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IOBC-WPRS Bulletin Vol. 73, 2012


IOBC-WPRS Bulletin Vol. 73, 2012

Working Group "GMOs in Integrated Plant Production".
Proceedings of the fifth meeting on Ecological Impact of Genetically Modified Organisms (EIGMO) at České Budějovice (Czech Republic), 22 - 25 June, 2011.
Editors: Jörg Romeis, Michael Meissle & Fernando Álvarez-Alfageme.
ISBN 978-92-9067-250-0 [XII + 134 pp.]


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Field trials to assess risks of transgenic crops for non-target arthropods:
Power analysis and surrogate arthropods in Spain

Ramon Albajes, Belén Lumbierres, Filipe Madeira, Xavier Pons

Abstract: Though genetically modified (GM) crops have been rapidly adopted in world
agriculture, concern has been expressed about the environmental risks that they may involve. In
order to identify and measure the effects on NTOs (non-target organisms) of transgenic traits of
crops such as Bt corn, which has been designed to kill target species, a tiered approach has been
proposed. When an effect is detected in laboratory or semi-field steps, it is measured in
subsequent higher-tier steps with an increasing complexity and realism in field conditions. In
some cases this sequential testing scheme is not applicable because potential effects are not
measurable in simple laboratory conditions and the testing procedure has to be initiated with field
trials. This is the case, for example, when indirect effects are expressed through the food web or
when the main expected effect is a consequence of changes in agricultural technology. However,
field trials have many disadvantages and, whenever possible, should be conducted after basic
data have been obtained in lower steps. After 13 years conducting field trials of Bt and herbicidetolerant
maize in Spain, the authors review the results to discuss how trials aimed at measuring
the effects of GM crops on NTOs can be improved. Two main aspects are considered: (i)
statistical power, that is, the probability of a null hypothesis (no differences between a transgenic
variety and a non-transgenic comparator in the effects on an NTO) being rejected when it is not
true; (ii) species or species assemblages that may be used as surrogates for testing effects on
NTOs in the field according to the power for each one, calculated in a number of field trials
selected among those conducted in the last years. In the selection it was attempted to combine the
maximum variation in trial characteristics: multiyear vs. one-year trials, few varieties vs. many
varieties, single vs. stacked transgenic traits, and finally plot size. Results are discussed in order
to make recommendations on selecting those surrogates with a power above 0.7 to detect 50% or
25% differences between the GM variety and a non-GM comparator. A classification of
suitability of non-target arthropods as surrogates for ERA trials according to the number of
replications required to reach at least 0.7 power is proposed.


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Novel approaches in genetic engineering in relation to the current regulatory frameworks
Ervin Balázs, Ákos Gellért

Abstract: Enormous research efforts and huge amount of funds have supported for more than a
decade the studies of potential ecological risks of genetically modified organisms all over the
World, especially in Europe. This vast amount of effort on this type of research with the first
generation of transgenic crops, currently grown over 148 million hectares in the World, have
revealed that cultivation of those crops have no negative impact on the environment that exceeds
that of conventional agricultural practices. Today, new and more elaborated alternative methods
are available for plant and microbial breeding, and their products will sooner or later be
submitted for commercialization. These new methods differ substantially from the classical
approaches of genetic engineering. Thus the definition of GMO has to be revisited since some of
the products derived may not need to be regarded as GM and thus not assessed based on the
GMO regulation.


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Genetically ‘sterile’ insects in pest control programmes for public health and agriculture:
Current status and future prospects

Camilla J. Beech

Abstract: New tools are urgently needed to help control insect pests of economic importance in
the fields of both agriculture and human health. Building on the well understood Sterile Insect
Technique (SIT), which has been used successfully for agricultural insect pest control for over 50
years, recent advances in insect genetic engineering can now provide novel solutions for effective
pest control in both agriculture and public health. SIT uses repeated releases of sterile male
insects to mate with a target female population but no progeny survive from these matings,
thereby causing the population of the wild insects to decline, hopefully to either below an
economic or disease transmission threshold or to local elimination.
Oxitec Ltd, a British SME is pioneering the use of genetic sterility in insect species and has
developed strains of insects that express dominant lethal genes and are genetically “sterile”,
unless supplied with a repressor molecule in the diet. Insect strains have been developed for use
in public health (Aedes aegypti and Aedes albopictus) and agricultural pest control programmes
(Pectinophora gossypiella, Plutella xylostella, and the Tephritid fruit flies Bactrocera oleae,
Ceratitis capitata, and Anastrepha ludens). Future projects include extending the techniques to
tomato leaf miner (Tuta absoluta) and the Anopheline mosquito malaria vectors.
The phased testing of GM insects is on-going with several insect strains tested by
independent collaborators in a variety of conditions, ranging from the laboratory, semi-field tests
and open field releases. The regulatory pathway for these insects will be described, along with
need for context specific community engagement. Consideration will also be given as to how
these “sterile” insect strains might be used in an Integrated Vector Management (IVM) or
Integrated Pest management (IPM) system.


