When the average hides the risk of Bt-corn pollen on non-target Lepidoptera: Application to Aglais io in Catalonia

Field cultivation of Genetically Modified (GM) Bt-plants has a potential environmental risk toward non-target Lepidoptera (NTLs) larvae through the consumption of Bt-maize pollen. The Bt-maize Cry protein targeting Lepidoptera species detrimental to the crop is also expressed in pollen which is dispersed by wind and can thus reach habitats of NTLs. To better assess the current ecological risk of Bt-maize at landscape scales, we developed a spatially-explicit exposure-hazard model considering (i) the dynamics of pollen dispersal obtained by convolving GM plants emission with a dispersal kernel and (ii) a toxicokinetic-toxicodynamic (TKTD) model accounting for the impact of toxin ingestion on individual lethal effects. We simulated the model using real landscape observations in Catalonia (Spain): GM-maize locations, flowering dates, rainfall time series and larvae emergence date of the European peacock butterfly Aglais io. While in average, the additional mortality appears to be negligible, we show significant additional mortality at sub-population level, with for instance a mortality higher than 40% within the 10m for the 10% most Bt-sensitive individuals. Also, using Pareto optimality we capture the best trade-off between isolation distance and additional mortality: up to 50 m are required to significantly buffer Bt-pollen impact on NTLs survival at the individual level. Our study clears up the narrow line between diverging conclusions: those claiming no risk by only looking at the average regional effect of Bt on NTLs survival and those pointing out a significant threaten when considering the variability of individuals mortality.

Management of Field-Evolved Resistance to Bt Maize in Argentina: A Multi-Institutional Approach

Evolution of resistance to control measures in insect populations is a natural process, and management practices are intended to delay or mitigate resistance when it occurs. During the 2012/13 season the first reports of unexpected damage by Diatraea saccharalis on some Bt maize hybrids occurred in the northeast of San Luis province, Argentina. The affected Bt technologies were Herculex I® (HX-TC1507) and VT3PRO® (MON 89034 × MON 88017^*). Event TC1507 expresses Cry1F and event MON 89034 expresses Cry1A.105 and Cry2Ab2, whichr are all Bt proteins with activity against the lepidopterans D. saccharalis and Spodoptera frugiperda (MON 88017 expresses the protein Cry3Bb1 for control of coleopteran insects and the enzyme CP4EPSPS for glyphosate tolerance). The affected area is an isolated region surrounded by sierra systems to the northeast and west, with a hot semi-arid climate, long frost-free period, warm winters, hot dry summers, and woody shrubs as native flora. To manage and mitigate the development of resistance, joint actions were taken by the industry, growers and Governmental Agencies. Hybrids expressing Vip3A protein (event MIR162) and/or Cry1Ab protein (events MON 810 and Bt11) as single or stacked events are used in early plantings to control the first generations of D. saccharalis, and in later plantings date's technologies with good control of S. frugiperda. A commitment was made to plant the refuge, and pest damage is monitored. As a result, maize production in the area is sustainable and profitable with yields above the average.

Metagenomic analyses of bacterial endophytes associated with the phyllosphere of a Bt maize cultivar and its isogenic parental line from South Africa

Genetic modification of maize with Bacillus thuringiensis (Bt) cry proteins may predispose shifts in the bacterial endophytes' community associated with maize shoots. In this study, the diversity of bacterial endophytes associated with a Bt maize genotype (Mon810) and its isogenic non-transgenic parental line were investigated at pre-flowering (50 days) and post-flowering (90 days) developmental stages. PCR-DGGE and high throughput sequencing on the Illumina MiSeq sequencer were used to characterize bacterial 16S rRNA gene diversity in leaves, stems, seeds and tassels. PCR-DGGE profile revealed similarity as well as differences between bacterial communities of shoots in both cultivars and at both developmental stages. A total of 1771 operational taxonomic units (OTUs) were obtained from the MiSeq and assigned into 14 phyla, 27 classes, 58 orders, 116 families and 247 genera. Differences in alpha and beta diversity measures of OTUs between the phyllospheres of both genotypes were not significant (P > .05) at all developmental stages. In all cultivars, OTU diversity reduced with plant development. OTUs belonging to the phyla Proteobacteria were dominant in all maize phyllospheres. The class Gammaproteobacteria was dominant in Bt maize while, Alphaproteobacteria and Actinobacteria were dominant in non-Bt maize phyllospheres. Differences in the abundance of some genera, including Acidovorax, Burkerholderia, Brachybacterium, Enterobacter and Rhodococcus, whose species are known beneficial endophytes were observed between cultivars. Hierarchical cluster analysis further suggests that the bacterial endophyte communities of both maize genotypes associate differently (are dissimilar). Overall, the results suggest that bacterial endophytes community differed more across developmental stages than between maize genotypes.

Resistance of Bt-maize (MON810) against the stem borers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) and its yield performance in Kenya

A study was conducted to assess the performance of maize hybrids with Bt event MON810 (Bt-hybrids) against the maize stem borer Busseola fusca (Fuller) in a biosafety greenhouse (BGH) and against the spotted stem borer Chilo partellus (Swinhoe) under confined field trials (CFT) in Kenya for three seasons during 2013-2014. The study comprised 14 non-commercialized hybrids (seven pairs of near-isogenic Bt and non-Bt hybrids) and four non-Bt commercial hybrids. Each plant was artificially infested twice with 10 first instar larvae. In CFT, plants were infested with C. partellus 14 and 24 days after planting; in BGH, plants were infested with B. fusca 21 and 31 days after planting. In CFT, the seven Bt hybrids significantly differed from their non-Bt counterparts for leaf damage, number of exit holes, percent tunnel length, and grain yield. When averaged over three seasons, Bt-hybrids gave the highest grain yield (9.7 t ha-1), followed by non-Bt hybrids (6.9 t ha-1) and commercial checks (6 t ha-1). Bt-hybrids had the least number of exit holes and percent tunnel length in all the seasons as compared to the non-Bt hybrids and commercial checks. In BGH trials, Bt-hybrids consistently suffered less leaf damage than their non-Bt near isolines. The study demonstrated that MON810 was effective in controlling B. fusca and C. partellus. Bt-maize, therefore, has great potential to reduce the risk of maize grain losses in Africa due to stem borers, and will enable the smallholder farmers to produce high-quality grain with increased yield, reduced insecticide inputs, and improved food security.

