Ecofriendly bioherbicide approach for Striga control

Abuelgasim Elzein, a.elzein@cgiar.org, and Fen Beed

Root parasitic weeds of the genus Striga are a significant constraint to cereal and cowpea production in sub-Saharan Africa. They can cause total crop losses particularly during drought, in infertile soils and cereal monocropping. Striga causes annual losses of US$7 billion and affects incomes, food security, and nourishment of over 100 million people mostly in sub-Saharan Africa.

Each Striga plant can produce thousands of seeds, viable for over 10 years. Their intimate interaction with different host plants prevents the development of a silver bullet control technology that subsistence farmers can adopt. Hence, it is widely accepted that an integrated approach to Striga management is required for which biocontrol represents a crucial component.

Bioherbicide innovation
A bioherbicide is a plant pathogen used as a weed biocontrol agent (BCA), which is applied at sufficient rates to rapidly cause a disease epidemic that kills or severely suppresses the target weed. The use of biocontrol technology to manage Striga is a desirable control method as it is environmentally friendly, safe to farmers and crop consumers, specific to the target host, and has the potential to be economically viable. In addition, biological control also assists in the development of a balance of nature, the creation of more biodiversity, and sustaining of complex ecological interactions.

Since the early 1990s, a series of intensive disease surveys in many countries of sub-Saharan Africa has evaluated hundreds of microorganisms for their pathogenicity and virulence against Striga. Fusarium oxysporum Schlecht isolates have been the most promising. However, the discovery of a highly effective pathogen is only one step in the process of developing bioherbicides, for which the inoculum mass production, formulation, delivery, and storage ability must be optimized, and the mode of action, host specificity, and biosafety evaluated and fully understood.

The most widely studied and used fungal isolate that met all requirements for a potential bioherbicide for Striga is F. oxysporum Schlecht f. sp. strigae Elzein et Thines (isolates Foxy2 and PSM197). These are highly virulent, attack Striga in all growth stages—from seed to germination, from seedling to flowering shoot; protect the current crop yield; and prevent seed formation and dispersal.

F. oxysporum f. sp. strigae is highly host-specific to the genus Striga, and does not produce any known mycotoxic compounds. Thus, its use does not pose health risks to farmers, input suppliers, traders or consumers or threaten crops or the environment. Its unique DNA constitution differs from other forms of F. oxysporum deposited in GenBank, known to cause crop diseases. Indeed, this ensures its biosafety and greatly facilitates its wider application and use as a bioherbicide.

In addition techniques for massive production of inoculum of F. oxysporum f. sp. strigae was optimized based on simple and low-cost methods and using inexpensive agricultural by-products available in sub-Saharan Africa. The chlamydospores produced by this fungus have the advantage of being able to survive extreme environmental events while still remaining viable. This is an important feature required for a BCA suited to hot and dry climatic conditions of cereal production in sub-Saharan Africa, and to produce stable, durable, and pathogenic propagules.

Extensive research by the University of Hohenheim (UH, Germany), IITA (Benin), McGill University (Canada), and Institute for Agricultural Research – Ahmadu Bello University (Nigeria), has enhanced application of F. oxysporum f. sp. strigae, its formulation into bioherbicidal products, and its delivery for practical field application. The Striga bioherbicide contains the Striga host-specific F. oxysporum f. sp. strigae, applied in massive doses to create a high infection and disease level to kill or severely suppress Striga.

Promotion in West Africa
The bioherbicide is a component of the IITA-led project, Achieving sustainable Striga control for poor farmers in Africa, funded by the Bill & Melinda Gates Foundation to intensively promote technologies to combat Striga in sub-Saharan Africa. The project will validate the potential of the bioherbicide seed treatment technology across major Striga-infested agroecological zones and maize-based farming systems, while also confirming the biosafety and developing molecular detection tools. Here are the highlights of the results:

Technology validation: Several multilocation trials were conducted under natural and artificial Striga infestation across two agroecological zones in northern Nigeria to evaluate the efficacy of Striga bioherbicide (F. oxysporum f. sp. strigae). The inoculum produced by UH and SUET seed company was delivered as a film-coat on maize seeds (see below).The application of the bioherbicide technology in combination with Striga resistant maize reduced Striga emergence by 73% and 39%, compared to the susceptible and resistant controls, respectively, and prevented 81% and 58% of emerged Striga plants from reaching flowering and 56% and 42% of the maize plants from attack by Striga (see next page). The combination of bioherbicide with Striga susceptible variety significantly reduced Striga emergence by 53%, resulting in 42% reduction in number of flowering plants and in 21% increase in grain yield compared to the susceptible control.

In addition, disease symptoms were recorded on emerged Striga plants parasitizing maize plants coated by the bioherbicide. The reduction in Striga emergence across maize varieties indicates the effectiveness of the bioherbicide to attack seeds under the soil surface. The synergistic effect of the bioherbicide technology combined with the Striga resistant maize is expected to reduce the Striga seedbank and thus the impact of Striga on subsequent maize crops.

Biosafety: To further ensure the safety of Striga BCA and to demonstrate and increase awareness among farmers, regulatory authorities, and stakeholders, a wide host range study was carried out using 25 crops in collaboration with IAR-ABU and the Nigerian Plant Quarantine Service (NPQS)  under field and screenhouse conditions in Nigeria. Results revealed that none of the test plants showed any infection by the biocontrol agent both in the field and screenhouse, and no detrimental growth effects were measured or visual losses to plant health recorded in any of the inoculated crops tested, i.e., inoculation with the Striga BCA did not cause any delay in emergence, and a decrease in plant height, plant vigor, chlorophyll content per leaf, shoot fresh and dry weight. Hence, the Nigerian regulatory authorities (NPQS, NAFDAC) and other stakeholders were satisfied and confident that no disease was produced on plants other than Striga by the BCAs and that it is safe to use. In addition, a mycotoxin produced by Striga bioherbicide  F. oxysporum f. sp. strigae was analyzed and evaluated by our project partner, the University of Stellenbosch in South Africa. An evaluation of existing isolates of F. oxysporum f. sp. strigae does not produce well-known mycotoxins (e.g., Fumonisin and Moniliformin) that pose a threat to animal or human health. This finding further confirms the safety of this bioherbicide.

