tag:theconversation.com,2011:/us/topics/gm-resistance-1498/articlesGM resistance – The Conversation2014-03-18T14:46:11Ztag:theconversation.com,2011:article/245052014-03-18T14:46:11Z2014-03-18T14:46:11ZGM debate will never be resolved unless the public is consulted properly<figure><img src="https://images.theconversation.com/files/44187/original/vnsqz85w-1395138592.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The debate can get pretty shouty.</span> <span class="attribution"><a class="source" href="http://en.wikipedia.org/wiki/File:March_Against_Monsanto_Vancouver.jpg">Rosalee Yagihara</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The UK Council for Science and Technology recently <a href="https://www.gov.uk/government/publications/genetic-modification-gm-technologies">called on prime minister David Cameron to reassess EU rules</a> on GM crops. Two days later the Observer <a href="http://www.theguardian.com/commentisfree/2014/mar/16/gm-crops-world-food-famine-starvation">published an editorial</a> bluntly declaring: “There’s no choice; we must grow GM crops now”. There is a high risk that a new round of the <a href="http://www.parliament.uk/business/publications/research/briefing-papers/POST-Report-11/the-great-gm-food-debate-a-survey-of-media-coverage-in-the-first-half-of-1999">shouting match that mired the debate 15 years ago</a> will begin again, with little real progress.</p>
<p>But research since the first failure of the debate on GM crops in the EU suggests there is a better way. Our <a href="https://www.dur.ac.uk/ihrr/gmfuturos/">GM-Futuros project</a> has recently explored the GM debates in depth at national and local levels in India, Mexico and Brazil – highlighting some stark lessons for the EU and UK. Quality engagement with the public is key.</p>
<p>Both of the recent UK publications call for a positive move towards GM agricultural technology. Ostensibly this is driven by <a href="http://www.cast-science.org/download.cfm?PublicationID=278268&File=1e30d111d2654524a7967353314f1529765aTR">forecasts</a> of global population increases and a shortfall in food supply from current agricultural land by 2050. The Council for Science and Technology letter also appeals to the current loss of economic opportunity in the UK from present <a href="http://www.thejournal.co.uk/business/eu-farming-groups-express-concerns-6267790">over-restrictive EU regulations</a>. The Observer piece is dismissive of objections: “Thirty years ago, it could be argued that we should proceed cautiously because of potential health dangers. That argument is no longer acceptable.”</p>
<h2>Troubled technologies</h2>
<p>The dangers of using language like this (and that <a href="http://www.theguardian.com/environment/2014/jan/07/owen-paterson-gm-crops-farming">used by the government itself recently</a>) has become clearer thanks to research into the debate around “troubled technologies” – technologies that touch sensitive public nerves. These are legion: nanotechnologies, nuclear power, GMOs, geoengineering and, more recently, fracking. </p>
<p>Some technology stirs up emotional opposition more than others, and this happens differently across cultures. This suggests that more is going on than an on-the-surface discussion of technological risk, potential benefits and possible harms. </p>
<p>The GM-Futuros project builds on a <a href="http://www.geography.dur.ac.uk/Projects/Portals/88/Publications/Reconfiguring%20Responsibility%20September%202009.pdf">previous study</a>, which found public concerns over certain new technologies reflected deeply-lying, and often hidden, beliefs.</p>
<p>They were full of powerful arguments using narratives such as “the rich get richer”, “we are kept in the dark”, “Pandora’s box”, “messing with nature” and “be careful what you wish for”. If the sources of this scepticism is not recognised and dealt with sensitively, proponents and opponents of policy simply talk past each other.</p>
<h2>Public interests</h2>
<p>In Mexico, there has been a slow and silent implementation of GM crops but the GM controversy truly exploded with the <a href="http://www.reuters.com/article/2013/11/12/us-mexico-corn-idUSBRE9AB11Q20131112">case of maize</a>, which holds an iconic (almost sacred) national status. It unites urban consumers and rural populations alike: the public resistance to GM maize is such that a recent moratorium has been mandated by a judge. </p>
<p>In Brazil, the growing numbers of urban middle class consumers are largely unaware that they are eating GM foods. When made aware, they feel they have been betrayed and kept in the dark by their government. In India, however, the debate centres around <a href="http://video.sciencemag.org/SciOriginals/2324676529001/1">Indian GM science</a>. Part of the national scientific community lobbies for the development of Indian GM technology, while another part argues that Indian science cannot guarantee a reliable assessment of risks and impacts at present. </p>
