaf, fruit or bark powders or ashes admixed with grain and compared with a commercial pesticide or an untreated control. Application rates ranged from 2-5% w/w on-station or on-farm while in laboratory bioassays 2-10% w/w were used. The plants tested included Dirostachys cinerea, Bobgunnia (Swartzia) madagascariensis, Bauhinia thoningii, Lippia javanica, Aloe spp., Spirostachys africana, Combretum imberbe and Maerua edulis. Based on % insect damaged grain and insect mortalities; B. madascariensis, L. javanica, Aloe spp. and Maerua edulis showed potential. The bruchids, Callosobruchus rhodesianus and Acanthosclides obtectus, were particularly susceptible while the bostrychids, Prostephanus truncates and Rhyzopertha dominica, were less susceptible. Most of the plant materials were not persistent on grain and were not effective for more than 16 weeks whereas smallholder farmers normally store for about 32 weeks. This raises the need to reapply the materials mid-way the storage season. There is scope for optimising the efficacy of the plant materials and possible strategies are discussed. The results are discussed in the context of effective and sustainable use of the pesticidal plants by resource-poor farmers

Evaluation of pesticidal plants for smallholder grain protection

Widespread and indiscriminate use of synthetic pesticides for storage pest control can cause serious problems including: pest resistance build-up, pest resurgence, environmental and health concerns. Pesticidal plants can be an effective alternative for resource-poor farmers because of their local availability, ease of use and minimal cost. Knowledge of application methods, safety and efficacy of these pesticidal plants based on scientific evidence is scanty even though farmers are already using the materials. The insecticidal properties of different pesticidal plants used as grain protectants by smallholder farmers in Zimbabwe were evaluated against maize, cowpeas and beans storage insect pests to validate, improve and optimize the efficacy of the plants. In a series of experiments, eight local plants already being used by smallholder farmers were tested separately as leaf, fruit or bark powders or ashes admixed with grain and compared with a commercial pesticide or an untreated control. Application rates ranged from 2-5% w/w on-station or on-farm while in laboratory bioassays 2-10% w/w were used. The plants tested included Dirostachys cinerea, Bobgunnia (Swartzia) madagascariensis, Bauhinia thoningii, Lippia javanica, Aloe spp., Spirostachys africana, Combretum imberbe and Maerua edulis. Based on % insect damaged grain and insect mortalities; B. madascariensis, L. javanica, Aloe spp. and Maerua edulis showed potential. The bruchids, Callosobruchus rhodesianus and Acanthosclides obtectus, were particularly susceptible while the bostrychids, Prostephanus truncates and Rhyzopertha dominica, were less susceptible. Most of the plant materials were not persistent on grain and were not effective for more than 16 weeks whereas smallholder farmers normally store for about 32 weeks. This raises the need to reapply the materials mid-way the storage season. There is scope for optimising the efficacy of the plant materials and possible strategies are discussed. The results are discussed in the context of effective and sustainable use of the pesticidal plants by resource-poor farmers

Field assessment of the efficacy and persistence of diatomaceous earths in protecting stored grain on small-scale farms in Zimbabwe

Farmers and grain traders in sub-Saharan Africa are forced to sell stored produce prematurely because of deterioration due mostly to insect damage. Producers expressed a need for a relatively cheap and safe method of insect control. Diatomaceous earths (DE) offer safer alternatives to synthetic chemicals, but information on their efficacy under tropical small-scale farming conditions is lacking. Two commercially available DE products, Protect-Its and Dryacides, were tested against the major post-harvest insect pests of grains and pulses. On-farm field trials in Zimbabwe showed that both inert dusts gave significant protection against insect damage when admixed with farm stored maize, sorghum and cowpeas for periods of 40 weeks. However, efficacy of these DEs is closely linked to the application rates and differs between commodities, locations and insect pests. An admixture application rate of 0.1% w/w of Protect-Its or Dryacides can be recommended to protect both maize and cowpea grain that is to be stored for 4 months or longer in Zimbabwe. However, Dryacides was not effective in preventing damage to sorghum grain by the bostrichid Rhyzopertha dominica unless applied at a higher rate of 0.2% w/w

Sustainable management of fall armyworm, Spodoptera frugiperda (J.E. Smith): challenges and proposed solutions from an African perspective