Molecular detection tools: Development of a monitoring tool specific to the Striga bioherbicide is important to certify inoculum quality, monitor the presence and persistence of the BCA in soils, and validate its environmental biosafety. UH is developing a monitoring tool.

The AFLP fingerprinting technique was successfully used in developing a primer pair capable of differentiating the F. oxysporum f. sp. strigae group from other Fusarium species. In addition, the monitoring tool has shown a high specificity for isolate Foxy2 and was used to monitor its spread and persistence in rhizobox experiments under different management practices using Kenyan soils. This promising result provides a proper baseline to further the existing primer set.

Bioherbicide + pesticide technology: The novel combination and integration of the bioherbicide technology plus imazapyr herbicide for Striga control with pesticides in a single-dose seed treatment to control fungal pests offers farmers with maize seed that is able to achieve its yield potential. The use of each technology (BCA or imazapyr) has been shown to be effective when applied independently using seed coating techniques, but have not been integrated.

The compatibility of Striga BCAs with different pesticides (herbicides and fungicides with insecticide components) was studied in vitro in the laboratory. Striga BCAs showed excellent compatibility with imazapyr (a herbicide seed coating used in combination with IR maize to control Striga), Metsulfuron Methyl (MSM) (a herbicide seed coating developed by DuPont to control Striga in sorghum), and glyphosate (an intensively used herbicide). A similar result was also achieved with the commonly used seed treatment fungicides at the recommended application doses.

Accordingly, doses and complementary seed coating protocols for the three compatible technologies (BCA, herbicide, and fungicides) have been developed and IR maize seeds were successfully coated with a single-dose seed treatment of BCA inoculums and imazapyr. The results showed that imazapyr did not interfere with the BCA during seed coating, with BCA growth and sporulation after coating, and with IR maize seed germination. Seeds of IR maize varieties can thus be coated with the herbicide and the BCA and then fungicide and delivered to farmers using the same input pathway. Screenhouse and field trials are being carried out to generate data on the combined efficacy of the applied technologies. The demonstrated compatibility of Striga BCA with the different pesticides that contain a wide range of active ingredients indicate that the combination and delivery of the Striga bioherbicide technology with a large number of pesticide products is possible. These findings are expected to provide a triple action seed coating package for direct control of Striga and fungal diseases of maize in sub-Saharan Africa.

Suitability to African farming systems
Our strategy for scaling-up the bioherbicide innovation is based on using technology appropriate to Africa to ensure that sustained production of the bioherbicide is feasible at a cost affordable to African small-scale farmers. The seed-coating treatment requires significantly less inoculums, establishes the BCA in the cereal rhizosphere, i.e., the infection site of Striga, and provides a simple, practical, cost-effective delivery system for adoption by input suppliers to subsistence farmers. Arabic gum as a coating material has been shown to increase the rate of mycelia development and enhance BCA sporulation. Its availability in sub-Saharan Africa at a low price is an additional economic advantage. A commercial seed coating process, developed and optimized at UH with SUET Seed Company in Germany, is being transferred and adapted at IITA, Ibadan, to be used as an experimental production unit for capacity building and as a model for eventual transfer of seed treatment technology to the private sector after validation.

Outlook
One unique advantage of this bioherbicide is that the ability of Striga to become resistant to it is virtually unknown as a consequence of the suite of enzymes and secondary metabolites that the BCA produce to become pathogenic and virulent against the target (Striga). Hence after validation, delivering the bioherbicide technology in combination with resistant maize or with the herbicide imazapyr is expected to increase efficacy in controlling Striga. Bioherbicide and other compatible technologies have different modes and sites of action against Striga, and in a combination they will have a much greater chance of reducing the potential risk of development of resistance to a single technology (resistant varieties or herbicides) used separately and repeatedly.
The potential delivery of coated seeds of resistant maize with bioherbicide in one package to farmers using the same input pathway will reduce transaction and application costs and enhances the economic feasibility and adoptability of the technologies. Similarly, compatibility of BCA with imazapyr and fungicides allow seed coating of IR-maize with bioherbicide, imazapyr, and fungicides with a single-dose seed coating application.

Future plans
Currently, large-scale field testing is ongoing and is being implemented to further validate bioherbicidal efficacy across two agroecological zones where the common scenarios for maize infestation by Striga in northern Nigeria are represented. For understanding of farmers’ preferences and perceptions, socioeconomic analysis and cost-benefit analysis of bioherbicidal technology based on field data/surveys and interviews, current market information, and links with other Striga control strategies will be undertaken. After validation, dissemination and commercialization will be promoted through private sector partnerships and integrated with other control options such as resistant varieties, IR varieties combined with seed treatment with imazapayr, crop rotation with legumes, and soil fertility management practices, to achieve sustainable management of Striga.

Partners
IITA (Dr F. Beed, Dr A. Elzein & Dr A. Menkir), Institute for Agricultural Research – Ahmadu Bello University (Dr A. Zarafi), Nigeria; University of Hohenheim (Prof G. Cadisch, Dr F. Rasche & Prof J. Kroschel), Germany; The Real-IPM Company Ltd (Dr H. Wainwright), Kenya; University of Stellenbosch (Prof A. Vilioen), South Africa; and McGill University (Prof A. Watson), Canada.

