Testing public Bt maize events for control of stem borers in the first confined field trials in Kenya

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.

[1]  H. Groote,et al.  Developing Bt maize for resource-poor farmers - Recent advances in the IRMA project , 2011 .

[2]  S. Mugo,et al.  Experiences with the biosafety regulatory system in Kenya during the introduction, testing and development of Bt maize , 2011 .

[3]  S. Mugo,et al.  Mass rearing of stem borers, maize weevil, and larger grain borer insect pests of maize , 2010 .

[4]  Jörg Romeis,et al.  Transgenic crops expressing Bacillus thuringiensis toxins and biological control , 2006, Nature Biotechnology.

[5]  F. Bigler,et al.  Biological Activity of Cry1Ab Toxin Expressed by Bt Maize Following Ingestion by Herbivorous Arthropods and Exposure of the Predator Chrysoperla carnea , 2006, BioControl.

[6]  F. Bigler,et al.  Assessing the risks of insect resistant transgenic plants on entomophagous arthropods Bt-maize expressing Cry1Ab as a case study , 2003, BioControl.

[7]  A.F.E. Palmer,et al.  Integrated Approaches to Higher Maize Productivity in the New Millennium , 2004 .

[8]  J. Huesing,et al.  The Impact of Bt Crops on the Developing World , 2004 .

[9]  Clive James,et al.  Global review of commercialized transgenic crops , 2003 .

[10]  F. Bigler,et al.  Uptake of Bt‐toxin by herbivores feeding on transgenic maize and consequences for the predator Chrysoperla carnea , 2002 .

[11]  H. Groote.  Maize yield losses from stemborers in Kenya , 2002 .

[12]  Clive James,et al.  Global Review of Commercialized Transgenic Crops: 2001 Feature: Bt Cotton , 2002 .

[13]  N. Bohorova,et al.  Novel synthetic Bacillus thuringiensiscry1B gene and the cry1B-cry1Ab translational fusion confer resistance to southwestern corn borer, sugarcane borer and fall armyworm in transgenic tropical maize , 2001, Theoretical and Applied Genetics.

[14]  J. Trumble,et al.  Interactions of Elevated CO2 and Nitrogen Fertilization: Effects on Production of Bacillus thuringiensis Toxins in Transgenic Plants , 2000 .

[15]  E. Bynum,et al.  Whorl and stalk damage by European and Southwestern corn borers to four events of Bacillus thuringiensis transgenic maize , 2000 .

[16]  H. Groote,et al.  Insect resistant maize for Africa (IRMA) project , 2000 .

[17]  C. Ndiritu,et al.  Kenya: biotechnology in Africa: why the controversy? , 2000 .

[18]  J. Greenplate.  Quantification of Bacillus thuringiensis Insect Control Protein Cry1Ac Over Time in Bollgard Cotton Fruit and Terminals , 1999 .

[19]  N. Bohorova,et al.  Production of transgenic tropical maize with cryIAb and cryIAc genes via microprojectile bombardment of immature embryos , 1999, Theoretical and Applied Genetics.

[20]  B. Federici.  Transgenic Bt crops and resistance: Broadscale use of pest-killing plants to be true test , 1998 .

[21]  Fred Gould,et al.  Do dynamics of crop maturation and herbivorous insect life cycle influence the risk of adaptation to toxins in transgenic host plants , 1998 .

[22]  D. Dean,et al.  Domain III exchanges of Bacillus thuringiensis CryIA toxins affect binding to different gypsy moth midgut receptors. , 1995, Biochemical and biophysical research communications.

[23]  P. Teng,et al.  Rice pest science and management. , 1994 .

[24]  L. Crossland,et al.  Field Performance of Elite Transgenic Maize Plants Expressing an Insecticidal Protein Derived from Bacillus thuringiensis , 1993, Bio/Technology.

[25]  S. Gill,et al.  The mode of action of Bacillus thuringiensis endotoxins. , 1992, Annual review of entomology.

[26]  Brian A. Croft,et al.  Arthropod biological control agents and pesticides , 1990 .