Presented thesis examines possible environmental impact of the genetically modified (GM) maize expressing insecticidal Cry proteins. The impact was assessed from differences in the communities of the ground and above-ground arthropods in plots sown with the standard and the GM maize, respectively. The results revealed that neither the abundance nor the species richness of arthropods was affected. Laboratory experiments were used to study effect of maize expressing several types of Cry proteins on the arthropod predators. Despite the proven exposure of the predators to Cry proteins in the food, no Cry proteins accumulation and deleterious effects on predators were observed. The results confirm the importance of predators in insect resistance management using the GM maize seed blends method.

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. / Transgenic plants expressing toxins from Bacillus thuringiensis Berliner (Bt) have been widely used to the control of Spodoptera frugiperda (J. E. Smith) in Brazil. However, the resistance evolution is one of the major threats to the continuous use of this technology. To subsidize Insect Resistance Management (IRM), studies were conducted to improve S. frugiperda resistance management programs to Bt technologies. Studies to determine functional dominance of resistance of S. frugiperda to Bt technologies were conducted by evaluating neonate larval survival of S. frugiperda strains resistant to Herculex® maize expressing Cry1F protein (HX-R), to YieldGard VT PRO™ maize expressing Cry1A.105 and Cry2Ab2 proteins (VT-R), to PowerCore™ maize expressing Cry1A.105, Cry2Ab2 and Cry1F proteins (PW-R) and to Agrisure Viptera™ maize expressing Vip3Aa20 protein (Vip- R), in addition to susceptible strain (Sus) and the respective heterozygous strains in several Bt maize and cotton technologies cultivated in Brazil. Then, a practical method for phenotypic resistance monitoring of several Bt maize and cotton were tested, based on neonate larval survival on Bt leaf tissue in S. frugiperda populations collected from Rio Grande do Sul, Paraná, São Paulo, Goiás and Bahia States. Finally, the F1 screen method was validated to estimate the frequency of Vip3Aa20 resistance alleles in S. frugiperda. In general, high mortality of heterozygous individuals was observed on Bt technologies, confirming that resistance of S. frugiperda to Bt proteins is functionally recessive and supporting the importance of refuge areas in IRM programs. No larval survival on Vip expressing maize was found with strains of S. frugiperda resistant to maize expressing Cry toxins. In the practical resistance monitoring, more than 70% of larval survival in field populations of S. frugiperda from Paraná, Goiás and Bahia was detected in Herculex® maize. Larval survival on PowerCore™ and YieldGard VT PRO™ maize technologies ranged from 1.1 to 17.9%. In contrast, no larval survival of field populations was observed on Viptera™ maize technologies. On WideStrike® cotton, more than 41% larval survival was observed in field populations of S. frugiperda. The larval survival was on Bollgard II® ranged from 14 to 40%. In TwinLink® the larval survival was lower than 20%. The F1 screen method was efficient in detecting Vip3Aa20 resistance alleles in field populations of S. frugiperda. From a total of 263 isofamily lines tested, three positive isofamily lines from Paraná, Mato Grosso and Goiás were found. The frequency of Vip3Aa20 resistance alleles ranged from 0.0140 to 0.0367, with overall frequency of 0.0076. In this study, we provide valuable information to improve IRM strategies and propose new methods to monitor resistance of S. frugiperda to Bt technologies in Brazil.

