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1.
Article | IMSEAR | ID: sea-189700

ABSTRACT

The environmental risk assessment of the insect resistant genetically modified maize MON 89034 (Reference EFSA/GMO/BE/2011/90) has been performed by the Panel on Genetically Modified Organisms (GMO) of the Norwegian Scientific Committee for Food Safety (VKM). VKM has been requested by the Norwegian Directorate for Nature Management and the Norwegian Food Safety Authority to issue a preliminary scientific opinion on the safety of the genetically modified maize MON 89034 (Unique identifier MON-89Ø34-3) for cultivation, and submit relevant scientific comments or questions to EFSA on the application EFSA/GMOBE/2011/90. The current submission is intended to complement application EFSA-GMO-NL-2007-37, which was approved by Commission Decision 2009/813/EC of 30 October 2009, authorising the placing on the market of products containing, consisting of, or produced from genetically modified maize MON 89034 (scope import, processing, food and feed). Maize MON89034 has previously been assessed by the VKM GMO Panel in connection with EFSA´s public hearing of the application EFSA/GMO/NL/2007/37 (VKM 2008a). Preliminary health- and environmental risk assessments of several stacked events, with MON 89034 as one of the parental lines, have also been performed by the VKM GMO Panel (VKM 2009a, b, c; VKM 2010a,b). The environmental risk assessment of the maize MON 89034 is based on information provided by the applicant in the application EFSA/GMO/BE/2011/90, and scientific comments from EFSA and other member states made available on the EFSA website GMO Extranet. The risk assessment also considered peer-reviewed scientific literature as relevant. The VKM GMO Panel has evaluated MON 89034 with reference to its intended uses in the European Economic Area (EEA), and according to the principles described in the Norwegian Food Act, the Norwegian Gene Technology Act and regulations relating to impact assessment pursuant to the Gene Technology Act, Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms, and Regulation (EC) No 1829/2003 on genetically modified food and feed. The Norwegian Scientific Committee for Food Safety has also decided to take account of the appropriate principles described in the EFSA guidelines for the risk assessment of GM plants and derived food and feed (EFSA 2006, 2011a), the environmental risk assessment of GM plants (EFSA 2010), the selection of comparators for the risk assessment of GM plants (EFSA 2011b), and for the post-market environmental monitoring of GM plants (EFSA 2006, 2011c). The scientific risk assessment of maize MON 89034 include molecular characterisation of the inserted DNA and expression of target proteins, comparative assessment of agronomic and phenotypic characteristics, unintended effects on plant fitness, potential for gene transfer, interactions between the GM plant and target and non-target organisms, effects on biogeochemical processes and evaluations of the post-market environmental plan. In line with its mandate, VKM emphasised that assessments of sustainable development, societal utility and ethical considerations, according to the Norwegian Gene Technology Act and Regulations relating to impact assessment pursuant to the Gene Technology Act, shall not be carried out by the Panel on Genetically Modified Organisms. The genetically modified maize MON 89034 was developed to provide protection against certain lepidopteran target pest, including European corn borer (Ostrinia nubilalis) and Mediterranean corn borer (Sesamia nonagrioides). Protection is achieved through expression in the plant of two insecticidal Cry proteins, Cry1A.105 and Cry2Ab2, derived from Bacillus thuringiensis, a common soil bacterium. Cry1A.105, encoded by the cry1A.105 gene, is a chimeric protein made up of different functional domains derived from three wild-type Cry proteins from B. thuringiensis subspecies kurstaki and aizawai. The Cry2Ab2 protein is encoded by the cry2Ab2 gene derived from B. thuringiensis subspecies kurstaki. Molecular characterization: Appropriate analysis of the integration site, including flanking sequence and bioinformatics analysis, has been performed to characterise the transformation event MON 89034. The results of the segregation analysis are consistent with a single site of insertion for the cry1A.105 and cry2Ab2 gene expression cassettes and confirm the results of the molecular characterisation. Molecular analysis of both self-pollinated and cross-fertilised lines, representing a total of seven different generations, indicates that the inserted DNA is stably transformed and inherited from one generation to the next. No genes that encode resistance to antibiotics