Larval development of Spodoptera eridania (Cramer) fed on leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 proteins and its non-Bt isoline

This study aimed to evaluate, in controlled laboratory conditions (temperature of 25±2 °C, relative humidity of 60±10%, and 14/10 h L/D photoperiod), the larval development of Spodoptera eridania (Cramer, 1784) (Lepidoptera, Noctuidae) fed with leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 insecticide proteins and its non-Btisoline. Maize leaves triggered 100% of mortality on S. eridania larvae independently of being Bt or non-Bt plants. However, it was observed that in overall Bt maize (expressing a single or pyramided protein) slightly affects the larval development of S. eridania, even under reduced leaf consumption. Therefore, these results showed that Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 can affect the larval development of S. eridania, although it is not a target pest of this plant; however, more research is needed to better understand this evidence. Finally, this study confirms that non-Bt maize leaves are unsuitable food source to S. eridania larvae, suggesting that they are not a potential pest in maize fields.

Does Bt maize cultivation affect the non-target insect community in the agro ecosystem?

ABSTRACT The cultivation of genetically modified crops in Brazil has led to the need to assess the impacts of this technology on non-target species. Under field conditions, the potential effect on insect biodiversity was evaluated by comparing a homogeneous corn field with conventional and transgenic maize, expressing different Bt proteins in seven counties of Minas Gerais, Brazil. The richness pattern of non-target insect species, secondary pests and natural enemies were observed. The results do not support the hypothesis that Bt protein affects insect biodiversity. The richness and diversity data of insects studied were dependent on the location and other factors, such as the use of insecticides, which may be a major factor where they are used.

Post-market environmental monitoring of Bt maize in Spain: Non-target effects of varieties derived from the event MON810 on predatory fauna

The Spanish Government has established post-market environmental monitoring (PMEM) as mandatory for genetically modified (GM) crop varieties cultivated in Spain. In order to comply with this regulation, effects of Bt maize varieties derived from the event MON810 on the predatory fauna were monitored for two years in northeast and central Spain. The study was carried out with a randomized block design in maize fields of 3-4 ha on which the abundance of plant-dwelling predators and the activity-density of soil-dwelling predators in Bt vs. non-Bt near-isogenic varieties were compared. To this end, the plots were sampled by visual inspection of a certain number of plants and pitfall traps 6 or 7 times throughout two seasons. No significant differences in predator densities on plants were found between Bt and non-Bt varieties. In the pitfall traps, significant differences between the two types of maize were found only in Staphylinidae, in which trap catches in non-Bt maize were higher than in Bt maize in central Spain. Based on the statistical power of the assays, surrogate arthropods for PMEM purposes are proposed; Orius spp. and Araneae for visual sampling and Carabidae, Araneae, and Staphylinidae for pitfall trapping. The other predator groups recorded in the study, Nabis sp. and Coccinellidae in visual sampling and Dermaptera in pitfall trapping, gave very poor power results. To help to establish a standardized protocol for PMEM of genetically modified crops, the effect-detecting capacity with a power of 0.8 of each predator group is given.

Short-term assessment of bt maize on non-target arthropods in Brazil

Embora não haja cultivos comerciais de milho geneticamente modificado no Brasil, o efeito de híbridos de milho Bt sobre inimigos naturais e artrópodos de solo deve ser avaliado antes da liberação aos produtores. Assim, ensaios foram conduzidos durante uma safra em duas localidades. Os híbridos de milho modificado geneticamente 7590-Bt11 e Avant-ICP4 foram comparados com seus respectivos isogênicos não transgênicos. Os artrópodes foram avaliados através de observação direta nas plantas e armadilhas de alçapão. de modo geral, não se observaram diferenças entre as populações de tesourinha (Dermaptera: Forficulidae), joaninhas (Coleptera: Coccinellidae), percevejo-pirata (Coleoptera: Anthocoridae), carabídeos (Carabidae), cicindelídeos (Cicindelidae) e aranhas (Araneae). Também não houve diferença no parasitismo de ovos de Helicoverpa zea (Boddie) por Trichogramma sp. (Hymenoptera: Trichogrammatidae). Assim, milho geneticamente modificado expressando as proteínas inseticidas Cry1A(b) e VIP 3A não causa redução nas populações dos principais predadores e parasitóides.

Life-history traits of Spodoptera frugiperda populations exposed to low-dose Bt maize.