A broca-da-cana Diatraeasaccharalis(Fabricius) é uma das pragas-alvo do milho geneticamente modificado que expressagene(s) que codifica(m) proteína(s) de BacillusthuringiensisBerliner(milho Bt) no Brasil. Para estabelecer estratégias proativas de manejo de resistência, os objetivos do presente trabalho foram (1)estabelecer linhas-básicas de suscetibilidade à proteína Cry1F de B. thuringiensisem populações de D. saccharalis coletadas nas principais regiões produtoras de milho no Brasil na safra de 2010/2011, (2) realizar monitoramentoda suscetibilidade de populações de D. saccharalis na safra 2011/2012 e (3) avaliar a atividade biológica do milho Bt (evento TC1507) em diferentes estádios fenológicos no controle de D. saccharalis em condições laboratoriais. Para a caracterização das linhas-básicas de suscetibilidade foram realizados bioensaios com a proteína purificada Cry1F aplicada superficialmente em dieta artificial.As CL50 de Cry1F estimadas variaram de 0,47 a 7,02 ng de Cry1F/ cm2 dieta artificial para as populações avaliadas (variação de ?15 vezes). Foi definida e validada a concentração diagnóstica de 112 ng de Cry1F/cm²,baseada na estimativa da CL99 das populações testadas para o monitoramento da suscetibilidade. A avaliação da atividade biológica de milho Bt (evento TC1507) foi realizada com dois híbridos (Pioneer 30F35 e Dow 2B688) nos estádios fenológicos V3, V6 e V9 e em duas épocas de plantio. Alta atividade de controle de D. saccharalis foi obtida para os dois híbridos de milho Bt nos diferentes estádios fenológicos e épocas de plantio. Portanto, verificou-se que a espécie D. saccharalis é altamente suscetível à proteína Cry1F. Contudo, a implementação de estratégias de manejo da resistência é de fundamental importância para preservar a vida útil da tecnologia de milho Bt como importante ferramenta em programas de MIP. / The sugarcane borer Diatraeasaccharalis (Fabricius) is one of the target pests of genetically modified maizeexpressinggenes that code for insecticidal proteins from Bacillus thuringiensis Berliner (Bt maize) in Brazil. To implement proactive resistance management strategies, we leaded studies (1) to establish baseline susceptibility to Cry1F protein from B. thuringiensis in populations of D. saccharalis collected from major maize production regions in Brazil during 2010/2011 growing season, (2) to leadsusceptibility monitoring in populations of D. saccharalis collected in 2011/2012 growing season, and (3) to assess the biological activity of Bt maize (event TC1507) at different growth stages forD. saccharaliscontrol under laboratory conditions. The baseline susceptibility wascharacterizedwith purified protein Cry1F applied superficially on artificial diet. The estimatesof LC50 of Cry1F ranged from 0.47 to 7.02 ng Cry1F/cm2of artificial diet for the populations evaluated (? 15-fold variation).A diagnostic concentration of 112 ng Cry1F/cm ² was defined and validated for monitoring the susceptibility based on estimation of CL99 of all tested populations. The biological activity of Bt maize (event TC1507) was assessed by using two hybrids (Pioneer 30F35 and Dow 2B688) at growth stages V3, V6 and V9 and two planting seasons. High level of D. saccharaliscontrol was obtained for the twoBt maize hybrids at different growth stages and planting seasons. Therefore, we conclude that D. saccharalis is highly susceptible to Cry1F protein. However, implementation of insect resistance management strategies is essentialin order to preserve the lifetime of Bttechnology as an important tool in IPM programs.

A estratégia de pirâmide de genes tem sido explorada para retardar a evolução da resistência de insetos a plantas geneticamente modificadas que expressam proteínas inseticidas de Bacillus thuringiensis Berliner (Bt). No Brasil, às tecnologias de milho YieldGard VT PRO™ (VT PRO) e PowerCore™ (PW) que expressam as proteínas Cry1A.105/Cry2Ab2 e Cry1A.105/Cry2Ab2/Cry1F, respectivamente, foram liberadas para uso comercial em 2009. Para subsidiar programas de Manejo da Resistência de Insetos (MRI) foram conduzidos trabalhos para avaliar o risco de evolução da resistência de Spodoptera frugiperda (J. E. Smith) ao milho VT PRO e PW. Inicialmente foram realizados estudos para avaliar a atividade biológica de proteínas Bt expressas em diferentes estruturas da planta de milho VT PRO e PW sobre S. frugiperda e monitorar a suscetibilidade a Cry1A.105 e Cry2Ab2 em populações da praga coletadas em diferentes regiões geográficas do Brasil durante as safras de 2011 a 2014. Houve 100% de mortalidade de neonatas de S. frugiperda quando expostas ao tecido foliar de milho VT PRO e PW. No entanto, em estilo-estigmas e grãos, a mortalidade foi inferior a 50 e 6% respectivamente. Variabilidade geográfica na suscetibilidade de populações S. frugiperda a Cry1A.105 e Cry2Ab2 foi detectada, com reduções significativas na suscetibilidade a essas proteínas para algumas