Aflatoxin contamination in groundnut by Aspergillus section Flavi is a major pre- and post-harvest problem causing kernel-quality loss. Post-harvest aflatoxin contamination is caused initially by infestation of aflatoxigenic strains at the pre-harvest stage, resulting in reduced kernel quality after harvest. Improper handling of pods and storage methods after harvest lead to high moisture and ambient temperatures, directly causing aflatoxin contamination. In this review, we report the extent of post-harvest contamination along the groundnut value chain in the Kolokani, Kayes, and Kita districts of Mali in West Africa. Groundnut kernels and paste samples were collected from retailers in selected markets from December 2010 to June 2011, and aflatoxin B1 (AFB1) content was estimated. Aflatoxin was significantly higher in groundnut paste than in kernels. Kolokani recorded the highest toxin levels in both kernels and groundnut paste compared with the other districts. Overall, AFB1 levels in kernels and paste increased during storage at the market level in the three districts and were above permissible levels (≯20 μg/kg). The effect of weather factors on post-harvest contamination and the reasons for aflatoxin build-up in Mali are discussed. This paper also highlights different management tools for reducing post-harvest aflatoxin contamination, such as post-harvest grain handling, post-harvest machinery, physical separation, storage methods and conditions, disinfestation, detoxification, inactivation, filtration, binding agents, and antifungal compounds. Post-harvest management options and enhanced use of good agricultural practices for mitigating this problem in Mali are also presented.

Aflatoxins produced by Aspergillus flavus and Aspergillus parasiticus are common contaminants of peanut (Arachis hypogea) and a major threat to consumers, particularly in Sub-Saharan Africa. Aflatoxin contamination is a serious concern given their hepatotoxic properties and their widespread occurrence during cultivation, harvest, drying, storage, transit and distribution. Preharvest infection by A. flavus is the major cause of aflatoxin contamination in peanut. Its prevention is a complicated task that requires a series of intervention strategies to be merged with traditional farming practices. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and its partners have developed an integrated approach to mitigate A. flavus infestation and aflatoxin contamination by combining: (i) host plant resistance, (ii) soil amendments with lime and organic supplements to enhance water holding capacity, plant vigor and seed health, (iii) timely harvesting and postharvest drying methods, (iv) the use of antagonistic biocontrol agents, such as Trichoderma and Pseudomonads, and (v) awareness campaigns and training courses to disseminate technology to the end-users. This approach can successfully reduce aflatoxin contamination in peanuts in West and Central Africa. This approach is simple, economical and suitable for subsistence farming conditions, but also can be scaled up for use on commercial farms in developing countries in Africa and Asia.

1 groundnut (Arachis hypogaea L.) in Mali, West Africa 2 3 ABSTRACT 13 Groundnut is a major source of livelihood for the rural poor in Mali. However, the crop is 14 prone to pre-and post-harvest aflatoxin contamination caused by Aspergillus flavus and A. 15 parasiticus. Therefore, to minimize health related hazards from exposure to aflatoxin 16 contaminated food, information on the prevalence and distribution of aflatoxins (AFB1) in 17 the groundnut value chain in Mali is needed for timely interventions. To this end, a study was 18 undertaken in three districts (Kayes, Kita and Kolokani) to assess aflatoxin contamination in 19 the field and storage. Ninety pod samples in each district were collected from fields (30 20 villages/district and 3 samples/village) during 2009 and 2010. Pre-harvest contamination was 21 estimated at harvest, whereas samples for post-harvest contamination were collected from 22 granaries of the same farmers at a monthly interval for 3 months. The villages in each district 23 were categorized into safe, acceptable, moderate risk and high risk areas based on pre-harvest 24 AFB1 levels. Kayes recorded more pod samples (77%) within 20 µg/kg of pre-harvest 25 aflatoxins followed by Kolokani (55.6%) and Kita (45.6%) based on 2009 and 2010 mean 26 values. Toxin concentrations at harvest were comparatively less in Kayes during both years. 27 Further, Kayes had more villages under safe and acceptable limits when compared to 28 Kolokani and Kita. Overall, 46 out of 90 villages in the three districts had acceptable pre-29 harvest toxin limits. Further, 12 villages in Kolokani were in the high risk category. An 30 increase in toxin levels was noticed with period of storage during both years. Comparatively, 31 toxin levels after storage were least in Kayes during 2009. Kayes also recorded less AFB1 32 levels in 2010 after Kita. Our results indicate that Kayes is relatively safe over Kita and 33 Kolokani in pre-harvest aflatoxin contamination. The reasons for district-wide variations in 34 pre-harvest contamination; and the reasons for post-harvest flare up of the problem are 35 discussed. Further, proper storage of pods at farmers' granaries in Mali is suggested to 36 overcome the problem from reaching alarming levels. 37 38

Aflatoxin contamination of peanut is a major threat to consumers in West Africa. High levels of aflatoxin have been reported in West and Central Africa, particularly in Niger. Field trials were conducted from 1991 to 1994 at ICRISAT Sahelian Center, Sadore Research Station near Niamey, Niger. Various production practices were compared to examine their effects on water stress and Aspergillus flavus infection and aflatoxin contamination. Different levels of water stress were achieved by varying planting date and frequency of irrigation in two resistant and two susceptible cultivars. Contamination of seed with A. flavus and aflatoxin was determined. The susceptible cultivars 28–206 and JL 24 had much higher levels of seed infection following 3 wk or more of water stress than did the resistant cultivars. Susceptible cultivars showed up to 81% seed infection. Cultivar 28–206 had low levels of contamination when there was low water stress but became very susceptible when the period of water stress increased (3 wk of drought). Seed infection by A. flavus and contamination by aflatoxin were highly correlated across years and cultivars. Although seed infection by A. flavus was very responsive to water stress in the field, aflatoxin contamination did not increase proportionally. This may have been influenced by high soil temperatures in Niger, which may exceed 40 C. Most reports indicate that a minimum of 20 to 30 d of drought is needed for significant aflatoxin contamination, but contamination was observed after 14 d of water stress in this study.

