Skip to main content

Author: Carolyn Cowan

New publications: Toxin-producing fungal strains can now be detected in maize field soils with a new technique

A novel approach allows the detection of aflatoxin-producing fungi in maize fields. A new study explains the technique and how it was tested. “Detection of Aflatoxigenic and Atoxigenic Mexican Aspergillus Strains by the Dichlorvos–Ammonia (DV–AM) Method” was developed in collaboration between scientists from the International Maize and Wheat Improvement Center (CIMMYT), the Japanese National Agriculture and Food Organization (NARO) and Fukui University of Technology, funded in part by the CGIAR Research Program on Maize (MAIZE).

Aflatoxins are harmful compounds produced by the fungi Aspergillus flavus, which can be found in the soil, plants and grain of a variety of cereals and commodities including maize, nuts, cottonseed, spices and dried fruit. The toxic carcinogenic qualities of aflatoxins pose serious health hazards to humans and animals when contaminated crops are ingested. These health risks include cancers of the liver and gallbladder, stunted development in children, premature births and abnormal fetal development.

Not all strains of A. flavus produce aflatoxins however, so it is important to be able to detect and distinguish between A. flavus strains that are benign (atoxigenic) and those that produce dangerous toxins (aflatoxigenic). Current methods of detection are often complicated by the fact that the fungal strains display very similar physiological and molecular traits, thus a new approach is required.

In the study, a novel approach to detect and distinguish A. flavus strains was tested. Using soil samples from a CIMMYT experimental maize field in Mexico, fungal isolates were chemically treated in-line with a method recently developed in Japan, resulting in a color change indicative of toxicity. The method was found to be effective and accurate in the detection of the aflatoxigenic strains of the fungus.

This study is foundational work in the development of a simple, cost-effective and efficient method of detecting aflatoxigenic strains of A. flavus, which will help inform growers about the potential aflatoxin contamination of their crops. This is of particular importance in the developing world, where the resources for effective control of the fungus are often lacking.

To read the original study, “Detection of Aflatoxigenic and Atoxigenic Mexican Aspergillus Strains by the Dichlorvos–Ammonia (DV–AM) Method”, please click here.

Original citation: Kushiro, M.; Hatabayashi, H.; Yabe, K.; Loladze, A. Detection of Aflatoxigenic and Atoxigenic Mexican Aspergillus Strains by the Dichlorvos–Ammonia (DV–AM) Method. Toxins 2018, 10, 263.

This article was originally published on the website of the CGIAR Research Program on Maize.

Maize ear infected with Aspergillus flavus. (Photo: Maize Pathology Laboratory/CIMMYT)
Maize ear infected with Aspergillus flavus. (Photo: Maize Pathology Laboratory/CIMMYT)

Check out other recent publications by CIMMYT researchers below:

  1. Genetic analysis of tropical midaltitude-adapted maize populations under stress and nonstress conditions. 2018. Makumbi, D., Assanga, S., Diallo, A., Magorokosho, C., Asea, G., Regasa, M.W., Bänziger, M. In: Crop Science v. 58, no. 4, p. 1492-1507.
  2. Interactions among genes Sr2/Yr30, Lr34/Yr18/Sr57 and Lr68 confer enhanced adult plant resistance to rust diseases in common wheat (Triticum aestivum L.) line ‘Arula’. 2018.  Randhawa, M.S., Caixia Lan, Basnet, B.R., Bhavani, S., Huerta-Espino, J., Forrest, K.L., Hayden, M., Singh, R.P. In: Australian Journal of Crop Science v. 12, no. 6, p. 1023-1033.
  3. Practical breeding strategies to improve resistance to Septoria tritici blotch of wheat. 2018. Tabib Ghaffary, S.M., Chawade, A., Singh, P.K. In: Euphytica v. 214, art. 122.
  4. Sashaydiall : A SAS program for hayman’s diallel analysis. 2018. Makumbi, D., Alvarado Beltrán, G., Crossa, J., Burgueño, J. In: Crop Science v. 58, no. 4, p. 1605-1615.
  5. Soil bacterial diversity under conservation agriculture-based cereal systems in indo-gangetic plains. 2018. Choudhary, M., Sharma, P.C., Jat, H. S., Dash, A., Rajashekar, B., McDonald, A., Jat, M.L.  In: 3 Biotech v. 8, art. 304.