References
Beed F.D., S.G. Hallet, J. Venne, and A. Watson. 2007. Biocontrol using Fusarium oxysporum; a Critical Component of Integrated Striga Management. Chapter 21 in Integrating New Technologies for Striga control: Towards ending the Witch-hunt (Ejeta, G. and J. Gressel, eds). World Scientific Publishing Co. Pte. Ltd. pp 283-301.

Ciotola, M., A. DiTommaso, and A. Watson. 2000. Chlamydospore production, inoculation methods and pathogenicity of Fusarium oxysporum M12-4A, a biocontrol for Striga hermonthica. Biocontrol Science and Technology 10: 129-145.

Ejeta, G. 2007. The Striga scourge in Africa: A growing pandemic In: Ejeta, G. and J. Gressel, eds. Integrating New Technology for Striga Control: Towards Ending the Witchhunt. World Scientific Publishing Co. Pte. Ltd., UK. pp. 3-16.

Elzein, A.E.M. 2003. Development of a granular mycoherbicidal formulation of Fusarium oxysporum “Foxy 2” for the biological control of Striga hermonthica. In: “Tropical Agriculture 12– Advances in Crop Research (2)” (J. Kroschel, ed.). Margraf Verlag, Weikersheim, Germany, 190 pp, ISBN 3-8236-1405-3.

Elzein, A., J. Kroschel, and V. Leth. 2006. Seed treatment technology: an attractive delivery system for controlling root parasitic weed Striga with mycoherbicide. Biocontrol Science and Technology, 16(1) 3-26.

Elzein, A., F. Beed, and J. Kroschel. 2012. Mycoherbicide: innovative approach to Striga management. SP-IPM Technical Innovations Brief, No. 16, March 2012.

Kroschel, J. and D. Müller-Stöver. 2004. Biological control of root parasitic weeds with plant pathogens. In: Inderjit, K. (ed.), Weed biology and management. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 423–438.

Kroschel, J., A. Hundt, A.A. Abbasher, J. Sauerborn. 1996. Pathogenicity of fungi collected in northern Ghana to Striga hermonthica. Weed Research 36 (6), 515–520.

Marley, P.S., S.M. Ahmed, J.A.Y. Shebayan, and S.T.O. Lagoke. 1999. Isolation of Fusarium oxysporum with potential for biocontrol of the witchweed Striga hermonthica in the Nigerian Savanna. Biocontrol Science and Technology 9: 159–163.

Venne J., F. Beed, A. Avocanh, and A. Watson. 2009. Integrating Fusarium oxysporum f. sp. strigae into cereal cropping systems in Africa. Pest Management Science 65: 572–580.

Ensuring the safety of African food crops

aflasafeâ„¢ team: Ranajit Bandyopadhyay, Joseph Atehnkeng, Charity Mutegi, Joao Augusto, Juliet Akello, Adebowale Akande, Lawrence Kaptoge, Fen Beed, Olaseun Olasupo, Tahirou Abdoulaye, Peter Cotty, Abebe Menkir, and Kola Masha, with several national partners

Ground-breaking research by scientists at IITA and partners is ensuring safe food and health for Africans.

IITA, in collaboration with the United States Department of Agriculture – Agricultural Research Service (USDA-ARS) and the African Agriculture Technology Foundation (AATF), has developed a natural, safe, and cost-effective biocontrol product that drastically cuts aflatoxin contamination in African food crops.

Aflatoxins are highly toxic chemical poisons produced mainly by the fungus Aspergillus flavus in maize and groundnut, and on yam chips, but which also affect other high-value crops such as oilseeds and edible nuts. The fungal chemicals cause liver cancer and also suppress the immune system, retard growth and development, lead to chronic liver disease and cirrhosis, and death in both humans and animals. Livestock are also at risk and poultry are particularly susceptible. Cattle are not so susceptible but if they are fed with contaminated feed the toxin “Aflatoxin M1” passes into the milk.

The biocontrol product – aflasafe™ uses native strains of A. flavus that do not produce aflatoxins (called atoxigenic strains) to “push out” their toxic cousins so that crops become less contaminated in a process called “competitive exclusion”. When appropriately applied before the plants produce flowers these native atoxigenic strains completely exclude the aflatoxin producers.

IITA recommends broadcasting 10 kg/ha aflasafe™ by hand on soil 2–3 weeks before the flowering stage of maize to prevent the aflatoxin- producing fungus from colonizing and contaminating the crop while it remains in the field and subsequently in storage. Even if the grains are not stored properly, or get wet during or after harvest, the product continues to prevent infestation and contamination.

The reduction of aflatoxin in maize fields is greater with the application of aflasafe™ than with the deployment of putative low-aflatoxin maize lines. For example, field studies during 2010 and 2011 in Nigeria established that aflatoxin reduction was 16–72%, due to resistant maize hybrids, 80–92% with aflasafe™, and 80–97% with the combined use of resistance and aflasafe™.

Field testing of aflasafe™ in Nigeria between 2009 and 2012 consistently showed a decrease in contamination in maize and groundnut by 80–90% or more.

In 2009, Nigeria’s National Agency for Food and Drug Administration and Control registered aflasafe™ and permitted treatment of farmers’ fields to generate the data on product efficacy for obtaining full registration. In 2011, IITA distributed about 14 t of aflasafe™ to more than 450 maize and groundnut farms, enabling farmers to achieve an 83% reduction in contamination.

The success of the project has led to the expansion of biocontrol research in Burkina Faso, Ghana, Kenya, Mozambique, Senegal, Tanzania, and Zambia.

Between 2004 and 2006, nearly 200 Kenyans died after consuming aflatoxin-contaminated maize. In 2010 over 2 million bags of maize in Kenya’s Eastern and Central provinces were found to be highly contaminated and were declared as non-tradable.

Research conducted by Leeds University and IITA found that 99% of children at weaning age are exposed to health risks linked to aflatoxin in Bénin and Togo.