are present in the genome of MON 89034 maize. The molecular characterisation confirmed the absence of both the aad and nptII genes, which were used in the cloning and transformation process. Event MON 89034 and the physical, chemical and functional characteristics of the proteins have previously been evaluated by The VKM Panel on Genetically Modified Organisms, and considered satisfactory (VKM 2008a). Comparative assessment: The field trials for comparative assessment of agronomic and phenotypic characteristics of maize MON 89034 in the USA (2004-2005) and Europe (2007), have been performed in accordance with the EFSAs guidelines for risk assessment of genetically modified plants and derived food and feed (EFSA 2010, 2011a). Based on results from the comparative analyses, it is concluded that maize MON 89034 is agronomically and phenotypically equivalent to the conventional counterpart and commercial available reference varieties, with the exception of the lepidopteran-protection trait. The field evaluations support a conclusion of no phenotypic changes indicative of increased plant weed/pest potential of MON 89034 compared to conventional maize. Evaluations of ecological interactions between maize MON 89034 and the biotic and abiotic environment indicate no unintended effects of the introduced trait on agronomic and phenotypic characteristics. Environmental risk: There are no reports of the target Lepidopteran species attaining pest status on maize in Norway. Since there are no Bt-based insecticides approved for use in Norway, and lepidopteran pests have not been registered in maize, issues related to resistance evolution in target pests are not relevant at present for Norwegian agriculture. Published scientific studies show no or negligible adverse effects of Cry1A.105 and Cry2Ab2 proteins on non-target arthropods that live on or in the vicinity of maize plants. Cultivation of maize MON 89034 is not considered to represent a threat to the prevalence of red-listed species in Norway. Few studies have been published examining potential effects of Cry1A.105 and Cry2Ab toxin on ecosystems in soil, mineralization, nutrient turnover and soil communities. Some field studies have indicated that root exudates and decaying plant material containing Cry proteins may affect population size and activity of rhizosphere organisms (soil protozoa and microorganisms). However, data are only available from short term experiments and predictions of potential long term effects are difficult to deduce. Most studies conclude that effects on soil microorganisms and microbial communities are transient and minor compared to effects caused by agronomic and environmental factors. Few studies have assessed the impact of Cry proteins on non-target aquatic arthropods and the fate of these proteins in senescent and decaying maize detritus in aquatic environments. Further studies with better experimental design are needed for the assessment of the potential effects of Bt crops on aquatic organisms. However, exposure of non-target organisms to Cry proteins in aquatic ecosystems is likely to be very low, and potential exposure of Bt toxins to non-target organisms in stream ecosystems in Norway is considered to be negligible. Maize is the only representative of the genus Zea in Europe, and there are no cross-compatible wild or weedy relatives outside cultivation with which maize can hybridise and form backcross progeny. Vertical gene transfer in maize therefore depends on cross-pollination with other conventional or organic maize varieties. In addition, unintended admixture of genetically modified material in seeds represents a possible way for gene flow between different crop cultivations. The risk of pollen flow from maize volunteers is negligible under Norwegian growing conditions. In addition to the data presented by the applicant, the VKM GMO Panel is not aware of any scientific report of increased establishment and spread of maize MON 89034 and any change in survival (including over-wintering), persistence and invasiveness capacity. Because the general characteristics of maize MON 89034 are unchanged, insect resistance are not likely to provide a selective advantage outside cultivation in Norway. Since MON 89034 has no altered agronomic and phenotypic characteristics, except for the specific target pest resistance, the VKM GMO Panel is of the opinion that the likelihood of unintended environmental effects due to the establishment and survival of maize MON 89034 will be no different to that of conventional maize varieties in Norway The environmental risk assessment will be completed and finalized by the VKM Panel on Genetically Modified Organisms when requested additional information from the applicant is available.

