Assessing the potential economic impact of Bacillus thuringiensis (Bt) maize in Kenya

The Insect Resistant Maize for Africa (IRMA) project is currently developing Bt maize for Kenya. So far, Bt genes with resistance to Chilo partellus, Chilo orichalcociliellus, Eldana sacharina, and Sesamia calamistis, four of the five major stemborers were successfully incorporated into elite CIMMYT maize inbred line (CML216) and tested in insect bioassays in Kenya. Participatory Rural Appraisals showed that stem borers are indeed major pest problems for farmers. Four seasons of on-farm crop loss assessment showed an average crop loss of 13.5%, or 0.4 million tons, valued at US$80 million. If the project manages to find a Bt gene that is effective to the fifth stemborer, Busseola fusca, adoption rates are likely to be high, and therefore the returns. Under standard assumptions, the economic surplus of the project is calculated at$ 208 million over 25 years (66% of which is consumer surplus) as compared to a cost of $5.7 million. Geographically, the project should focus on the high production moist-transitional zone. However, if such gene cannot be found, Bt maize technology would only be effective in the low potential areas, and adoption rates would be fairly low, although benefits would still exceed costs.Key words: Maize, genetically modified crops, Bacillus thuringiensis, adoption, economic impact

Farmers, consumers and gatekeepers and their attitudes towards biotechnology

In 1999, a project to develop insect resistance maize for Africa was launched. Social scientists from this team used participatory rural appraisals, consumer studies, a baseline and gatekeeper survey to study the awareness and attitudes towards biotechnology among farmers, consumers and gatekeepers. Farmers’ awareness of biotechnology was very low (12.7%). Awareness on genetically modified (GM) crops among consumers was also found to be low, although it was higher among urban consumers (38%) than among rural ones (31%). Radio was the main source of information. A large majority of consumers agreed to statements expressing the benefits of biotechnology such as increasing productivity. However, they had environmental and health concerns. Half of the urban consumers expressed concerns about the environment, in particular, loss of biodiversity. In contrast, awareness about GM was found to be high for the gatekeepers (87% for millers, and 79% for supermarkets). A majority of gatekeepers in the food industry were concerned that GM food could cause allergic reactions or antibiotic-resistant diseases. Almost all consumers were willing to purchase GM maize meal at the same price. Of those in the industry, more than two thirds, were hesitant to use them preferring to make the decision on a case-by-case basis.Key words: Biotechnology, genetically modified (GM), consumer, attitudes, gatekeeper

Evaluation of stem borer resistance management strategies for Bt maize in Kenya based on alternative host refugia

Stem borers are the major insect pests of maize in Kenya. The use of Bacillus thuringiensis (Bt) technology is an effective way of controlling lepidopteran pests. However, the likelihood of development of resistance to the Bt toxins by the target stem borer species is a concern. Forages, sorghum and maize varieties were evaluated for stem borer preference and survivorship in the laboratory and field in four locations in Kenya to identify suitable species and varieties for refugia. The economics of using the different kinds of refugia was also investigated. Vegetation surveys were conducted in 15 districts of Kenya to quantify the area covered by natural refugia. The field and laboratory trials indicated highest egg production, survivorship and more exit holes in all sorghum and maize varieties and some forages. Sorghum, non-Bt Maize, and improved Napier grass varieties Kakamega 1 and Kakamega 2) should be promoted as refugia species in Kenya. Some species and cultivars were identified as cost-effective, flexible, easily adoptable and compatible with farmers’ common production practices. Refugia cultivar with multiple uses is expected to give higher pay-offs than one with single use. However, for successful management of a refugia strategy, strict stewardship is required from appropriate government or community institutions.Key words: Refugia, cost-benefit analysis, Bt-maize, insect pest resistance management

Mycobacteria counteract a TLR-mediated nitrosative defense mechanism in a zebrafish infection model.

Pulmonary tuberculosis (TB), caused by the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb), is a major world health problem. The production of reactive nitrogen species (RNS) is a potent cytostatic and cytotoxic defense mechanism against intracellular pathogens. Nevertheless, the protective role of RNS during Mtb infection remains controversial. Here we use an anti-nitrotyrosine antibody as a readout to study nitration output by the zebrafish host during early mycobacterial pathogenesis. We found that recognition of Mycobacterium marinum, a close relative of Mtb, was sufficient to induce a nitrosative defense mechanism in a manner dependent on MyD88, the central adaptor protein in Toll like receptor (TLR) mediated pathogen recognition. However, this host response was attenuated by mycobacteria via a virulence mechanism independent of the well-characterized RD1 virulence locus. Our results indicate a mechanism of pathogenic mycobacteria to circumvent host defense in vivo. Shifting the balance of host-pathogen interactions in favor of the host by targeting this virulence mechanism may help to alleviate the problem of infection with Mtb strains that are resistant to multiple drug treatments