Multilevel assessment of Cry1Ab Bt-maize straw return affecting the earthworm Eisenia fetida

Non-target effects of two varieties of Bacillus thuringiensis (Bt)-maize straw (5422Bt1 [event Bt11] and 5422CBCL [MON810]) return on the Eisenia fetida were investigated by using multilevel assessments, compared to near-isogenic non-Bt-maize (5422). 5422Bt1 straw return had no deleterious effects on adult earthworms and had significantly positive effects on juveniles over three generations. Negative, no, and positive effects on adults treated with 5422CBCL straw were observed in the 1st, 2nd and 3rd generation, respectively. Negative and positive effects were observed on juveniles produced from the 1st- and 2nd-generation adults treated with 5422CBCL straw, respectively. Glutathione peroxidase activity of earthworms from Bt-maize treatments was significantly higher than that of control on the 90th d. Translationally controlled tumour protein (TCTP) and superoxide dismutase (SOD) genes were down-regulated, while annetocin (ANN) expression was up-regulated in 5422Bt1 treatments. TCTP and SOD genes were up-regulated, while ANN and heat shock protein 70 were down-regulated in E. fetida from 5422CBCL treatments. Enzyme-linked immunosorbent assay revealed that Cry1Ab released from 5422Bt1 and 5422CBCL straw degraded rapidly on the 15th and 30th d and had a slow decline in the rest testing time. Cry1Ab concentrations in the soil, casts and guts of earthworm significantly decreased over the course of the experiment. This study was the first to evaluate generational effects of Bt-maize straw return on earthworms under laboratory conditions. The responses of enzymes activity and genes expression may contribute to better understand above different effects of Bt-maize straw return on earthworms from the 1st generation.

Small-scale microcosms to detect chemical induced changes in soil nematode communities--effects of crystal proteins and Bt-maize plant material

Small-scale laboratory microcosms (30 g soil in 50 ml tubes) were evaluated for their suitability to assess the impact of chemicals on in situ soil nematode communities. For this purpose, appropriate conditions in the microcosms were explored to ensure stable conditions and a homogenous distribution of the nematodes. Then, the microcosms were used to assess the toxicity of insecticidal crystal proteins (Cry1A.105, Cry2Ab2, Cry3Bb1) present in genetically modified maize (MON89034×MON88017) on in situ nematode communities. Highly abundant and genus rich nematode communities could be maintained over a period of 12 weeks. Due to a low variance between the replicates of the treatments, low detection limits could be achieved. Using meaningful stress indices, such as the maturity indices, the microcosm study revealed dose-dependent effects of the insecticidal Cry proteins that could be verified as toxic effects by comparing with effects of two positive controls (Cu, nematicidal Cry5B). Moreover, toxic effects could be differentiated from organic enrichment effects that were induced by the addition of plant material. With a NOECCommunity of 0.1 mg kg(-1) dry wt, the nematode communities reacted considerably more sensitive to the Cry proteins than a single-species nematode toxicity test (NOEC: 29 mg l(-1)). The small-scale microcosm set-up turned out to be a suitable, low-budget tool for assessing the toxicity of chemicals on soil nematodes on community level, representing a link between single-species toxicity tests and large scale outdoor mesocosms.

How can flexibility be integrated into coexistence regulations? A review

Member states in the European Union (EU) implemented both ex ante coexistence regulations and ex post liability schemes to ensure that genetically modified (GM) and non-GM crops can be cultivated side by side without excluding any agricultural option. Although proportionate coexistence is best achieved if regulated in a flexible manner, most implemented coexistence regulations merely rely on rigid measures. Flexible coexistence regulations, however, would reduce the regulatory burden on certain agricultural options and avoid jeopardizing economic incentives for coexistence. Flexibility can be integrated at: (i) the regulatory level by relaxing the rigidity of coexistence measures in ex ante regulations, yet without offsetting incentives to implement coexistence measures; (ii) the farm level by recommending the use of pollen barriers instead of large and fixed isolation distances; and (iii) the national/regional level by allowing diversified coexistence measures, which are adapted to the heterogeneity of farming in the EU. Owing to difficulties of implementation, the adoption of flexible and proportionate coexistence regulations will inevitably entail challenges.

Effects of Consumption of Bt-maize (MON 810) on the Collembolan Folsomia candida, Over Multiple Generations: A Laboratory Study

The effect of long-term feeding on Bt-maize by collembolans in the laboratory is virtually unestablished. That is why the aim of the present study was to test whether the reproduction, fecal pellet production or food preference of the collembolan F. candida is affected when fed on Bt-maize for several consecutive generations. The collembolans were fed with Bt-maize for 0, 6, 16 and 22 months and the number of eggs and fecal pellets were determined. The experiment was repeated seven months later with the same populations. Food preference tests were additionally performed. Significant differences were found in food consumption, egg production and food preference between populations in some cases, but no time-response effect was observed. In conclusion, several generations feeding of F. candida on Cry1Ab toxin containing Bt-maize seems not to be harmful to this collembolan species.