Based on surface area, South Africa is currently ranked 8th in planting genetically modified (GM) crops in the world. The stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is of economic importance throughout sub–Saharan Africa. Bt maize (MON810) has been grown to control lepidopterous stem borers in South Africa since its first release in 1998. The first report of resistance to Bt maize was made in the Christiana area of South Africa in 2007. The objectives of this study were to evaluate the status of resistance of populations of B. fusca to Bt maize; to evaluate farmers' perceptions of the regulatory aspects guiding the planting of Bt maize and refugia and how the field situation developed between 1998 and 2010; to compare the fitness of the fertility, fecundity and longevity of Bt–resistant and susceptible B. fusca populations and to determine if there are fitness costs associated with resistance of B. fusca to Bt maize. Questionnaire surveys were conducted amongst 185 farmers in seven districts throughout the maize production region. The questionnaire addressed signing of contracts upon purchasing GM seed, refuge compliance, pest management practices, perceived benefits and risks relating to Bt maize. In order to study fitness and fitness costs that may be associated with resistance development, the life history parameters of known Bt–resistant and susceptible populations were compared in the laboratory using a diapauses–as well as second–generation populations collected in maize fields. The following parameters were compared between different stem borers populations and treatments: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. This study confirmed resistance of B. fusca to the Cry1Ab toxin (MON810) and that larvae collected from refugia at Vaalharts were resistant and survived on Bt maize. Compliance to refugia requirements was low especially during the initial 5 – 7 years after release. An alarmingly high number of farmers applied insecticides as preventative sprays on Bt maize and refugia. Except for moth longevity and LT50– values, no other fitness costs were observed to be associated with the resistance trait in the highly resistant B. fusca population used in this study. The LT50 may indicate some degree of fitness cost but does not translate into observable costs in terms of fecundity, larval mass and survival. The absence of fitness costs may promote the use of alternative Bt–resistance management strategies, such as the introduction of a multigene strategy. The introduction of a stacked event such as MON89034 which produces more than one protein with activity active against the resistant target pest, together with compliance to the refuge strategy, is most likely the only solution to managing Btresistant stem borer populations in South Africa. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Based on surface area, South Africa is currently ranked 8th in planting genetically modified (GM) crops in the world. The stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is of economic importance throughout sub–Saharan Africa. Bt maize (MON810) has been grown to control lepidopterous stem borers in South Africa since its first release in 1998. The first report of resistance to Bt maize was made in the Christiana area of South Africa in 2007. The objectives of this study were to evaluate the status of resistance of populations of B. fusca to Bt maize; to evaluate farmers' perceptions of the regulatory aspects guiding the planting of Bt maize and refugia and how the field situation developed between 1998 and 2010; to compare the fitness of the fertility, fecundity and longevity of Bt–resistant and susceptible B. fusca populations and to determine if there are fitness costs associated with resistance of B. fusca to Bt maize. Questionnaire surveys were conducted amongst 185 farmers in seven districts throughout the maize production region. The questionnaire addressed signing of contracts upon purchasing GM seed, refuge compliance, pest management practices, perceived benefits and risks relating to Bt maize. In order to study fitness and fitness costs that may be associated with resistance development, the life history parameters of known Bt–resistant and susceptible populations were compared in the laboratory using a diapauses–as well as second–generation populations collected in maize fields. The following parameters were compared between different stem borers populations and treatments: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. This study confirmed resistance of B. fusca to the Cry1Ab toxin (MON810) and that larvae collected from refugia at Vaalharts were resistant and survived on Bt maize. Compliance to refugia requirements was low especially during the initial 5 – 7 years after release. An alarmingly high number of farmers applied insecticides as preventative sprays on Bt maize and refugia. Except for moth longevity and LT50– values, no other fitness costs were observed to be associated with the resistance trait in the highly resistant B. fusca population used in this study. The LT50 may indicate some degree of fitness cost but does not translate into observable costs in terms of fecundity, larval mass and survival. The absence of fitness costs may promote the use of alternative Bt–resistance management strategies, such as the introduction of a multigene strategy. The introduction of a stacked event such as MON89034 which produces more than one protein with activity active against the resistant target pest, together with compliance to the refuge strategy, is most likely the only solution to managing Btresistant stem borer populations in South Africa. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

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.