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Are concerns about feral genetically modified herbicide tolerant oilseed
resulting from seed import spills scientifically justified?

Yann Devos, Rosemary S. Hails, Antoine Messéan, Joe N. Perry, Geoffrey R. Squire

Abstract: One of the concerns surrounding the import (for food and feed uses or processing) of
genetically modified herbicide tolerant oilseed rape (GMHT OSR) is that, through seed spillage,
the herbicide tolerance (HT) trait will escape into agricultural or semi-natural habitats, causing
environmental or economic problems. Whether the concerns posed by feral GMHT OSR from
seed import spills are scientifically justified is debatable. While OSR has characteristics such as
secondary dormancy and small seed size that enable it to persist and be redistributed in the
landscape, the presence of ferals is not in itself an environmental or economic problem.
Crucially, feral OSR has not become invasive outside cultivated and ruderal habitats, and HT
traits are not likely to result in increased invasiveness. Feral GMHT OSR has the potential to
introduce HT traits to volunteer weeds in agricultural fields, but would only be amplified if the
herbicides to which HT volunteers are tolerant were used routinely in the field. This worst-case
scenario is most unlikely, as seed import spills are mostly confined to port areas. Economic
concerns revolve around the potential for feral GMHT OSR to contribute to GM admixtures in
non-GM crops. Since feral plants derived from cultivation (as distinct from import) occur at too
low a frequency to affect the coexistence tolerance threshold of 0.9% in the EU, it can be
concluded that feral GMHT plants resulting from seed import spills will have little relevance as a
potential source of pollen or seed for GM admixture. This paper concludes that feral OSR in
Europe should not be routinely managed, and certainly not in semi-natural habitats, as the
benefits of such action would not outweigh the negative effects of management.


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EFSA’s work on the safety assessment of genetically modified animals
Yann Devos, Anna Christodoulidou, Christina Ehlert, Antonio Fernandez-Dumont, Yi Liu, Nancy Podevin, Karine Lheureux, Elisabeth Waigmann

Abstract: Genetically modified organisms (GMOs) and derived food and feed products are
subject to a risk analysis before they can be placed on the market in the European Union. In this
risk analysis process, the role of the European Food Safety Authority (EFSA) is to independently
evaluate the risk assessment provided by applicants and to provide scientific advice to risk
managers on any possible risks of GMOs to human and animal health and the environment.
EFSA’s scientific advice is elaborated by its GMO Panel with the scientific support of several
Working Groups and its GMO Unit. This paper describes EFSA’s activities pertaining to the
safety assessment of GM animals, with a focus on GM fish, GM insects and GM mammals and


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EFSA GMO Panel guidance on the evaluation of potential adverse effects
of GM plants on non-target organisms

Yann Devos, Detlef Bartsch, Achim Gathmann, Rosemary S. Hails, Jozsef Kiss, Antoine Messéan, Sylvie Mestdagh, Joe N. Perry, Jeremy B. Sweet, Salvatore Arpaia

Abstract: In November 2010, the Panel on Genetically Modified Organisms (GMO Panel) of the
European Food Safety Authority (EFSA) issued a Scientific Opinion (SO) that delivers guidance
on the environmental risk assessment (ERA) of genetically modified (GM) plants. Beside the
ERA SO, the EFSA GMO Panel developed a separate SO that provides specific guidance for the
evaluation of potential adverse effects of GM plants on non-target organisms (NTOs). This paper
describes some elements of the ERA SO and NTO SO pertaining to NTO risk assessment, with a
focus on: (1) problem formulation; (2) protection goals and limits of concern; (3) intended and
unintended effects; (4) species selection for testing purposes; and (5) stacked transformation
events. Some scientific comments from EU Member States and stakeholders received during the
development of both documents through public consultations are also presented.