Waliyar, F., Adamou, M., and Traoré, A. 2000. Rational use of fungicide applications to maximize peanut yield under foliar disease pressure in West Africa. Plant Dis. 84:1203-1211.Foliar diseases caused by Cercospora arachidicola, Cercosporium personatum, and Puccinia arachidis are major constraints to peanut production in the world. Fungicides are among the most efficient available control methods. Field trials were conducted in 1991 and 1992 in Benin and Niger, West Africa, to evaluate the cost effectiveness of fungicide application timings and frequencies on four peanut cultivars. A combination of four timings (40, 55, 70, and 85 days after sowing) was scheduled. Early (causal organism, C. arachidicola) and late (caused by C. personatum) leaf spot were prevalent in both years, but late leaf spot was the more economically important disease as shown by high values of area under the disease progress curve. Application of fungicide reduced late leaf spot incidence and increased pod yield. Pod yield responded to an interaction of number and timing of fungicide applications. With appropriate timing two or three fungicide applications were enough to significantly increase pod yield. Properly timed fungicide sprays can result in substantial monetary gains for peanut farmers in West Africa.

Aflatoxin contamination in groundnut byAspergillus flavus has assumed global significance and is considered a potential threat to human and animal health. The present study focused on the screening and identification of stable and reliable resistance sources to pre-harvest aflatoxin contamination in ICRISAT's groundnut mini core germplasm accessions. . In total, 31 accessions had less aflatoxin accumulation than the resistant check, 55-437. The seven best accessions, ICGs 13,603, 1415ICGs 13,603, , 14,630, 3584, 5195, 6703 and 6888, over six years (2008ICGs 13,603, -2013 consistently accumulated very low levels of aflatoxin (<4 μg kg −1). These seven accessions could be potential sources for understanding the resistant mechanisms and can be further used in developing resistant cultivars or introgressing resistance in popular released varieties.

Fumonisins are mycotoxins that frequently contaminate maize, a dietary staple in Burkina Faso. Fumonisins have been linked with both the incidence of oesophageal cancer, and to neural tube defects. However, epidemiological studies of these associations are hampered by lack of validated exposure biomarkers. One candidate biomarker is the sphinganine/sphingosine (Sa/So) ratio in biological samples. Twenty husband-wife pairs aged 20-40 were recruited from Dingasso-1, western Burkina Faso. Plate ready food was sampled over three consecutive days (day one to three) for fumonisin B1 and B2, to provide a measure of total fumonisin intake. The Sa/So ratio was determined in (1) first morning urines taken on days two to four, (2) buccal cells and (3) serum on days one and four only. Fumonisin intake was moderate (mean 0.81 µg/kg bw/day (range 0.01-2.40 µg/kg bw/day) compared to exposures reported in China and South Africa. For each person the mean fumonisin intake over three days was compared to the mean Sa, So and Sa/So ratio in urine, buccal cells and serum. A modest positive trend between mean fumonisin intake and mean serum Sa/So was observed (P=0.067). When individuals were dichotomised based on the median fumonisin intake (<0.75 µg/kg bw/day), the serum Sa/So ratio was moderately higher (P=0.044) in the high intake group (geometric mean 0.64; 95% CI: 0.54, 0.75) compared to the low intake group (0.49; 95% CI: 0.41, 0.59). Neither urinary nor buccal cell Sa/So ratio was associated with mean fumonisin intake. Neither mean individual Sa nor So level for urine, buccal cells or urine was associated with mean individual fumonisin intake. The study population was exposed to moderate levels of fumonisin with limited evidence of altered Sa/So ratio. Further work on serum Sa/So ratio is merited in comparison with other biomarker approaches such as urinary fumonisin B1 or sphingolipid 1-phosphate metabolites.

Maize throughout the world is frequently contaminated with a family of mycotoxins, the fumonisins, produced by species of Fusaria. The study investigated the level of fumonisin contamination of maize samples from village farms and large market traders in Burkina Faso, West Africa. Maize samples (5 kg) from each of five to six large storage barns from farms in five villages in the district of N'Dorola, Kénédougou province, western Burkina Faso, were sampled (n = 26) in Jan 1999 (> 1 year storage), and a further 26 maize samples from the same farms were collected directly from the field in October 1999. In addition, 72 maize samples were obtained in July 1999 from large markets in Bobo Dioulasso. Fumonisins were extracted from dried maize, derivatized with o-phthaldialdehyde and quantified by reversed-phase high-performance liquid chromatography with fluorescence detection. All 26 samples from the first (mean 1170 microg kg(-1), range 110-3120 microg kg(-1)) and from the second (mean 130 microg kg(-1), range 10-450 microg kg(-1)) village collection were fumonisin positive. All 72 maize samples from the large markets were also positive for fumonisins, and had the highest levels of contamination (mean 2900 microg kg(-1), range 130-16,040 microg kg(-1)). As fumonisins were a ubiquitous contaminant of maize and given that this crop is a dietary staple in this region, chronic exposure is likely.