Transportable data from nontarget arthropod field

Authors: Aqeel Ahmad Ignacio Negri Wladecir Oliveira Christopher Brown Peter Asiimwe Bernard Sammons Michael Horak Changjian Jiang David Carson

Publish Date: 2015/10/03

Volume: 25, Issue: 1, Pages: 1-17

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Abstract

As part of an environmental risk assessment the potential impact of genetically modified GM maize MON 87411 on nontarget arthropods NTAs was evaluated in the field MON 87411 confers resistance to corn rootworm CRW Diabrotica spp by expressing an insecticidal doublestranded RNA dsRNA transcript and the Cry3Bb1 protein and tolerance to the herbicide glyphosate by producing the CP4 EPSPS protein Field trials were conducted at 14 sites providing high geographic and environmental diversity within maize production areas from three geographic regions including the US Argentina and Brazil MON 87411 the conventional control and four commercial conventional reference hybrids were evaluated for NTA abundance and damage Twenty arthropod taxa met minimum abundance criteria for valid statistical analysis Nine of these taxa occurred in at least two of the three regions and in at least four sites across regions These nine taxa included aphid predatory earwig lacewing ladybird beetle leafhopper minute pirate bug parasitic wasp sap beetle and spider In addition to wide regional distribution these taxa encompass the ecological functions of herbivores predators and parasitoids in maize agroecosystems Thus the nine arthropods may serve as representative taxa of maize agroecosystems and thereby support that analysis of relevant data generated in one region can be transportable for the risk assessment of the same or similar GM crop products in another region Across the 20 taxa analyzed no statistically significant differences in abundance were detected between MON 87411 and the conventional control for 123 of the 128 individualsite comparisons 961  For the nine widely distributed taxa no statistically significant differences in abundance were detected between MON 87411 and the conventional control Furthermore no statistically significant differences were detected between MON 87411 and the conventional control for 53 out of 56 individualsite comparisons 946  of NTA pest damage to the crop In each case where a significant difference was observed in arthropod abundance or damage the mean value for MON 87411 was within the reference range and/or the difference was not consistently observed across collection methods and/or sites Thus the differences were not representative of an adverse effect unfamiliar to maize and/or were not indicative of a consistent plant response associated with the GM traits Results from this study support a conclusion of no adverse environmental impact of MON 87411 on NTAs compared to conventional maize and demonstrate the utility of relevant transportable data across regions for the ERA of GM cropsPrior to commercialization of a genetically modified GM crop a sciencebased environmental risk assessment ERA is conducted to assess for potential harmful effects on human and animal health and the environment This process has been described in detail by a number of regulatory agencies worldwide eg USDAAPHIS CFR 2008 the US Environmental Protection Agency US EPA 1998 the Canadian Food Inspection Agency CFIA 2012 and the European Union EFSA 2004 For insectprotected GM crops a stepwise tiered testing approach using surrogate species within the framework of problem formulation is recognized as the most appropriate and rigorous approach to assess for potential effects on nontarget organisms in many regulatory frameworks Rose 2006 US EPA 2007 Romeis et al 2008 Wolt et al 2010 In this tiered approach risk a function of hazard and exposure is evaluated within different levels or “tiers” that progress from worstcase exposure scenarios to realworld field scenarios if the earlier tiered tests fail to indicate adequate certainty of acceptable risk Romeis et al 2008 Duan et al 2010In the ERA of GM crops plant characterization studies are also conducted under diverse geographic and environmental conditions to assess potentially adverse effects of the GM crops on its receiving environment relative to an appropriate conventional control that is genetically similar but lacks the introduced trait Raybould 2007 Horak et al 2007 Nickson 2008 Raybould 2010 Wolt et al 2010 Horak et al 2015a b These studies are used by risk assessors and regulators to determine whether cultivation and/or import of a GM crop is acceptable in a particular regionNontarget arthropod NTA field evaluations are conducted when needed as an important part of plant characterization and are utilized in an overall ERA of the GM crop The purpose of these