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Defining environmental risk assessment criteria for GM insects to be placed on the EU market
Michael Eckerstorfer, Mark Benedict, Gerald Franz, Helmut Gaugitsch, Anita Greiter, Andreas Heissenberger, Bart Knols, Sabrina Kumschick, Wolfgang Nentwig, Wolfgang Rabitsch

Abstract: Global efforts towards the development of genetically modified (GM) arthropods have
progressed to a stage where some might possibly be placed on the EU market within the next
decade. To facilitate the risk assessment of particular GM arthropod applications the specific risk
issues associated with these applications need to be addressed. To inform the development of
adequate and comprehensive guidelines by EFSA, a study was carried out to provide background
information on the possibilities and state of development of GM arthropods, the potential adverse
effects associated with applications relevant for release in the EU and the methods to investigate
these effects.
The ERA of GM arthropods should consider various issues regarding the genetic
modification and the method used for modification, as well as the purpose of the GM arthropod
application. In that respect the specifics of potential applications, e.g. control of a target species
by population suppression or applications designed for population replacements need to be
acknowledged during assessment. Potential risks also depend on the respective species, which is
modified and the receiving environment for releases. Issues concerning gene flow and its
consequences, effects on target and non-target organisms, management practices and human
health need to be considered in a specific way. It is recommended to follow a case-by-case
approach for the ERA of GM arthropods to identify the specific risk issues. Key parameters for
the assessment of risk issues were proposed and described and available methods for assessment
were evaluated.


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Areawide suppression of European corn borer with Bt maize reaps savings to
non-Bt maize growers: A new rationale for Bt maize adoption in Europe?

William D. Hutchison

Abstract: Historically, the European corn borer (ECB), Ostrinia nubilalis, has been the most
widespread insect pest of maize in the U.S.; damage was typically estimated at more than
$1billion per year. Due to the difficulty in monitoring for the pest, or timing insecticide
applications, most growers acquiesced and accepted annual yield losses. Beginning in 1996,
transgenic maize, engineered to express insecticidal proteins from the bacterium Bacillus
thuringiensis (Bt) became one of the most widely adopted technologies in U.S. agriculture. In
2010, Bt maize was planted on more than 22.2 million ha, constituting 63% of the U.S. crop.
Using statistical analysis of per capita growth rate estimates (for 3 states; 1996-2009), it was
determined that areawide suppression of ECB was significantly associated with Bt maize use
(Hutchison et al. 2010). Cumulative net revenues over 14 years, for 5 major maize producing
states (Illinois, Iowa, Nebraska, Minnesota and Wisconsin) were conservatively estimated at $6.9
billion (U.S.) for both the Bt maize and non-Bt maize hectares. However, ~$4.3 billion, or ca.
62% of the total benefit accumulated on the non-Bt maize hectares. These value estimates are
conservative in that they do not include additional savings that may have accrued as a result of
less disease pressure (stalk or ear fungal infections) or savings due to less insecticide use. Given
the fact that the same target pest species occurs throughout much of the European maize
producing countries, the possibility of similar areawide economic benefits are discussed.


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Assessing the impact of Cry1Ab expressing corn pollen on larvae
of Aglais urticae in a laboratory bioassay

Anne-Katrin Müller, Mechthild Schuppener, Stefan Rauschen

Abstract: Laboratory bioassays were conducted to assess the impact of pollen from the
genetically modified corn (Zea mays) event Mon810 on larvae of the Small Tortoiseshell (Aglais
urticae), a non-target butterfly species. Plants with the event Mon810 express the Cry1Ab protein
from Bacillus thuringiensis in all tissues and are resistant against the European corn borer. Third
instar larvae of A. urticae were fed with corn pollen deposited on leaves of its host plant (stinging
nettle) in no-choice tests (I) once in a single dose experiment (1,000 Bt-pollen grains per cm2)
and (II) over two and a half days to assess impacts of prolonged exposure. Additionally, a (III)
single dose experiment with 9,000 pollen grains per cm2 was performed. Larval mortality,
development, weight gain and feeding activity were observed. No statistically significant
differences in mortality, developmental time and weight gain in comparison to control groups
were detected either in the single dose or the multiple dose experiment. However there was a
significantly lower feeding activity in the Bt-treatment groups in both the single and the multiple
dose experiments. Based on literature data on expected environmental concentrations of corn
pollen a negligible risk for A. urticae larvae is determined in this study.