<p>The three countries show huge differences in how social responsibility is appreciated by scientists. Our experience has been that “the public interest”, while a common broadcast message, has not been a key driver of protest in practice. </p>
<p>The reality is that GM has benefited some (typically large producers) at the expense of others (small producers and other alternative methods of organising agriculture such as agro-ecology). The use of GM crops in India, Brazil and Mexico has also pointed to degrees of “lock-in” (where farmers are left with no alternatives) and few sustainability benefits.</p>
<h2>Engagement done properly</h2>
<p>The quality of public engagement is a critical element in implementing GM. Brazilian, Mexican and Indian citizens (the consumers) have been more or less wholly absent from the debate, as have many others, including the vital voices of local farmers. When eventually informed they are often angry.</p>
<p>This means engaging with the UK public is necessary but likely to prove insufficient unless this is done properly. Real consideration must be given to what constitutes the public good, the conditions under which it is likely to be realised in practice, and the plausibility of these conditions being implemented under current arrangements.</p>
<p>Simply calling for the relaxation of regulations on GMOs therefore misses the point to a large extent. The key issue is to move the debate away from an analysis of harms (as assessed exclusively by scientists and regulators) towards a more inclusive discussion of the issues that actually constitute the public interest. What kind of agriculture do we want as a nation? How should different citizens be involved in the process? How contingent will public trust be on how the issue is framed and deliberated?</p>
<h2>Building trust</h2>
<p>An essential starting point is the realisation that government is not trusted on this issue; indeed, the way they’ve framed the debate has been largely unhelpful, in that GM so far has embraced a model of agriculture that people are uneasy with (for good reason) and about which they feel they have not been consulted.</p>
<p>We need to move forward, making scientific decisions more democratic. A new <a href="http://www.sciencedirect.com/science/article/pii/S0048733313000930">framework for responsible innovation</a> details how this can be done in practice, through anticipating impacts, reflecting on motivations, engaging with the public and then using these processes to influence the direction of the research process itself. </p>
<p>To this end, we are holding a workshop at the Royal Society on 13th June to discuss GM in the UK and EU and to draw research findings together into policy recommendations. We are optimistic, in spite of the hard lessons, that a way forward in framing policy is possible, but only if those lessons are learnt well.</p><img src="https://counter.theconversation.com/content/24505/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tom McLeish receives funding from EPSRC, AHRC and the Templeton Foundation. </span></em></p><p class="fine-print"><em><span>Phil Macnaghten receives funding from the EPSRC, the John Templeton Foundation, the FAPESP Sao Paulo Science Foundation and the British Council.</span></em></p><p class="fine-print"><em><span>Susana Carro-Ripalda receives funding from The John Templeton Foundation and the University of Durham.</span></em></p>The UK Council for Science and Technology recently called on prime minister David Cameron to reassess EU rules on GM crops. Two days later the Observer published an editorial bluntly declaring: “There’s…Tom McLeish, Professor of Physics and Pro-Vice-Chancellor for Research, Durham UniversityPhil Macnaghten, Professor of Geography, Durham UniversitySusana Carro-Ripalda, Senior Research Fellow in Anthropology, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/36102011-10-16T19:22:56Z2011-10-16T19:22:56ZBusting the GM myths: a view from Greenpeace<figure><img src="https://images.theconversation.com/files/4130/original/gm_canola_Ngarkat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Canola is one of two GM crops approved in Australia.</span> <span class="attribution"><span class="source">Ngarkat</span></span></figcaption></figure><p>The Conversation recently published an article looking at the myths about <a href="http://theconversation.com/top-five-myths-about-genetic-modification-2664">genetic modification</a>. This article is a rejoinder to that piece, and a contribution to the ongoing debate about whether there is any safe way to genetically modify our food. </p>
<h2>GM is crude science</h2>
<p>Genetic engineering (or genetic modification) inserts DNA (or genes) into the genome of a plant. The genomes of plants and animals are controlled by a complex regulatory network that controls gene expression (the production of proteins). Genetic engineering <a href="http://www.abbeys.com.au/book/lewins-genes-x-10e.do">does not take account of this</a>. </p>
<p>The inserted GM genes operate outside this regulatory network. Because the exact nature of this network is poorly understood, it is not possible to predict the interaction of the inserted genes with the plant’s own genome when the genes are being expressed. </p>
