A laboratory bioassay that incorporates Bacillus thuringiensis (Bt) purified crystal protein toxins into an artificial diet has identified three toxins, CryIA(b), CryIA(c), and CryIIA, to by effective against the yellow stemborer, Scirpophaga incertulas(Walker). Research is aimed at engineering rice that incorporates genes of one of or more of these toxins so as to mimic the insecticidal action of the insect to Bt. The paper discusses potential strategies for slowing the rate of adaptation that include the use of multiple Bt toxins, promoters that express the toxins only in specific plant tissues at specific times, and mixing transgenic and non-transgenic plants.

• D.G. Bottrell
• R.M. Aguda
• F.L. Gould
• W. Theunis
• C.G. Demayo
• V.F. Magalit