Exposure to Bacillus thuringiensis (Bt) toxins in low- and moderate-dose transgenic crops may induce sublethal effects and increase the rate of Bt resistance evolution, potentially compromising control efficacy against target pests. We tested this hypothesis using the fall armyworm Spodoptera frugiperda, a major polyphagous lepidopteran pest relatively tolerant to Bt notorious for evolving field-relevant resistance to single-gene Bt maize. Late-instar larvae were collected from Bt Cry1Ab and non-Bt maize fields in five locations in Brazil, and their offspring was compared for survival, development, and population growth in rearing environment without and with Cry1Ab throughout larval development. Larval survival on Cry1Ab maize leaves varied from 20 to 80% among the populations. Larvae reared on Cry1Ab maize had seven-day delay in development time in relation to control larvae, and such delay was shorter in offspring of armyworms from Cry1Ab maize. Population growth rates were 50?70% lower for insects continuously exposed to Cry1Ab maize relative to controls, showing the population-level effect of Cry1Ab, which varied among the populations and prior exposure to Cry1Ab maize in the field. In three out of five populations, armyworms derived from Bt maize reared on Cry1Ab maize showed higher larval weight, faster larval development and better reproductive performance than the armyworms derived from non-Bt maize, and one of these populations showed better performance on both Cry1Ab and control diets, indicating no fitness cost of the resistance trait. Altogether, these results indicate that offspring of armyworms that developed on field-grown, single-gene Bt Cry1Ab maize had reduced performance on Cry1Ab maize foliage in two populations studied, but in other three populations, these offspring had better overall performance on the Bt maize foliage than that of the armyworms from non-Bt maize fields, possibly because of Cry1Ab resistance alleles in these populations. Implications of these findings for resistance management of S. frugiperda in Bt crops are discussed.

Resistance of Bt transgenic maize to lesser cornstalk borer (Lepidoptera: Pyralidae).

To determine if Bt maize seedlings are protected against lesser cornstalk borer damage, Bt hybrids at the 3 and 4 leaf stages were tested under temperatures between 20-32oC and artificial infestation. A high level of resistance was reported in all Bt maize as expressed by larval survival, larval weight, damage score, and number of surviving plants. All Bt maize protected plants against lesser cornstalk borer damage. Also, the resistance present in the Bt maize was not affected by daytime temperature.

Wirkung von Ernterückständen transgener Pflanzen auf die mikrobielle C- und N-Transformation in landwirtschaftlich genutzten Böden am Beispiel von Bt-Mais

In der vorliegenden Arbeit ging es um die Erarbeitung, Anwendung und Beurteilung von quantitativen Analysenverfahren / Methoden für ein Monitoring von durch Bt-Mais verursachbaren Umwelteffekten im Boden. Die Ausgangsthese besagte, dass sich transgene Maisstreu beim mikrobiellen Abbau anders verhält als konventionelle. Bezugnehmend auf die These wurden zwei Freilandversuche (Freilandmikrokosmenmethode nach Raubuch 1997 über 2 Jahre, Quantifizierung des Maisstreuabbaus mit Hilfe kleiner Bodensäulen über 1 Jahr) und zwei Inkubationsversuche im Labor (INK bei drei verschiedenen Temperaturen über 49 Tage und INK mit verschiedenen landwirtschaftlich genutzten Böden über 49 Tage mit jeweils kontinuierlicher Respirationsratenermittlung nach Isermeyer 1952) sowie Inhaltsstoffbestimmungen der Maisstreu durchgeführt. Für alle Untersuchungen wurde Streu der vier Maissorten Novelis (transgen, Monsanto 810), Nobilis (Isolinie von Novelis), Valmont (transgen, Bt 176, Fa. Syngenta) und Prelude (Isolinie von Valmont) eingesetzt. Nach Beendigung der Laborversuche sowie des Freilandversuches nach der Freilandmikrokosmenmethode wurden mikrobielle Messgrößen wie Adenylategehalt, Ergosterolgehalt, Cmik- und Nmik-Gehalt am Boden-Streu-Gemisch bestimmt. Der Einsatz der Isotopentechnik (Bestimmung von 13C/12C an gemahlenem Boden-Streu-Gemisch bzw. gefriergetrocknetem K2SO4 als Extrakt aus dem Boden-Streu-Gemisch) ermöglichte eine genaue Quantifizierung der abgebauten Maisstreu und brachte dadurch Aufschluss über das Abbauverhalten verschiedener Maissorten. Bezüglich der Ermittlung der mikrobiellen Messgrößen ergab sich für die transgene Sorte Novelis* stets eine durchschnittlich geringere pilzliche Biomasse. Langfristig ergaben sich bei der Kohlenstoff- und Stickstoffdynamik keine Trends hinsichtlich transgener bzw. konventioneller Maisstreu. Sowohl im Freilandversuch nach der Mikrokosmenmethode als auch in den Inkubationsversuchen trat das Phänomen der kurzzeitigen Respirationsratenerhöhung der Mikroorganismen nach Zugabe der transgenen Maissorten auf, welches nicht bei Zugabe der konventionellen Maisstreu auszumachen war. ______________________________

Dominância funcional e monitoramento da resistência de Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) a tecnologias Bt no Brasil