populações de 2011 a 2014. A técnica de \"F2 screen\" foi utilizada para a caracterização da resistência de S. frugiperda ao milho VT PRO e PW a partir de populações coletadas na safra de 2012. Verificou-se uma alta variabilidade na frequência fenotípica de isofamílias resistentes ao milho VT PRO e PW, sendo que as maiores frequências foram observadas em populações coletadas na região Central do Brasil. Com a técnica de \"F2 screen\" foi possível selecionar linhagens resistentes ao milho VT PRO e PW, denominadas de RR-2 e RR-3 respectivamente. Tanto a linhagem RR-2 quanto a RR-3 que foram criadas por 18 gerações consecutivas nos respectivos eventos de milho Bt apresentaram razões de resistência superiores a 3300, 2700 e ≈ 10 vezes a Cry1A.105, Cry1F e Cry2Ab2, respectivamente. Cruzamentos recíprocos das linhagens RR-2 e RR-3 com uma linhagem suscetível de referência revelaram que o padrão da herança da resistência é autossômica recessiva. A recessividade genética da resistência também foi confirmada pela mortalidade completa de indivíduos heterozigotos (descendentes provenientes de cruzamentos entre as linhagens RR-2 ou RR-3 com a linhagem suscetível) em tecidos de milho VT PRO e PW, demonstrando que esses eventos atendem ao conceito de alta dose para o MRI. Em retrocruzamentos da progênie F1 dos cruzamentos recíprocos com as linhagens resistentes confirmou-se a hipótese de que a resistência é poligênica. A presença de custo adaptativo associado à resistência foi verificada para as linhagens RR-2 e RR-3, porém ausente para os indivíduos heterozigotos, baseado nos parâmetros biológicos avaliados. Neste estudo fornecemos a primeira evidência do potencial de evolução da resistência de S. frugiperda a eventos de milho Bt piramidados e informações para o refinamento das estratégias de MRI para preservar a vida útil das tecnologias de milho Bt para o controle de S. frugiperda no Brasil. / The strategy of pyramid of genes has been exploited to delay the evolution of insect resistance to genetically modified crops expressing insecticidal proteins from from Bacillus thuringiensis Berliner (Bt). In Brazil, YieldGard VT Pro™ (VT PRO) and PowerCore™ (PW) corn technologies expressing Cry1A.105/Cry2Ab2 and Cry1A.105/Cry2Ab2/Cry1F proteins respectively were released for commercial use in 2009. Resistance risk assessment were conducted to support an Insect Resistance Management (IRM) program of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) to VT PRO and PW corn. Initially, studies were conducted to evaluate the biological activity of Bt proteins expressed in different plant structures of VT PRO and PW corn on S. frugiperda and to monitor the susceptibility to Cry1A.105 and Cry2Ab2 in pest populations collected from different geographical regions in Brazil from 2011 to 2014 growing seasons. The mortality of neonate larvae of S. frugiperda was 100% when fed on leaf tissue of VT PRO and PW corn. However, the larval mortality when fed on silks and grains was less than 50 and 6% respectively. A geographical variation in the susceptibility of S. frugiperda to Cry1A.105 and Cry2Ab2 proteins was detected among populations, with significant reduction in susceptibility to these proteins in some populations from 2011 to 2014. The F2 screen technique was used to characterize the resistance of S. frugiperda to VT PRO and PW corn from populations sampled in 2012 growing season. High variability in the frequency of resistant phenotypic isofamilies to VT PRO and PW corn was obtained with higher frequencies in S. frugiperda populations from Midwestern region of Brazil. Resistant populations to VT PRO and PW corn were selected by using F2 screen which were designated as RR-2 and RR-3 strains respectively. Both RR-2 and RR-3 strains reared on respective Bt maize events for 18 consecutive generations showed resistance ratios greater than 3,300; 2,700 and ≈ 10-fold to Cry1A.105, Cry1F and Cry2Ab2 respectively. Reciprocal crosses of RR-2 and RR-3 strains with a susceptible reference strain revealed that the inheritance of resistance is autosomal recessive. The genetic recessiveness of the resistance was also confirmed by the complete mortality of heterozygous individuals (offspring from the crosses between RR-2 or RR-3 strains with susceptible strain) on VT PRO and PW corn leaf tissues, indicating that these events meet the concept of high-dose for IRM strategies. Backcrosses of F1 progenies with both resistant strains revealed that resistance is polygenic. Fitness costs associated with resistance were found in RR-2 e RR-3 strains but not in heterozygous individuals, based on life history traits. In this study, we reported the first evidence of the potential of S. frugiperda to evolve resistance to pyramided Bt corn events, as well as provide valuable information to support the current IRM strategies to preserve the useful life of Bt corn technologies for S. frugiperda control in Brazil.