<p>Inserting DNA can cause additional fragments to be inserted and can also delete and rearrange the plant’s own DNA.</p>
<p>Unexpected and unknown fragments of genetic material have been found in commercial GM crops¹ (for example, Roundup Ready soya² and insect resistant maize³, MON810).</p>
<p>As a consequence, GM crops could produce unintended novel proteins, or altered plant proteins. Because most allergens are proteins, this raises concerns about these crops’ potential to cause allergies. </p>
<p>As Richard Richards <a href="http://theconversation.com/top-five-myths-about-genetic-modification-2664">points out</a>, genetic engineering is not a good way to develop plant varieties with complex traits (such as drought resistance). </p>
<p>This doesn’t mean we can’t develop these types of varieties. Other biotechnologies, such as <a href="http://en.wikipedia.org/wiki/Marker_assisted_selection">marker assisted selection</a> (an advanced form of breeding) can be used to develop new varieties, such as drought-resistant rice and wheat. </p>
<p>These technologies use our knowledge of how plant genomes function, but do not result in the deliberate release of a GM plant. Plants developed <a href="http://www.greenpeace.org/australia/en/what-we-do/Food/resources/reports/Smart-Breeding/">using this method</a> are already in farmer’s fields.</p>
<h2>GM crops do not increase yield and will not solve hunger</h2>
<p>The United Nations/World Bank <a href="http://www.agassessment.org">assessment of agriculture</a> was performed by 400 scientists from over 100 countries. They carefully examined whether GM crops increased yields and could not come to a firm conclusion: </p>
<p>“The pool of evidence of the sustainability and productivity of GMOs in different settings is relatively anecdotal, and the findings from different contexts are variable, allowing proponents and critics to hold entrenched positions about their present and potential value. </p>
<p>"Some regions report increases in some crops and positive financial returns have been reported for GM cotton in studies including South Africa, Argentina, China, India and Mexico. </p>
<p>"In contrast, the US and Argentina may have slight yield declines in soybeans, and also for maize in the US⁴”.</p>
<p>The evidence is clear that GM plants are unlikely to play any effective role in increasing food security. In fact, the expense and risk of GM crops could actually decrease food security. GM seeds are subject to patent claims which will indirectly increase the price of food; this will not alleviate poverty or hunger and will pose a threat to food sovereignty. </p>
<p>As the UN Agriculture Assessment states: “In developing countries especially, instruments such as patents may drive up costs, restrict experimentation by the individual farmer or public researcher while also potentially undermining local practices that enhance food security and economic sustainability"⁵.</p>
<p><a href="https://theconversation.com/topics/food-security">Food insecurity</a> is related to industrial farming, bad harvests related to climate change, unjust distribution of food, changes in consumption patterns, financial speculation on agricultural commodities and the rush for agrofuels. </p>
<p>This problem is not restricted to the <a href="http://www1.american.edu/academic.depts/acainst/cgs/about.html">Global South</a>. In 2005, one in 20 Victorians <a href="http://www.vichealth.vic.gov.au/%7E/media/ResourceCentre/FactsAndStats/fact%20sheets/food_security_fact.ashx">experienced food insecurity</a>.</p>
<p>Solutions to hunger and malnutrition are not easy. But supporting farmers and farm workers in eco-agriculture systems that minimise dependency on external inputs, such as artificial fertilisers and pesticides, is a major option to fight hunger and improve food security worldwide⁶.</p>
<h2>GM crops pose risks to the environment </h2>
<p>Most GM crops are either insect-resistant (that is, produce their own pesticide), herbicide-tolerant or sometimes both. </p>
<p>The environmental risks of GM insect-resistant crops have been documented in a review of the scientific literature⁷ and are summarised briefly here. Many GM insect-resistant crops produce the same or a similar toxin to GM maize so many of the concerns can, in general, be extrapolated to other GM insect-resistant crops.</p>
<p>GM insect resistant crops are designed to kill specific pests, by exuding a toxin called <em>Bacillus thuringiensis</em> (or Bt). </p>
<p>This Bt is different from the bacterial sprays used in conventional and organic agriculture: it is less specific to the organisms it can affect. For example, GM insect-resistant crops may be toxic to "non-target” organisms, such as butterflies. Long-term exposure to pollen from GM insect-resistant maize causes a decreased survival rate in monarch butterfly larvae⁸. </p>
<p>GM insect-resistant crops can be toxic to other, beneficial insects which are important in the natural control of maize pests, such as green lacewings. </p>
