Highlights - Western Africa
A “cottage industry” in Bénin for biocontrol of cowpea pod borer
Maruca vitrata or pod borer, is an endemic pest of cowpea in West Africa and can result in over 80% of losses in both indigenous and high-yielding varieties. With funds from both USAID (through the Dry Grain Pulses Collaborative Research Support Program) and GIZ/BMZ (through the World Vegetable Center [AVRDC]) we have investigated developing and implementing biological control as one of the most effective, sustainable, and economically viable options for managing this major pest.
We used a novel approach for producing the specific virus (MaviMNPV) for M. vitrata by soaking cowpea grains until germination, and subsequently rearing the insect host on those cowpea sprouts. The work is still ongoing, but early results clearly indicated that soaking the grains for 48 h and subsequently infesting the sprouts with neonate M. vitrata larvae at the appearance of the first green parts of the germinating seeds allowed optimal pod borer rearing. Infesting two layers of sprouting cowpea seeds with the larvae, and subsequently inoculating the virus at the third instar, gave the highest yields in terms of virus production.
Following up on the successful field deployment of the combination of neem oil and MaviMNPV observed last year, more detailed studies were carried out to assess the nature of these interactions. The combination of neem oil and MaviMNPV resulted in a significantly higher larval mortality than treatment with either virus or botanical insecticide alone at the corresponding concentrations.
Meanwhile, neem oil has been re-formulated as an emulsifiable mixture of neem and essential oil from lemon grass, which is planted by women groups and sold to the self-help enterprise together with the neem seeds, thus providing additional household income. This mixture is sold commercially by the Bio-Phyto communal enterprise under the brand name, Top-Bio. IITA scientists and their partners have been assessing the viability of the MaviMNPV virus kept in Top-Bio for several months, to determine if the two components can be pre-mixed and sold in the same container. Top-Bio has been dispatched with the virus to our collaborators in Burkina Faso, Niger, and Nigeria for proper multilocational field testing.
Nutritional enhancement and stress tolerance in maize
Much attention has been devoted to the continual infusion of new and diverse germplasm towards the expansion of the genetic base of adapted inbred lines with high pro-vitamin A content. This work is mainly funded by the BMGF through HarvestPlus, an interdisciplinary program coordinated by the International Center for Tropical Agriculture (CIAT) and the International Food Policy Research Institute (IFPRI). The micronutrient target that HarvestPlus has determined would improve poor people’s nutrition and health is 15 μg /g beta-carotene.
In recognition of the importance of the adaptation of the nutritionally enhanced maize lines to the challenging environments in which they have to perform, we have been working to incorporate drought tolerance and Striga resistance into them.
New ways to genetically improve cassava
Cassava breeding at IITA is being redefined thanks to the increasing availability and deployment of cutting-edge genomic tools. Combining these resources with IITA’s long-standing, conventional breeding approaches will ultimately satisfy the increasing need for more healthy and nutritious food produced in environmentally sustainable ways.
Over the years, hundreds of improved varieties that are not only high-yielding but also nutritious and tolerant to biotic and abiotic stresses have been developed and extensively deployed in sub-Saharan Africa. Most of these advances were achieved through conventional breeding, which is often a lengthy process due to cassava’s long growth cycle and low rate of multiplication. Scientists are now working to cut short this lengthy breeding process through genomic resources. In collaboration with researchers from Cornell University, USA, we are developing and adapting the rapidly advancing next-generation sequencing technologies by generating high-density molecular markers, unravelling the crop’s genetic diversity and structure, and locating genomic regions that control quantitative and qualitative breeding traits.
Two varieties of cassava, three of cowpea, three of soybean, and 15 of maize were released by our partner institutes based on germplasm provided as part of our collaboration in the genetic improvement of these crops.