O uso de culturas GM (geneticamente modificadas) tem sido questionado quanto ao destino dos produtos derivados da transgenia no ambiente. Com a liberação de exsudatos das raízes das plantas e a decomposição dos resíduos culturais, aumenta-se a quantidade de DNA transgênico no ambiente, que pode ser adsorvido à superfície ativa das partículas do solo e/ou degradado pela ação de enzimas microbianas. A comunidade microbiana do solo pode entrar em contato direto com estes produtos, aumentando a probabilidade de transferência horizontal de fragmentos de DNA transgênico para os microrganismos. Também, alterações na composição dos exsudatos das plantas GM e mudanças em função das práticas de manejo, podem resultar em alterações na composição funcional e estrutural da comunidade microbiana. Assim, faz-se necessário avaliar a persistência dos produtos derivados da transgenia no solo e seus possíveis efeitos sobre a comunidade microbiana. Os objetivos deste estudo foram: avaliar a persistência dos fragmentos 35S-hsp70, hsp70-cry1Ab e cry1Ab-planta da construção gênica do milho Bt (evento MON810) em diferentes tipos de solo e temperaturas, em condições de microcosmo e de campo; e determinar a abundância do número de cópias dos gene 16S rRNA de Bacteria, Firmicutes, Verrucomicrobria e Archaea, e 18S rRNA de Fungo nas mesmas condições, e avaliar a estrutura da comunidade bacteriana em áreas agrícolas de cultivo de milho Bt. No primeiro estudo, o DNA do milho Bt MON810 foi adicionado em solos arenoso e argiloso. Como controle negativo, apenas água estéril foi misturada ao solo. Amostras de solo foram incubadas a 15 e 25ºC. Em campo, os solos foram amostrados em três áreas agrícolas em Fátima do Sul, MS, em dois anos consecutivos. Após extração de DNA, os fragmentos foram quantificados por qPCR. No segundo estudo, foram determinadas a abundância dos genes 16S rRNA de Bacteria, Firmicutes, Verrucomicrobria e Archaea e 18S rRNA de Fungo e avaliada a estrutura da comunidade bacteriana por T-RLFP. Os resultados mostraram que em condições de microcosmo, os fragmentos hsp70-cry1Ab e cry1Ab-planta persistiram até 291 dias, e o fragmento 35S-hsp70 até 180 dias. A temperatura e o tipo de solo não afetaram a persistência dos fragmentos. Em campo, o número de cópias desses fragmentos foi maior na segunda coleta. No segundo estudo, o número de cópias do gene 16S rRNA de Bacteria aumentou com adição de DNA do milho Bt nos microcosmos, e uma redução do número de cópias foi verificada para Archaea, Verrucomicrobia e Fungo. Para Firmicutes, os resultados não foram consistentes. As temperaturas não resultaram em efeito na abundância dos genes, enquanto o tipo de solo teve efeito apenas para Archaea e Verrucomicrobia. Áreas agrícolas com cinco anos de cultivo de milho Bt apresentaram variações na estrutura da comunidade bacteriana em nível de filo, e maior abundância de Fungos no segundo ano de amostragem, enquanto em área com um ano de cultivo, observouse uma redução da população de Firmicutes e Verrucomicrobia. Os maiores efeitos na comunidade microbiana foram verificados entre os anos de amostragem / The use of GM (genetically modified) crops has been questioned about the fate of transgenes is derived products on the environment. With the release of exudates from roots of GM plants and the decomposition of its residues, the amount of transgenic DNA in the environment increases, which can be adsorbed to the active surface of soil particles and/or be degraded by the action of microbial enzymes. Soil microbial communities can come into direct contact with these products, raising the probability of horizontal transfer of transgenic DNA fragments to soil microorganisms. Moreover, changes in exudates composition of GM plants and changes depending on the management practices may result in structural and functional alterations in the microbial community. Thus, it is necessary to evaluate the persistence of transgenes is derivatives in the soil and effects on microbial community. The objectives of this study were to assess the persistence of fragments 35S-hsp70, hsp70-cry1Ab and cry1Abplant from the genetic construct of Bt corn (event MON810) in different soil types and temperatures, in microcosm and field conditions; and to determine the abundance of 16S rRNA copy number of Bacteria, Firmicutes, Verrucomicrobria and Archaea and 18S rRNA of Fungi under the same conditions, and to evaluate the structure of bacterial communities in agricultural areas of Bt corn cultivation. In the first study, DNA from Bt corn MON810 was added to sandy and clay soils. As negative control, only sterile water was mixed with soil. Soil samples were incubated at 15 and 25°C. At the field, soils were sampled in three agricultural areas in Fátima do Sul, MS, in two consecutive