<p>Studies have shown that other, new pest insects are filling the void left by the absence of the specific insect pests controlled Bt crops target⁹. This leads to the spraying of additional pesticides with additional costs to both farmers and the environment.</p>
<p>GM herbicide-tolerant crops are generally associated with one of two herbicides: glyphosate (sold as Roundup), associated with GM <a href="http://www.monsanto.com.au/products/roundup/roundup_ready_herbicide.asp">Roundup Ready</a> crops, or glufosinate, associated with GM <a href="http://www.bayercropscience.com.au/cs/OurCompany/Libert%20Link.asp">Liberty Link</a> crops. Both these herbicides raise concerns but, in terms of environmental effects, most studies have focussed on glyphosate (or Roundup). </p>
<p>In the past 10-15 years, many new studies suggest that Monsanto’s Roundup is far less environmentally benign than previously thought. These studies are the subject of a recent review¹⁰ but are summarised briefly here.</p>
<p>There are concerns Roundup (or glyphosate) is toxic to aquatic biodiversity¹¹, such as frog larvae (tadpoles). </p>
<p>Glyphosate applications are associated with nutrient (nitrogen and manganese) deficiencies in GM Roundup Ready soya, thought to be induced by its effects on soil microorganisms¹².</p>
<p>Evolution of weed resistance to Roundup is now well-documented as a serious problem where Roundup Ready crops are grown on a large scale. Increasing amounts of herbicide have to be used to control these weeds, or else additional herbicides have to be used to supplement Roundup. This implies an increased toxic burden on the environment and people.</p>
<h2>We do not know if GM foods are safe to eat</h2>
<p>Many GM crops end up in food for humans and animals. In Australia, only <a href="http://ogtr.gov.au/internet/ogtr/publishing.nsf/Content/ir-1">two GM crops</a> are cultivated – canola and cotton – but many are approved for <a href="http://www.foodstandards.gov.au/consumerinformation/gmfoods/gmcurrentapplication1030.cfm">food imports</a>. </p>
<p>There are two ways in which genetic engineering may affect food safety: </p>
<ul>
<li>Gene disruption or instability may lead to new toxins being produced.</li>
<li>The new protein produced by the foreign gene may cause allergies or toxicity.</li>
</ul>
<p>Because GM crops are prone to unexpected and unpredictable effects, the evaluation of food safety requires looking for unexpected and unpredictable effects. This is extremely difficult, if not impossible. Therefore, all current testing regimes for GM foodstuffs around the world are inadequate.</p>
<p>National inadequacies also exist. A recent report of the Australian Auditor General questioned whether <a href="http://www.foodstandards.gov.au/">Food Standards Australia New Zealand (FSANZ)</a> gets sufficient information from applicants to be an effective regulator. </p>
<p>The Auditor found that FSANZ has no procedure for ensuring the data provided by corporate applicants is actually correct and complete. They found gaps in supporting data and evidence that some applications were approved¹³, despite these gaps.</p>
<p>In 2005, the development of an Australian GM pea was dramatically stopped because a study found serious health impacts in mice¹⁴. Small changes in the structure of the GM protein were found to unexpectedly cause allergenic reactions in mice.</p>
<p>The incident sent shockwaves around the world. People wanted to know whether this toxicity would have been detected in routine testing to evaluate GM food safety.</p>
<p>As the editor of New Scientist said¹⁵:</p>
<p>“The important question is whether national regulatory authorities would have spotted the allergy. In Australia, where the research was done, the answer is no. Although researchers ended the project voluntarily when they discovered the allergic reactions, the tests they did are not mandatory.” </p>
<p>We simply do not know if GM crops are safe for animal or human consumption.</p>
<p><strong>References</strong></p>
<p>1) <a href="http://cera-gmc.org/docs/articles/09-090-008.pdf">Windels, P. et al</a>. 2001. European Food Research Technology 213:107-112 </p>
<p>2) <a href="http://www.springerlink.com/content/4puxnt5x0yw15qmm/">Rang, A. et al</a> 2004. European Food Research Technology 220: 438-443</p>
<p>3) <a href="http://www.ncbi.nlm.nih.gov/pubmed/12739886">Hernandez, M. et al</a>. 2003. Transgenic Research 12: 179–189 </p>
<p>4) <a href="http://www.agassessment.org/reports/IAASTD/EN/Agriculture%20at%20a%20Crossroads_Synthesis%20Report%20(English).pdf">IAASTD</a>. 2009. Agriculture at a Crossroads - Synthesis report.</p>
<p>5) <a href="http://www.agassessment.org/reports/IAASTD/EN/Agriculture%20at%20a%20Crossroads_Synthesis%20Report%20(English).pdf">IAASTD</a>. 2009. Agriculture at a Crossroads - Synthesis report.</p>
<p>6) <a href="http://www.grida.no/publications/rr/food-crisis/">Nellemann, C. et al</a>.2009. The Environmental Food Crisis.</p>
<p>7) <a href="http://www.greenpeace.to/publications/Bt-maize-in-Europe-2009.pdf">Cotter, J.</a> 2009.
