Environmental impact of conventional and Bt insecticidal cotton expressing one and two Cry genes in Australia

Abstract

Genetically modified Bt cotton, expressing the Cry1Ac protein for specific insecticidal activity against economically significant lepidopteran pests, has been available commercially in Australia since 1996. This technology has been improved and superseded by the addition of a second gene, allowing new varieties to express both the Cry1Ac the Cry2Ab proteins. Bt cotton offers several advantages to the grower, mainly through reduced insecticide spray requirements. The environmental benefits of reduced insecticide usage are assessed in this paper using the environmental impact quotient (EIQ). The assessment included consideration of the impact of the expressed transgenic proteins Cry1Ac and Cry2Ab. EIQ values of the Cry1Ac and Cry2Ab proteins were calculated at 9.9 and 7.9, respectively. Bt protein expression, plant biomass, insecticide application records, constituent of active ingredient, and insecticide EIQ values were used to produce an environmental impact (EI) value for insecticide use (kg a.i./ha) for conventional non-GM and single- and 2-gene Bt cotton for the 1997–98 to 2003–04 seasons. Inclusion of the Cry proteins in the assessment increased the EI values for Bt cotton by only 2%. The average insecticide EI value, for 2002–03 and 2003–04 seasons, for conventional cotton was 135 kg a.i./ha, whereas for the 2-gene Bt variety it was only 28 kg a.i./ha. Results of the EI evaluation indicate that, due to changes in insecticidal choice and reduction in usage, there was a reduction of >64% in EI from growing Bt cotton compared with conventional non-GM cotton in Australia.

Improving Environmental Loading Assessments of Cry Protein from GM Plants Based on Experimentation in Cotton~!2008-09-12~!2008-11-15~!2008-12-05~!

“…Plant biomass at this time had a mean of 385.3 g dry weight per plant with a stand count of 8 plants per metre, which represented 8000 plants in a hectare. The top 15 cm of field soil, the depth to which the soil was mechanically worked post slashing of the crop, had an averaged bulk density of 1.49 g/cm 3 . This data provided an estimate for the soil mass, into which the plants were incorporated at the end of season of 2.24 x 10 6 kg.…”

“…Reliable estimates of transgenic protein expression in genetically modified (GM) crops can provide a valuable tool in assisting with understanding the development and management of resistance, non-target implications, economic performance and environmental loading of the transgenic proteins [1][2][3]. GM cotton, Gossypium hirsutum, expressing the insecticidal Cry1Ac gene, from the soil bacterium Bacillus thuringiensis (Bt), was introduced commercially in Australia in 1996 [4].…”

The application of GMOs in agriculture and in food production for a better nutrition: two different scientific points of view

“…Second- and third-generation GM crops have been developed to address these issues directly by improving nutrition or providing inexpensive drugs, but even the first-generation crops have indirectly led to improvements simply by increasing the profitability of farms and empowering the smallholders in a socioeconomic context. There have also been more direct health benefits of GM agriculture by reducing exposure to pesticides (Brimner et al 2005; Knox et al 2006), changing the patterns of herbicide use to favor those with lower toxicity such as glyphosate, and as mentioned above, reducing the exposure of populations to mycotoxins (Munkvold et al 1999). Work is also well advanced in the development of GM crops that will have a direct impact on health, e.g.…”

Synthetic Pesticides in Agro-Ecosystems: Are They as Detrimental to Nontarget Invertebrate Fauna as We Suspect?

“…There have been few attempts to move toward using more selective chemicals (also referred to as ÔsoftÕ chemicals) over conventional broad-spectrum pesticides even though selective chemicals can help in maintaining populations of beneÞcial species that provide important ecosystem services in terms of pest control, pollination of plants, seed dispersal, and enhancing soil health , Macfadyen and Zalucki 2012. In contrast, in the Australian cotton industry the integration of selective chemicals in conjunction with new gene technologies has resulted in a reduction of pesticide use by up to 80% (Knox et al 2006), while in the Australian viticulture industry the impact of beneÞcial species is widely appreciated and selective chemicals are routinely applied to conserve and enhance beneÞcial invertebrate activity . Selective chemicals are generally more expensive in the Þrst instance, but may become economically viable when long-term beneÞts are considered.…”