Aflatoxin control and prevention strategies in maize for Sub-Saharan Africa

Mycotoxins are secondary fungal metabolites that contaminate agricultural commodities and can cause sickness or death in humans and animals. Risk of mycotoxin contamination of food and feed in Africa is increased due to environmental, agronomic and socio-economic factors. Environmental conditions especially high humidity and temperature favour fungal proliferation. Farming practices in Africa sustain fungal and toxin contamination of food and feed. The socio-economic and food security status of the majority of inhabitants of sub-Saharan Africa leaves them little option in choosing good quality products. Several technologies have been tested in Africa to reduce mycotoxin risk. Field management practices that increase yields may also prevent aflatoxin. They include use of resistant varieties, timely planting, fertilizer application, weed control, insect control and avoiding drought and nutritional stress. Other options to control the toxin causing fungi A. flavus contamination in the field are use of atoxigenic fungi to competitively displace toxigenic fungi, and timely harvest. Post-harvest interventions that reduce mycotoxins are rapid and proper drying, sorting, cleaning, drying, smoking, post harvest insect control, and the use of botanicals or synthetic pesticides as storage protectant. Another approach is to reduce the frequent consumption of ‘high risk’ foods (especially maize and groundnut) by consuming a more varied diet, and diversifying into less risky staples like sorghum and millet. Chemo-preventive measures that can reduce mycotoxin effect include daily consumption of chlorophyllin or oltipraz and by incorporating hydrated sodium calcium aluminosilicates into the diet. Detoxification of aflatoxins is often achieved physically (sorting, physical segregation, flotation etc.), chemically (with calcium hydroxide, ammonia) and microbiologically by incorporating probiotics or lactic acid bacteria into the diet. There is need for efficient monitoring and surveillance with costeffective sampling and anlytical methods. Sustaining public education and awareness can help to reduce aflatoxin contamination. Keywords: Aflatoxin, Sub-Saharan Africa, Control measure

Infection of maize by Fusarium species and contamination with fumonisin in Africa

Fusarium is one of the major fungal genera associated with maize in Africa. This genus comprises several toxigenic species including F. verticillioides and F. proliferatum, which are the most prolific producers of fumonisins. The fumonisins are a group of economically important mycotoxins and very common contaminants of maize-based foods and feeds throughout the world. They have been found to be associated with several animal diseases such as leukoencephalomalacia in horses and pulmonary oedema in pigs. Effects of fumonisins on humans are not yet well understood. However, their occurrence in maize has been associated with high incidences of oesophageal and liver cancer. Infection of maize by Fusarium species and contamination with fumonisins are generally influenced by many factors including environmental conditions (climate, temperature, humidity), insect infestation and pre- and postharvest handling. Attempts to control F. verticillioides and to detoxify or reduce fumonisin levels in maize have been undertaken. However, more research studies are urgently needed in order to understand more about this toxin. Fumonisins are less documented because they are recently discovered mycotoxins compared to aflatoxins. To date in Africa, apart from South Africa, very little information is available on Fusarium infection and fumonisin contamination in maize. It is a matter of great concern that on this continent, millions of people are consuming contaminated maize and maize-based foods daily without being aware of the danger. Key words: Fusarium, fumonisins, maize, Africa. African Journal of Biotechnology Vol. 2 (12), pp. 570-579, December 200

Analysis of pre- and post-harvest practices of cowpea (Vigna unguiculata (L.) Walp.) in Benin

Cowpea is an important leguminous crop in Benin. Practices such as farming and storage conditions may influence the production yield and the grain quality. In this study, pre- and post-harvest practices ofcowpea were analysed in relation to the quality of the grains. A survey on cowpea farming activities was conducted in the four agro-ecological zones of Benin. Three localities producing cowpea were selected in eachagro-ecological zone. Information was obtained through individual interview and focus group discussions. Cowpea was mainly cultivated either as a monocrop or intercropped with maize and groundnuts in the fouragro-ecological zones. Cowpea infestation by insects on farm and in storage was a major problem mentioned by farmers. To prevent insects’ infestation in storage, cowpeas were thoroughly sundried at harvest andadequately sorted prior to storage. Such post-harvest practices could limit cowpea grains quality deterioration. Cowpeas were mainly stored in bags for about 3 months. About 23 cowpea based foods were identified. Majorcowpea foods were ata (akara), moin-moin and adowe. Common processing operations included sorting, washing, dehulling of cowpeas, boiling and frying. These processing operations as practiced by processors are generally recognized as a good practice in food preparation