Fall armyworm reported in India: battle against the pest extends now to Asia

A fall armyworm found on maize plants in Khamman district, Telangana state, India. (Photo: ICAR-Indian Institute of Maize Research)
A fall armyworm found on maize plants in Khamman district, Telangana state, India. (Photo: ICAR-Indian Institute of Maize Research)

The fall armyworm (FAW), Spodoptera frugiperda, a devastating insect-pest, has been identified for the first time on the Indian subcontinent. Native to the Americas, the pest is known to eat over 80 plant species, with a particular preference for maize, a main staple crop around the world. The fall armyworm was first officially reported in Nigeria in West Africa in 2016, and rapidly spread across 44 countries in sub-Saharan Africa.  Sightings of damage to maize crops in India due to fall armyworm mark the first report of the pest in Asia.

Scientists from the College of Agriculture at the University of Agricultural and Horticultural Sciences (UAHS) confirmed the arrival of the pest in maize fields within campus grounds in Shivamogga, in the state of Karnataka, southern India. Both morphological and molecular techniques confirmed the identity as FAW.

A pest alert published on July 30 by the National Bureau of Agricultural Insect Resources (NBAIR), part of the Indian Council of Agricultural Research (ICAR), further confirmed a greater than 70% prevalence of fall armyworm in a maize field in the district of Chikkaballapur, in the state of Karnataka.  Unofficial reports of incidence of FAW are rapidly emerging from several states in India, including Andhra Pradesh, Maharashtra and Telangana.

The pest has the potential to spread quickly not only within India, but also to other neighboring countries in Asia, owing to suitable climatic conditions.

Since the arrival of FAW in Africa in 2016, the CGIAR Research Program on Maize (MAIZE) has intensively worked with partners on a variety of fronts to tackle the challenge. At a Stakeholders Consultation Meeting held in Nairobi in April 2017, 160 experts from 29 countries worked together and developed an Action Plan to fight fall armyworm. The meeting was co-organized by the International Maize and Wheat Improvement Center (CIMMYT), the Alliance for a Green Revolution in Africa (AGRA) and the Food and Agriculture Organization of the United Nations (FAO), in partnership with the government of Kenya.

In early 2018 MAIZE, in partnership with the United States Agency for International Development (USAID) and other collaborators, released a comprehensive manual on effective management of this pest in Africa. The manual, “Fall Armyworm in Africa: A Guide for Integrated Pest Management,” provides tips on FAW identification as well as technologies and practices for effective and sustainable management.

Leaf damage from fall armyworm on maize plants in Khamman district, Telangana state, India. (Photo: ICAR-Indian Institute of Maize Research)
Leaf damage from fall armyworm on maize plants in Khamman district, Telangana state, India. (Photo: ICAR-Indian Institute of Maize Research)

“The strategies outlined in this manual can be of great importance to farmers in India when dealing with this insect pest. FAW is indeed one of the most destructive crop pests, and there is no option than to adopt an integrated pest management strategy to effectively tackle this complex challenge,” said B.M. Prasanna, director of MAIZE and the Global Maize Program at CIMMYT. “MAIZE and partners are dedicated to finding solutions to this problem that will protect the food security and incomes of smallholder farmers across Asia and Africa.”

Other regions are at risk as well. Researchers have warned of the potential impacts if FAW spreads to Europe, where customs inspectors have already reported having discovered and destroyed the pest on quarantined crops imported from Africa on several occasions.

Global experts on maize and key stakeholders in Asia will gather together in Ludhiana, India, on October 8-10, 2018, for the 13th Asian Maize Conference to discuss pressing issues to the crop across the continent, including the spread of fall armyworm. The conference, organized by the Indian Council of Agricultural Research (ICAR), the Indian Institute of Maize Research (IIMR), CIMMYT, MAIZE, Punjab Agricultural University (PAU) and the Borlaug Institute for South Asia (BISA), is expected to attract more than 250 participants from almost all the major maize-growing countries in Asia.