years. After DNA extraction, fragments were quantified by qPCR. In the second study, the abundance of 16S rRNA of Bacteria, Firmicutes, Verrucomicrobria and Archaea and 18S rRNA of Fungi were determined and the structure of bacterial communities was evaluated by T-RFLP. The results showed that in microcosm conditions, hsp70-cry1Ab and cry1Ab-plants fragments persisted until 291 days and the 35S-hsp70 up to 180 days. The temperature and the type of soil did not affect the persistence of fragments. In field, the copy number of these fragments was greater in the second sampling. In the second study, the copy number of 16S rRNA of Bacteria increased with the addition of DNA from Bt corn in microcosm, and a reduction in copy number was observed for Archaea, Verrucomicrobia and Fungi. The results were not consistent for Firmicutes. Temperatures resulted in no effect in gene abundance, while the soil was effective only for Archaea and Verrucomicrobia. Agricultural areas with five years of Bt corn cultivation showed variations in bacterial community structure at the phylum level, and greater abundance of fungi in the second year of sampling, while in the area with a year of cultivation, a reduction in population of Firmicutes and Verrucomicrobia was observed. The largest effects on the microbial community were observed between the sampled years

A evolução da resistência de insetos a culturas que expressam proteínas derivadas de Bacillus thuringiensis (Bt) é o maior desafio para a manutenção dessa biotecnologia em programas de manejo integrado de pragas. Diante do risco de evolução de resistência de Helicoverpa armigera (Hübner) à soja MON87701 × MON89788 foi realizada uma análise de risco levando em consideração o conjunto de fatores que influenciam no processo de seleção. Portanto, os objetivos do presente estudo foram a de caracterizar a suscetibidade à proteína Cry1Ac em populações de H. armigera e H. zea, caracterizar a eficácia da soja MON87701 × MON89788, bem como a adequação do produto ao conceito de alta dose para H. armigera e H. zea, avaliar a frequência dos alelos que conferem resistência à proteína Cry1Ac em populações de H. armigera, identificar a preferência hospedeira de H. armigera e H. zea em diferentes culturas e paisagens agrícolas e avaliar os parâmetros biológicos e demográficos de H. armigera e H. zea em diferentes hospedeiros. A espécie H. zea foi aproximadamente 60 vezes mais tolerante à proteína Cry1Ac que H. armigera. Além disso, baixa variabilidade na suscetibilidade à Cry1Ac foi verificada em populações de H. armigera coletadas em diferentes regiões do Brasil, o que pode ser explicada pela recente introdução dessa espécie no continente americano. A soja MON87701 × MON89788 resultou em mortalidade completa de H. armigera durante todo o ciclo da cultura, enquanto que para H. zea não foi verificado 100% de mortalidade sob condições de laboratório em bioensaios de cinco dias de duração, apesar dos altos níveis de mortalidade encontrados. Uma baixa frequência (frequência estimada = 0,0011) de alelos que conferem resistência à soja MON87701 × MON89788 em populações de campo de H. armigera foi estimada pelo método de F2 screen. A avaliação da tabela de vida em laboratório demonstrou que H. armigera tem altos níveis de desenvolvimento e a reprodução nas principais culturas das regiões dos Cerrados, sendo a cultura do algodão a que resulta nos maiores valores de crescimento populacional e menor tempo entre gerações. Por outro lado, H. zea se mostrou menos polífaga, se estabelecendo até a fase adulta e gerando descendentes apenas em milho e milheto. A ocorrência das duas espécies no campo corrobora com as informações encontradas na tabela de vida, na qual H. armigera foi encontrada em grande parte as culturas da soja e algodão, e em menor frequência à cultura do milho, enquanto que H. zea apresentou comportamento funcionalmente monófago no campo, associada apenas à cultura do milho. Os parâmetros toxicológicos da soja MON87701 × MON89788 associada à alta suscetibilidade de H. armigera à proteína Cry1Ac e à baixa frequência inicial de alelos que conferem resistência se adéquam aos preceitos da estratégia de alta dose/refúgio. A manutenção das áreas de refúgio com plantas não-Bt, de acordo com as recomendações, é essencial para retardar o processo de seleção de resistência de populações de H. armigera à soja MON87701 × MON89788 no Brasil. / Insect resistance to crops expressing proteins derived from Bacillus thuringiensis proteins (Bt) impose the biggest challenge to maintaining the value of this biotechnology in integrated pest management programs. To support a resistance to Helicoverpa armigera (Hübner) to soybean MON87701 × MON89788 was carried out a risk analysis taking into account all factors that