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Protease inhibitors as a possible new factor in agricultural plant protection
against microbial and fungal attack

Oldřich Navrátil, Dalibor Kodrík, Barbara Kludkiewicz, Konstatntin S. Vinokurov, František Sehnal, Vendulka Horáčková

Abstract: Extracellular serine proteases are produced by a wide range of microbial and fungal
pathogens of agricultural plants. For example, they are involved in potato blight and wilting
caused by Phytophthora infestans and Fusarium oxysporum, respectively. To improve potato
resistance to the pathogens, we prepared plants containing a gene derived from the wax moth
Galleria mellonella and expressing the silk protease inhibitor 2 (SPI2). SPI2 is secreted by the
silk glands and inhibits microbial peptidases such as subtilisin and proteinase K. The synthetic
SPI2 gene (modified to match the codon usage in potato) was fused with mGFP-5 to facilitate
detection of the transgene and its protein product. A construct of the fusion gene with plant
regulatory elements (promoter 35S and terminator OCS) was prepared in a plasmid and inserted
as a restriction fragment EcoRI – HindIII into the binary vector pRD400. The final construct was
introduced into Agrobacterium tumefaciens (strain GV2260 with plasmid pGV2260). Leaf discs
of potato cultivar Velox, which exhibits medium resistance to Phytophthora infestans, were
transformed with A. tumefaciens. Transgenic plants were regenerated in the presence of
kanamycin antibiotics and the content of SPI2 DNA was confirmed in the plantlets by PCR.
Polyclonal antibodies were raised commercially against the natural SPI2 purified from the extract
of G. mellonella silk using the RP HPLC. Western blotting was used to verify antibody reaction
with a protein of expected size in the extracts of transformed potato plants. The presence of the
fusion protein in resistant plants was confirmed with additional analytical methods. Indirect
ELISA was employed for the quantification of SPI2. The results showed up to 3 fold increase of
protease inhibition in transformed plants compared to the control background level. Potato plants
expressing the SPI2 gene were tested for resistance to late blight either in vitro (isolates of
Phytophthora were collected from infected potato plants in the latter half of growing season) or
in field trials (actual isolates of Phytophthora). The results revealed heterogeneity among
transgenic lines, i.e. some lines were more resistant and others were more susceptible than the
non-transgenic plants.


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Botanical and arthropod diversity in GM HT maize treated with glyphosate
or conventional herbicides

Zoltán Pálinkás, Mihály Zalai, Ágnes Szénási, Zita Dorner, Dóra Szekeres

Abstract: Weed management in genetically modified herbicide tolerant (GMHT) crops may
change the weed composition and arthropod (specifically non-target arthropod) species spectrum,
densities and impact higher trophic layers as well. Integrated Pest Management aims at
maintaining biological diversity, and ecological functions (e.g. natural control mechanisms) in
agro-ecosystems. Changes however do not necessarily result in adverse effects. Therefore the
magnitude and direction of changes outlined above needs to be understood and studied. HT
maize hybrids (including stacked events of lepidopteran and coleopteran resistance), were
surveyed for botanical and arthropod diversities in maize hybrid treated with glyphosate or with
conventional herbicides. Our null hypothesis was that there is difference between the effects of
glyphosate and non-glyphosate treatment on above diversities. HT maize plots were treated twice
with glyphosate or once with non-glyphosate herbicides in 2007 and 2008. These plots were
established and arranged in a randomized complete block design with four replications. Weed
species and their area coverage were estimated on 3x1 m on each plot in the same growth maize
stages in both years. Arthropods were sampled at four dates by visual observation, pitfall, and
yellow sticky traps. Total weed coverage was significantly lower in glyphosate treated plots
compared to plots with conventional herbicide treatment. Weed composition was also altered by
herbicide treatments. The Rényi diversity profile showed higher weed diversity in glyphosate
treated plots in most cases. Indirect effects of altered weed composition and coverage did not
result in significant changes of abundance of most invertebrate groups.