GM insect-resistant (Bt) maize in Europe:
a growing threat to wildlife and agriculture</p>
<p>8) <a href="http://www.cib.org.br/estudos/estudos_cientificos_ambiental_17.pdf">Dively, Galen P. et al</a>. 2004. Entomological Society of America 33: 1116-25.</p>
<p>9) <a href="http://www.ask-force.org/web/Cotton/Wang-Bt-Cotton-Secondary-Pests-2008.pdf">Wang, S. et al</a> 2008. Int J Biotechnology 10: 113-21.</p>
<p>10) <a href="http://www.greenpeace.org/australia/en/what-we-do/Food/resources/reports/Herbicide-tolerance-and-GM-crops/">Riley, P. et al</a>. 2011. Herbicide Tolerance and GM Crops.</p>
<p>11) <a href="http://www.esajournals.org/doi/abs/10.1890/04-1291">Relyea, Rick A.</a>. 2005. Ecological Applications 15:1118–1124</p>
<p>12) <a href="http://www.sciencedirect.com/science?_ob=MiamiImageURL&_cid=271285&_user=559483&_pii=S1161030109000641&_check=y&_origin=gateway&_coverDate=31-Oct-2009&view=c&wchp=dGLbVlB-zSkzk&md5=ce608b193c4aac9307805ee031911485/1-s2.0-S1161030109000641-main.pdf">Kremer, R.J. and Means, N.E.</a>. 2009. European Journal of Agronomy 31: 153-161.</p>
<p>13) <a href="http://www.anao.gov.au/%7E/media/Uploads/Documents/2010%202011_audit_report_no15.pdf">ANAO</a>. 2010. Food Standards Australia New Zealand.</p>
<p>14) <a href="http://pubs.acs.org/doi/abs/10.1021/jf050594v">Prescott, Vanessa E. et al</a>. 2005. J. Agric. Food Chem. 53: 9023–9030.</p>
<p>15) <a href="http://www.newscientist.com/article/mg18825273.400-editorial-no-genetically-modified-peas-please.html">Editorial</a>. 2005. New Scientist 2527.</p>
<p><em>Greenpeace campaigns to prevent the deliberate release of genetically modified (GM) or genetically engineered (GE) organisms into the environment. GM organisms (plants, animals, micro-organisms) are living organisms that can multiply and cross-breed and pose a threat of irreversible damage to biodiversity and ecosystems. The safety, long term, of GM food for humans and feed for animals is unknown.</em></p>
<p><em>Dr Cotter is visiting Australia from October 16-26 to highlight concerns over the safety of GM wheat.</em></p><img src="https://counter.theconversation.com/content/3610/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Janet Cotter is a senior scientist at the Greenpeace International Science Unit, based at the University of Exeter UK, supporting Greenpeace's campaigns on forests and agriculture.</span></em></p>The Conversation recently published an article looking at the myths about genetic modification. This article is a rejoinder to that piece, and a contribution to the ongoing debate about whether there is…Janet Cotter, Honorary Research Fellow, University of ExeterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/31472011-09-21T04:24:15Z2011-09-21T04:24:15ZWill superbugs overwhelm insect-resistant GM crops?<figure><img src="https://images.theconversation.com/files/3764/original/Cotton_Bollworm_AAP_Image_University_of_Melbourne.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">GM crops are used in Australia to thwart pests such as the Cotton Bollworm (which also destroys corn).</span> <span class="attribution"><span class="source">AAP/University of Melbourne</span></span></figcaption></figure><p>A recent <a href="http://www.commondreams.org/headline/2011/08/29-4">report</a> in the Wall Street Journal spoke of rootworms in the US state of Iowa that had evolved resistance to a strain of genetically modified (GM) corn developed especially to thwart those rootworms.</p>
<p><a href="http://www.foodrepublic.com/2011/09/01/monsanto-corn-under-attack-superbugs">Some media coverage</a> at the time suggested the resistance could lead to the evolution of “superbugs” and expressed concern about GM food more generally.</p>
<p>But just how common is the evolution of resistance to GM crops? And how justified are concerns about the use of GM food crops more generally?</p>
<p>First, it’s worth noting that in 2010, more than 10% of the world’s arable land was sowed with genetically modified (GM) crops.</p>
<p>In fact, GM crops are one of the most rapidly adopted agricultural technologies in history, with <a href="http://www.isaaa.org/resources/publications/briefs/42/executivesummary/default.asp">more than 1 billion hectares</a> planted since 1996.</p>
