Trials on bollworm resistant (bt) Cotton variety in Thailand
Jinda Jan-orn, Amara Trisiri, Samphan Khumpiranon, Karin Tanphiphat, Pokrong Chareontoh, Somyos Phichitporn, Phornsak Duangphuttan and Naritsorn Khachornphon
Field Crops research Institute, Department of agriculture, Bangkok 10900
Fax: 662 5613486 and 5790604 e-mail : jjanorn@yahoo.com
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Bollgard or Nucotn33B cotton variety or DPX 973 (DP 5415 with cry 1A (c) or bt gene from Bacillus thuringiensis sub sp. Kurstaki bacteria) was tested in comparison with normal cotton varieties (without the bt gene) in Thailand during 1996 – 1997. The first test, conducted in containment conditions (a large cage covered with 32 mesh wire net) started in March 1996 and was testing for the crop resistant to bollworm (Helicoverpa armigera) and for any effect on bee and bollworm egg parasite, for example, Trichogramma sp.
The strip plot design was used with 4 replications, the factors are variety and bollworm control spraying regime (no bollworm spraying versus bollworm spraying). The results indicated significant differences between bt and non-bt cotton varieties tested and showed a merit of the Bollgard cotton for the resistance to bollworm with no adverse effect on bee and egg parasitized insect. Agronomic traits, such as fibre quality are (substantially) equivalent between bt cotton and normal cotton.
Further trials to test crop performance under field conditions were further conducted in the late rainy season of 1996 and the rainy season of 1997. The results indicated that the cotton with bt (cry 1 A ( c)) gene was resistant to bollworm (Helicoverpa armigera) and pink bollworm (Pectinophora gossypiella) and relatively resistant to looper (Cosmophila flava) and leaf roller (Sylepta derogata). It has not been found to have an effect on army worm or cluster caterpillar (spodoptera litura), aphids, jassids or cotton leaf hopper, spider mite which are pest of cotton including beneficial spiders, lady bird beetle and other predators and parasites.
From the data indicated by Berberich et al. (1996), Sims and Berberich (1996) and sim et al. (1996), the amount of bt toxin protein encoded or produced by cry 1 A ( c) gene for controlling bollworm was about 1.6 – 2.6 micrograms per gram of fresh leaf, 0.9 –2.2 micrograms per gram of seed, 11.5 nanograms (1 of 1,000,000,000 grams)per grams of pollen and 1.6 nanograms per gram of nectare from cotton nectary gland. The quantity in the lint or fiber and fuzz (linter or very short fiber) was about 0.1 micrograms per gram.
During the performance trials under fields conditions and two years period after finishing the trials, various monitoring activities involving weed and crop growth in the cotton tested plots, the occurrence of noxious weed from an out-cross with bt cotton, etc, have been done for risk assessment. The conclusions of these are as follows:
The insect incidences including spider mites, Army worm (Spodoptera litura), aphids, jassids and thrips which are cotton pests and some beneficial insects, were found to be similar (no statistically significant difference) between the Bollgard cotton with the cry 1 A ( c) gene and the normal cotton without the cry 1 A ( c) gene. Bollworm (Helicoverpa armigera), pink bollworm (Pectinophora gossypiella), looper (Cosmophilla flava) and leaf roller (Sylepta derogata) were rarely found significantly in the Bollgard cotton.
Soil and land used for planting the Bollgard cotton with the cry 1A ( c) gene have not caused any problem related to plant disease in subsequent other crops. Soil and land characteristics and production were the same as for normal crops.
An out-crossing occurred between the tested Bollgard cotton (glanded cotton) and non bt cotton (glandless cotton controlled by recessive gene), which had been planted as guard row surrounding the tested plots. This guard row cotton is also Gossypium hirsutum but is susceptible to leaf eating beetles (for example, Monolepta signata). In order to detect any adverse effect which may happen by an out-cross, Observation on growth of crops and plants in the tested plots were made. These included the progenies obtained from the out-crossing of glandless cotton with the tested glanded cotton. However, the Bollgard cotton with the cry 1A ( c) gene and the progenies derived from out-crossing behaved similarly to the normal cotton. There was no sign of noxious weed. The plants and crops that germinated in the tested plots and surrounding area were also normal.
Since there were no adverse effects found on bee and some bollworm egg parasites including beneficial insects in general from the studies and trials, it can, therefore, be assume that by using the Bollworm resistant cotton variety, that is, cotton containing the cry 1 A ( c) gene, cotton production with appropriated management, especially pest management, can be improved with less insecticide spraying and less polluted environment.
Reference
Berberich, S.A., Ream, J.E., Jackson, T.L., Wood,R., Stipanovic,R., harvey, P., patzer, S., and Fuchs, R.L. 1996. The composition of insect – protected cotton Cottonseed is equivalent to that of Conventional Cottonseed. Journal of Agricultural and Food Chemistry 44: 365-371.
Sim, S.R., and berberich, S.A. 1996. Bacillus thuringiensis cry 1 A protein level in Raw and processed Seed of Transgenic Cotton : Determination Using Insect Bioassay and ELISA. J. Econ. Entomology 89(1) : 247 – 251.
Sims, S.R., Berberich, S.A., Nida, D.L., Segalini,L.L., Leach, N.J., Ebert, C.C. and Fuchs, R.L. 1996. Analysis of Expressed Proteins in Fiber Fractions from Insect – protected and glyphosate – Tolerant Cotton Varieties. Crop Science 36 : 1212 – 1216.
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