Bt cotton

from Wikipedia, the free encyclopedia

As Bt cotton referred to genetically altered cotton , in the genes from the soil bacterium Bacillus thuringiensis has been transferred. The aim is to improve the control of cotton insect pests. Bt cotton is more common than herbicide-resistant cotton, which is resistant to broad spectrum herbicides .

Mechanism of action and general aspects

Cotton boll drills
Red cotton bollworm

A ( single trait ) or more ( stacked traits ) genes from the soil bacterium Bacillus thuringiensis which, depending on subtype proteins encode, which are reacted in the intestine of many insects to toxins, be in the DNA transfer of the cotton. The resulting plant contains the appropriate toxins in each cell. Depending on the Bt gene used, the toxins formed are fatal for certain beetles , butterflies and / or two-winged birds and especially for the cotton owl. The constant presence of the toxin in the field differs from the periodic use of biological or chemical insecticides in that the harmful insects are constantly exposed to the toxin. Another difference to the use of Bt toxins in the form of suspensions is that pests eat the poison directly with their food (the cotton plant) instead of having to ingest the suspension separately. According to Bravo et al. compared to conventional cotton in connection with chemical pesticides an increased precision. Pests can be combated in a more targeted manner and non-target organisms can be spared more easily, as they do not eat the plant or the toxin has no effect on them.

From the farmer's perspective, potential savings with conventional insecticides and income increases through possible higher yields contrast with the often higher costs of Bt cotton seeds compared to conventional seeds.

Observations of pest populations in the USA and China have shown that the use of Bt cotton has temporarily not only led to a lower pest infestation in the Bt fields, but also to a lower pest infestation in conventional cotton and other crops fields ( positive externality ) . Studies in China also showed that non-target organisms were able to spread at times and have caused damage to Bt cotton and conventional crops ( negative externality ).

If conventional insecticides without the aid of sprayers are applied in the field, as in many developing countries happens, the replacement by Bt cotton damage to health can reduce because of the direct contact with insecticides decreases. Furthermore, the can untreated ground - and surface water through the lower entry conventional insecticides safe for human consumption are, which may also be relevant for farmers in developing countries.

Formation of resistance and secondary pests

In Mississippi and Arkansas , the sensitivity of the cotton boll drill to the Bt toxin Cry1Ac, which was primarily used in the first Bt varieties, has already decreased significantly. No resistance to Bt toxins has been observed in 5 other important pests. In the southwest of the USA, resistances of the cotton boll drill to Cry2Ab were also found in some fields .

Resistance of the red cotton bollworm to first-generation Bt cotton varieties (Bollgard I, since 2002) was observed for the first time in four districts of the Indian state of Gujarat at the beginning of 2010 . According to scientists from the manufacturers Monsanto and Mahyco, this could be due to the inadequate compliance with refugee areas or the illegal cultivation of Bt varieties with lower toxin content. No resistance was found for the second generation of Bt varieties (Bollgard II, since 2006), which contain two Bt genes. Bollgard III, which has three Bt genes, is currently being developed. Several independent insecticides make the development of resistance more difficult. Appropriate precautions to prevent or slow down the spread of resistant pests are considered to be of appropriate size, planted with non-genetically modified cotton, cultivation measures such as deep plowing, a wide-ranging crop rotation and the removal of residues that arise during harvest. Jens Karg, genetic engineering spokesman for Global 2000 , assumes that the development of resistance by harmful insects will result in an increased use of stronger insecticides. A widespread development of resistance could mean that the Bt agent previously used and approved by sustainable forms of agriculture can no longer be used as a spray.

According to a report by Monsanto to the Central Institute for Cotton Research in India, the cultivation of BT cotton has led to an increase in non-target organisms, i.e. pests of cotton for which the poison against the red cotton rootworm is ineffective. Insect pests that have so far not been seen in India have been found. This is particularly the case with sucking insects, the most common group found to have caused significant economic losses. The cotton yield decreased from 560 kg per hectare in 2007 to 512 kg per hectare in 2009. The consumption of pesticides increased from 5970 million rupees in 2002 to 7910 million rupees in 2009.

In China, a research group led by the scientist Kongming Wu from the Chinese Academy of Agricultural Sciences examined cotton fields in six regions of China for pest infestation over a period of 10 years. It was found that there is a massive spread of soft bugs on cultivated areas with Bt cotton . Soft bugs are considered secondary pests . They have a tolerance to the BT toxin and benefit - due to the cultivation of BT cotton - from reduced insecticide spraying. The insects, which to date have been classified as insignificant pests in China, cause considerable damage. Since the soft bugs have a wide range of food, the harvest losses are not limited to the BT cotton plantations, but also affect agricultural areas in the vicinity, such as orchards. The use of insecticides has increased again due to measures against the soft bugs.