Across the world, about US$1.2 billion in commerce is lost annually due to aflatoxin contamination, with African economies losing $450 million each year. Aflatoxins are also non-tariff barriers to international trade since agricultural products are rejected that have more than the permissible levels of contamination (4 ppb for the European Union and 20 ppb for USA).

IITA has identified separate sets of four competitive atoxigenic strains isolated from locally grown maize to constitute a biocontrol product called aflasafe KE01â„¢ in Kenya and aflasafe BF01 in Burkina Faso and aflasafe SN01 in Senegal.

The adoption of this biocontrol technology with other management practices by farmers will reduce contamination by more than 70% in maize and groundnut, increase crop value by at least 5%, and improve the health of children and women.

In 2012, G20 leaders launched a new initiative – AgResults – which included aflasafe™ in Nigeria as one of the first three pilot projects to encourage the adoption of agricultural technologies by smallholder farmers.

IITA’s experience in Nigeria has shown that the cost of biocontrol (about $1.5/kg with a recommended use of 10 kg/ha) is affordable for most farmers in the country.

The biocontrol product aflasafe SN01 can potentially reinstate groundnut exports to the European Union lost by Senegal and The Gambia due to aflatoxin contamination. The World Bank has estimated that in Senegal, an added capital investment cost of $4.1 million and 15% recurring cost would attract a 30% price differential to groundnut oil cake. Exports are expected to increase from 25,000 to 210,000 t. The increased export volume and price would annually add $281 million to groundnut exports. For confectionery groundnut, adherence to good management practices would increase export value by $45 million annually.

Currently, a demonstration-scale manufacturing plant for aflasafeâ„¢ is under construction at IITA with a capacity to produce 5 t/h. Market linkages between aflasafeâ„¢ users, poultry producers, and quality conscious food processors are also being created to promote aflasafeâ„¢ adoption, in collaboration with the private sector.

Costs and benefits
Biocontrol of aflatoxin is one of the most cost-effective control methods, with the potential to offer a long-term solution to aflatoxin problems related to liver cancer in Africa. Cost-effectiveness ratio (CER) of treating all maize fields in Nigeria with aflasafeâ„¢ is between 5.1 and 9.2, rising to between 13.8 and 24.8 if treatments were restricted to maize intended for human consumption. Up to 162,000 disability-adjusted life years (DALYs) can be saved annually by biocontrol in Nigeria.

Initial data from a separate study in Nigeria suggest that farmers will receive a return of from 20 to 60% on investment in aflasafeâ„¢ from the sale of maize harvested from treated fields to poultry feed manufacturers and quality-conscious food processors.

Donor support
Research and development efforts on aflasafe™ have been supported by the following donors: Bill & Melinda Gates Foundation, USAID, USAID-FAS, AATF, Commercial Agriculture Development Project of the Government of Nigeria, The World Bank, Austrian Development Cooperation (ADC), Deutsche Gesellschaft für Internationale Zusammenarbeit, GmbH (GIZ), the European Commission (EC KBBE-2007-222690-2 MYCORED), and Meridian Institute. In addition, IITA has received support from Belgium, Denmark, The German Federal Ministry for Economic Cooperation and Development (GTZ BMZ), Ireland, Norway, Sweden, Switzerland, and the UK Department for International Development (DFID).

References
Atehnkeng, J., P.S. Ojiambo, M. Donner, T. Ikotun, R.A. Sikora, P.J. Cotty, and R. Bandyopadhyay. 2008. Distribution and toxigenicity of Aspergillus species isolated from maize kernels from three agroecological zones in Nigeria. International Journal of Food Microbiology 122 (1-2): 74-84.
Atehnkeng, J., P.S. Ojiambo, T. Ikotun, R.A. Sikora, P.J. Cotty, and R. Bandyopadhyay. 2008. Evaluation of atoxigenic isolates of Aspergillus flavus as potential biocontrol agents for aflatoxin in maize. Food Additives and Contaminants 25 (10): 1266-1273.
Bandyopadhyay, R., M. Kumar, and J.F. Leslie. 2007. Relative severity of aflatoxin contamination of cereal crops in West Africa. Food Additives and Contaminants 24 (10): 1109-1114.
Diedhiou, P.M., R. Bandyopadhyay, J. Atehnkeng, and P.S. Ojiambo. 2011. Aspergillus colonization and aflatoxin contamination of maize and sesame kernels in two agroecological zones in Senegal, Journal of Phytopathology 159 (4): 268-275.
Donner, M., J. Atehnkeng, R.A. Sikora, R. Bandyopadhyay, and P.J. Cotty. 2009. Distribution of Aspergillus section flavi in soils of maize fields in three agroecological zones of Nigeria. Soil Biology and Chemistry 41 (1): 37-44.
Donner, M., J. Atehnkeng, R.A. Sikora, R. Bandyopadhyay, and P.J. Cotty. 2010. Molecular characterization of atoxigenic strains for biological control of aflatoxins in Nigeria. Food Additives 27(5): 576-590.
Egal, S., A. Hounsa, Y.Y. Gong, P.C. Turner, C.P. Wild, A.J. Hall, K. Hell, and K.F. Cardwell. 2005. Dietary exposure to aflatoxin from maize and groundnut in young children from Bénin and Togo, West Africa. International Journal of Food Microbiology 104 (2): 215-224.
Kankolongo, M.A., K. Hell, and I.N. Nawa. 2009. Assessment for fungal, mycotoxin and insect spoilage in maize stored for human consumption in Zambia. Journal of the Science of Food and Agriculture 89 (8): 1366-1375.
Oluwafemi, F., M. Kumar, R. Bandyopadhyay, T. Ogunbanwo, and K.B. Ayanwande. 2010. Bio-detoxification of aflatoxin B1 in artificially contaminated maize grains using lactic acid bacteria. Toxin Reviews 29 (3-4): 115-122.
Wu, F. and Khlangwiset, P. 2010. Health and economic impacts and cost-effectiveness of aflatoxin-reduction strategies in Africa: case studies in biocontrol and postharvest interventions. Food Additives and Contaminants: Part A, 27: 496-509.