Plantas transgênicas que expressam toxinas de Bacillus thuringiensis Berliner (Bt) têm sido amplamente utilizadas para o controle de Spodoptera frugiperda (J. E. Smith) no Brasil. Entretanto, a evolução da resistência é um dos maiores entraves para a continuidade do uso desta tecnologia. Para subsidiar programas de Manejo da Resistência de Insetos (MRI), foram conduzidos estudos para o aprimoramento dos programas de manejo da resistência de S. frugiperda a tecnologias Bt. Foram realizadas estudos para determinar a dominância funcional da resistência de S. frugiperda a tecnologias Bt mediante a avaliação da sobrevivência de larvas neonatas provenientes das linhagens de S. frugiperda resistentes ao milho Herculex® que expressa a proteína Cry1F (HX-R), ao milho YieldGard VT PRO™ que expressa as proteínas Cry1A.105 e Cry2Ab2 (VT-R), ao milho PowerCore™ que expressa as proteínas Cry1A.105, Cry2Ab2 e Cry1F (PW-R), e ao milho Agrisure Viptera™ que expressa a proteína Vip3Aa20 (Vip-R), além da linhagem suscetível (Sus) e de suas respectivas linhagens heterozigotas em diversas tecnologias de milho e algodão Bt. Posteriormente, um método prático para o monitoramento fenotípico da suscetibilidade a diferentes tecnologias de milho e algodão Bt foi testado a partir da avaliação da sobrevivência de larvas neonatas em folhas de plantas Bt em populações de S. frugiperda provenientes dos Estados do Rio Grande do Sul, Paraná, São Paulo, Goiás e Bahia na safra agrícola 2014/15. E por último, a estimativa da frequência de alelos de resistência de S. frugiperda a Vip3Aa20 foi validada pelo método de F1 screen. Em geral, observou-se alta mortalidade dos heterozigotos nas tecnologias Bt testadas, comprovando que a resistência de S. frugiperda a proteínas Bt é funcionalmente recessiva o que suporta a estratégia de refúgio em programas de MRI. Verificou-se também que linhagens resistentes a eventos que expressam proteínas Cry não sobrevivem em tecnologias que expressam proteína Vip. No monitoramento prático da suscetibilidade a tecnologias Bt, sobrevivência larval superior a 70% foi observada para populações de campo do Paraná, Goiás e Bahia no milho Herculex®. Em tecnologias de milho PowerCore™ e YieldGard VT PRO™ houve sobrevivência larval variando de 1,1 a 17,9%. Em contraste, não houve sobreviventes em tecnologias de milho Viptera™. Em algodão WideStrike® que expressa as proteínas Cry1Ac e Cry1F, sobrevivência acima de 41% foi observada para populações de campo de S. frugiperda. A sobrevivência larval em Bollgard II® que expressa as proteínas Cry1Ac e Cry2Ab2 variou de 14 a 40%. No algodão TwinLink® que expressa as proteínas Cry1Ab e Cry2Ae, a sobrevivência larval das populações foi menor que 20%. O método de F1 screen foi eficiente na detecção de alelos de resistência a Vip3Aa20 em populações de S. frugiperda provenientes de diferentes regiões produtoras de milho no Brasil na safra 2014/2015. De 263 isofamílias testadas, foram detectadas três isofamílias positivas oriundas do Paraná, Mato Grosso e Goiás. A frequência de resistência estimada a Vip3Aa20 variou de 0,0140 a 0,0367 nas populações avaliadas, sendo que a frequência total foi de 0,0076. Neste estudo, fornecemos informações para refinar as estratégias de MRI, além de introduzir novas técnicas para monitorar a resistência de S. frugiperda a tecnologias Bt no Brasil.

Desarrollo larvario y número de estadios larvarios de "Pseudaletia unipuncta" alimentada con dos variedades de maíz y dos dietas semisintéticas

Pseudaletia ( Mythimna) unipuncta (Haworth) es una plaga defoliadora del maíz presente año tras año en la Cuenca del Ebro, que realiza en el maíz daños esporádicos pero a veces devastadores. La implantación creciente de maíz resistente a taladros ha producido, en la zona del presente estudio, la disminución casi total de los daños debidos a los taladros Sesamia nonagrioides (Lefebvre) y Ostrinia nubilalis (Hübner). Sin embargo, no se sabe aún cómo el incremento de maíz transgénico puede afectar a las poblaciones de P. unipuncta. Actualmente no hay datos sobre biología o parámetros del desarrollo de la especie en la Península Ibérica necesarios para evaluar los posibles efectos de las nuevas variedades utilizadas. Para ello es necesario primero establecer un método de cría adecuado y posteriormente iniciar los estudios sobre la biología de la misma. En el presente trabajo se planteó conocer diferentes parámetros del desarrollo larvario de poblaciones locales de P. unipuncta alimentada sobre hoja de maíz (variedades Tietar y PR33P66) y sobre dos dietas semisintéticas, una a base de alubias. Phaseolus vulgaris, y otra a base de maíz, Zea maya. Los resultados mostraron que las larvas desarrolladas en dieta a base de alubias sufrieron menor mortalidad, que las desarrolladas con planta o sobre la otra dieta, además el peso de las pupas resultantes fue mayor y presentaron menos malformaciones. En cuanto al numero de estadios larvarios, la mayoría pupó tras seis mudas larvarias, necesitando, las de dieta de maíz, estadios larvarios adicionales. Estos resultados indican que la dieta a base de alubias es la más adecuada para posteriores trabajos con esta especie.