Genetically modified (GM) maize was developed mainly to control lepidopteran pests such as the maize stem borer (Busseola fusca) (Lepidoptera: Noctuidae). Since the first commercialization of GM crops with insecticidal properties, possible non-target effects such as the effect at the third trophic level on important predators for example lacewing species (Chrysoperla spp.) have been of concern. Contradicting results were reported in previous studies with regard to the effect of Cry 1Ab protein produced by Bt maize on the performance of lacewings. Some studies found that Bt proteins had no effect while others reported that C. carnea performed poorly if they consumed prey that consumed Cry 1Ab protein. In South Africa one of the most common chrysopid species in maize ecosystems is Chrysoperla pudica (Navás) (Neuroptera: Chrysopidae). Evolution of Bt resistant pests, such as B. fusca in South Africa facilitates a new pathway for exposure of predators to healthy prey that consumes Cry 1Ab proteins. The aims of this study was to determine the effect of the Cry 1Ab protein expressed in Bt maize on a non-target organism‟s (C. pudica) biology via indirect exposure, and to determine the concentration of Cry 1Ab protein in the plant, prey and predator. Chrysoperla pudica larvae were indirectly exposed to the Bt-toxin through healthy Bt-maize feeding prey (B. fusca larvae) in two feeding experiments and lacewing survival and life history parameters recorded. Bt had a limited effect on some parameters that were evaluated. The larval and pupal periods of C. pudica larvae that were exposed to the Bt-toxin had a significant difference from that of the control treatment. The Bt-toxin had a significant effect on fecundity, fertility and malformation after emergence of C. pudica adults of which larvae fed only on Bt resistant B. fusca larvae, but not on the mortality rate. Cry 1Ab concentration was the highest in the plant, followed by the prey and lacewing larvae. This study showed that the Cry 1Ab protein had a slight adverse effect only on certain life parameters of C. pudica, and that Cry 1Ab protein was hardly detectable in C. pudica larvae. However, since this study represented a worst-case scenario where diverse prey was not available, insignificant effects is expected under field conditions where prey is diverse. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Die vorliegende Arbeit untersucht kooperative und hierarchische Erscheinungsformen des institutionellen Wandels am Beispiel des Anbaus von gentechnisch verändertem Bt-Mais MON810 in Deutschland. In den Jahren 2005 bis 2008 war der kommerzielle Anbau dieser Pflanze in Deutschland möglich, und überwiegend Landwirte in den ostdeutschen Bundesländern machten von dieser Möglichkeit der Bekämpfung des Maisschädlings Ostrinia nubilalis Hübn. (Maiszünsler) Gebrauch. Unter Zuhilfenahme des Analyserahmens „Institutionen der Nachhaltigkeit“ werden in vier empirischen Kapiteln die Aspekte 1) Risikowahrnehmung und institutionelle Präferenz, 2) Möglichkeiten der Bereitstellung des Gutes „Gentechnikfreie Atmosphäre, 3) regionale Faktoren für Adaptionsunterschiede und 4) Adaption von Bt-Mais als Verhandlungsspiel zwischen Akteuren des ländlichen Raums beleuchtet. Hierbei wird deutlich, dass eine verstärkte Risikowahrnehmung beim Anbau von Bt-Mais MON810 eine Präferenz für eine Verschärfung des gegenwärtigen gesetzlichen Rahmens zum Umgang mit gentechnisch veränderten Pflanzen bedingt. Ebenso bevorzugen Akteure mit einer entsprechenden Risikowahrnehmung eine hierarchische Steuerung zur Sicherstellung der Gentechnikfreiheit, beispielsweise in Form von staatlich ausgewiesenen Gentechnikfreien Regionen oder Anbauverboten. Bei der Adaption von Bt-Mais kommt der Maisfläche je Betrieb eine große Bedeutung zu. Durch den rechtlichen Rahmen in Deutschland, die jeweilige Agrarstruktur und das soziale Umfeld wird der Anbau von Bt-Mais erschwert. Die unterschiedlichen Akteure wenden daher Maßnahmen an, um ihre eigene Verhandlungsposition zu verbessern oder die des Mitspielers zu verschlechtern. Hierzu zählen beispielsweise die Reduktion von Mindestabständen durch nachbarschaftliche Absprachen oder auch die Ausübung von öffentlichem Druck auf Bt-Mais anbauende Landwirte sowie Feldzerstörungen. / This work aims at analysing co-operative and hierarchical forms of institutional change in the case of Bt-maize cultivation in Germany. Genetically modified Bt-maize expresses a toxin which is lethal for the larvae of a main pest in maize production, the European Corn Borer. From 2005 to 2008, the cultivation of this transgenic crop was legally possible in Germany and adoption took mainly place in the former eastern German federal states. In four empirical chapters, the aspects of 1) risk perception and institutional preferences, 2) hierarchical or co-operative provision of the good “GMO-free atmosphere”, 3) regional adoption patterns of Bt-maize and 4) the adoption as a bargaining game will be analysed. It becomes apparent that actors with a strong risk perception prefer stricter institutions when dealing with the cultivation of GM crops and also favour hierarchical governance forms instead of co-operative solutions. The adoption of Bt-maize at the federal state level in Germany is significantly influenced by the factor maize area per farm. When conceptualizing Bt-maize adoption as a game under a strict regulatory framework and different agricultural and social structures, several measures can be identified which are employed by the actors to improve one’s own bargaining position, such as private agreements on the reduction of isolation distances or impair the one of the opposite player through public pressure or field destructions.