Biocontrol offers benefits to Africa

Biological control programs implemented by IITA and partners on cassava green mite have brought benefits worth more than $1.7 billion to Nigeria, Bénin, and Ghana in the last 18 years.

Diseased plant. Photo by IITA.
Diseased plant. Photo by IITA.

Ousmane Coulibaly, IITA Agricultural Economist, describes the figure as “a conservative estimate.”

“The figure represents the amount those countries would have spent over the years on other methods such as chemical control and/or yield losses if they never adopted biological control,” said Coulibaly.

The cassava green mite is a pest that was responsible for a yield loss in cassava in Africa of between 30 and 50% until a natural enemy of the pest helped to contain the devastation. In 1993, scientists from IITA and partners identified Typhlodromalus aripo as one of the most efficient enemies against cassava green mite. The introduction of T. aripo reduced pest populations by as much as 90% in the dry season when pest populations are usually high; in the wet season, pest attacks are not as severe.

T. aripo from Brazil was first released on cassava farms in Bénin and, subsequently, in 11 countries; it is now confirmed as established in all of them, except Zambia. T. aripo has also spread into Togo and Côte d’Ivoire from neighboring countries. It spread to about 12 km in the first year, and as much as 200 km in the second year. Today, the predator of the cassava green mite has been established on more than 400,000 km2 of Africa’s cassava-growing areas.

Scientists say chemical control of the pest was ruled out because of possible adverse effects of chemicals on illiterate farmers and the environment. Also, disease pathogens and pests tend to develop gradual resistance to chemical pesticides over time. Moreover, most chemical pesticides are not selective and might destroy the natural enemies and the pests together.

Coulibaly notes that since the release of T. aripo, benefits in Nigeria have been estimated at $1.367 billion, followed by Ghana $305 million, and Bénin $54 million. Consumed by more than 200 million people in sub-Saharan Africa, cassava is a staple food that is rich in calories, highly drought tolerant, thriving in poor soils, and easy to store in the ground.

Initiative tackles killer aflatoxin

IITA and partners recently launched a project that will provide farmers in Nigeria and Kenya with a natural, safe, and cost-effective solution to prevent the contamination of maize and groundnut by a cancer-causing poison, aflatoxin. It is funded by the Bill & Melinda Gates Foundation.

Maize cobs attacked by fungi. Photo by IITA.
Maize cobs attacked by fungi. Photo by IITA.

Aflatoxin is produced by a fungus (Aspergillus flavus). It damages human health and is a barrier to trade and economic growth. The toxin, however, is not produced in all strains of the fungus. The project’s biocontrol technology introduces nontoxic strains of the fungus in the affected fields. These “good guys” overpower and reduce the “bad guys,” the population of toxic strains, drastically reducing the rate of contamination.

During the launching of the project, Wilson Songa, Agricultural Secretary in Kenya’s Ministry of Agriculture, said that Kenya welcomed the initiative after recent losses of lives and millions of tons of maize to aflatoxin contamination.

“Kenya has become a hotspot of aflatoxin contamination. Since 2004, nearly 150 people have died after eating contaminated maize,” he said.

IITA had worked with the United States Department of Agriculture to develop a biocontrol solution for aflatoxin, testing it in many fields in Nigeria. The project will take the biocontrol product, commercialize it, and make it available to farmers.

Ranajit Bandyopadhyay, IITA’s plant pathologist, says the project is adding value to previous investments in biocontrol. It will support the final stage of commercialization of aflasafe™ in Nigeria and selection of the most effective strains, development of a biocontrol product, and gathering of data on efficacy in Kenya.

The Nigerian government has joined forces with IITA and the World Bank to help contain the contamination of food crops by aflatoxins.

The collaboration will make aflasafeâ„¢ available to farmers to greatly reduce the aflatoxin menace.

The new approach is part of the Commercial Agriculture Development Program supported by the World Bank and implemented in Kano, Kaduna, Enugu, Cross River, and Lagos States in Nigeria.

In Nigeria, produce from resource-poor maize farmers faces rejection from the premium food market because of aflatoxin contamination.

In on-farm research trials in Kaduna State—north-central Nigeria—during 2009 and 2010, farmers who treated their fields with aflasafe™ were able to reduce the levels of contamination by 80 to 90%.

Related website

Aflatoxin management website – www.aflasafe.com

aflasafeâ„¢: a winning formula

Biological control of aflatoxins using aflasafeâ„¢ is providing hope for African farmers battling with crop contamination and opening doors for the private sector looking to invest on a winning formula in the agricultural sector.

Scientists have developed a cost-effective, safe, and natural method to prevent aflatoxin formation in maize while in the field. Aflatoxin causes liver cancer and suppresses the immune system, endangering both humans and animals. It also retards growth and development of children. This colorless chemical is invisible and its presence and contamination levels can only be confirmed by laboratory tests.

The biocontrol technology works by introducing native (local) strains of the fungus Aspergillus flavus that do not produce the aflatoxin (the ‘good guys’) in the affected fields. This good fungus boxes out and drastically reduces the population of the poison-producing strains (the ‘bad guys’).

The aflasafeâ„¢ technology has the potential to provide relief to millions of maize farmers in sub-Saharan Africa depending on agriculture as a source of livelihood.

According to Ranajit Bandyopadhyay, IITA Plant Pathologist, a single application of this biopesticide 2-3 weeks before maize flowering is sufficient to prevent aflatoxin contamination throughout and beyond a cropping season and even when the grains are in storage.

With an initial investment outlay of US$1−3 million in an aflasafe™ manufacturing plant, investors are likely to reap about $1.33 million annually. Bandyopadhyay said that investing in an aflasafe™ manufacturing plant in Nigeria would pay off considering the huge demand for quality maize in the country. His estimates showed that over 60% of harvested maize in Nigeria currently has high levels of aflatoxins and are prone to being rejected by the feed industry.