influence the selection process. Therefore, the objectives of this study were to characterize the suscetibidade the Cry1Ac protein in H. armigera populations and H. zea, characterize the effectiveness of soybean MON 87701 × MON 89788, as well as the suitability of the product to the concept of high dose H. armigera and H. zea, evaluate the frequency of alleles that confer resistance to Cry1Ac protein in H. armigera populations from different regions of agricultural production, understand the host preference of H. armigera and H. zea in different crops in and agricultural landscapes and evaluate the biological and demographic parameters of H. armigera and H. zea on different hosts. The species H. zea was approximately 60 times more tolerant to Cry1Ac protein than H. armigera. Low variability on susceptibility to Cry1Ac was found among field H. armigera populations, what can be explained by the recent introduction of this species into America. MON 87701 × MON 89788 soybean resulted in complete mortality of H. armigera throughout the crop cycle, while incomplete mortality was found for H. zea using leaf disc bioassays, although high levels of mortality were found. A low resistance allele frequency (estimated frequency = 0.0011) to MON 87701 × MON 89788 soybean was estimated by using the F2 screen methodology. The assessment of the Life Table parameters in laboratory demonstrated the main row crops such as cotton, soybean and maize are suitable for the development and reproduction of H. armigera, wherein cotton resulted in higher values of population growth parameter and shorter times between generations. Conversely, H. zea was less polyphagous in which only corn and millet were suitable hosts. Field occurrence of both species was consistent with laboratory studies. H. amigera was mostly found in soybean and cotton, and rarely on corn, while H. zea was found mainly on maize. Overall, toxicological aspects of MON87701 × MON89788 soybean associated with high susceptibility of H. armigera to Cry1Ac protein and low initial resistance allele frequency fit properly to the highdose/ refuge strategy to delay resistance evolution. Therefore, maintenance of compliance with the refuge recommendation is essential to delay the evolution of resistance in H. armigera to MON87701 × MON89788 soybean in Brazil.

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.

Made available in DSpace on 2016-02-26T14:53:09Z (GMT). No. of bitstreams: 1 DanielleThomazoni.pdf: 361748 bytes, checksum: e23c010490a33e575109ef09926a6f11 (MD5) Previous issue date: 2008-01-22 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The impact of transgenic cotton NuOpal® (Bollgard®) which expreses the Cry1Ac gene of bacteria Bacillus thuringiensis (Bt), producing insecticidal protein against the lepidopteran target-pests Alabama argillacea (Hübner, 1823), Heliothis virescens (Fabricius, 1781) and Pectinophora gossypiella (Saunders, 1844) was evaluated in field conditions during crop season 2006/2007 in Dourados/MS, Brazil. We compared the effect of NuOpal® with non-transgenic isogenic DeltaOpal®on the biodiversity of target-pests, the nontarget pests and the natural enemies (mainly predators) to a non-treated crop. Two methodologies of visual sampling were evaluated: whole plant observation and beatsheet. Bollgard® technology presented efficient control on the target-pests. The average number of species was significantly lower in Bt-cotton than in non-Bt cotton. In the whole plant sampling, pests the verage number of specimes of non-target pests was significantly higher in NuOpal® than DeltaOpal®. This difference was not observed with beatsheet sampling. The diversity of nontarget pests characterized by Shannon-Wiener index was higher in NuOpal® than DeltaOpal® in the whole plant observation. The average number of specimes and the diversity of natural enemies also characterized by Shannon-Wiener index did not differ significantly between Bt-cotton and non-Bt cotton in both sampling methods / O impacto da cultivar de algodoeiro transgênica NuOpal® (Bollgard®), a qual expressa o gene Cry1Ac da bactéria Bacillus thuringiensis (Bt) que produz proteína de efeito inseticida contra os lepidópteros Alabama argillacea (Hübner, 1823), Heliothis virescens (Fabricius, 1781) e Pectinophora gossypiella (Saunders, 1844) foi avaliado no campo durante a safra 2006/2007 em Dourados/MS, Brasil. Comparamos o efeito de NuOpal® e da cultivar isogênica não-transgênica DeltaOpal® sobre a biodiversidade de pragas-alvo, pragas não-alvo e inimigos naturais (principalmente predadores), através de cultivo sem aplicação de inseticidas. Foram utilizadas duas metodologias de amostragem visual: planta inteira e pano-de-batida. Verificou-se que a tecnologia Bollgard® apresentou eficiência