Genetically modified maize expressing the Bt-protein Cry1Ab (Bt maize) is planted widely in South Africa. Crop residues of Bt maize often end up in aquatic ecosystems where aquatic organisms are exposed to Cry1Ab protein. The effect of this protein on non-target aquatic organisms has not yet been studied in South Africa. The aim of this study was to evaluate the possible effect of exposure to Bt maize on morphological development of Xenopus laevis and Amietophrynus gutturalis tadpoles. Three experiments were conducted with each of X. laevis and A. gutturalis. Five of these were conducted in the bio-secure Amphibian Biology laboratory and one with A. gutturalis in a shade-house facility where microcosms were exposed to natural conditions. In the first experiment of X. laevis and A. gutturalis, which was replicated three times, large portions of maize leaves were placed in the bottoms of microcosms. X. laevis received supplementary pulverised leaves in suspension while A. gutturalis tadpoles fed on provided leaves. For both control and experimental groups microcosms were divided in three groups receiving respectively 15, 30 and 45 g of maize leaves. In the second and third experiment tadpoles only received pulverised Bt maize leaves in suspension. Each replicate (microcosm) contained 50 one-day old tadpoles. Experiment two was conducted to determine whether the Bt-protein has adverse effects on A. gutturalis tadpoles when tadpoles are exposed to the protein in the water but not feeding on the plant material. A total of 100 tadpoles were used during the experiment and tadpoles were placed individually in 250 ml plastic cups that were filled with 100 ml water witch contained an extract of either Bt and non-Bt maize leaves. Tadpoles were fed twice a week with TetraTabimin bottom-feeding fish pellets in suspension. Experiment three was conducted to determine whether the Bt-protein will have adverse effects on A. gutturalis tadpoles when tadpoles feed on Bt maize leaves. Tadpoles were divided into a treatment in which 50 tadpoles were fed Bt maize leaves and a control treatment in which 50 tadpoles were fed non-Bt maize leaves. Tadpoles were placed individually in 250 ml plastic cups that were each filled with 100 ml borehole water. On a weekly basis 10 randomly selected tadpoles were collected, measured and staged for morphological development, using the Nieuwkoop and Faber Normal Table for X. laevis and Gosner stages for A. gutturalis tadpoles. The significant effects observed in some life history parameters of tadpoles exposed to Cry1Ab protein cannot be ascribed to the effect of the protein. Poor husbandry turned out to be the single most important confounding factor. Before follow-up studies are conducted husbandry practices should be optimized. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.