Transfer of the transgenic property to wild species

During studies of the gene flow in wild cotton plants of the species Gossypium hirsutum in Mexico, transgenes from genetically modified plants were found in wild populations . Transgenes of insect-resistant, antibiotic-resistant, or herbicide-resistant cotton were found in about a quarter of the 270 wild cottonseed seeds examined. One seed came from a population that was 755 kilometers from the nearest GM cotton plantation. Other seeds could be identified as successors to the first hybrid generation because they had several and different transgenes. Losses in the transport of seeds for the animal feed industry or oil processing, transport by wind or salt and fresh water or digestive spread by animals were given as causes . It was also considered that human actions caused gene flow. Gene flow from GM cotton crops to wild relatives reduces the genetic diversity of cotton and can impact the environment, food safety and health, as well as legal and trade regulations. Ana Wegier, lead author on the study, stated that stopping the flow of genes between cultivars and wild species is an urgent task. From their point of view, seeds produced after the harvest would have to be destroyed. In addition, Mexico needs active monitoring as well as control and preventive programs in this regard .

Effect on non-target organisms

A meta-analysis published in 2007 evaluated 42 field experiments with invertebrates. Accordingly, non-target organisms are generally more numerous in Bt cotton and Bt maize fields than in conventional fields that have been treated with insecticides. However, certain taxa were more common in conventional fields without insecticide treatment than in Bt fields.

Overview of cultivation data

A Bt cotton variety developed by the Monsanto Group was first approved in the USA in 1996. In 2010, 64% (21 million hectares) of the global cotton acreage was planted with transgenic seeds. Transgenic cotton was grown in 12 countries in 2009 (the proportion of transgenic cotton in the total cultivated area in brackets): Argentina (95%), Australia (95%), Brazil (18%), Burkina Faso (29%), China (60%) ), India (89%), Colombia (31%, 2007), Mexico (56.5%), South Africa (98%), USA (88%), Indonesia, and Costa Rica; Pakistan and Myanmar were added in 2010. In Brazil, unauthorized Bt seeds from neighboring Argentina were sown for seven years until the Brazilian government granted approval in 2005. In Pakistan in 2007/08 an estimated 40% of the cotton area was sown with officially unauthorized Bt seeds, which mainly came from India, China and Australia. In order to regulate this high black market share and based on the positive experience in India, Pakistan announced in July 2009 that it would officially start growing in the following year.

Genetically modified cotton varieties are also permitted in Japan, but are not grown there. In addition to the countries mentioned, transgenic cotton varieties are also permitted as feed in Canada, Korea, and the Philippines. Applications for approval have also been submitted in the EU, but this has not yet been granted.

Experience with Bt cotton

There are many publications on the effects of the introduction of Bt cotton. However, only 56 of the studies published between 1996 and 2006 meet scientific standards ( peer review , method and data transparency). These studies relate to a smaller number of random samples and relatively short periods of time. Most of these scientific studies deal with Bt cotton in China, India and South Africa.

Asia

People's Republic of China

For the People's Republic of China , in the largest study to date (282 farmers in several provinces) for the 1999, 2000 and 2001 growing seasons, average insecticide savings of 66% and yield increases of 24% with increases in seed costs of US $ 32 per hectare were observed, leading to increases in contribution margins of US $ 32 $ 470 led. In Hebei and Shandong provinces , Bt cotton spread rapidly (100% in Hebei and 80% in Shandong in 2001) and significantly reduced pesticide use, as the cotton owl is the primary pest in these regions . In the provinces of Anhui and Jiangsu , where instead the red spider mite is the main pest of cotton, Bt cotton has not spread as much (around a third of the cotton area in 2001) and pesticide use has been reduced less. Effects on the health of farmers from the reduction in insecticide applications associated with the adoption of Bt cotton have so far been scientifically investigated, especially in China. Chinese crop protection applications cause an estimated 500 deaths and 45,000 serious illnesses per year, and substitution with Bt cotton has resulted in a reduction of 44,000 tons. This is accompanied by a significant decrease in the number of poisoning cases.

According to a study carried out between 1992 and 2007, the presence of Bt cotton in China has also led to a reduction in pest infestation with the cotton boll drill (Helicoverpa armigera) on maize, peanuts, soybeans and various types of vegetables.

According to research by Huang and Pray in 1999, shortly after the introduction of Bt cotton, the number of insecticide sprayings fell three to twelve times. Due to an increased number of non-target pests, which affected 30.9 to 97.1% of farmers in all three Bt cotton-growing areas, the reduction in insecticide spraying after 5 years was five to six times. This increased consumption significantly again. Depending on the region, the main secondary pests were species from the soft bug family and the red cotton bollworm . 60% of the farmers included in the study stated that the total production costs had not decreased due to increased seed prices for Bt cotton. Another problem that was found was that farmers had little in-depth knowledge of Bt cotton and its technical handling. In this respect, there is little potential to interpret economic yield problems in such a way that they can be meaningfully implemented in agricultural practice. The development of agricultural advice and practical training measures are considered necessary.

