Baseline susceptibility of Helicoverpa armigera (Hilbner) to Bt toxins in West and Central Africa

Brévault Thierry, Prudent Patrick, Vaissayre Maurice. 2007. Baseline susceptibility of Helicoverpa armigera (Hilbner) to Bt toxins in West and Central Africa. In : Ecological impact of genetically modified organisms (EIGMO), 23-25 May 2007, Warsaw, Poland : program, abstracts and list of participants. IOBC. Varsovie : Wies Jutra, Résumé, p. 45. Meeting on Ecological Impact of Genetically Modified Organisms (EIGMO). 3, Varsovie, Pologne, 23 Mai 2007/25 Mai 2007.

Résumé : Burkina Faso will be the first country in West Africa to introduce Bt cotton on a commercial scale in 2007. Undoubtedly other cotton producing countries in this region will adopt the technology soon thereafter. These countries will directly introduce Bt cotton expressing two toxins (Cryl Ac and Cry2Ab)-unlike cotton producing countries elsewhere in the world that began by introducing Bt cotton expressing just one toxin. The susceptibility of African populations of the boll worm Helicoverpa armigera (Hilbner) to Bt toxins is still unknown, and nothing has been published regarding resistance management measures required as a follow-up to the introduction of Bt cotton in Africa. CIRAD is currently building a model to help local authorities develop a strategy for a sustainable use of Bt cotton in small farming systems. Key input factors for the model are: 1) the efficacy of Bt toxins against the bollworm, and 2) the frequency of resistant individuals in naive bollworm populations. The purpose of the present study was to determine the susceptibility of boll worm strains collected. in various cotton growing areas of western and central Africa to Cry! Ac and Cry2Ab and combined, in terms of mortality or, according to the specificity of Bt toxins, in terms of larval growth inhibition. The results were obtained during the 2006 growing season. They demonstrate the difficulty in evaluating larval mortality (LD50), as well as the advantages of using a growth inhibition index (GI50) for bioassays with Bt toxin. Despite these methodological considerations, the LD50 range as well as the GI50 values obtained in West Africa were quite similar to data published elsewhere.

Auteurs et affiliations

• Brévault Thierry, CIRAD-PERSYST-UPR Systèmes cotonniers (CMR) ORCID: 0000-0003-0159-3509
• Prudent Patrick, CIRAD-PERSYST-UPR Systèmes cotonniers (BEN)
• Vaissayre Maurice, CIRAD-PERSYST-UPR Systèmes cotonniers (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/603777/)

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