Institutions involved in the initiative include IITA, Agriculture Research Service of the United States Department of Agriculture, AATF, and local partners.

Related website

Aflatoxin management website – www.aflasafe.com

Ken Neethling: Biocontrol champion

Ken Neethling, CEO, BCP
Ken Neethling, CEO, BCP

Ken Neethling is the chief executive officer of Biocontrol Products (BCP) based in South Africa. An engineer by training, he started working for BCP 13 years ago. Commercial biocontrol was a relatively new concept then, he says. Along the way, he became exposed to commercial fermentation and the world of microbes. Today, he manages the business and works with a “very competent team”.

BCP started as a biocontrol company, initially producing a fungal nematicide (egg stage) to work alongside those targeted at adult nematodes in an IPM program. In 1997, the Biological Control of Locusts and Grasshoppers (LUBILOSA) project approached BCP to commercially produce Green Muscle®, a flagship product, for the control of locusts, relates Ken. BCP has subsequently used its platforms of research, registrations, and production to bring other microbes to a commercial level. BCP’s range today includes many bacteria, fungi and plant extracts—for a diversity of uses in agriculture, including growth promotion, insecticides, nematicides, fungicides, and nutrition.

What are the prospects of biological control products in Africa?
BCP’s corporate slogan is “restoring nature’s balance”. In many respects this sums up the case for biocontrol products: They’re natural, generally safe to nontargets and already found in nature; they have a smaller environmental footprint and work in harmony with nature; they restore balance; this recognizes that the way we have historically treated our environment was out of balance. Restoring balance also implies sustainability and “subeconomic threshold” control strategies.

Biocontrol products are not a silver bullet—they’re part of a solution. When considering the growing global population that needs to be fed, the fertile soils of Africa are also part of the solution.

If Africa’s decision makers are receptive, then I believe biological control has a bright future in this continent.

IITA was part of the team that developed Green Muscle® years ago. The technology is one product of research that has proved quite successful. Tell us more about Green Muscle®.
I have a very high regard for IITA’s researchers…The development of Green Muscle® was truly a multidisciplinary, multicultural and multinational success story. BCP’s contribution to the development of Green Muscle® was in the areas of production, stability, formulation, costing, packaging, and providing product for trials. Over the years, BCP has also provided training on aspects of quality control and standard operating procedures. We advise on storage and provide analytical services to our Green Muscle® customers. BCP has also contributed to the registration process in some of the affected countries.

Ken Neethling, CEO of Biocontrol Products, South Africa. Photo from K. Neethling.
Ken Neethling with colleague Sifiso showing off one of BCP's industrial fermenters. Photo from K. Neethling.

Why did it take Green Muscle® almost 10 years from development to deployment to get into the market when it was so obviously a very effective product?
BCP is but one of the many champions of Green Muscle®. We worked tirelessly over the last 10 years. There were, and still are, many challenges.

The technology had to break new ground. For example, biocontrol has a completely different mode of action to the commonly used synthetic chemicals—it is slower acting on the knockdown, but with a longer residual and less environmental effect. In the case of Green Muscle®, the locusts stop feeding after 2 days. They become lethargic and, due to predation (they’re safe for birds and mammals to eat) they are quickly picked off. So the challenge was to show that not having hundreds of poisoned locust cadavers lying around was a good result!

The other challenge was cost—I’m sure many can appreciate that a biocontrol product, produced initially in small quantities, would have a very hard time competing in terms of price or cost against chemicals churned out in massive factories. Make no mistake, cost is important and especially in locust control, every dollar needs to be stretched to extract maximum benefit.

However, cost is a much bigger picture than simply the price of the active ingredient per hectare. Recent studies have indicated that the lifecycle cost of chemical control (including disposal of obsolete stock, soil decontamination, loss of pollination services, etc.), is higher than that of biocontrol.

I believe that there is still scope for even wider deployment—for example, preventative treatment campaigns in eco-sensitive breeding grounds that could prove more cost-effective than an emergency response to an outbreak.

What have been your challenges and opportunities in marketing Green Muscle®?
Our main marketing challenge is that we have so many different “customers” to consider.

First and most importantly the general population, who risk losing their food and livelihood to locust swarms of sometimes biblical proportions; the governmental plant protection departments of the various countries, who manage smaller campaigns within their borders; regional (i.e., cross border) emergency outbreak management bodies that largely depend on external funding; the United Nations, which coordinate and disperse donor funding for locust control; and the donor community, who ultimately hold the purse strings that need to be opened in large emergency campaigns.

How much is the demand for Green Muscle® in Africa?
Demand is obviously directly linked to locust outbreaks and contingent donor funding. To be honest, it has been frustratingly sporadic. This is not ideal from a production perspective, as it is more cost-effective to run continuously, with regular planned off-takes. To date, supply has been able to keep up, but we have also had to burn the midnight oil a few times in an emergency.

Is there any interest in the product outside Africa?
Yes there is interest outside Africa. My interpretation of this is that “good news travels fast”. But finding the right partners, doing trials, establishing market potential, drawing up agreements, licensing and all the other factors mean that this type of product can never be expected to be an “overnight success”.

What is the outlook of biocontrol, in general, in Africa? The world?
In summary, I would say the outlook is good, but this needs work and commitment from all stakeholders before it can have a meaningful impact on Africa. The same would apply to the rest of the world, except that consumer awareness (and hence demand) is higher in the developed world.

Do you think biocontrol would become competitive enough against chemical-based control measures?
Historically it can be argued that biocontrol hasn’t challenged chemical-based control measures, but that was partly due to the way we viewed this notion of control. What we have seen is that novel strains and human ingenuity are helping to make biocontrol a worthy alternative to chemicals. We’ve experienced this first hand with Green Muscle® in large-scale control operations, where we have had control comparable to that of the chemicals. In some extreme situations, such as in Algeria, we saw exceptional control, a level greater than 90%.