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Determination of the Cry1Ab toxin in Helicoverpa armigera larvae fed on a diet
containing lyophilized Bt leaves

Meritxell Pérez-Hedo, Tania Marques, Carmen López, Ramon Albajes, Matilde Eizaguirre

Abstract: Genetically modified maize with the insecticidal capacity of Bacillus thuringiensis
(expressing Cry1Ab) represents almost 80% of the total maize sown in the study area (Lleida,
Catalonia, NE Iberian Peninsula). Bt corn is highly effective for controlling maize borers but 2
other non-target Lepidoptera, Mythimna unipuncta (Haworth) and Helicoverpa armigera
(Hübner), cause occasional but severe damage to maize in the study area. Previous studies carried
out in the laboratory and the field on the effect of Bt maize on these 2 Lepidoptera demonstrated
that some larvae of the 2 species can survive and complete their development when feeding on Bt
maize. In this study the suitability of a diet containing lyophilized maize leaves for trials
conducted to evaluate the susceptibility of H. armigera larvae to Bt maize varieties was
demonstrated. Bt toxin produced a quite steady cumulative mortality in the different larval instars
of H. armigera. The Bt protein was well detected in the lyophilized Bt leaves and in the diet
prepared with lyophilized leaves. In the H. armigera larvae the protein was detected in the
content of the peritrophic membrane, in the midgut and in the hemolymph of the larvae fed on a
Bt diet. Once ingested, the majority of the toxin was degraded inside the peritrophic membrane
and the growth rate of these larvae was lower than that of larvae fed on a non-Bt diet. These may
be some of the reasons for the low susceptibility of H. armigera larvae to the Bt toxin.


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Research on the influence of genetically modified maize on the Coccinellidae fauna
Ioan Rosca, Ludovit Cagan

Abstract: We present the results from a field experiment in Borovce, Slovakia, during 2008 and
2009 with eight maize hybrids. Three genetically modified hybrids expressing Bacillus
thuringiensis insecticidal proteins (MON 8903, MON 88017, and MON 8903 × MON 88017)
were included. Coccinellidae abundance was assessed using yellow sticky traps (Pherocone AM).
A synecological analysis to reveal the role of each species was conducted, taking into account the
abundance, constancy, dominance and ecological significance index. The species with the
greatest ecological significance (W5) was Propylea quatuordecimpunctata. Psyllobora vigintiduopunctata
was considered as accompanying species (W3) in 2008 and as accessory species
(W2) in 2009. Coccinella septempunctata was considered as accessory species (W2), and Adalia
bipunctata as accidental species (W1) in 2008 and accessory species in 2009. Finally, Chilocorus
bipustulatus and Cynegetis impunctata, collected only in 2008, were accidental species (W1).
There were no significant differences in the structure and quantity of Coccinellidae among the
maize hybrids.


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Research on the influence of genetically modified maize on the Neuroptera fauna
Ioan Rosca, Ludovit Cagan

Abstract: We present the results from a field experiment in Borovce, Slovakia, during 2008 and
2009 with eight maize hybrids including 3 genetically modified ones expressing Bacillus
thuringiensis insecticidal proteins (MON 8903, MON 88017, and MON 8903 × MON 88017).
The Neuroptera abundance was assessed using yellow sticky traps (Pherocone AM). A
synecological analysis taking into consideration abundance, constancy, dominance and ecological
significance index was conducted. Regarding dominance, in 2008, 3 species (Chrysoperla
carnea, Osmylus fulvicephalus and Hemerobius humulinus) were eudominant species, and
Drepanepteryx phalaenoides was a dominant species. In 2009, C. carnea, and O. fulvicephalus
were eudominant species, while D. phalaenoides became a subdominant species. The ecological
significance index, which is most important as it takes into consideration both constancy and
dominance, revealed that in 2009, all 3 observed species (C. carnea, O. fulvicephalus, and
D. phalaenoides) were edifying species. In 2008, O. fulvicephalus and H. humulinus were
dominant species, D. phalaenoides was accompanying species and C. carnea an accessory
species. No significant differences in the structure and quantity of Neuroptera species was
observed among the different hybrids.


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Effects of aphids and virus infection on the metabolism of conventional
and transgenic potato plants

André Schlichting, Anja Hühnlein, Jörg Schubert, Peter Leinweber, Thomas Thieme

Abstract: In order to determine the effect of aphid (Myzus persicae) feeding and infection with
potato leafroll virus (PLRV) on the metabolism of potato (Solanum tuberosum) plants, two
sequential trials were designed and carried out, followed by a molecular-chemical
characterization of the tissue (leaves) of the plants using Pyrolysis-Field Ionisation Mass
Spectrometry (Py-FIMS). Thus the comparison of the samples is based on the application of
pattern-recognition techniques in combination with multivariate statistics. The m/z-signals of
highest discriminative power indicate the molecular-chemical diversity. In the first experiment
we tested the effects of aphid feeding and virus infection. The discriminant analysis resulted in a
complete separation of the treatments. The second experiment provided evidence of the effects of
grafting and transgenes, but there were fewer significant differences in the m/z-signals than in the
first experiment. As a consequence, separation of the sample sets by only one factor was
impossible. The m/z-signals of highest discriminating power were evaluated and verified and the
majority were tentatively assigned to marker signals of isoprenoids, which are associated with
plant defence and aphid and/or virus modulated metabolism.