evaluations is to confirm the results of the early tier testing and address any uncertainties in the risk assessment by collecting meaningful data on NTAs that are closely associated with the plant Romeis et al 2006 2008 NTAs are selected based on criteria that they are sufficiently abundant in the crop of interest exhibit low mobility and possess a clear path of exposure eg nontarget herbivores Prasifka et al 2008 Romeis et al 2009 Rauschen et al 2010a b Romeis et al 2013 Results from these evaluations which may be considered higher tier “realworld” assessments aid in the ERA to reduce uncertainty of unintended effects through collection of in planta data While NTA field data for plant characterization may be confirmatory of the tiered approach a key distinction between the environmental interactions assessment and a highertier NTA field study is that the latter is conducted only if results from lowertier laboratory NTA testing fail to indicate acceptable environmental risk for the GM crop productIt is important that risk assessors and regulators have access to and utilize environmental assessment data on the crop and trait that are generated in other relevant geographic regions Roberts et al 2014 GarciaAlonso et al 2014 Horak et al 2015a b The results from welldesigned studies conducted in the field greenhouse or laboratory and used for ecological risk assessments are relevant and transportable to other geographies for the ERA of the same GM crop or related traits or GM crop/trait combinations where the ecological assessment endpoints are similar Leveraging existing relevant data for the ERA of GM crops across regions will conserve resources eliminate redundancy and support conclusions with high certainty for assessing potential environmental risk from the commercial release of a GM cropMonsanto Company has developed GM maize MON 87411 that confers resistance to corn rootworm CRW Diabrotica spp and tolerance to the herbicide glyphosate MON 87411 contains a suppression cassette that expresses an inverted repeat sequence designed to match a partial sequence of the Snf7 gene from western corn rootworm WCR Diabrotica virgifera virgifera The expression of the suppression cassette results in the formation of a double stranded RNA dsRNA transcript containing a 240 bp fragment of the WCR Snf7 gene DvSnf7 Bolognesi et al 2012 Upon consumption the plantproduced dsRNA in MON 87411 is recognized by the CRW’s RNA interference RNAi machinery resulting in downregulation of the targeted DvSnf7 gene leading to CRW mortality Bolognesi et al 2012 MON 87411 also contains a Cry3Bb1 gene that produces a modified Bacillus thuringiensis Bt subsp kumamotoensis Cry3Bb1 protein to protect against CRW larval feeding In lab studies the snf7 ortholog has been shown to have a very specific and narrow spectrum of activity limited to the Galerucinae subfamily of Chrysomelidae Bachman et al 2013 In addition MON 87411 contains the cp4 epsps gene from Agrobacterium sp strain CP4 that encodes for the 5enolpyruvylshikimate3phosphate synthase EPSPS protein which confers tolerance to glyphosate the active ingredient in Roundup® agricultural herbicides MON 87411 builds upon the current Bt proteinbased modeofaction MOA for CRW control by the addition of a new RNAibased MOA that offers enhanced control of target insect pests and prolonged durability of existing Bt technologies designed to control CRWSeveral studies have demonstrated the absence of adverse effects of crops expressing Bt proteins on nontarget arthropods in the lab or field Li and Romeis 2009 2010 2011 Ahmad et al 2005 2006 Bhatti et al 2005a b Naranjo et al 2005 Naranjo 2009 Marvier et al 2007 Duan et al 2008a b Rauschen et al 2010a b Rosca and Cagan 2012a b Comas et al 2014 however no published study has evaluated the effect of an RNAbased trait stacked with Bt proteins on abundance of NTAs in the field This study evaluated the effect of MON 87411 on the abundance of NTAs relative to its conventional control in maize fields in three separate geographic regions the US Argentina and Brazil In addition plant damage from major nontarget pests was evaluated to determine whether MON 87411 had any increased or decreased susceptibility to these pests providing more information on potential harmful effects for the ERA Since the studies are conducted in diverse geographic regions representing a broad range of environmental conditions and agricultural ecosystems and given the similarity of the endpoints being assessed these results could be ‘‘transportable’’ to other countries This paper also provides data supporting the concept of data transportability where results on NTA data with proper justification can be leveraged across regions to support ERA

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