What would help to popularize the adoption of biocontrol technologies?
This challenge requires total commitment from many diverse stakeholders. But the basic principle, “Use it or lose it,” applies. Biocontrol technologies must be used and must make a difference in areas that count; otherwise they will forever remain in the research domain.

Green Muscle has gone the way of traditional R&D (i.e., research/science -> product development -> commercialization). When should the private sector come in?
Necessity is the mother of invention, so while I lean towards the commercial sector as being more in touch with the needs of the market, there is nothing to say that scientists can’t also fulfill this role. What is important is that there is a clear path to market, with early involvement of a commercial partner and good communication among all stakeholders during the development cycle.

What is needed to push agricultural technologies, such as biocontrol, from the research shelves to the market and eventually to the intended end-users?
A lot of money, for starters! Much more than I think anyone ever estimated. And a lot of time too. It needs product champions across the board: in government, in research, in the media, and in the procurement and purchasing channels.

What would you tell scientists or research organizations, such as IITA, working on biocontrol development?
There is a lot of good work being done by scientists around the world—biocontrol technology development is one of the many exciting and challenging areas with so much potential. The aim of science is to increase knowledge for the purposes of serving humanity and protecting our planet—whatever we research, develop, and commercialize must have these values as their foundation.

The power of biocontrol

Farmers and scientists have, time and time again, turned back to nature to find solutions to pest problems in crop fields.

Variegated grasshopper (<em srcset=Zonocerus variegatus). Photo from Wikimedia commons ” width=”250″ height=”188″ />
Variegated grasshopper (Zonocerus variegatus). Photo from Wikimedia commons

When several exotic pests were accidentally introduced into Africa from South America through infected planting materials in the early 1970s, ravaging economically important crops, such as cassava, scientists turned to the origins of the pests to solve the problem.

A lot has been said about the benefits of biological control or biocontrol. It is natural and safe to the environment and humans, and rigorous tests ensure that it is effective only on the target pests.

And almost three decades of research and development at IITA have shown the continuing effectiveness and sustainability of biological control in combination with other approaches for managing insect pests.

These biocontrol practices and technologies provide the subsistence farmers in sub-Saharan Africa with solutions that are sometimes their only safety net.

This issue on biocontrol celebrates the success of solutions to problems in tropical agriculture that IITA and its partners have developed for millions of African farmers.

The witch menace

Maize ravaged by Striga
Maize ravaged by Striga. Photo by IITA

The witch’s spell on millions of hectares of cereal crops in sub-Saharan Africa (SSA) will soon be broken. A deadly “potion” using natural enemies is being developed by IITA and its partners to manage the menace.

Striga hermonthica or witchweed, the parasitic weed that attacks cereal crops, such as maize, sorghum, and millet, has caused devastating annual production losses estimated at US$7 billion among small-scale farmers, contributing to hunger, malnutrition, and poverty in SSA.

The sight of the deceptively beautiful pink flowers of Striga spells doom for farmers. The weed grows on the roots of host plants absorbing the plant’s water, photosynthates, and minerals. When the flowers are in bloom, it is already firmly established. Thus, the use of aboveground herbicides is ineffective, since the damage has occurred long before the weed is visible to farmers. Each plant can produce tens of thousands of seeds that are dispersed far and wide by man and nature, and which lie dormant but still potentially active for many years.

Angry farmer with Striga plant
An angry farmer with Striga plant. Photo by IITA

Loss of millions of tons of food
Fen Beed, an IITA plant pathologist, explains that production losses from Striga routinely range from 15 to 90% depending on the crop cultivar, degree of infestation, rainfall pattern, and degree of soil degradation.

Striga infests about 50 million hectares of land in SSA resulting in the loss of over 8 million tons of food annually. The larger areas affected are in Nigeria, Niger, Mali, and Burkina Faso.

Unfortunately, measures developed to control the weed in the developed world, such as soil fumigation, are too costly for the poor subsistence farmers who make up 70 to 80% of farmers in SSA. New management options are thus urgently needed.

One promising, sustainable, and environmentally friendly technology under development is biocontrol using indigenous fungi that are natural enemies of the weed.

Poisoning the witch
A team led by Beed with partners from the University of McGill (Canada) and University of Hohenheim (Germany), and national agricultural research systems (NARS) and universities in West Africa, have identified isolates of a fungus that attacks Striga for use as a bioherbicide.

By studying over hundreds of diseased shoots of Striga in Bénin, Burkina Faso, Ghana, Mali, Niger, and Nigeria, scientists discovered isolates of Fusarium oxysporum f. sp. striga that controlled the weed.

Container trial, Ibadan, Nigeria
Container trial, Ibadan, Nigeria. Photo by IITA

A series of controlled laboratory studies identified the most effective of these as M12-4A, an isolate from Mali, Foxy 2 from Ghana, and PSM-197 from the Nigerian savanna. The isolates attacked Striga in all its growth stages—from seed to germination, from seedling to flowering shoot. They significantly lessened the number of attachments and flowering Striga plants, thus reducing the number of seeds deposited in the soils and limiting the future reappearance of the weed. Furthermore, the isolates were specific to S. hermonthica, had no impact on cereal hosts or any other plants, and did not produce any toxins that harm man or livestock.

Repeated field trials were performed for the first time under West African conditions using Striga-resistant and Striga-susceptible varieties of sorghum and maize in Nigeria, Burkina Faso, and Bénin in partnership with various NARS and universities. The efficacy of the three isolates selected from laboratory studies were compared with other isolates originating from Bénin and Burkina Faso. Amino acids found to disrupt germination of Striga under laboratory conditions were also included but failed to produce significant improvements in weed control under field conditions.

