Effects of Bacillus thuringiensis Toxins in Transgenic Cotton and Potato on Folsomia candida (Collembola: Isotomidae) and Oppia nitens (Acari: Orbatidae)

1997 ◽  
Vol 90 (1) ◽  
pp. 113-118 ◽  
Author(s):  
L. Yu ◽  
R. E. Berry ◽  
B. A. Croft
Keyword(s):  
Bacillus Thuringiensis ◽  
Transgenic Cotton ◽  
Folsomia Candida

Explaining contradictory evidence regarding impacts of genetically modified crops in developing countries. Varietal performance of transgenic cotton in India

2005 ◽  
Vol 143 (1) ◽  
pp. 35-41 ◽  
Author(s):  
R. BENNETT ◽  
Y. ISMAEL ◽  
S. MORSE
Keyword(s):  
Developing Countries ◽  
Bacillus Thuringiensis ◽  
Genetically Modified Crops ◽  
Transgenic Cotton ◽  
Hybrid Vigour ◽  
Bt Cotton ◽  
Yield Performance ◽  
Contradictory Evidence ◽  
Bt Gene ◽  
Better Than

A study of the commercial growing of different varieties of Bacillus thuringiensis (Bt) cotton compares the performance of growing official and unofficial hybrid varieties of Bt cotton and conventional (non-Bt) hybrids in Gujarat by 622 farmers. Results suggest that the official Bt varieties (MECH 12 and MECH 162) significantly outperform the unofficial varieties. However, unofficial, locally produced Bt hybrids can also perform significantly better than non-Bt hybrids, although second generation (F2) Bt seed appears to have no yield advantage compared to non-Bt hybrids but can save on insecticide use. Although hybrid vigour is reduced, or even lost, with F2 seed the Bt gene still confers some advantage. The F2 seed is regarded as ‘GM’ by the farmers (and is sold as such), even though its yield performance is little better than the non-GM hybrids. The results help to explain why there is so much confusion arising from GM cotton release in India.

scholarly journals Control of Resistant Pink Bollworm (Pectinophora gossypiella) by Transgenic Cotton That Produces Bacillus thuringiensis Toxin Cry2Ab

2002 ◽  
Vol 68 (8) ◽  
pp. 3790-3794 ◽  
Author(s):  
Bruce E. Tabashnik ◽  
Timothy J. Dennehy ◽  
Maria A. Sims ◽  
Karen Larkin ◽  
Graham P. Head ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
First Generation ◽  
Second Generation ◽  
Transgenic Cotton ◽  
Larval Survival ◽  
Genetically Engineered ◽  
Pink Bollworm ◽  
Pectinophora Gossypiella ◽  
Cross Resistance ◽  
Average Survival

ABSTRACT Crops genetically engineered to produce Bacillus thuringiensis toxins for insect control can reduce use of conventional insecticides, but insect resistance could limit the success of this technology. The first generation of transgenic cotton with B. thuringiensis produces a single toxin, Cry1Ac, that is highly effective against susceptible larvae of pink bollworm (Pectinophora gossypiella), a major cotton pest. To counter potential problems with resistance, second-generation transgenic cotton that produces B. thuringiensis toxin Cry2Ab alone or in combination with Cry1Ac has been developed. In greenhouse bioassays, a pink bollworm strain selected in the laboratory for resistance to Cry1Ac survived equally well on transgenic cotton with Cry1Ac and on cotton without Cry1Ac. In contrast, Cry1Ac-resistant pink bollworm had little or no survival on second-generation transgenic cotton with Cry2Ab alone or with Cry1Ac plus Cry2Ab. Artificial diet bioassays showed that resistance to Cry1Ac did not confer strong cross-resistance to Cry2Aa. Strains with >90% larval survival on diet with 10 μg of Cry1Ac per ml showed 0% survival on diet with 3.2 or 10 μg of Cry2Aa per ml. However, the average survival of larvae fed a diet with 1 μg of Cry2Aa per ml was higher for Cry1Ac-resistant strains (2 to 10%) than for susceptible strains (0%). If plants with Cry1Ac plus Cry2Ab are deployed while genes that confer resistance to each of these toxins are rare, and if the inheritance of resistance to both toxins is recessive, the efficacy of transgenic cotton might be greatly extended.

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