Lu et al. (2012) used data in the period 1990–2010 to study the incidence of cotton lice and their natural predators at 36 locations in six provinces in northern China. It was observed that, due to lower insecticide consumption - especially pyrethroid and organophosphate applications - there was a long-term increase in field populations of spiders, ladybirds and lacewings and a decrease in specific aphids in Bt cotton fields and in conventional cotton crops with comparable insecticide use. Since the predators have a wide range of food, studies were carried out to determine whether this effect would be carried over to neighboring fields. The frequency of predators in cotton crops was related to that of three adjacent fields (soybean, corn and peanut). A positive relationship was found for the frequency of aphid predators between cotton and soybeans ( p-value : 0.019), between cotton and peanut the p-value was 0.075, which was rated as slightly significant , and between cotton and maize was based on the frequency of occurrence of the Robbers had a P value of 0.216, which was classified as not statistically significant. Study author Desneux sees in the study results the message to make agriculture sustainable and environmentally friendly and to significantly reduce the use of pesticides. Bt cotton is one means among other things. The small-scale cultivation areas in China also differ significantly from the large-scale cultivation areas in the USA.

India

The effects of Bt technology in Indian cotton cultivation have been examined in numerous studies.

Cotton is mainly grown in India by smallholders with farms of less than 15 acres . The first Bt cotton hybrids were approved in 2002, and in 2011 the number of Bt varieties was over 880. The first Bt hybrids came from the Indian seed company Mahyco, which used Monsanto's Bt technology. In the years that followed, further Bt hybrids were approved in later years, which mainly relied on Monsanto's first (Bollgard I, with one Bt gene) and second generation (Bollgard II, with two Bt genes) technologies but also on Bt technologies from other providers. This increased the availability of a wide range of locally adapted hybrids with Bt genes. In 2011, 7 million farmers used Bt cotton on 26 million acres, which is about 90% of the Indian cotton growing area.

According to a study by Arora & Bansal (2012), state price controls on Bt seeds, which were implemented in 2006, were partly responsible for the increase in the adoption rate of Bt cotton, in addition to the increasing number of available Bt hybrids. Although farmers benefit from price controls in the short term, price controls can have negative effects on research and innovation in the long term. For example, Pray & Nagarajan (2011) found that the implementation of price controls was followed by an immediate and large drop in seed company profits. According to the authors, economic theory, interviews with seed companies and the experience in China indicate a possible threat to innovation rates from continued price controls on seed prices. Experience in Argentina can, however, be interpreted in such a way that the pricing policy of the provider, who is in fact a monopoly, can even accept its own economic disadvantages due to excessively high prices in a certain market in order to achieve higher profits in a more important market (here: the USA) so that price controls can reduce negative externalities.

According to the second status report by the Asia-Pacific Association of Agricultural Research Institutions (APAARI) , the yield rose by 135% and the proportion of Bt cotton to over 80%. The revenues from Bt cotton were on average 83% above those from conventional cultivation and the use of pesticides fell by 46%.

The socio-economic effects of Bt cotton cultivation in several states and years were examined in 13 scientifically peer-reviewed studies up to August 2009 . Of 36 results, 4 showed negative effects on the yield compared to conventional cotton, 2 neutral and 32 positive ones. The income effect was positive in 19 cases, neutral in 1 and negative in 4. The use of insecticides decreased according to all available 16 results from scientifically appraised studies.

The accusation expressed by critics (e.g. Vandana Shiva ) that Bt cotton would drive farmers to suicide has not yet been empirically proven. Peasant suicides are a phenomenon with a long history. An investigation showed that the number of suicides among farmers did not increase, while the cultivation of Bt cotton expanded massively. In addition, studies have demonstrated that Bt cotton is highly effective in India. In individual districts and years, Bt cotton may have made an indirect contribution to indebtedness and suicides, for example because early Bt hybrids were not well adapted to dry conditions or the new technology was poorly understood by farmers in the early years. However, there is no robust evidence of a definitive connection.

According to an eight - year long - term study by Glenn Davis Stone in four villages in a district in Andhra Pradesh , a major cotton-growing area, between 2003 and 2007 the use of Bt cotton increased by an average of 18% and the use of insecticides decreased by 55%. In the later years a considerable increase in secondary pests was observed, which makes an increase in the use of insecticides likely. Even if this problem is likely to be dealt with by new generations of Bt seeds, the study identifies the underlying problem as the fact that farmers are inadequate to adapt to the rapid change of seeds and technologies and have little know-how about processes to steer sensibly for their own interests. Accompanying concepts of intensive advisory measures would be required.

Investigations into the effects of Subramanian and Qaim on differently wealthy farmers and non-agricultural households took place in a typical village in the state of Maharashtra. It was found that Bt cotton increased labor income, especially for women who worked as harvest workers on cotton farms. Household incomes rose overall, also for poor and poverty-risk households. The authors therefore assume that Bt cotton makes a contribution to reducing poverty.

