African Journal of Biotechnology Vol. 5 (10), pp. 781-785, 16 May 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Review

Gene pyramiding as a Bt resistance management strategy: How sustainable is this strategy?

Manyangarirwa, W.¹, Turnbull, M.¹, McCutcheon, G.S.², and Smith, J.P.³

¹Department of Entomology, Soils and Plant Sciences, Clemson University, Clemson, SC 29634-0315, USA.

²Coastal Research and Education Center, Clemson University, 2700 Savannah Highway, Charleston, SC 29414-5329, USA.

³Edisto Research and Education Center, Clemson University, 64 Research Road, Blackville, SC 29817, USA.

*Corresponding authors E-mail:wmanyan@clemson.edu.

Accepted 24 January, 2006

Reports on the emergence of insect resistance to Bacillus thuringiensis delta endotoxins have raised doubts on the sustainability of Bt-toxin based pest management technologies. Corporate industry has responded to this challenge with innovations that include gene pyramiding among others. Pyramiding entails stacking multiple genes leading to the simultaneous expression of more than one toxin in a transgenic variety. Questions have been raised on the sustainability of gene pyramiding since the use of insecticide mixtures has shown that cross resistance and/or multiple resistance can render such strategies to be less effective in the long term. Current theoretical and practical evidence in insect population genetics suggest that gene pyramiding cannot be sustained as a resistance management strategy per se. Pyramiding is useful as a strategy to broaden the range of insect pests controlled in each transgenic variety, and it still has to be deployed in tandem with Bt resistance management strategies such as crop refugia, biological pest control, temporal and spatial crop rotations among others.

Key words: Gene pyramiding, Bacillus thuringiensis, resistance management.