de controle sobre as pragas-alvo. O número médio de espécimes de pragas-alvo foi significativamente menor em algodão-Bt do que em algodão não-Bt. Na amostragem planta inteira, pragas não-alvo apresentaram em NuOpal® número médio de indivíduos significativamente maior do que o apresentado em DeltaOpal®, enquanto que no método de observação com pano-de-batida esta diferença não existiu. A diversidade de pragas não-alvo caracterizada pelo índice de Shannon-Wiener foi maior em NuOpal® do que em DeltaOpal® no método de planta inteira. O número médio de espécimes e a diversidade de inimigos naturais também caracterizada pelo índice de Shannon-Wiener não apresentaram diferença significativa entre as cultivares Bt e não-Bt em ambos os métodos de amostragem

Biotechnologies potentially have significant benefits for developing countries but many countries lack complete regulatory processes to allow their release. In evaluating the potential benefits of genetically modified crops, one must be able to measure the true cost of regulations in addition to the other costs associated with bringing the crop to market. The objectives of this paper are to (1) identify the direct costs of the regulation of Bt eggplant, Bt rice, ringspot virus resistant (PRSV) papaya and virus resistant tomatoes in the Philippines, and (2) estimate the opportunity cost of time lost in the regulatory process. The study compares the cost of regulations as they differ by factors such as the existence of previous studies on the product or the intention for export or domestic use. It is hypothesized that the costs are greater for products that are intended for export or human consumption or are produced by the private sector. It is also hypothesized that these factors increase the time to complete the regulatory process, therefore increasing the opportunity cost of time. This study evaluates the economic impact of the GMO regulatory process on the change in producer surplus, the net present value and the internal rate return using an economic surplus model. Scientists and other experts in the field of GMOs and regulation were interviewed to obtain the necessary data on the regulatory process. The evaluation was carried out for four different commodities in the Philippines, Bt Rice, Bt Eggplant, PRSV Papaya and MVR Tomato. The results for the open economy model revealed a change in producer surplus, as a result of the GMO research, of $418.3 million for Bt Rice and $353.7 million for PRSV Papaya. The closed economy model of Bt Eggplant has a change in producer surplus of $25.1 million and a change in total surplus of $40.8 million while the result for the change in producer surplus for MVR Tomato is $19.3 million and the change in total surplus is $51.6 million. A sensitivity analysis of the results was then carried out in which the elasticity of supply, the cost of regulation, and the release date were each varied in order to show the welfare impact of such changes. The sensitivity analysis revealed limited changes in surplus when elasticity and regulatory costs were changed. However, changing the date of release or commercialization resulted in monumental changes in surplus. / Master of Science

Organic insecticides play a big role in reducing the usage of chemical insecticides and their negative impact on the environment. Bacillus thuringiensis (Bt) spays are the only tool that organic farmers are allowed to use for the control of pests. Genetic engineering and modification of crops have been made possible with scientific advances in cell and molecular biology. These advances are used to transfer some of the Bt Cry toxins into crops for control of target species to reduce yield loss. Bt maize were commercialised for the first time in South Africa in 1998 and the economic important stem borers, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) and Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae) were exposed to the Cry1Ab toxin that is found in Bt maize. Busseola fusca developed resistance to Cry1Ab under field conditions within eight years after it had been released. Eldana saccharina (Walker) (Lepidoptera: Pyralidae) is a major pest on sugarcane in South Africa and although it has not been recorded on maize in this country, is it known as a major pest of maize in other African countries. African armyworm, Spodoptera exempta (Walker) (Lepidoptera: Noctuidae) has a very wide distribution in Africa and is known to be an occasional pest on maize. The aims of this dissertation were to determine the efficacy of Bt spray applications for control of four lepidopteran pests and whether development of Cry1Ab resistance by B. fusca caused a loss in susceptibility to other Bt toxins (i.e. cross-resistance). Susceptibility bioassays with 10 day old larvae