Presentation on theme: "Aflatoxin Stakeholders Workshop. Dar es Salaam December 3-4, 2012 Massomo, SMS 1 CAAREA Activities & Key post- harvest solutions for aflatoxin control."— Presentation transcript:
Aflatoxin Stakeholders Workshop. Dar es Salaam December 3-4, 2012 Massomo, SMS 1 CAAREA Activities & Key post- harvest solutions for aflatoxin control Said M.S. Massomo Open University of Tanzania Morogoro Regional Centre www.out.ac.tz Email: firstname.lastname@example.org email@example.com
CAAREA Objectives 1.Establish aflatoxin diagnostics platform at BecA-ILRI, and develop novel aflatoxin diagnostics 2.Characterize maize fungi from around Kenya and Tanzania: information, biobank and inoculum. 3.Identify maize germplasm resistant to aflatoxin accumulation (G x E). 4.Test modelling as a potential predictive tool and to contextualize findings regionally (risk map). 5.National breeders will affect subsequent changes to maize breeding programs in Kenya and Tanzania.
Introduction Aflatoxins are primarily produced by the fungi – Aspergillus flavus Link – A. parasiticus Speare Optimal conditions for fungal development are – high temperatures 36 to 38 C – high humidity >85% A. flavus image from: http://www.pfdb.net/photo/mirhendi_h/box020909/
Factors influencing Aflatoxin Production Interaction vary with Geographic location, agricultural and agronomic practices, The susceptibility of commodities to fungal invasion during pre- harvest, storage, and/or processing periods Interaction vary with Geographic location, agricultural and agronomic practices, The susceptibility of commodities to fungal invasion during pre- harvest, storage, and/or processing periods Pathogen Aggressiveness Host Plant Susceptibility Favourable Environment Other factors Fungal growth and aflatoxin contamination are the consequence of interactions among the fungus, the host and the environment
CAAREA objective II To characterize the diversity, distribution and toxigenicity of Aspergillus flavus (and to a limited extent, other relevant fungi) in Kenya and Tanzania Determine relation to maize contamination by aflatoxins across AEZs/regions Mainly focused on pre harvest with some post harvest component
Country Wide Survey Work with and through the NARs Activity I: Field trials – 20 sites of 10 varieties will be planted across Agro Ecological Zones – Data/item to be collected Maize phenotypic characters Insect abundance, Weather … Collection of maize cob samples Activity II: Interviews of farmers Activity III: Collection of maize samples from farmers Biophysical data Management data Maize Genotyping (maize map) Area planted to maize Planting density Integrated index of insect load Maize sample aflatoxin concentration Biophysical data Management data Maize Genotyping (maize map) Area planted to maize Planting density Integrated index of insect load Maize sample aflatoxin concentration
Isolation & Characterization of A. flavus Isolation of fungi from seeds at ARI-Mikocheni & at BECA-ILRI Characterization work at BECA- ILRI lab Characterization of A. flavus isolates: – Morphology (S or L strain) – Toxigenicity (extent & type(s) of toxin produced) – Microsatellite genotyping – Other Molecular tools Grouping of A. flavus basing on vegetative compatibility groups Characterization Strain selection for Inoculum production &Field inoculation (screening for resistance) Strain selection for Inoculum production &Field inoculation (screening for resistance) Isolation & Identification Biobank for future studies Biobank for future studies
Fungi survey data from 11 sites in two zones ActivityAspergillus flavus isolates Mid and highland Tanzania19 Lowland in Tanzania57 Total Tanzania76 16 genera identified Fungal isolations/training, ARI Mikocheni, Dar Tanzania
Distribution and diversity of toxigenic A. flavus strains in Kenya
Fungal survey: postharvest component PCR assay being used to determine prevalence of Aspergillus flavus and A. parasiticus in post harvest samples. This will ensure that pre harvest prevalence data does not “miss” part of the problem in some areas.
Major Drivers: Pre Harvest Pathogen abundance Basal inoculum load & prevalence of toxigenic strains and microbiological interactions – Continuous cropping, double cropping & Soil etc. Stressful Environment Untimely planting Water stress or wetness at harvest High-temperature stress Low input farming practice stressed plants – high crop densities, low fertility and weed competition Low host plant resistance Other factors Insect damage of the host plant Growth of other molds or microbes
Major Drivers: Post Harvest Environment High-temperature & High humidity Host Resistance factors – (i.e. Grain texture, resistance to Aspergillus & insect infestation) Pathogen Basal inoculum density in & around the store Other factors Pest infestation & microbe interactions & endophytes
Interventions: Post Harvest, Pre processing Public education and awareness to sensitize the population on aflatoxin risk and its management – Across all the relevant industry sectors – Using effective communication strategies e.g Mobile phone sms & Community radios Timely harvesting Moisture control/Drying of crop – Rapid and proper drying – Avoid drying on bare ground (Use of drying platforms and drying on mats)
Interventions: Post Harvest, Pre processing cont.. Sorting (infected and insect damaged cobs) Improved farm storage and drying methods – e.g Hermetic storage (sealed/air tight containers) Proper transportation and packaging (dry & aerated) Pest Management – Cleaning of store before introduction of new produce – Reduce pest infestation
Interventions: Post Harvest, Pre processing Good food regulatory systems – To regulate quality & safety of food Efficient monitoring and surveillance with rapid, cost-effective sampling and analytical methods Finding alternative uses for contaminated grain Behavioural changes on food supplementation Dietary change?
Interventions: Post Harvest, Pre processing cont.. Other strategies – Mould inhibitors – Detoxification of aflatoxins Physical (Sorting, Flotation & Physical segregation) Chemically (e.g. Ammonia & Calcium hydroxide) Microbiologically (e.g. Fermentation, pro-biotics or lactic acid bacteria into the diet) – Alteration of Bioavailability by Aflatoxin Enterosorbents in human diets Chemisorbents in livestock
Interventions: Post Harvest, Processing period Practising food processing procedures that may involve processes such as Grain cleaning, dehulling, washing, wet and dry milling, roasting, baking, frying etc. Integrated suite of intervention measures should be advocated Integrated suite of intervention measures should be advocated
Challenges Existence of favourable climatic conditions for fungal development & aflatoxin accumulation Difficult to accurately estimate aflatoxins concentration – When large quantity of material are involved – Variability associated with testing procedures Cost-effectiveness of the control methods Food insecurity and drought Limited resources at Household level