<p>GM crops have reduced the use of pesticides by at least 352 million kilograms since 1996, reducing the environmental impact of agriculture by 16%, <a href="http://www.agbioforum.org/v13n1/v13n1a06-brookes.htm">compared with conventional production methods</a>.</p>
<p>In this way, the development of GM crops has been beneficial, well beyond its <a href="http://theconversation.com/csiro-gm-essential-for-health-and-food-security-3080">health and food security benefits</a>.</p>
<h2>Pest protection</h2>
<p>GM insect tolerance is created by enhancing crops with genes taken (and then modified) from a bacterium called <em>Bacillus thuringiensis</em>. Crops modified in this way are typically referred to as “Bt crops”.</p>
<p>Bt crops are very specific in their ability to target pest species and, compared with traditional insecticides, have minimal impact on species they don’t target.</p>
<p>But as was true even before GM crops, farmers have had to deal with agronomic issues, including slowing (or attempting to prevent) the <a href="http://grapes.msu.edu/pesticideResist.htm">evolution of resistance</a> in pests. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/3759/original/diamondback_moth_servitude.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/3759/original/diamondback_moth_servitude.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/3759/original/diamondback_moth_servitude.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/3759/original/diamondback_moth_servitude.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/3759/original/diamondback_moth_servitude.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/3759/original/diamondback_moth_servitude.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/3759/original/diamondback_moth_servitude.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The diamondback moth.</span>
<span class="attribution"><span class="source">servitude/Flickr</span></span>
</figcaption>
</figure>
<p>So far, resistance to Bt proteins has been relatively modest. This is in sharp contrast to chemical insecticides, for which <a href="http://www.irac-online.org/about/resistance/">resistance has typically evolved in five to seven years</a> in most of the targeted pests.</p>
<p>While some species have evolved a resistance to Bt sprays – species such the <a href="http://www.sardi.sa.gov.au/pestsdiseases/horticulture/horticultural_pests/diamondback_moth">diamondback moth</a>, a pest of crucifers such as cabbage – there have been only three cases of resistance to Bt crops.</p>
<p>In all three cases, the resistance evolved in caterpillars: </p>
<ul>
<li><p>the <a href="http://www.eppo.org/QUARANTINE/insects/Spodoptera_frugiperda/LAPHFR_images.htm">armyworm</a> (<em>Spodoptera frugiperda</em>) which <a href="http://www.nature.com/nbt/journal/v26/n10/full/nbt1008-1072.html">evolved a resistance to Bt corn in Puerto Rico</a></p></li>
<li><p>the maize stalk borer (<em>Busseola fusca</em>), which <a href="http://www.sciencedirect.com/science/article/pii/S0261219409000921">evolved a resistance to Bt corn in South Africa</a></p></li>
<li><p>and more recently, the pink bollworm (<em>Pectinophora gossypiella</em>) which <a href="http://indiatoday.intoday.in/story/Bt+cotton+has+failed+admits+Monsanto/1/86939.html">evolved a resistance to Bt cotton in some areas of India</a>.</p></li>
</ul>
<p>In all of these cases, the primary drivers of resistance were:</p>
<ul>
<li><p>a relative insensitivity to the Bt protein (the GM-insecticide), and</p></li>
<li><p>the lack of “refuges” – small crop areas that were not GM. Refuges ensure that Bt-susceptible insects can continue to reproduce and dilute any resistance that might evolve in other insects.</p></li>
</ul>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/KaTr2BUCKSY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bt-resistance was discovered in corn rootworms in Illinois as well.</span></figcaption>
</figure>
<p>It’s not too surprising that resistance evolved in the large areas planted by thousands of small landholders in South Africa (2 million hectares of Bt corn), or millions of farmers in India (9 million hectares of Bt cotton). Among small landholders, it is very difficult to organise refuges.</p>
