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Gichuki, S.T.

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Gichuki
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S.T.
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Gichuki, S.T.

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Author: Karaya, H. × Region: Eastern Africa ×

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    Testing public Bt maize events for control of stem borers in the first confined field trials in Kenya
    (Academic Journals, 2011) Mugo, S.N.; Mwimali, M.; Taracha, C.; Songa, J.M.; Gichuki, S.T.; Tende, R.; Karaya, H.; Bergvinson, D.J.; Pellegrineschi, A.; Hoisington, D.A.
    Transgenic maize (Zea mays L), developed using modified genes from the bacterium Bacillus thuringiensis (Bt), controls stem borers without observable negative effects to humans, livestock or the environment, and is now sown on 134 million hectares globally. Bt maize could contribute to increasing maize production in Kenya. Nine public Bt maize events of cry1Ab and cry1Ba genes were tested in confined field trials site (CFTs) to assess the control of four major Kenyan stem borer species. Leaf damage rating, number of exit holes and tunnel length were scored in the field evaluations. Leaf area consumed and mortality rates among stem borers were scored in the leaf bioassays in a Biosafety Level II laboratory, located at the Kenya Agricultural Research Institute (KARI), National Agricultural Research Laboratories (NARL). Field evaluations showed that Bt maize controlled Chilo partellus with mean damage scores of 1.2 against 2.7 for the non-Bt CML216 control. Laboratory bioassays showed high control for Eldana saccharina and Sesamia calamistis, with mean larval mortality of 64 and 92%, respectively. However, substantial control was not observed for Busseola fusca. These results showed that Bt maize could control three of the four major stem borers in Kenya with mortality records of 52.7% for B. fusca, 62.3% for E. saccharina and 85.8% for S. calamistis. Additional Bt genes need to be sought and tested for effective stem borer control in all maize growing ecologies in Kenya.
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    Control of Busseola fusca and Chilo partellus stem borers by Bacillus thuringiensis (Bt)-δ-endotoxins from Cry1Ab gene Event MON810 in greenhouse containment trials
    (Academic Journals, 2011) Mugo, S.N.; Murenga, M.G.; Karaya, H.; Tende, R.; Taracha, C.; Gichuki, S.T.; Ininda, J.; M'bijjewe, K.; Chavangi, A.
    Previous testing of several public Bacillus thuringiensis (Bt)-maize events did not show control of the African stem borer (Busseola fusca Fuller), an important stem borer species, without which stewardship would be compromised by the possibility of rapid development of resistance to Bt delta-endotoxins. This study was carried out to test Bt-maize Event MON810 as an option to control all major stem borer species in Kenya. Two Bt-maize hybrids, DKC8073YG and DKC8053YG, both containing Bt Event MON810 of Cry1Ab gene were imported to carry out greenhouse containment trials. The hybrids together with the controls were grown in 10 replications upto the V6 and V8 stages. Infestations on whole plants were carried out at two stages of growth using 5 neonates of the spotted stem borer (Chilo partellus Swinhoe) and B. fusca. Bt-maize Event MON810 hybrids showed resistance to both stem borer species with low leaf damage scores and few surviving larvae recovered from the whole plant. The public Bt-maize Event 223 did not control B. fusca. Deploying Bt-maize Event MON810 may, therefore, be used to control the two species of stem borers. However, the efficacy of Bt-maize Event MON810 will, need to be evaluated under field environments.
    Publication