A long-term study by Kathage and Qaim published in 2012 examined a representative sample of 533 small farms in the states of Maharashtra , Karnataka , Andhra Pradesh and Tamil Nadu over a period of seven years . Bt cotton delivered 24% higher yields and 50% more profit than conventional cotton. In the period under study, the standard of living of mostly poor households rose by an average of 18%. The authors come to the conclusion that Bt cotton has a major, lasting positive influence on the economic and social development of India. The president of the agricultural interest group Vidarbha Jan Andolan Samiti (VJAS), Kishor Tiwari, considers the study by Kathage and Qaim to be unrepresentative, as only 533 agricultural households were included in the study, although in India around 10 million farmers on an area of ​​12 Growing millions of hectares of genetically modified cotton.

A long-term study by Kouser and Qaim (2002–2008) looked at the cases of poisoning that often occur due to the application of chemical insecticides without adequate protective clothing. Since Bt cotton reduced the use of insecticides by around 50% compared to conventional cotton and the use of the most toxic insecticides by 70%, far fewer acute symptoms of poisoning occurred among cotton farmers. In the course of the increasing use of Bt cotton, this decline intensified over time. Bt cotton prevents several million cases of poisoning every year, which also leads to savings in health costs.

Another study by Krishna and Qaim, covering the period from 2002 to 2008, examined how sustainable the reduction in insecticide use through Bt cotton was. The results showed a sustained decrease in the use of insecticides. The use of insecticides against secondary pests increased over time, but decreased overall due to the more significant use against capsule drills. In later years, Bt cotton cultivation also reduced the use of insecticides on conventional fields because the pest populations were decimated on a large scale as a result of the increasing Bt cultivation.

A study from 2015 came to the conclusion that the cultivation of Bt cotton in India could make economic sense if the cultivation method is based on artificial irrigation. The use of Bt crops in rain -fed crops appears economically dubious, as the cost of seeds and insecticides would increase the risk of economic failure. Furthermore, there are difficulties on the part of the farmers in finding the right seeds for them and in receiving appropriate agricultural advice. The ratio of annual suicides in areas with rain-fed crops is inversely proportional to farm size and yield and directly proportional to the increase in the cultivation of Bt cotton. Jairam Ramesh , former Minister for Rural Development and member of Rajya Sabha , called for the results of the study to be taken seriously and for a discussion on the long-term sustainability of GM crops in Indian agriculture.

In the context of a 20-year long-term study in India, Glenn Davis Stone and Keshav Raj Kranthi (International Cotton Advisory Committee, Washington DC) came to the conclusion in 2020 that the described yield increases in the early 2000s were less related to the cultivation of Bt cotton than more correlated with increased fertilization and the use of more effective insecticides. The nationwide yields have therefore not increased in the last 13 years. The initial positive effects in terms of lower insecticide use turned out to be short-term. The authors see the reason for this primarily in an increase in non-target organisms such as sucking pests and a development of resistance of the red cotton bollworm to the Bt toxin. In 2020, Indian cotton farmers would use more insecticides per hectare than they did before growing Bt cotton.

Another stress factor for farmers is the sudden need to assert themselves in a steadily accelerating capital-intensive production system, where economic safety nets, unlike other countries with capital-intensive agriculture, do not exist in India. According to the study, in the decade after 2005, when Bt seeds were increasingly grown, the costs per hectare for seeds rose by 78%, for insecticides by 158% and for fertilizers by 245%. The situation, which is characterized by constant income and increasing input costs, continues to exist. The authors conclude that the main impact of the cultivation of Bt cotton on Indian agriculture will lie primarily in its growing capital-intensive character and less in sustainable agronomic benefits.

Pakistan

In Pakistan, Bt cotton was not officially approved until 2010, but was smuggled from India and grown in Pakistan beforehand. The evaluation of a survey of 325 cotton farmers in the province of Punjab carried out in 2007 showed that Bt cotton increases yields and household incomes and reduces poverty. In addition, the use of pesticides decreased.

A study published in 2013 examined the monetary impact of Bt cotton on health and the environment. Due to a lower use of pesticides, there are significantly fewer acute cases of poisoning; In addition, there is a higher biodiversity and less contamination of soil and water. Farmers rate this benefit, roughly half health and environmental, at $ 79 per acre. Together with the contribution margin effects of 204 US dollars found, this results in a benefit increase of 283 US dollars per acre, which corresponds to 1.8 billion US dollars on the entire cultivation area of ​​Bt cotton in Pakistan.

America

United States

In the USA , according to a study, insecticide savings are 36%, while yield increases of only 10% have been observed (which can be explained by an already very good pest control with conventional insecticides). The seed price premiums for Bt cotton are also higher in the USA than in other countries (US $ 79), so that the increase in the contribution margin is a comparatively low US $ 58.

Argentina

In Argentina , a representative survey of 299 farmers was carried out in 2001, which compared the results of Bt cultivation with conventional cotton cultivation. In comparison, BT cotton saw 47% insecticide savings and 33% yield gains. The cost of seeds for BT cotton increased by a little more than 400% (from US $ 18 for conventional cultivation to US $ 103 for BT cotton cultivation). In the case of BT cotton cultivation, a subtle but not significant increase in the contribution margin was recorded.

Mexico

For the first years of Bt cotton cultivation in Mexico , a survey of 152 (1997) and 242 (1998) farmers showed on average pesticide reductions of 77%, yield gains of 9%, increases in seed costs of US $ 58 and contribution margin increases of US $ 295 per hectare . According to another study, the increases in yield between 1996 and 2004 varied between 3% and 37%.

Colombia

Transgenic cotton has been grown in Colombia since 2002. In 2013 transgenic cotton (95% varieties with combined insect resistance and herbicide tolerance) was sown on 24,000 hectares. Zambrano et al. (2009) found in a survey for the 2007-08 cultivation season increases in yield due to less damage caused by Bt cotton. Zambrano et al. (2011) examined the effects of growing transgenic cotton on women. The women saved time and money because there was less manual work involved in pulling weeds and less effort hiring men to apply insecticides. According to a study sponsored by Monsanto, the cost of the technology is $ 50-172 and the additional income after costs is $ 67 per hectare, according to authors Brookes and Barfoot (2013).

Africa

South Africa

A survey of 143 farmers between 2000 and 2001 in South Africa showed average pesticide reductions of 33% and yield increases of 22%. For small farmers, the Bt cotton brought higher seed costs of US $ 13 and profit margins of US $ 18 per hectare. In South Africa, the increased adoption of Bt cotton reduced the number of poisoning cases, especially among women and children who helped with the application of insecticides. A study carried out from 2002 to 2003 and 2003 to 2004 during the growing seasons using the method of daily monitoring among smallholders in Makhathini , KwaZulu Natal, South Africa, came to the following results: The cultivation of Bt cotton led to a decrease in pyrethroid -Sprayings, due to the insufficient resistance of the BT variety, however, applications with this insecticide were still necessary. Likewise were organophosphates used in large quantities. The authors of the study asked themselves the question of the impact of Bt cotton cultivation on the health of farmers. The macroeconomic results with Bt cotton were given a decent positive rating. The cultivation of Bt cotton was associated with savings in working hours, with the profit margin falling short of expectations. The authors of the study conclude that the cultivation of BT cotton in Makhathini does not have the potential, due to the current management, to generate sufficient income to be able to expect lasting and sustainable socio-economic improvements. The use of Bt cotton seems to be worthwhile only in an agricultural system with an already existing high degree of intensification.

Burkina Faso

Based on a survey of 160 cotton farmers in the first year of approval (2009), Bt cotton increased yields by 18% compared to conventional cotton. The production costs did not differ between transgenic and conventional cotton, as the saved insecticide costs were outweighed by the higher seed prices and the labor savings in the application of insecticides due to the higher harvest effort. Because of the higher yields, farmers were able to achieve a profit per hectare of 39 US dollars (62 US dollars higher) with Bt cotton than with conventional cotton.

Other countries

To date, no extensive scientific studies on the agronomic and economic effects in other countries have been published. Several studies have attempted to estimate the benefits that various African countries are missing from not using Bt cotton. A study relating to Benin, Burkina Faso, Mali, Senegal, Togo, Tanzania and Uganda, assuming a 50% adoption rate in these seven countries, found the opportunity costs of non-adoption totaling USD 41 million per year.

Individual evidence

  1. ^ Murray W. Nabors: Botany. Pearson Studium, ISBN 978-3-8273-7231-4 , pp. 354f.
  2. ^ A. Bravo, S. Gill, M. Soberón: Mode of action of Bacillus thuringiensis Cry and Cyt toxins and their potential for insect control. In: Toxicon . 49 (4), 2007, pp. 423-435. doi: 10.1016 / j.toxicon.2006.11.022 . PMID 17198720
  3. ^ National Research Council: The Impact of Genetically Engineered Crops on Farm Sustainability in the United States. The National Academies Press, Washington, DC 2010.
  4. ↑ a b Yanhui Lu, Kongming Wu, Yuying Jiang, Bing Xia, Ping Li, Hongqiang Feng, Kris AG Wyckhuys, Yuyuan Guo: Mirid Bug Outbreaks in Multiple Crops Correlated with Wide-Scale Adoption of Bt Cotton in China. In: Science. Vol. 328 no. 5982, 28 May 2010, pp. 1151-1154. doi: 10.1126 / science.1187881
  5. ↑ a b M. Qaim, C. Pray, D. Zilberman: Economic and Social Considerations in the Adoption of Bt Crops. In: J. Romeis, A. Shelton, G. Kennedy (Eds.): Integration of Insect-Resistant GM Crops Within IPM Programs. Springer, New York 2008.
  6. ↑ Bruce E Tabashnik, Aaron J Gassmann u. a .: Insect resistance to Bt crops: evidence versus theory. In: Nature Biotechnology. 26, 2008, pp. 199-202, doi: 10.1038 / nbt1382 .
  7. ↑ Bruce E. Tabashnik, Aaron J. Gassmann, David W. Crowder, Yves Carrière: Field-Evolved Insect Resistance to Transgenic Bt Crops.
  8. ↑ a b Bruce E. Tabashnik, Yves Carrière: Field-Evolved Resistance to Bt Cotton: Bollworm in the US and Pink Bollworm in India. In: Southwestern Entomologist. Volume 35, Number 3, 2010, pp. 417-424, doi: 10.3958 / 059.035.0326 .
  9. ↑ a b Resistant pests detected in India. in Biosafety from March 16, 2010.
  10. ↑ Study confirms the dangers of genetically modified plants for the first time. In: derStandard . February 27, 2008, accessed March 27, 2012.
  11. ^ A b Dinesh C. Sharma: Bt cotton has failed admits Monsanto. In: India Today . March 6, 2010, accessed March 30, 2012.
  12. ↑ Bt toxin favors new pests. ( Memento of March 12, 2014 in the Internet Archive ) In: Spectrum of Science. May 13, 2010, accessed March 21, 2012.
  13. ↑ Secondary pests in genetically modified plants - The phenomenon is as old as the plant protection itself. ( Memento of the original from September 4, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: Biosafety. June 10, 2010, accessed March 21, 2012.  @1@ 2Template: Webachiv / IABot / www. Pflanzenforschung.de
  14. ↑ A. Wegier, A. Pineyro-Nelson, J. Alarcon, A. Galvez Mariscal, ER Álvarez-Buylla, D. Pinero: Recent long-distance transgenic flow into wild populations Conforms to historical patterns of gene flow in cotton (Gossypium hirsutum) at its center of origin. In: Molecular Ecology. Volume 20, No. 19, October 2011, pp. 4182-4194, doi: 10.1111 / j.1365-294X.2011.05258.x
  15. ↑ Michelle Marvier, Chanel McCreedy, James Regetz, Peter Kareiva: A Meta-Analysis of Effects of Bt Cotton and Maize on Nontarget Invertebrates . In: Science . tape 316 , no. 5830 , 2007, p. 1475–1477 , doi : 10.1126 / science.1139208 .
  16. ↑ James, Clive. 2010. ISAAA letter no. 42. ISAAA: Ithaca, NY.
  17. ↑ cotton. Transgen.de, March 25, 2011.
  18. ↑ James, Clive. 2010. ISAAA letter no. 41. ISAAA: Ithaca, NY.
  19. ↑ Genetically Modified Plants: Cultivated Areas Worldwide: Cotton. Transgen.de, March 2, 2010.
  20. ^ J. Silveira, I. Borges: Brazil: Confronting the Challenges of Global Competition and Protecting Biodiversity. In: S. Fukuda-Parr (Ed.): The Gene Revolution. Earthscan, London 2007.
  21. ↑ fas.usda.gov (PDF file; 18 kB) USDA (2007): Pakistan Agricultural Situation Cotton Update 2007. GAIN Report Number: PK7026. United States Department of Agriculture: Washington, DC
  22. ↑ The News: BT cotton to be officially sown from next year (English)
  23. ↑ transgenic database
  24. ↑ M. Smale, P. Zambrano, M. Cartel: Bales and Balance: A Review of the Methods Used to Assess the Economic Impact of Bt Cotton on Farmers in Developing Economies. In: AgBioForum. Vol. 9, No. 1, 2006, pp. 195-212.
  25. ^ A b C. Pray, J. Huang, R. Hu, S. Rozelle: Five Years of Bt Cotton in China - The Benefits Continue. In: The Plant Journal. Vol. 31, 2002, pp. 423-430. doi: 10.1046 / j.1365-313X.2002.01401.x
  26. ↑ J. Huang, R. Hu, C. Pray, F. Qiao, S. Rozelle: Biotechnology as an alternative to chemical pesticides: a case study of Bt cotton in China. In: Agricultural Economics. Vol. 29, 2003, pp. 55-67.
  27. ^ F. Hossain, C. Pray, Y. Lu, J. Huang, R. Hu: Genetically modified cotton and farmers' health in China. In: International Journal of Occupational and Environmental Health. Vol. 10, 2004, pp. 296-303.
  28. ↑ K. Wu, Y. Lu, H. Feng, Y. Jiang, J. Zhao: Suppression of Cotton Bollworm in Multiple Crops in China in Areas with Bt Toxin-Containing Cotton. In: Science. Vol. 321, 2008, pp. 1676-1678.
  29. ↑ Jennifer H. Zhao, Peter Ho, Hossein Azadi: Benefits of Bt cotton counterbalanced by secondary pests? Perceptions of ecological change in China. In: Environmental Monitoring and Assessment. Volume 173, Numbers 1-4, pp. 985-994, doi: 10.1007 / s10661-010-1439-y .
  30. ↑ Yanhui Lu, Kongming Wu, Yuying Jiang, Yuyuan Guo, Nicolas Desneux: Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services . In: Nature . June 2012, ISSN  0028-0836 , doi : 10.1038 / nature11153 ( nature.com [accessed June 21, 2012]).
  31. ↑ Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services study as pdf.
  32. ↑ Green genetic engineering with broad-based cultivation of genetically modified cotton promotes biological pest control in China. In: Deutschlandfunk. June 14, 2012, accessed June 24, 2012.
  33. ↑ A more recent overview of published studies on Bt cotton in India is provided in the table on p. 9 of the meta-analysis by Riesgo et al., 2012: FJ Areal, L. Riesgo, E. Rodríguez-Cerezo: Economic and agronomic impact of commercialized GM crops: a meta-analysis. ( Memento of the original from November 11, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: The Journal of Agricultural Science. 2012. @1@ 2Template: Webachiv / IABot / cambridgefluids.org
  34. ↑ a b Jonas Kathage, Matin Qaim: Economic impacts and impact dynamics of Bt (Bacillus thuringiensis) cotton in India . In: Proceedings of the National Academy of Sciences . July 2012, ISSN  1091-6490 , doi : 10.1073 / pnas.1203647109 ( pnas.org [accessed July 4, 2012]).
  35. ↑ Anchal Arora, Sangeeta Bansal: Diffusion of Bt Cotton in India: Impact of Seed Prices and Varietal Approval. In: Applied Economic Perspectives and Policy. 34, 2012, pp. 102-118.
  36. ^ Carl E. Pray, Latha Nagarajan: Price Controls and Biotechnology Innovation: Are State Government Policies Reducing Research and Innovation by the Ag Biotech Industry in India? In: AgBioForum. 13, 2011, pp. 297-307.
  37. ↑ Matin Qauim, Alain de Janvry: Genetically Modified Crops, Corporate Pricing Strategies, and Farmers' Adoption: The Case of Bt Cotton in Argentina. In: American Journal of Agricultural Economics. Volume 85, No. 4, 2003, pp. 814-828, doi: 10.1111 / 1467-8276.00490 .
  38. ↑ apaari.org Bt Cotton in India - A Status Report ( Memento of the original dated August 16, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English). @1@ 2Template: Webachiv / IABot / www.apaari.org
  39. ↑ Peer-reviewed surveys indicate positive impact of commercialized GM crops. In: Nature Biotechnology . Vol. 28, No. 4, April 2010, pp. 319-321.
  40. ↑ G. Gruère, P. Mehta-Bhatt, D. Sengupta: Bt Cotton and Farmer Suicides in India. In: Reviewing the Evidence. IFPRI Discussion Paper No. 808.Washington, DC 2008.
  41. ↑ Guillaume Gruèrea, Debdatta Sengupta: Bt Cotton and Farmer Suicides in India: An Evidence-based Assessment. In: Journal of Development Studies. 47, 2011, pp. 316-337.
  42. ↑ Glenn Davis Stone: Field versus Farm in Warangal: Bt Cotton, Higher Yields, and Larger Questions . In: World Development . tape 39 , no. 3 , March 2011, ISSN  0305-750X , p. 387–398 , doi : 10.1016 / j.worlddev.2010.09.008 ( wustl.edu [PDF; accessed on May 6, 2012]). Field versus Farm in Warangal: Bt Cotton, Higher Yields, and Larger Questions ( Memento of the original from December 9, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / anthropology.artsci.wustl.edu
  43. ↑ India - Is the importance of Bt cotton overrated? Editor Pflanzenforschung.de, February 14, 2011, accessed on March 29, 2012.
  44. ↑ Arjunan Subramanian, Matin Qaim: The Impact of Bt Cotton on Poor Households in Rural India. In: Journal of Development Studies. 46, 2010, pp. 295-311.
  45. ↑ Study on genetic engineering cotton arouses strong criticism . In: Genetic Engineering Information Service. July 4, 2012, accessed February 20, 2013.
  46. ↑ Shahzad Kouser, Matin Qaim: Impact of Bt cotton on pesticide poisoning in smallholder agriculture: A panel data analysis. (PDF file; 465 kB). In: Ecological Economics. 70, 2011, pp. 2105-2113.