Genetically modified (GM) maize was developed mainly to control lepidopteran pests such as the maize stem borer (Busseola fusca) (Lepidoptera: Noctuidae). Since the first commercialization of GM crops with insecticidal properties, possible non-target effects such as the effect at the third trophic level on important predators for example lacewing species (Chrysoperla spp.) have been of concern. Contradicting results were reported in previous studies with regard to the effect of Cry 1Ab protein produced by Bt maize on the performance of lacewings. Some studies found that Bt proteins had no effect while others reported that C. carnea performed poorly if they consumed prey that consumed Cry 1Ab protein. In South Africa one of the most common chrysopid species in maize ecosystems is Chrysoperla pudica (Navás) (Neuroptera: Chrysopidae). Evolution of Bt resistant pests, such as B. fusca in South Africa facilitates a new pathway for exposure of predators to healthy prey that consumes Cry 1Ab proteins. The aims of this study was to determine the effect of the Cry 1Ab protein expressed in Bt maize on a non-target organism‟s (C. pudica) biology via indirect exposure, and to determine the concentration of Cry 1Ab protein in the plant, prey and predator. Chrysoperla pudica larvae were indirectly exposed to the Bt-toxin through healthy Bt-maize feeding prey (B. fusca larvae) in two feeding experiments and lacewing survival and life history parameters recorded. Bt had a limited effect on some parameters that were evaluated. The larval and pupal periods of C. pudica larvae that were exposed to the Bt-toxin had a significant difference from that of the control treatment. The Bt-toxin had a significant effect on fecundity, fertility and malformation after emergence of C. pudica adults of which larvae fed only on Bt resistant B. fusca larvae, but not on the mortality rate. Cry 1Ab concentration was the highest in the plant, followed by the prey and lacewing larvae. This study showed that the Cry 1Ab protein had a slight adverse effect only on certain life parameters of C. pudica, and that Cry 1Ab protein was hardly detectable in C. pudica larvae. However, since this study represented a worst-case scenario where diverse prey was not available, insignificant effects is expected under field conditions where prey is diverse. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Genetically modified maize expressing the Bt-protein Cry1Ab (Bt maize) is planted widely in South Africa. Crop residues of Bt maize often end up in aquatic ecosystems where aquatic organisms are exposed to Cry1Ab protein. The effect of this protein on non-target aquatic organisms has not yet been studied in South Africa. The aim of this study was to evaluate the possible effect of exposure to Bt maize on morphological development of Xenopus laevis and Amietophrynus gutturalis tadpoles. Three experiments were conducted with each of X. laevis and A. gutturalis. Five of these were conducted in the bio-secure Amphibian Biology laboratory and one with A. gutturalis in a shade-house facility where microcosms were exposed to natural conditions. In the first experiment of X. laevis and A. gutturalis, which was replicated three times, large portions of maize leaves were placed in the bottoms of microcosms. X. laevis received supplementary pulverised leaves in suspension while A. gutturalis tadpoles fed on provided leaves. For both control and experimental groups microcosms were divided in three groups receiving respectively 15, 30 and 45 g of maize leaves. In the second and third experiment tadpoles only received pulverised Bt maize leaves in suspension. Each replicate (microcosm) contained 50 one-day old tadpoles. Experiment two was conducted to determine whether the Bt-protein has adverse effects on A. gutturalis tadpoles when tadpoles are exposed to the protein in the water but not feeding on the plant material. A total of 100 tadpoles were used during the experiment and tadpoles were placed individually in 250 ml plastic cups that were filled with 100 ml water witch contained an extract of either Bt and non-Bt maize leaves. Tadpoles were fed twice a week with TetraTabimin bottom-feeding fish pellets in suspension. Experiment three was conducted to determine whether the Bt-protein will have adverse effects on A. gutturalis tadpoles when tadpoles feed on Bt maize leaves. Tadpoles were divided into a treatment in which 50 tadpoles were fed Bt maize leaves and a control treatment in which 50 tadpoles were fed non-Bt maize leaves. Tadpoles were placed individually in 250 ml plastic cups that were each filled with 100 ml borehole water. On a weekly basis 10 randomly selected tadpoles were collected, measured and staged for morphological development, using the Nieuwkoop and Faber Normal Table for X. laevis and Gosner stages for A. gutturalis tadpoles. The significant effects observed in some life history parameters of tadpoles exposed to Cry1Ab protein cannot be ascribed to the effect of the protein. Poor husbandry turned out to be the single most important confounding factor. Before follow-up studies are conducted husbandry practices should be optimized. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.