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Environmental risk assessment for European non-target butterfly species and
a Lepidoptera-resistant stacked Bt-maize variety

Mechthild Schuppener, Julia Aha, Stefan Rauschen

Abstract only


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Impact of genetically modified maize expressing Cry3Bb1 on non-target arthropods:
First year results of a field study

Zdeňka Svobodová, Oxana Habuštová, Hany Mohamed Hussein, Vladimír Půža, František Sehnal

Abstract: The expression of the insecticidal toxin Cry3Bb1 in maize MON 88017 can curb
spreading of the Western corn rootworm (WCR, Diabrotica virgifera virgifera), and the tolerance
of this maize to glyphosate can facilitate weed management. To examine the general
environmental impact of this GM maize, it was planted along with a non-GM but otherwise
nearly isogenic cultivar (treated or not treated with the insecticide Dursban 10G) and with two
reference cultivars. Effects on non-target organisms were studied in each treatment on 5 plots of
0.5ha each. The content of Cry3Bb1 measured in plant tissues by ELISA fluctuated during season
and depended on the weather condition and the growth phase of maize. The diversity and
abundance of plant-dwelling arthropods (plant sucking arthropods, predators, and parasitoids)
and epigeic arthropods (spiders, ground and rove beetles) were monitored three times and five
times during the season, respectively. Neither the abundance nor the species composition, were
affected by the transgenic plant. The data indicate that MON 88017 has no effect on the nontarget
arthropod fauna.


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Characterisation of tritrophic effects of DAS-59122-7 maize
on the seven-spotted ladybird (Coccinella septempunctata)
feeding on the bird cherry-oat aphid (Rhopalosiphum padi)

Eszter Takács, Adrien Fónagy, Judit Juracsek, Nikolett Kugler, András Székács

Abstract: The long-term effects on the fecundity and fertility of Coccinella septempunctata
preying on Rhopalosiphum padi living on maize containing genetic event 59122 (Herculex® RW
Bt maize, DAS-59122-7), its isogenic counterpart (PR36D79) and three other commercial Pioneer
hybrids (37M34, 37N01 and 36V52) were characterised during and following pollen shed. The
concentration of the Cry34Ab1 and Cry35Ab1 binary toxin was analysed by commercial
enzyme-linked immunosorbent assays (ELISAs). Concentrations of Cry34Ab1 and Cry35Ab1 in
R1 phenological stage green leaf blades were 81.1 ± 17.7 and 75.1 ± 11.9ng/mg lyophilised dry
weight, respectively. Pollen contained 47.4 ± 12.3ng Cry34Ab1/mg fresh weight, whereas
concentrations of Cry35Ab1 were below the limit of detection of the ELISA (< 0.12ng/mg).
Maize plants in the V14-R1 phase (8 from each variety) under mesh cages (full plant isolator)
were pre-infested with approximately 500 aphids at least one week prior to placing 20 newly
emerged L1 C. septempunctata larvae onto each plant. Larval to adult development was
monitored every 3-4 days. Remaining within the isolators, the adults were allowed to prey on R.
padi feeding on the respective maize variety and to copulate under semi-field conditions for two
more weeks after adult emergence. In mid-September (2010) entire plants with isolators were
transferred into the laboratory, where sexing and weighing of the ladybirds was performed.
Additionally, in the laboratory under a long photoperiod (L:D 16:8, 25°C) females were paired
with two males under a cob isolator. Under each isolator, a cob and adjacent ear leaves fixed in a
water flask were infested with R. padi. C. septempunctata mating groups were monitored and the
frequency of egg laying was recorded daily. Results from this study demonstrate that for all
treatment groups, the sex ratio was 45:55 female/male, and the female average weight (45.3 ±
6.2mg) was not significantly different across varieties. Additionally, no significant differences
were observed during the tested period in either fecundity or fertility across varieties (the DAS-
59122-7 treatment group averaged 25 eggs/female and 56% fertility; the isogenic or commercial
hybrid treatment groups averaged 24-34 egg/female and 58-77% fertility).


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