Published online: 27 Jan 2022Fall armyworm (FAW), Spodoptera frugiperda, is threatening food security in Africa and thus sustainable management strategies are required. The pest has spread to over 44 countries in Africa since its first detection in 2016, causing maize yield losses valued at between US$2,531 and US$6,312 million per annum. Owing to FAW’s damaging potential, many untested management strategies, including those of doubtful efficacy, are being used by smallholder farmers in Africa. We analysed existing and emerging FAW management strategies on the continent. Research and training has focussed on FAW identification, scouting, digital monitoring tools, pest distribution, natural enemy database, and FAW impact on crops. Gaps identified include lack of clear national policies and regulations, FAW identification challenges, absence of reliable and sustainable management options, and FAW insecticide resistance development. Conservation of FAW natural enemies could enhance sustainable natural control. Farmer Field Schools and mass rearing of natural enemies for augmentative release are sustainable FAW control strategies. The “push-pull” strategy in controlling FAW has potential in Africa. Existing policies and regulations to facilitate better FAW management are discussed

Small-scale farmer perceptions of diatomaceous earth products as potential stored grain protectants in Zimbabwe

Farmers repeated prioritisation of the need for improved methods of controlling insect damage to stored commodities in Zimbabwe led to the search for alternative grain protectants to the locally available organophosphate-based pesticides. In field trials the diatomaceous earth (DE) products, Protect-Its and Dryacides, gave good protection to threshed maize, sorghum and cowpea from insect attack during 8 months storage, enabling households to increase both their food security and control over grain sales. However the initial trials, although on-farm, were researcher-managed and only evaluated by farmers at the end of the storage period. No information existed on how effective DEs were under real farmer management. At the start of the 1999/2000 storage season, farmers in Buhera and Binga districts set up trials in their own granaries using their own maize and sorghum grain, respectively. During a 7 months storage period they evaluated the application of 0.1% w/w Protect-Its compared to their typical grain protection methods. At 5 and 7 months storage, farmers compared the treatments using the parameters they view as important such as insect damage, expected ‘sadza’ yield and quality and sale price. The DE treatments outscored other practices for all parameters and farmers were keen to purchase DEs to protect their future harvests. Grain samples from the same trial were also analysed in the laboratory at 5 and 7 months for insect populations, damage and moisture content. Although grain damage and insect numbers were higher in the typical grain protection treatment than the DE treatment, the differences were not statistically significant

Do diatomaceous earths have potential as grain protectants for small-holder farmers in sub-Saharan Africa? The case of Tanzania

Participatory on-farm field trials were set up over three storage seasons, from 2002 to 2005, in different agroecological zones of Tanzania to compare the efficacy of the enhanced diatomaceous earths (DEs) Protect-Its and Dryacides alone or combined with the pyrethroid permethrin. Other treatments included three commercially available synthetic chemical dilute dusts, containing 1.6% pirimiphos-methyl and 0.3% permethrin (Actellic Super and Stocal Super from different manufacturers) and 1% fenitrothion and 0.13% deltamethrin (Shumba Super); traditional protectants; and a locally available DE collected from Kagera in north-west Tanzania. Treatments were applied to maize and sorghum grain and dried beans. Insect pests are the main threat during storage, which in Tanzania includes the devastating larger grain borer, Prostephanus truncatus. All the grain protectants, except the traditional ones, kept damage incidence well below that of the untreated controls, and usually below 10% for periods of 40 weeks of storage. Exceptions occurred when grain was badly infested prior to treatment, in which case Actellic Super dust was more effective than the DEs. Very little difference in damage was observed between the DE treatments until 40 weeks of storage. In addition to the commercially available synthetic grain protectants, Protect-Its 0.25% w/w or Protect-Its 0.1% w/w plus permethrin at 2 mg/kg can be recommended to protect dry un-infested, winnowed maize and sorghum grain that is to be stored on-farm in sacks or woven granary baskets for periods of 4 months or more in Tanzania. Beans can be protected with lower application rates of Protect-Its 0.05% w/w or Dryacides 0.1% w/w. The study also demonstrated that Actellic Super dust obtained from an approved source and applied according to the manufacturer’s recommendations is effective in protecting stored maize, sorghum and beans for periods of at least 40 weeks—contrary to many of the suggestions that this product is no longer effective in Tanzania