Global Adoption of Genetically Modified (GM) Crops: Challenges for the Public Sector

Advances in biotechnology continue to drive the development of a wide range of insect-protected, herbicide-tolerant, stress-tolerant, and nutritionally enhanced genetically modified (GM) crops, yet societal and public policy considerations may slow their commercialization. Such restrictions may disproportionately affect developing countries, as well as smaller entrepreneurial and public sector initiatives. The 2014 IUPAC International Congress of Pesticide Chemistry (San Francisco, CA, USA; August 2014) included a symposium on “Challenges Associated with Global Adoption of Agricultural Biotechnology” to review current obstacles in promoting GM crops. Challenges identified by symposium presenters included (i) poor public understanding of GM technology and the need for enhanced communication strategies, (ii) nonharmonized and prescriptive regulatory requirements, and (iii) limited experience with regulations and product development within some public sector programs. The need for holistic resistance management programs to enable the most effective use of insect-protected crops was also a point of emphasis. This paper provides details on the symposium discussion and provides background information that can be used in support of further adoption of beneficial GM crops. Overall, it emphasizes that global adoption of modern agricultural biotechnology has not only provided benefits to growers and consumers but has great potential to provide solutions to an increasing global population and diminishing agricultural land. This potential will be realized by continued scientific innovation, harmonized regulatory systems, and broader communication of the benefits of the high-yielding, disease-resistant, and nutritionally enhanced crops attainable through modern biotechnology

Deriving criteria to select arthropod species for laboratory tests to assess the ecological risks from cultivating arthropod-resistant genetically engineered crops

Arthropods form a major part of the biodiversity in agricultural landscapes. Many species are valued because they provide ecosystem services, including biological control, pollination and decomposition, or because they are of conservation interest. Some arthropods reduce crop yield and quality, and conventional chemical pesticides, biological control agents and genetically engineered (GE) crops are used to control them. A common concern addressed in the ecological risk assessment (ERA) that precedes regulatory approval of these pest control methods is their potential to adversely affect valued non-target arthropods (NTAs). A key concept of ERA is early-tier testing using worst-case exposure conditions in the laboratory and surrogate test species that are most likely to reveal an adverse effect. If no adverse effects are observed in those species at high exposures, confidence of negligible ecological risk from the use of the pest control method is increased. From experience with chemical pesticides and biological control agents, an approach is proposed for selecting test species for early-tier ERA of GE arthropod-resistant crops. Surrogate species should be selected that most closely meet three criteria: (i) Potential sensitivity: species should be the most likely to be sensitive to the arthropod-active compound based on the known spectrum of activity of the active ingredient, its mode of action, and the phylogenetic relatedness of the test and target species; (ii) Relevance: species should be representative of valued taxa or functional groups that are most likely to be exposed to the arthropod-active compound in the field; and (iii) Availability and reliability: suitable life-stages of the test species must be obtainable in sufficient quantity and quality, and validated test protocols must be available that allow consistent detection of adverse effects on ecologically relevant parameters. Our proposed approach ensures that the most suitable species are selected for testing and that the resulting data provide the most rigorous test of the risk hypothesis of no adverse effect in order to increase the quality and efficiency of ERAs for cultivation of GE crops

A Meta-Analysis of Effects of Bt Crops on Honey Bees (Hymenoptera: Apidae)

L.) are the most important pollinators of many agricultural crops worldwide and are a key test species used in the tiered safety assessment of genetically engineered insect-resistant crops. There is concern that widespread planting of these transgenic crops could harm honey bee populations.We conducted a meta-analysis of 25 studies that independently assessed potential effects of Bt Cry proteins on honey bee survival (or mortality). Our results show that Bt Cry proteins used in genetically modified crops commercialized for control of lepidopteran and coleopteran pests do not negatively affect the survival of either honey bee larvae or adults in laboratory settings.Although the additional stresses that honey bees face in the field could, in principle, modify their susceptibility to Cry proteins or lead to indirect effects, our findings support safety assessments that have not detected any direct negative effects of Bt crops for this vital insect pollinator

Assessment of risk of insect-resistant transgenic crops to nontarget arthropods

An international initiative is developing a scientifically rigorous approach to evaluate the potential risks to nontarget arthropods (NTAs) posed by insect-resistant, genetically modified (IRGM) crops. It adapts the tiered approach to risk assessment that is used internationally within regulatory toxicology and environmental sciences. The approach focuses on the formulation and testing of clearly stated risk hypotheses, making maximum use of available data and using formal decision guidelines to progress between testing stages (or tiers). It is intended to provide guidance to regulatory agencies that are currently developing their own NTA risk assessment guidelines for IRGM crops and to help harmonize regulatory requirements between different countries and different regions of the world

Recommendations for the design of laboratory studies on non-target arthropods for risk assessment of genetically engineered plants