Impact of indigenous storage systems and insect infestation on the contamination of maize with fumonisins

Four storage systems of maize commonly used by farmers in Benin, West Africa, were tested to determine their impact on infection of maize by Fusarium and subsequent contamination with fumonisins. The study showed that Fusarium incidence was significantly higher when maize was stored on a cemented floor in a house, a non ventilated facility (40.3 ± 17.4%), than in the other tested systems (p < 0.05). The lowest Fusarium incidence was recorded when maize was stored in a bamboo granary that is a ventilated facility (25.5 ± 13.5%) (p < 0.05). All maize samples from the tested storage systems were found to be fumonisin positive, with levels ranging from 0.6 to 2.4 mg/kg. Fumonisin level, overall, was found to decrease over the storage period, but not significantly in all the tested storage systems. Damage by lepidopterous pests was significantly and positively correlated with both infection of maize with Fusarium and contamination by fumonisin. In contrary, damage by coleopterous insects was significantly and negatively correlated with infection of maize with Fusarium and contamination by fumonisin. Avoiding the use of non-ventilated systems to store maize and reducing insect infestation in field and during storage are very important recommendations for farmers.Keywords: Maize, storage systems, Fusarium, fumonisins, insect infestatio

Yam bean (Pachyrhizus erosus) tuber processing in Benin: production and evaluation of the quality of yam bean-gari and yam bean-fortified gari

Yam bean (Pachyrhyzus erosus) tubers were processed singly and mixed with cassava into different types of gari (100% yam bean gari, 75% yam bean gari, 50% yam bean gari and 25% yam bean gari) following the traditional gari processing method. Conventional gari from cassava was processed following the same approach and used as control. Physical characteristics, proximate composition and sensory quality of the garis obtained were assessed. Results showed that low and medium (25% and 50%) yam bean fortified gari processing yielded better than 75% and 100% yam bean gari processing. Low and medium yam bean gari were the closest to conventional gari regarding the brown index (18.0 and 18.3 respectively), had good swelling capacity (≥ 3) and had higher relative bulk density (0.57 and 0.53 respectively). The proteins content of the processed yam bean garis increased with increasing incorporation rate of yam bean but, similarly, the crude fibres content increased going beyond the recommended level of 2% maximum. The processed garis were used to cook èba which were submitted to panellists’ appreciation. Panellists scored better low and medium yam bean fortified garis and the resulting èba. Combining the results, the highest suggested incorporation rate was 50% yam bean tubers. © 2013 International Formulae Group. All rights reserved.Keywords: Legume tuber-root crop, quality, physical characteristics, chemical composition, sensory evaluation

West African Cattle Farmers’ Perception of Tick-Borne Diseases

Worldwide, cattle production is struggling to face the negative impacts caused by ticks and Rhipicephalus (Boophilus) microplus is one of the most harmful ticks for livestock. Most of the people in West Africa depend on cattle farming and subsistence agriculture. The presence of ticks on cattle is a major problem faced by smallholder farmers who fight for their livelihood. National and regional tick control programs could assist these rural communities in protecting their livelihoods against ticks and tick-borne diseases, but only if they take into account the targeted herders and their perception on cattle management and tick control. This paper aims to provide a better insight in the socio-economic characteristics of Beninese cattle farmers, and their perception on tick burden, as well as to document common tick control strategies. Different tick species and their seasonality are well understood by cattle herders. For tick control, many still use manual tick removal, especially in the north of the country. The high cost of acaricides, the lack of financial means of African farmers, and of the local stockbreeders in particular, limits the use of acaricides in livestock breeding in Benin. While aiming to increase the meat or milk production of their animals, stockbreeders who can afford it sometimes turn to an abusive use of acaricides, which might in time lead to an increase in tick resistance. This study remains one of the rare studies to report extensively on the perceptions of West African cattle herders

A phylogenetic classification of the world’s tropical forests

Knowledge about the biogeographic affinities of the world’s tropical forests helps to better understand regional differences in forest structure, diversity, composition and dynamics. Such understanding will enable anticipation of region specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present the first classification of the world’s tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (1) Indo-Pacific, (2) Subtropical, (3) African, (4) American, and (5) Dry forests. Our results do not support the traditional Neo- versus Palaeo-tropical forest division, but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar and India. Additionally, a northern hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern hemisphere forests

Evenness mediates the global relationship between forest productivity and richness

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions