Bt cotton

Last updated

Bt cotton is a genetically modified pest resistant plant cotton variety that produces an insecticide to combat bollworm.

Contents

Description

Strains of the bacterium Bacillus thuringiensis produce over 200 different Bt toxins, each harmful to different insects. Most notably, Bt toxins are insecticidal to the larvae of moths and butterflies, beetles, cotton bollworms and flies but are harmless to other forms of life. [1] The gene coding for Bt toxin has been inserted into cotton as a transgene, causing it to produce this natural insecticide in its tissues. In many regions, the main pests in commercial cotton are lepidopteran larvae, which are killed by the Bt protein in the genetically modified cotton they eat. This eliminates the need to use large amounts of broad-spectrum insecticides to kill lepidopteran pests (some of which have developed pyrethroid resistance). This spares natural insect predators in the farm ecology and further contributes to noninsecticide pest management.

Bt cotton is ineffective against many cotton pests such as plant bugs, stink bugs, and aphids; depending on circumstances it may be desirable to use insecticides in prevention. A 2006 study done by Cornell researchers, the Center for Chinese Agricultural Policy and the Chinese Academy of Science on Bt cotton farming in China found that after seven years these secondary pests that were normally controlled by pesticide had increased, necessitating the use of pesticides at similar levels to non-Bt cotton and causing less profit for farmers because of the extra expense of GM seeds. [2]

Mechanism

Bt cotton was created through the addition of genes encoding toxin crystals in the Cry group of endotoxin. [1] When insects attack and eat the cotton plant the Cry toxins or crystal protein are dissolved due to the high pH level of the insect's stomach. The dissolved and activated Cry molecules bond to cadherin-like proteins on cells comprising the brush border molecules. [1] The epithelium of the brush border membranes separates the body cavity from the gut while allowing access to nutrients. The Cry toxin molecules attach themselves to specific locations on the cadherin-like proteins present on the epithelial cells of the midgut and ion channels are formed which allow the flow of potassium. [1] Regulation of potassium concentration is essential and, if left unchecked, causes death of cells. Due to the formation of Cry ion channels sufficient regulation of potassium ions is lost, resulting in the death of epithelial cells. The death of such cells creates gaps in the brush border

History

Bt cotton was first approved for field trials in the United States in 1993, and first approved for commercial use in the United States in 1995. [3] Bt cotton was approved by the Chinese government in 1997. [4]

In 2002, a joint venture between Monsanto and Mahyco introduced Bt cotton to India. [5]

In 2011, India grew the largest GM cotton crop at 10.6 million hectares. The U.S. GM cotton crop was 4.0 million hectares, the second largest area in the world, followed by China with 3.9 million hectares and Pakistan with 2.6 million hectares. [6] By 2014, 96% of cotton grown in the United States was genetically modified [7] and 95% of cotton grown in India was GM. [8] India is the largest producer of cotton, and GM cotton, as of 2014.

Advantages

Bt cotton has several advantages over non-Bt cotton. The important advantages of Bt cotton are briefly :

The main selling points of Bt cotton are the reductions in pesticides to be sprayed on a crop and the ecological benefits which stem from that. China first planted Bt cotton in 1997 specifically in response to an outbreak of cotton bollworm, Helicoverpa armigera, that farmers were struggling to control with conventional pesticides. [9] Similarly in India and the US, Bt cotton initially alleviated the issues with pests whilst increasing yields and delivering higher profits for farmers. [10] [11] [12]

Studies showed that the lower levels of pesticide being sprayed on the cotton crops promoted biodiversity by allowing non-target species like ladybirds, lacewings and spiders to become more abundant. [9] Likewise it was found that integrated pest management strategies (IPM) were becoming more effective due to the lower levels of pesticide encouraging the growth of natural enemy populations. [9]

In India alone widespread adoption of Bt cotton led to 2.4-9 million less cases of pesticide poisoning, with similar reduction also seen in other countries. [13]

Bt-resistant pests

After the introduction of Bt cotton in northern China, non-target pests such as mirid bugs (Heteroptera: Miridae) became more abundant, because less pesticides were sprayed. [14] In 2013, a second issue being seen across the world, was the development of Bt resistant pests limiting the usefulness of Bt crops. [15]

Main drivers for the widespread resistance in India and China included the high proportion of Bt cotton being planted, 90% and 95% respectively in 2011, [9] [16] and few refuge areas. [12] [17] [18]

Refuge areas of non-Bt crops limit resistance development in targeted pests. [17] The US Environmental Protection Agency requires farmers to have refuge areas of 20–50% non-Bt crops within 0.8 km of their Bt fields. [19] Such requirements were not seen in China, where instead farmers relied on natural refuge areas to decrease resistance. [18]

In 2009, a novel solution to the resistance problem was trialed in Arizona, when sterile male pink bollworms (Pectinophora gossypiella) were released into populations of their wild Bt-resistant counterparts. The hypothesis was that sterile males mating with the few surviving females, who had developed resistance, would lead to a decrease in pests in the following generation. There was a dramatic reduction in pink bollworms, with only two pink bollworm larvae being found by the third year of the study. [17]

Controversies

In India, Bt cotton has been enveloped in controversies due to its supposed failure to reduce the need for pesticides and increase yield. [20] The link between the introduction of Bt cotton to India and a surge in farmer suicides has been refuted by other studies, [21] with decreased farmer suicides since Bt cotton was introduced. [22] Bt cotton accounts for 93% of cotton grown in India. [16]

By country

In India

Bt cotton is supplied in Maharashtra by the agri-biotechnology company Mahyco, which distributes it. [23]

In 2001, prior to the approval of Monsanto/Mahyco Bt cotton, Navbaharat Seeds sold illegal, unapproved Bt cotton, which was grown on 11,000 hectares in Gujarat. [24]

The use of Bt cotton in India has grown exponentially since its introduction in 2002. [25] Eight years after the deployment of Bt cotton, India became the number one exporter of cotton globally and the second largest cotton producer in the world. India has bred Bt-cotton varieties such as Bikaneri Nerma and hybrids such as NHH-44. [26]

Socio-economic surveys confirm that Bt cotton continues to deliver significant and multiple agronomic, economic, environmental and welfare benefits to Indian farmers and society including halved insecticide requirements and a doubling of yields. [27]

India's success has been subject to scrutiny. Monsanto's seeds are expensive and lose vigour after one generation, prompting the Indian Council of Agricultural Research to develop a cheaper Bt cotton variety with seeds that could be reused. The cotton incorporated the cry1Ac gene from the soil bacterium Bacillus thuringiensis (Bt), making the cotton toxic to bollworms. This variety showed poor yield, was removed within a year,[ when? ] and contained a DNA sequence owned by Monsanto, prompting an investigation. [16] In parts of India cases of acquired resistance against Bt cotton has occurred. Monsanto has admitted[ when? ] that the pink bollworm is resistant to the first generation transgenic Bt cotton that expresses the single Bt gene (Cry1Ac). [26] [ failed verification ]

The state of Maharashtra banned the sale and distribution of Bt cotton in 2012, to promote local Indian seeds, which demand less water, fertilizers and pesticide input, [28] but lifted the ban in 2013. [23]

Punjab Agricultural University (PAU) has successfully developed the country's first Bt cotton varieties. ICAR has identified three varieties, namely PAU Bt 1, F1861 and RS 2013, for cultivation in Punjab, Haryana, Rajasthan. [29] [30] It is a cheaper alternative to Bt cotton hybrid seed.

In the US

In Hawaii, growing GMO cotton has been prohibited since 2013. [31] Hybridization with the wild cotton species Gossypium tomentosum may be possible. Transgenic cotton is also banned in some parts of Florida.

In Africa

Burkina Faso

Burkina Faso, Africa's top cotton producer, banned GM cotton in 2016, because of economic and quality concerns. [32]

Kenya

Bt cotton is legal in Kenya having been conditionally approved by the National Biosafety Authority in 2016, conditional on the approval of the National Environment Management Authority of Kenya. The Kenyan government is promoting its use, expecting greatly increased output and some greater filling of its own domestic demand. [33]

See also

Notes and references

  1. 1 2 3 4 "Bt cotton - Explanation". University of Montana - Ethics and Public Affairs Program. 2013. Archived from the original on 9 July 2015. Retrieved 9 July 2015.
  2. ↑ Susan Lang (25 July 2006). "Seven-year glitch: Cornell warns that Chinese GM cotton farmers are losing money due to 'secondary' pests". Cornell news. Cornell University.
  3. ↑ James, Clive (1996). "Global Review of the Field Testing and Commercialization of Transgenic Plants: 1986 to 1995" (PDF). The International Service for the Acquisition of Agri-biotech Applications. Retrieved 17 July 2010.
  4. ↑ Qiu, Jane (13 May 2010). "GM crop use makes minor pests major problem". Nature. Retrieved 10 June 2016.
  5. ↑ Kazmin, Amy (18 October 2015). "Monsanto faces growing troubles in India". Financial Times. Retrieved 8 June 2016.
  6. ↑ ISAAA Brief 43-2011: Executive Summary Global Status of Commercialized Biotech/GM Crops: 2011. Retrieved 24 September 2012.
  7. ↑ Adoption of Genetically Engineered Crops in the U.S. – Economic Research Service, of the U.S. Department of Agriculture
  8. ↑ "Facts and trends - India" (PDF). International Service for the Acquisition of Agri-biotech Applications.
  9. 1 2 3 4 Lu, Y; Wu, K; Jiang, Y; Guo, Y; Desneux, N (July 2012). "Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services". Nature. 487 (7407): 362–5. Bibcode:2012Natur.487..362L. doi:10.1038/nature11153. PMID   22722864. S2CID   4415298.
  10. ↑ Kathage, J; Qaim, M (July 2012). "Economic impacts and impact dynamics of Bt (Bacillus thuringiensis) cotton in India". Proc Natl Acad Sci U S A. 109 (29): 11652–6. Bibcode:2012PNAS..10911652K. doi: 10.1073/pnas.1203647109 . PMC   3406847 . PMID   22753493.
  11. ↑ Morse, S; Bennett, RM; Ismael, Y (2005). "Genetically modified insect resistance in cotton: some farm level economic impacts in India". Crop Prot. 24 (5): 433–40. Bibcode:2005CrPro..24..433M. doi:10.1016/j.cropro.2004.09.008.
  12. 1 2 Wu, K-M; Lu, Y-H; Feng, H-Q; Jiang, Y-Y; Zhao, J-Z (September 2008). "Suppression of cotton bollworm in multiple crops in China in areas with Bt toxin-containing cotton". Science. 321 (5896): 1676–8. Bibcode:2008Sci...321.1676W. doi:10.1126/science.1160550. PMID   18801998. S2CID   18498845.
  13. ↑ Smyth, Stuart J. (2020). "The human health benefits from GM crops". Plant Biotechnology Journal. 18 (4): 887–888. doi:10.1111/pbi.13261. ISSN   1467-7652. PMC   7061863 . PMID   31544299.
  14. ↑ Lu, Y; Wu, K; Jiang, Y; Xia, B; Li, P; Feng, H; et al. (2010). "Mirid bug outbreaks in multiple crops correlated with wide-scale adoption of Bt cotton in China". Science. 328 (5982): 1151–4. Bibcode:2010Sci...328.1151L. doi: 10.1126/science.1187881 . PMID   20466880. S2CID   2093962.
  15. ↑ Tabashnik, BE; Brévault, T; Carrière (2013). "Insect resistance to Bt crops: lessons from the first billion acres". Nat Biotechnol. 31 (6): 510–21. doi:10.1038/nbt.2597. PMID   23752438. S2CID   205278530.
  16. 1 2 3 Jayaraman KS (2012). "India investigates Bt cotton claims". Nature. Nature News. doi:10.1038/nature.2012.10015. S2CID   167762098.
  17. 1 2 3 Tabashnik, BE; Sisterson, MS; Ellsworth, PC; Dennehy, TJ; Antilla, L; Liesner, L; et al. (December 2010). "Suppressing resistance to Bt cotton with sterile insect releases". Nat Biotechnol. 28 (12): 1304–7. doi:10.1038/nbt.1704. PMID   21057498. S2CID   4988462.
  18. 1 2 Wan, P; Huang, Y; Wu, H; Huang, M; Cong, S; Tabashnik, BE; et al. (2012). "Increased frequency of pink bollworm resistance to Bt toxin Cry1Ac in China. Smagghe G, editor". PLOS ONE. 7 (1): e29975. doi: 10.1371/journal.pone.0029975 . PMC   3251611 . PMID   22238687.
  19. ↑ Hutchison, WD; Burkness, EC; Mitchell, PD; Moon, RD; Leslie, TW; Fleischer, SJ; et al. (October 2010). "Areawide suppression of European corn borer with Bt maize reaps savings to non-Bt maize growers". Science. 330 (6001): 222–5. Bibcode:2010Sci...330..222H. doi:10.1126/science.1190242. PMID   20929774. S2CID   238816.
  20. ↑ Vandana, Dr. Shiva; Afsar H. Jafri (Winter 2004). "Failure of GMOs in India". Research Foundation for Science, Technology and Ecology. Retrieved 27 September 2013.
  21. ↑ Gruere, Guillaume (2008). "Bt Cotton and farmer suicides in India: Reviewing the Evidence" (PDF). International Food Policy Research Institute. Retrieved 24 February 2014.
  22. ↑ Plewis, I (2014). "Indian farmer suicides: Is GM cotton to blame?". Significance. 11 (1): 14–18. doi: 10.1111/j.1740-9713.2014.00719.x .
  23. 1 2 Vivek Deshpande (6 May 2013). "Maharashtra lifts ban on Mahyco's Bt cotton seeds". Nagpur. Indian Express . Retrieved 3 September 2013.
  24. ↑ Jayaraman, K.S. (December 2001). "Illegal Bt cotton in India haunts regulators". Nature Biotechnology. 19 (12): 1090. doi: 10.1038/nbt1201-1090 . PMID   11731762. S2CID   5158158.
  25. ↑ KV Kurmanath (22 March 2016). "Bt cotton: how it flowered and is losing lustre now". The Hindu.
  26. 1 2 Choudhary, B.; Gaur, K. (2010). "Bt Cotton in India: A Country Profile". ISAAA. Series of Biotech Crop Profiles. Ithaca, New York.
  27. ↑ James, Clive (2009). "Global Status of Commercialized Biotech/GM Crops: 2009" (PDF). ISAAA. ISAAA Briefs (41). Ithaca, New York.
  28. ↑ "Maharashtra bans Bt cotton seeds". The Times of India. 9 August 2012.
  29. ↑ "Indian Universities Develop Bt Cotton Varieties with Reusable Seeds". Crop Biotech Update. ISAAA (International Service for the Acquisition of Agri-biotech Applications). 15 March 2017. Retrieved 2 May 2022.
  30. ↑ "PAU develops country's first Bt cotton varieties". The Hindu . 8 March 2017. Retrieved 2 May 2022.
  31. ↑ Robynne Boyd (19 November 2013). "Hawaii's Big Island Bans Biotech Companies & GMO Crops". Huffington Post. Retrieved 24 October 2015.
  32. ↑ "Top African producer bans GM cotton". Phys.org. Retrieved 9 June 2016.
  33. ↑ "Bt Cotton Ready For Harvesting". Kenya News Agency . 9 August 2021.

Related Research Articles

<i>Bacillus thuringiensis</i> Species of bacteria used as an insecticide

Bacillus thuringiensis is a gram-positive, soil-dwelling bacterium, the most commonly used biological pesticide worldwide. B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterflies, as well on leaf surfaces, aquatic environments, animal feces, insect-rich environments, flour mills and grain-storage facilities. It has also been observed to parasitize moths such as Cadra calidella—in laboratory experiments working with C. calidella, many of the moths were diseased due to this parasite.

<span class="mw-page-title-main">Genetically modified maize</span> Genetically modified crop

Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both traits are now in use in multiple countries. GM maize has also caused controversy with respect to possible health effects, impact on other insects and impact on other plants via gene flow. One strain, called Starlink, was approved only for animal feed in the US but was found in food, leading to a series of recalls starting in 2000.

The Monsanto Company was an American agrochemical and agricultural biotechnology corporation founded in 1901 and headquartered in Creve Coeur, Missouri. Monsanto's best-known product is Roundup, a glyphosate-based herbicide, developed in the 1970s. Later, the company became a major producer of genetically engineered crops. In 2018, the company ranked 199th on the Fortune 500 of the largest United States corporations by revenue.

Agricultural biotechnology, also known as agritech, is an area of agricultural science involving the use of scientific tools and techniques, including genetic engineering, molecular markers, molecular diagnostics, vaccines, and tissue culture, to modify living organisms: plants, animals, and microorganisms. Crop biotechnology is one aspect of agricultural biotechnology which has been greatly developed upon in recent times. Desired trait are exported from a particular species of Crop to an entirely different species. These transgene crops possess desirable characteristics in terms of flavor, color of flowers, growth rate, size of harvested products and resistance to diseases and pests.

<span class="mw-page-title-main">Insecticide</span> Pesticide used against insects

Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Acaricides, which kill mites, ticks, and spiders are not strictly insecticides, but are usually classified together with insecticides. The major use of Insecticides is agriculture, but they are also used in home and garden, industrial buildings, vector control and control of insect parasites of animals and humans. Insecticides are distinct from repellents, which repel but do not kill.

<span class="mw-page-title-main">Pesticide resistance</span> Decreased effectiveness of a pesticide on a pest

Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring. If a pest has resistance then that will reduce the pesticide's efficacy – efficacy and resistance are inversely related.

A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships.

<span class="mw-page-title-main">Genetically modified crops</span> Plants used in agriculture

Genetically modified crops are plants used in agriculture, the DNA of which has been modified using genetic engineering methods. Plant genomes can be engineered by physical methods or by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors. In most cases, the aim is to introduce a new trait to the plant which does not occur naturally in the species. Examples in food crops include resistance to certain pests, diseases, environmental conditions, reduction of spoilage, resistance to chemical treatments, or improving the nutrient profile of the crop. Examples in non-food crops include production of pharmaceutical agents, biofuels, and other industrially useful goods, as well as for bioremediation.

<span class="mw-page-title-main">Pink bollworm</span> Species of moth

The pink bollworm is an insect known for being a pest in cotton farming. The adult is a small, thin, gray moth with fringed wings. The larva is a dull white caterpillar with eight pairs of legs with conspicuous pink banding along its dorsum. The larva reaches one half inch in length.

<i>Helicoverpa armigera</i> Species of moth

Helicoverpa armigera is a species of Lepidoptera in the family Noctuidae. It is known as the cotton bollworm, corn earworm, Old World (African) bollworm, or scarce bordered straw. The larvae feed on a wide range of plants, including many important cultivated crops. It is a major pest in cotton and one of the most polyphagous and cosmopolitan pest species. It should not be confused with the similarly named larva of the related species Helicoverpa zea.

<span class="mw-page-title-main">Genetically modified food controversies</span>

Genetically modified food controversies are disputes over the use of foods and other goods derived from genetically modified crops instead of conventional crops, and other uses of genetic engineering in food production. The disputes involve consumers, farmers, biotechnology companies, governmental regulators, non-governmental organizations, and scientists. The key areas of controversy related to genetically modified food are whether such food should be labeled, the role of government regulators, the objectivity of scientific research and publication, the effect of genetically modified crops on health and the environment, the effect on pesticide resistance, the impact of such crops for farmers, and the role of the crops in feeding the world population. In addition, products derived from GMO organisms play a role in the production of ethanol fuels and pharmaceuticals.

<span class="mw-page-title-main">Delta endotoxins</span> Insecticide

Delta endotoxins (δ-endotoxins) are a family of pore-forming toxins produced by Bacillus thuringiensis species of bacteria. They are useful for their insecticidal action and are the primary toxin produced by the genetically modified (GM) Bt maize/corn and other GM crops. During spore formation the bacteria produce crystals of such proteins that are also known as parasporal bodies, next to the endospores; as a result some members are known as a parasporin. The Cyt (cytolytic) toxin group is another group of delta-endotoxins formed in the cytoplasm. VIP toxins are formed at other stages of the life cycle.

The MON 810 corn is a genetically modified maize used around the world. It is a Zea mays line known as YieldGard from the company Monsanto. This plant is a genetically modified organism (GMO) designed to combat crop loss due to insects. There is an inserted gene in the DNA of MON 810 which allows the plant to make a protein that harms insects that try to eat it. The inserted gene is from the Bacillus thuringiensis which produces the Bt protein that is poisonous to insects in the order Lepidoptera, including the European corn borer.

<span class="mw-page-title-main">SmartStax</span> Seeds protected against bugs, weeds

SmartStax is a brand of genetically modified seed made through a collaboration between Monsanto Company and Dow Chemical Company. It takes advantage of multiple modes of insect protection and herbicide tolerance. SmartStax takes advantage of Yieldgard VT Triple (Monsanto), Herculex Xtra (Dow), RoundUp Ready 2 (Monsanto), and Liberty Link (Dow). The traits included protect against above-ground insects, below-ground insects, and provide broad herbicide tolerance. It is currently available for corn, but cotton, soybean, and specialty crop variations are to be released. Previously, the most genes artificially added to a single plant was three, but Smartstax includes eight. Smartstax also incorporates Monsanto's Acceleron Seed Treatment System which protects against insects at the earliest stages of development. Smartstax is sold under the Genuity (Monsanto) and Mycogen (Dow) brands.

The United States is the largest grower of commercial crops that have been genetically engineered in the world, but not without domestic and international opposition.

The genetically modified brinjal is a suite of transgenic brinjals created by inserting a crystal protein gene (Cry1Ac) from the soil bacterium Bacillus thuringiensis into the genome of various brinjal cultivars. The insertion of the gene, along with other genetic elements such as promoters, terminators and an antibiotic resistance marker gene into the brinjal plant is accomplished using Agrobacterium-mediated genetic transformation. The Bt brinjal has been developed to give resistance against lepidopteron insects, in particular, the Brinjal Fruit and Shoot Borer (FSB) by forming pores in the digestive system. Mahyco, an Indian seed company based in Jalna, Maharashtra, has developed the Bt brinjal.

<span class="mw-page-title-main">Cry1Ac</span> Crystal protein

Cry1Ac protoxin is a crystal protein produced by the gram-positive bacterium, Bacillus thuringiensis (Bt) during sporulation. Cry1Ac is one of the delta endotoxins produced by this bacterium which act as insecticides. Because of this, the genes for these have been introduced into commercially important crops by genetic engineering in order to confer pest resistance on those plants.

<span class="mw-page-title-main">Cry6Aa</span> Bacterial toxins

Cry6Aa is a toxic crystal protein generated by the bacterial family Bacillus thuringiensis during sporulation. This protein is a member of the alpha pore forming toxins family, which gives it insecticidal qualities advantageous in agricultural pest control. Each Cry protein has some level of target specificity; Cry6Aa has specific toxic action against coleopteran insects and nematodes. The corresponding B. thuringiensis gene, cry6aa, is located on bacterial plasmids. Along with several other Cry protein genes, cry6aa can be genetically recombined in Bt corn and Bt cotton so the plants produce specific toxins. Insects are developing resistance to the most commonly inserted proteins like Cry1Ac. Since Cry6Aa proteins function differently than other Cry proteins, they are combined with other proteins to decrease the development of pest resistance. Recent studies suggest this protein functions better in combination with other virulence factors such as other Cry proteins and metalloproteinases.>

India and China are the two largest producers of genetically modified products in Asia. India currently only grows GM cotton, while China produces GM varieties of cotton, poplar, petunia, tomato, papaya and sweet pepper. Cost of enforcement of regulations in India are generally higher, possibly due to the greater influence farmers and small seed firms have on policy makers, while the enforcement of regulations was more effective in China. Other Asian countries that grew GM crops in 2011 were Pakistan, the Philippines and Myanmar. GM crops were approved for commercialisation in Bangladesh in 2013 and in Vietnam and Indonesia in 2014.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.