The fall armyworm, Spodoptera frugiperda (J. E. Smith 1797) (Lepidoptera: Noctuidae), is considered the main insect-pest of corn in Brazil. Its control, in recent years, is mainly accomplished through the use of Bt plants and spray insecticides. Aiming to evaluate the efficiency of Bt proteins expressed by maize commercially available, as well as their interaction with the use of insecticides for the control of S. frugiperda to subsidize IPM and IRM programs in Bt maize, experiments were carried under field condition during two crop seasons in the 2015-16. Eight technologies of Bt maize and one non-Bt hybrid were evaluated, as well as seven insecticide application programs. Damage assessments were performed every five days, counting the number of damaged plants and assigning a score according to the Davis Scale (1992). For the application of the insecticides, a control level was established in which the spraying was carried out whenever 10% of the plants showed a damage score > 3. In the 1st season 2015/16, Agrisure TL (Cry1Ab), Herculex (Cry1F) and Optimum Intrasect (Cry1Ab/ Cry1F) and non-Bt maize required 1 to 3 sprays of insecticides to complement the control of S. frugiperda. In this season, all tested insecticides were efficient in control. In the case of YieldGard VT PRO (Cry1A.105 / Cry2Ab2), YieldGard VT PRO 3 (Cry1A.105 / Cry2Ab2 / Cry3Bb1), PowerCore (Cry1A.105 / Cry2Ab2 / Cry1F), Agrisure Viptera (Vip3Aa20) and Agrisure Viptera 3 (Vip3Aa20 / Cry1Ab) the use of insecticides was not necessary. In the second crop year 2015/16, with the exception of Agrisure Viptera and Agrisure Viptera 3, all other hybrids of Bt and non-Bt maize required 1 to 4 sprays of insecticides. The results obtained in the present work demonstrate that some Bt maize technologies (expressing genes that encode Cry1 proteins) present low control efficiency, thus making insecticides indispensable to complement the control of S. frugiperda. In contrast, the Vip3Aa20 protein shows high toxicity to S. frugiperda, showing insignificant damage to the culture. Among the insecticides tested in the work, spinetoram (12 g of a.i./ha), in general presented the highest control efficiency for fall armyworm. / A lagarta-do-cartucho, Spodoptera frugiperda (J. E. Smith 1797) (Lepidoptera: Noctuidae), é considerada o principal inseto-praga da cultura do milho no Brasil. Seu controle, nos últimos anos, é realizado principalmente por meio do uso de plantas Bt e pulverização de inseticidas. Visando avaliar a eficiência das proteínas Bt expressas pelos milhos disponíveis no mercado, bem como sua interação com o uso de inseticidas para o controle de S. frugiperda para subsidiar programas de MIP e MRI em milho Bt, foram realizados experimentos, em condição de campo, durante duas épocas de cultivo na safra 2015-16. Foram avaliadas oito tecnologias de milho Bt e um híbrido não-Bt, bem com sete programas de aplicação de inseticidas. A cada cinco dias, foram realizadas avaliações de dano, contabilizando o número de plantas danificadas e atribuindo uma nota de acordo com a Escala de Davis (1992). Para a aplicação dos inseticidas, foi estabelecido um nível de controle em que era realizada a pulverização sempre que 10% das plantas apresentassem nota de dano >3. Na 1a safra 2015/16, Agrisure TL (Cry1Ab), Herculex (Cry1F) e Optimum Intrasect (Cry1Ab/Cry1F) e milho não-Bt necessitaram de 1 a 3 pulverizações de inseticidas para complementar o controle de S. frugiperda. Nesta safra, todos os inseticidas testados foram eficientes no controle. Já em milho YieldGard VT PRO (Cry1A.105/Cry2Ab2), YieldGard VT PRO 3 (Cry1A.105/Cry2Ab2/Cry3Bb1), PowerCore (Cry1A.105/Cry2Ab2/ Cry1F), Agrisure Viptera (Vip3Aa20) e Agrisure Viptera 3 (Vip3Aa20/Cry1Ab) não foi necessário o uso de inseticidas. Na 2a safra 2015/16, com exceção de Agrisure Viptera e Agrisure Viptera 3, todos as demais híbridos de milho Bt e não-Bt necessitaram de 1 a 4 pulverizações de inseticidas. Os resultados obtidos no presente trabalho demonstram que algumas tecnologias de milho Bt (expressando genes que codificam proteínas Cry1) apresentam baixa eficiência de controle, tornando-se assim indispensável o uso de inseticidas para complementar o controle de S. frugiperda. Em contraste, a proteína Vip3Aa20 apresenta alta toxicidade para S. frugiperda, apresentando danos insignificantes à cultura. Dentre os inseticidas testados no trabalho, spinetoram (12 g de i.a./ha), de modo geral apresentou a maior eficiência de controle para lagarta-do-cartucho.