  47. ↑ Vijesh V. Krishna, Matin Qaim: Bt cotton and sustainability of pesticide Reductions in India. In: Agricultural Systems. 107, 2012, pp. 47-55.
  48. ^ Andrew Paul Gutierrez, Luigi Ponti, Hans R Herren, Johann Baumgärtner, Peter E Kenmore: Deconstructing Indian cotton: weather, yields, and suicides. In: Environmental Sciences Europe. 27, 2015, p. 12, June 17, 2015, doi: 10.1186 / s12302-015-0043-8 .
  49. ↑ Bt Cotton responsible for suicides in rain-fed areas, says study. In: The Hindu . June 21, 2015.
  50. ↑ KR Kranthi, Glenn Davis Stone: Long-term impacts of Bt cotton in India in Nature Plants 6, (2020), pages 188-196. doi: 10.1038 / s41477-020-0615-5
  51. ↑ Glenn Davis Stone: A Long-term Analysis of a Controversial GMO Crop in Nature research ecology & evolution - behind the paper, March 13, 2020.
  52. ^ A. Ali, A. Abdulai: The Adoption of Genetically Modified Cotton and Poverty Reduction in Pakistan. In: Journal of Agricultural Economics. 61, 2010, pp. 175-192. doi: 10.1111 / j.1477-9552.2009.00227.x
  53. ↑ Shahzad Kouser, Matin Qaim: Valuing financial, health, and environmental benefits of Bt cotton in Pakistan. In: Agricultural Economics. February 18, 2013. doi: 10.1111 / agec.12014 .
  54. ↑ J. Carpenter, A. Felsot, T. Goode, M. Hammig, D. Onstad, S. Sankula: Comparative Environmental Impacts of Biotechnology-derived and Traditional Soybean, Corn, and Cotton Crops. Council for Agricultural Science and Technology, Ames 2002, ISBN 1-887383-21-2 .
  55. ^ A. Naseem, C. Pray: Economic Impact Analysis of Genetically Modified Crops. In: P. Christou, H. Klee (Eds.): Handbook of Plant Biotechnology. John Wiley & Sons, Chichester 2004, pp. 959-991.
  56. ^ M. Qaim, A. De Janvry: Bt Cotton and Pesticide Use in Argentina: Economic and Environmental Effects. In: Environment and Development Economics. Vol. 10, 2005, pp. 179-200.
  57. ↑ Matin Qaim: Bt cotton in Argentina: Distribution, use and willingness to pay of the farmers . In: GEWISOLA's writings . tape 39 , 2004, p. 391–399 ( gewisola.de [PDF; accessed September 30, 2012]).
  58. ^ G. Traxler, S. Godoy-Avila, J. Falck-Zepada, J. Espinoza-Arellano: Transgenic Cotton in Mexico: Economic and Environmental Impacts. In: N. Kalaitzandonakes (Ed.): Economic and Environmental Impacts of First Generation Biotechnologies. Kluwer Academic Publishers, New York 2003, pp. 183-202.
  59. ^ G. Brookes, P. Barfoot: GM Crops: The Global Economic and Environmental Impact — The First Nine Years 1996-2004. ( Memento from October 14, 2009 in the Internet Archive ) In: AgBioForum. 8 (2 & 3), 2005, pp. 187-196.
  60. ↑ Patricia Zambrano, Luz Amparo Fonseca, Iván Cardona, Eduardo Magalhaes, 2009: The socio-economic impact of transgenic cotton in Colombia. In: RB Tripp (Ed.): Biotechnology and Agricultural Development. Routledge, 2009.
  61. ↑ Patricia Zambrano, Melinda Smale, Jorge H. Maldonador, Sandra L. Mendoza: Unweaving the Threads: The Experiences of Female Farmers with Biotech Cotton in Colombia . In: AgBioForum . tape 15 , no. 2 , 2012, p. 125-137 .
  62. ↑ Graham Brookes, Peter Barfoot: The global income and production effects of genetically modified (GM) crops 1996-2011 . In: GM Crops and Food . tape 4 , no. 1 , 2013, p. 74-83 .
  63. ↑ M. Gouse, C. Pray, D. Schimmelpfennig: The Distribution of Benefits from Bt Cotton Adoption in South Africa. In: AgBioForum. Vol. 7, 2004, pp. 187-194.
  64. ^ R. Bennett, S. Morse, Y. Ismael: Bt cotton, pesticides, labor and health: A case study of smallholder farmers in the Makhathini Flats, Republic of South Africa. In: Outlook on Agriculture. Vol. 32, 2003, pp. 123-128.
  65. ↑ Jean-Luc Hofsa, Michel Fokb, Maurice Vaissayre: Impact of Bt cotton adoption on pesticide use by smallholders: A 2-year survey in Makhatini Flats (South Africa). In: Crop Protection. Volume 25, No. 9, September 2006, pp. 984-988. doi: 10.1016 / j.cropro.2006.01.006
  66. ↑ Jeffrey D. Vitale, Gaspard Vognan, Marc Ouattarra, Ouola Traore: The Commercial Application of GMO Crops in Africa: Burkina Faso's Decade of Experience with Bt Cotton. In: AgBioForum. Volume 13, No. 4, 2010.
  67. ↑ Antoine Bouët, Guillaume P. Gruère: Refining Opportunity Cost Estimates of Not Adopting GM Cotton: An Application in Seven Sub-Saharan African Countries. In: Applied Economic Perspectives and Policy. 33, 2011, pp. 260-279.