This paper provides recommendations on experimental design for early-tier laboratory studies used in risk assessments to evaluate potential adverse impacts of arthropod-resistant genetically engineered (GE) plants on non-target arthropods (NTAs). While we rely heavily on the currently used proteins from Bacillus thuringiensis (Bt) in this discussion, the concepts apply to other arthropod-active proteins. A risk may exist if the newly acquired trait of the GE plant has adverse effects on NTAs when they are exposed to the arthropod-active protein. Typically, the risk assessment follows a tiered approach that starts with laboratory studies under worst-case exposure conditions; such studies have a high ability to detect adverse effects on non-target species. Clear guidance on how such data are produced in laboratory studies assists the product developers and risk assessors. The studies should be reproducible and test clearly defined risk hypotheses. These properties contribute to the robustness of, and confidence in, environmental risk assessments for GE plants. Data from NTA studies, collected during the analysis phase of an environmental risk assessment, are critical to the outcome of the assessment and ultimately the decision taken by regulatory authorities on the release of a GE plant. Confidence in the results of early-tier laboratory studies is a precondition for the acceptance of data across regulatory jurisdictions and should encourage agencies to share useful information and thus avoid redundant testing

An assessment of the risk of Bt-cowpea to non-target organisms in West Africa

Cowpea (Vigna unguiculata Walp.) is the most economically important legume crop in arid regions of sub-Saharan Africa. Cowpea is grown primarily by subsistence farmers who consume the leaves, pods and grain on farm or sell grain in local markets. Processed cowpea foods such as akara (a deep-fat fried fritter) are popular in the rapidly expanding urban areas. Demand far exceeds production due, in part, to a variety of insect pests including, in particular, the lepidopteran legume pod borer (LPB) Maruca vitrata. Genetically engineered Bt-cowpea, based on cry1Ab (Event 709) and cry2Ab transgenes, is being developed for use in sub-Saharan Africa to address losses from the LBP. Before environmental release of transgenic cowpeas, the Bt Cry proteins they express need to be assessed for potential effects on non-target organisms, particularly arthropods. Presented here is an assessment of the potential effects of those Cry proteins expressed in cowpea for control of LPB. Based on the history of safe use of Bt proteins, as well as the fauna associated with cultivated and wild cowpea in sub-Saharan Africa results indicate negligible effects on non-target organisms

The Impact of Bt Crops on the Developing World

Genetically modified (GM) plants are grown on more than 67 million hectares in 18 countries worldwide. A major trait used in GM crops is plant resistance to insects; this trait is based on several Bt proteins. The benefits accruing to farmers growing Bt crops are substantial across a number of geographies and economic strata, especially in developing countries. These benefits include increased crop yields, reduced pesticide use, less environmental damage, less fungal contamination, and reduced labor. Constraints to broader use of GM traits in a wider variety of food crops and in a larger range of countries include the lack of regulatory bodies in some countries, access to credit, support institutions such as extension or seed company technical advisors, and public acceptance, especially as it relates to international trade.Includes bibliographical reference

Lectins as plant chemical defenses against insects

To determine the potential of plant lectins as chemical defenses against insects and to broaden our knowledge of the roles plant lectins play in nature, seventeen plant lectins were screened in an artificial seed system using the cowpea weevil, Callosobruchus maculatus, as a model insect. Five caused significant delays in cowpea weevil developmental time. These lectins were classed into one of two groups: lectins with specificity for N-acetylgalactosamine residues (GalNAc), which included osage orange lectin and peanut agglutinin, and lectins with specificity for N-acetylglucosamine residues (GlcNAc), a constituent of chitin. The results suggest that GlcNAc-specific plant lectins represent a class of biologically active proteins effective against the cowpea weevil. The GlcNAc-specific lectins studied were derived from wheat germ (WGA), rice (RL), tomato (TL), Jimson weed (DSA) and stinging nettle (UDA). Among the most active lectins is WGA, the isolectins of which were found to be equally detrimental to the cowpea weevil. To better understand which molecular properties, such as relative binding affinity, binding site number, and molecular size affect GlcNAc-specific lectin toxicity, the five above named lectins were analyzed in an in vivo structure-activity analysis. The relative toxicity of the GlcNAc-specific lectins on a molar basis is WGA$\u3e$RL$\u3e$TL${\u3e\u3e}$UDA${\u3e\u3e\u3e}$DSA. On a binding site basis, the relative order is WGA=TL$\u3e$RL$\u3e$UDA$\u3e$DSA. Toxicity appears to be a function of the number of GlcNAc-binding sites. The GlcNAc-specific lectins appear to be members of the chitin-binding protein family, which is characterized by stable proteins containing extensive disulfide cross linkages. Histological evidence suggests that WGA acts in the midgut to cause pathology. Good correlation exists between lectin dose, lesion intensity, and impact on insect growth and survival. It appears that there exists in cowpea weevil physiological/biochemical systems vulnerable to selected plant lectins. The genes coding for effective plant lectins could, in principle, serve as antibiosis factors to use in plant transformation to confer insect resistance. Previous claims that phytohemagglutinin (PHA) is toxic to the cowpea weevil were not supported in the present investigation. The toxic effects of a commercial PHA preparation are due to an $\alpha$-amylase inhibitor impurity, a lectin-like protein of the common bean lectin gene family