DNA Barcoding Simplifies Environmental Risk Assessment of Genetically Modified Crops in Biodiverse Regions

Transgenes encoding for insecticidal crystal (Cry) proteins from the soil-dwelling bacterium Bacillus Thuringiensis have been widely introduced into Genetically Modified (GM) crops to confer protection against insect pests. Concern that these transgenes may also harm beneficial or otherwise valued insects (so-called Non Target Organisms, NTOs) represents a major element of the Environmental Risk Assessments (ERAs) used by all countries prior to commercial release. Compiling a comprehensive list of potentially susceptible NTOs is therefore a necessary part of an ERA for any Cry toxin-containing GM crop. In partly-characterised and biodiverse countries, NTO identification is slowed by the need for taxonomic expertise and time to enable morphological identifications. This limitation represents a potentially serious barrier to timely adoption of GM technology in some developing countries. We consider Bt Cry1A cowpea (Vigna unguiculata) in Nigeria as an exemplar to demonstrate how COI barcoding can provide a simple and cost-effective means of addressing this problem. Over a period of eight weeks, we collected 163 insects from cowpea flowers across the agroecological and geographic range of the crop in Nigeria. These individuals included 32 Operational Taxonomic Units (OTUs) spanning four Orders and that could mostly be assigned to genus or species level. They included 12 Lepidopterans and two Coleopterans (both potentially sensitive to different groups of Cry proteins). Thus, barcode-assisted diagnoses were highly harmonised across groups (typically to genus or species level) and so were insensitive to expertise or knowledge gaps. Decisively, the entire study was completed within four months at a cost of less than 10,000 US$. The broader implications of the findings for food security and the capacity for safe adoption of GM technology are briefly explored

Outcome of a workshop

International audience; In tackling agricultural challenges, policy-makers in sub-Saharan Africa (SSA) have increasingly considered genetically modified (GM) crops as a potential tool to increase productivity and to improve product quality. Yet, as elsewhere in the world, the adoption of GM crops in SSA has been marked by controversy, encompassing not only the potential risks to animal and human health, and to the environment, but also other concerns such as ethical issues, public participation in decision-making, socio-economic factors and intellectual property rights. With these non-scientific factors complicating an already controversial situation, disseminating credible information to the public as well as facilitating stakeholder input into decision-making is essential. In SSA, there are various and innovative risk communication approaches and strategies being developed, yet a comprehensive analysis of such data is missing. This gap is addressed by giving an overview of current strategies, identifying similarities and differences between various country and institutional approaches and promoting a way forward, building on a recent workshop with risk communicators working in SSA

Cuckoo leaf-cutter bee clade collected from cowpea flowers in Nigeria.

<p>Neighbour Joining tree representing COI barcodes for individuals clustering in the <i>Coelioxys</i> clade. The tree is based on Kimura two-parameter distances (K2P). The five OTUs (presumed species) of <i>Coelioxys</i> collected in Nigeria are highlighted. Individuals specified using site code and sample number (e.g. MA-1 was collected MA: Mbano site A and 1 is the sample ID) see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035929#pone.0035929.s002" target="_blank">Table S1</a> for site code. Reference sequences have been downloaded from ncbi and CBOL and they indicate species name plus entry ID.</p

Insects in the Lepidoptera clade collected from cowpea flowers in Nigeria.

<p>Neighbour Joining tree representing COI barcodes for Lepidoptera showing clear separation according to genus and species. The tree is based on Kimura two-parameter distances (K2P). The samples collected in Nigeria are highlighted and specified using site code and samples number (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035929#pone.0035929.s002" target="_blank">Table S1</a>). Reference sequences have been downloaded from ncbi and CBOL.</p

Carpenter bee (<i>Xylocopa</i>) clade collected from cowpea flowers in Nigeria.

<p>Neighbour Joining tree representing COI barcodes for <i>Xylocopa</i> clade showing separation into 5 distinct OTUs (presumed species). The tree is based on Kimura two-parameter distances (K2P). The five species of <i>Xylocopa</i> collected in Nigeria are highlighted and samples specified using site code and sample number (e.g. MA-1 was collected MA: Mbano site A and 1 is the sample ID) see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035929#pone.0035929.s002" target="_blank">Table S1</a> for site code. Reference sequences have been downloaded from ncbi and CBOL and they indicate species name plus entry ID.</p

Insects in the Diptera clade collected from cowpea flowers in Nigeria.

<p>Neighbour Joining tree representing COI barcodes for Diptera showing species separation. The tree is based on Kimura two-parameter distances (K2P). The four species collected in Nigeria are highlighted and samples specified using site code and samples number (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035929#pone.0035929.s002" target="_blank">Table S1</a>). Reference sequences have been downloaded from ncbi and CBOL and they indicate species name plus entry ID.</p

Insect diversity on cowpea flowers.

<p>Neighbour Joining tree representing COI barcodes for all species collected in the 7 different cowpea fields against barcode references downloaded from ncbi and CBOL. The tree has been build based on Kimura two-parameter distances (K2P) and 1000 bootstrap replications.</p

Honey bee clade collected from cowpea flowers in Nigeria.

<p>Neighbour Joining tree representing COI barcodes for <i>Apis mellifera</i> showing no clear separation between subspecies. The tree has been build based on Kimura two-parameter distances (K2P). The samples collected in Nigeria are specified using site code and samples number (e.g. MA-1 was collected MA: Mbano site A and 1 is the sample ID) see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035929#pone.0035929.s002" target="_blank">Table S1</a> for site code. Reference sequences have been downloaded from ncbi and CBOL and they indicate species name plus entry ID.</p

Experiences in sub-Saharan Africa with GM crop risk communication

International audience; In tackling agricultural challenges, policy-makers in sub-Saharan Africa (SSA) have increasingly considered genetically modified (GM) crops as a potential tool to increase productivity and to improve product quality. Yet, as elsewhere in the world, the adoption of GM crops in SSA has been marked by controversy, encompassing not only the potential risks to animal and human health, and to the environment, but also other concerns such as ethical issues, public participation in decision-making, socio-economic factors and intellectual property rights. With these non-scientific factors complicating an already controversial situation, disseminating credible information to the public as well as facilitating stakeholder input into decision-making is essential. In SSA, there are various and innovative risk communication approaches and strategies being developed, yet a comprehensive analysis of such data is missing. This gap is addressed by giving an overview of current strategies, identifying similarities and differences between various country and institutional approaches and promoting a way forward, building on a recent workshop with risk communicators working in SSA