were conducted under laboratory conditions. Treatments included application of various dosage rates of Dipel® and deltamethrin as well as exposure to MON810 (maize leaves). Stemborer populations of C. partellus, E. saccharina, and B. fusca (Venda) as well as the S. exempta were effectively controlled by the Bt spray, Dipel®. Care should be taken not be interpret the percentage C. partellus, E. saccharina and S. exempta larvae that survived after exposure to MON810 and Bt spray treatments as development of resistance without verification of these experiments with earlier instars that are known to be more susceptible. Spodoptera exempta is active throughout a year in temperate zones of Africa. If S. exempta develop resistance to Cry toxins and Bt maize events would be released for commercial planting in these areas, S. exempta pose a threat added to their injuriousness. Busseola fusca larvae were sampled from Venda (susceptible population), Ventersdorp and the Vaalharts Irrigation Scheme (resistant population). The Ventersdorp B. fusca population was controlled by MON810 and MON89034 and Bt sprays, but the percentage larvae that survived showed reduced susceptibility within the population. Dipel® treatments, MON810 and MON89034 did not provide effective control of the Vaalharts B. fusca population reported to be resistant to Cry1Ab, in two experiments. The high survival rates indicate a reduction in susceptibility to Cry toxins other than Cry1Ab and therefore development of cross resistance in the Vaalharts B. fusca population. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Organic insecticides play a big role in reducing the usage of chemical insecticides and their negative impact on the environment. Bacillus thuringiensis (Bt) spays are the only tool that organic farmers are allowed to use for the control of pests. Genetic engineering and modification of crops have been made possible with scientific advances in cell and molecular biology. These advances are used to transfer some of the Bt Cry toxins into crops for control of target species to reduce yield loss. Bt maize were commercialised for the first time in South Africa in 1998 and the economic important stem borers, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) and Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae) were exposed to the Cry1Ab toxin that is found in Bt maize. Busseola fusca developed resistance to Cry1Ab under field conditions within eight years after it had been released. Eldana saccharina (Walker) (Lepidoptera: Pyralidae) is a major pest on sugarcane in South Africa and although it has not been recorded on maize in this country, is it known as a major pest of maize in other African countries. African armyworm, Spodoptera exempta (Walker) (Lepidoptera: Noctuidae) has a very wide distribution in Africa and is known to be an occasional pest on maize. The aims of this dissertation were to determine the efficacy of Bt spray applications for control of four lepidopteran pests and whether development of Cry1Ab resistance by B. fusca caused a loss in susceptibility to other Bt toxins (i.e. cross-resistance). Susceptibility bioassays with 10 day old larvae were conducted under laboratory conditions. Treatments included application of various dosage rates of Dipel® and deltamethrin as well as exposure to MON810 (maize leaves). Stemborer populations of C. partellus, E. saccharina, and B. fusca (Venda) as well as the S. exempta were effectively controlled by the Bt spray, Dipel®. Care should be taken not be interpret the percentage C. partellus, E. saccharina and S. exempta larvae that survived after exposure to MON810 and Bt spray treatments as development of resistance without verification of these experiments with earlier instars that are known to be more susceptible. Spodoptera exempta is active throughout a year in temperate zones of Africa. If S. exempta develop resistance to Cry toxins and Bt maize events would be released for commercial planting in these areas, S. exempta pose a threat added to their injuriousness. Busseola fusca larvae were sampled from Venda (susceptible population), Ventersdorp and the Vaalharts Irrigation Scheme (resistant population). The Ventersdorp B. fusca population was controlled by MON810 and MON89034 and Bt sprays, but the percentage larvae that survived showed reduced susceptibility within the population. Dipel® treatments, MON810 and MON89034 did not provide effective control of the Vaalharts B. fusca population reported to be resistant to Cry1Ab, in two experiments. The high survival rates indicate a reduction in susceptibility to Cry toxins other than Cry1Ab and therefore development of cross resistance in the Vaalharts B. fusca population. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014