<h2>Two Bt genes are better than one </h2>
<p>In Australia and the US, two different Bt genes are often used in each GM plant to thwart bugs with a low sensitivity to GM insecticides (such as cotton bollworms and corn earworms). The rationale being: if one Bt protein doesn’t get them, the combination will.</p>
<p>In the case of Iowa’s Bt-resistant corn rootworms, the bugs <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146474/">evolved resistance</a> to plants containing one particular Bt toxin, but not to plants that contained a separate toxin type.</p>
<p>Corn rootworms are quite a devastating pest to corn, and have a history of evolving resistance, not only to insecticides, but even to <a href="http://www.abc.net.au/gardening/vegieguide/crop_rotation.htm">crop rotation</a>.</p>
<p>Traditionally, corn is rotated with soybeans (which rootworms don’t eat) but rootworms have evolved the ability to survive the soy year and come back to attack corn. </p>
<p>So how did the rootworms evolve resistance? For a start, they aren’t very sensitive to the unique Bt proteins used to try and kill them. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/3763/original/Joseph_Spencer_INHS.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/3763/original/Joseph_Spencer_INHS.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=732&fit=crop&dpr=1 600w, https://images.theconversation.com/files/3763/original/Joseph_Spencer_INHS.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=732&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/3763/original/Joseph_Spencer_INHS.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=732&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/3763/original/Joseph_Spencer_INHS.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=920&fit=crop&dpr=1 754w, https://images.theconversation.com/files/3763/original/Joseph_Spencer_INHS.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=920&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/3763/original/Joseph_Spencer_INHS.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=920&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The corn rootworm beetle.</span>
<span class="attribution"><span class="source">Joseph Spencer/INHS</span></span>
</figcaption>
</figure>
<p>For resistance to evolve to corn expressing only the one toxin is not a great surprise – recall that two different Bt toxins are often used in the one plant.</p>
<p>But in the paddocks of Iowa (and Illinois, see video above) in which resistance evolved in rootworms, the risk had to be taken. There was an urgent need to reduce the use of soil insecticides for rootworm control, especially in areas where crop rotation was failing.</p>
<p>It was a gamble that, ultimately, didn’t pay off.</p>
<p>Dealing with resistance in weeds and insects has been a problem for farmers globally for at least 40 years. Indeed, it will continue to be a challenge for farmers into the foreseeable future.</p>
<p>The greater challenge is in assisting farmers in developing countries (such as South Africa, China, India, Pakistan and Burkina Faso) with <em>their</em> Bt crops.</p>
<p>If we can help keep the bugs (and “superbugs”) away from crops in developing countries, it will make the fight for global <a href="https://theconversation.com/topics/food-security">food security</a> that little bit easier.</p><img src="https://counter.theconversation.com/content/3147/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rick Roush has advised the US Environmental Protection Agency (EPA) on resistancemanagement issues twice in the last three years, including for corn rootworms. The US EPA requires a formal disclosure process, which Rick has passed. Rick does not work for, consult for, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.</span></em></p>A recent report in the Wall Street Journal spoke of rootworms in the US state of Iowa that had evolved resistance to a strain of genetically modified (GM) corn developed especially to thwart those rootworms…Richard Roush, Professor; Dean, Melbourne School of Land and Environment, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.