Results showed that PSM-197 and Foxy 2 were the most effective in repressing witchweed, whereas isolate M12-4A was less effective under the range of field conditions tested. Also, there was a 90% reduction in Striga emergence when the biocontrol technology was used in combination with a Striga-resistant maize line.

Two methods were used to apply the fungi: either directly coating the seed using locally available gum arabic or directly adding the fungus in powder formulations of kaolin-based PESTA granules into planting holes. The granular formulation was found to be more efficient, especially for sorghum which has much smaller seeds than maize, where the larger seeds receive more fungal inoculum when applied as a seed coating. However, it is more costly and difficult to distribute to farmers.

Drying sorghum and maize seed coated with PESTA
Drying sorghum and maize seed coated with PESTA. Photo by IITA

Therefore, the seed-coating method offers the most cost-effective method, especially when combined with Striga-resistant germplasm.

Another important finding is that the biocontrol agent works most efficiently when the soil is rich in beneficial (friendly) and not antagonist (nuisance) microorganisms. Container trials at IITA Ibadan showed that the profile of both bacterial and fungal microorganisms was changed when different species of cereals were grown in the same soil—this is because each plant type produces different exudates that are excreted around roots that promote or inhibit the growth of different microorganisms.

Furthermore the profile was changed when different cultivars of the same species of cereal crop (maize or sorghum) were grown. Different fertilizer combinations had similar impacts on microorganism profiles—all of these changes in profiles affect the success of introduced biocontrol agents. This study was done using state of the art PCR-DGGE technology in collaboration with the University of Purdue.

Making the potion available and affordable
Supplying fungal-coated seeds of improved varieties to farmers requires a delivery pathway. Researchers face the challenge of mass producing the biocontrol agents and encouraging farmers to use them. The models being tested for mass production of the F. oxysporum inoculum include on-farm, cottage-industry, small entrepreneur industry, and government initiatives, such as that in Senegal initiated by Foundation Agir pour l’Education et la Santé.

Under the small entrepreneur industry models, one company in Kenya, Real-IPM, has secured funding to register Foxy 2 before mass production using large-scale commercial tanks for liquid culture of the fungus. Another company, Western Seed Company Ltd., has carried out preliminary field tests with support from the Kenya Plant Health Inspectorate Services.

Finding a way to curtail the negative impact of witchweed has been a long journey, but the biocontrol option can provide an important component in an integrated package of strategies for managing this pest.

PESTA granules
PESTA granules. Photo by IITA

“There will never be a silver bullet solution to alleviate the problems faced by farmers from witchweed. It is important to recognize that efficacy and persistence of the biocontrol agent is improved when steps are taken to prevent the soil from being degraded and to enrich it with organic matter,” says Beed.

New techniques are also needed for measuring the extent of losses caused by witchweed and their economic impact. Likewise, control technologies need to be developed and implemented, and their efficacy assessed across the different environments scourged by the pest, he added.

Biocontrol combined with the use of improved cereal cultivars that have increased tolerance/resistance to Striga, and the use of seed-coated herbicides such as imazapyr, in addition to the regular use of trap crops, at last offers small-scale farmers real hope against the “witch”.

O.A. Adenola: More awareness needed on the dangers of aflatoxins

Pastor O.A. Adenola
Pastor O.A. Adenola. Photo by IITA

The president of one of the strongest crop networks in Nigeria, Pastor O.A. Adenola, talks about the need for stakeholders to join forces against aflatoxin spread and other issues. This is an excerpt from his interview with Godwin Atser.

Do farmers understand what aflatoxins are?
They may see the fungus on the maize cob but really many Nigerian farmers do not know the danger in what they see: what it is… what effects it has on people as a result of eating grain that is already contaminated… I think we need a lot of awareness, a lot of teaching to get our farmers to know the dangers of aflatoxins in our foods. The problem is that you don’t see them and their effect physically. If you look at the cassava mealybug, for instance, the farmer sees the plant die. In the case of aflatoxins, you don’t see them causing anything bad to maize; it is the after-effect that damages people’s health.

What can be done to bring the message to the people?
It has to involve a collective effort from all of us: the research institutes, the Agricultural Development Programs, the Maize Association of Nigeria, and the media. We won’t make any progress if we don’t collaborate to get the farmers to know the importance of the effect of aflatoxins on human beings and on animals.

You participated in the Doubling Maize Project. What were your observations?
At the time the project was initiated in 2006, the maize production level on average was 1.5 t/ha. The project target was to double production—from 1.5 to 3 t/ha. A farmer who could not combine production inputs to give us 3 t/ha was not qualified to be involved in the scheme because we did not want to increase the area planted. We wanted to increase production per unit area. The intention was to intensify production so that we could double what was on the ground.

So what happened?
I tell you, farmers made more than 3 t/ha! Also if the technology is properly applied, Nigeria can easily double maize production.

What effort is your association making to disseminate some of the findings of that research to increase maize production?
The maize network is stronger than the networks of other crops in Nigeria, maybe, because of the facilities we have at IITA that are linking us up properly with research and also with Ministries of Agriculture all over the country. And since we were the beneficiaries of the research findings, it was easier for us and for our members to adopt the improved technologies.

All that the researchers were telling us was “You can be better farmers if you take the technology.” I must tell you that every farmer is out there in the field because he wants to make more money. So the benefit is good enough to propel the technology.

How is the collaboration between MAAN and IITA?
Excellent! I have been relating with IITA since 1984 and when this Association was formed in 1992, it was formed in IITA. Since then we have had very good collaboration.

What can IITA do to make this partnership grow?
Whenever there is a need and we call on IITA, they have always answered. The Director General and the maize “chief”, Dr Sam Ajala and his team, have been very cooperative. That collaboration is what is important. If you have a problem and you call your friend and he answers, then you are okay.