2.
Article | IMSEAR | ID: sea-189687

ABSTRACT

In preparation for a legal implementation of EU-regulation 1829/2003, the Norwegian Scientific Committee for Food Safety (VKM) has been requested by the Norwegian Directorate for Nature Management to conduct final environmental risk assessments for all genetically modified organisms (GMOs) and products containing or consisting of GMOs that are authorized in the European Union under Directive 2001/18/EC or Regulation 1829/2003/EC. The request covers scope(s) relevant to the Gene Technology Act. The request does not cover GMOs that VKM already has conducted its final risk assessments on. However, the Directorate requests VKM to consider whether updates or other changes to earlier submitted assessments are necessary. MON810 notification C/F/95/12-02 is approved under Directive 90/220/EEC for cultivation, seed production, import and processing into feeding stuffs and industrial purposes since 22 April 1998 (Commission Decision 98/294/EC). In December 1997, food and food ingredients derived from the progeny of maize line MON810 were notified under Article 5 of Regulation (EC) No 258/97 on novel foods and novel food ingredients. In addition, existing food and feed products containing, consisting of or produced from MON810 were notified according to Articles 8 and 20 of Regulation (EC) No 1829/2003 and were placed in the Community Register in 2005. Three applications for renewal of the authorisation for continued marketing of (1) existing food and food ingredients produced from MON810; (2) feed consisting of and/or containing maize MON810, and MON810 for feed use (including cultivation); and (3) food and feed additives, and feed materials produced from maize MON810 within the framework of Regulation (EC) No 1829/2003 were submitted in 2007. Maize MON810 has previously been assessed by the VKM GMO Panel commissioned by the Norwegian Directorate for Nature Management in connection with the national finalisation of the procedure of the notification C/F/95/12/02 (VKM 2007a,b). In addition, MON810 has been evaluated by the VKM GMO Panel as a component of several stacked GM maize events (VKM 2005a,b,c, VKM 2007c, VKM 2008, VKM 2009, VKM 2012). Due to the publication of updated guidelines for environmental risk assessments of genetically modified plants and new scientific literature, the VKM GMO Panel has decided to deliver an updated environmental risk assessment of MON810. The environmental risk assessment of the maize MON810 is based on information provided by the applicant in the notification C/F/95/12/02 and application EFSA/GMO/RX/MON810, and scientific comments from EFSA and other member states made available on the EFSA website GMO Extranet. The risk assessment also considered other peer-reviewed scientific literature as relevant. The VKM GMO Panel has evaluated MON810 with reference to its intended uses in the European Economic Area (EEA), and according to the principles described in the Norwegian Food Act, the Norwegian Gene Technology Act and regulations relating to impact assessment pursuant to the Gene Technology Act, Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms, and Regulation (EC) No 1829/2003 on genetically modified food and feed. The Norwegian Scientific Committee for Food Safety has also decided to take account of the appropriate principles described in the EFSA guidelines for the risk assessment of GM plants and derived food and feed (EFSA 2006, 2011a), the environmental risk assessment of GM plants (EFSA 2010), the selection of comparators for the risk assessment of GM plants (EFSA 2011b), and for the post-market environmental monitoring of GM plants (EFSA 2006, 2011c). The scientific risk assessment of maize MON810 include molecular characterisation of the inserted DNA and expression of the target protein, comparative assessment of agronomic and phenotypic characteristics, unintended effects on plant fitness, potential for gene transfer, interactions between the GM plant and target and non-target organisms, effects on biogeochemical processes and evaluations of the post-market environmental plan. In line with its mandate, VKM emphasised that assessments of sustainable development, societal utility and ethical considerations, according to the Norwegian Gene Technology Act and Regulations relating to impact assessment pursuant to the Gene Technology Act, shall not be carried out by the Panel on Genetically Modified Organisms. The genetically modified maize MON810 was developed to provide protection against certain lepidopteran target pests, including European corn borer (Ostrinia nubilalis) and species belonging to the genus Sesamia. Protection is achieved through expression in the plant of the insecticidal Cry protein, Cry1Ab, derived from Bacillus thuringiensis ssp. kurstaki, a common soil bacterium. Molecular characterisation Appropriate analysis of the integration site including flanking sequences and bioinformatics analyses have been performed to analyse the construct integrated in the GM plant. Updated bioinformatics analyses revealed that one ORF shared sequence similarity to a putative HECT-ubiquitin ligase protein. The VKM GMO Panel found no safety implications from the interruption of this gene sequence. Analyses of leaf, grains, whole plant tissue and pollen from the maize MON 810 demonstrated that the Cry1Ab protein is expressed at very low levels in all tissues tested and constitutes less than 0.001% of the fresh weight in each tissue. The cry1Ab gene is the only transgene expressed in line MON 810 and was expressed highest in the leaves. The stability of the genetic modification has been demonstrated over several generations. Event MON810 and the physical, chemical and functional characteristics of the proteins have previously been evaluated by The VKM Panel on Genetically Modified Organisms, and considered satisfactory (VKM 2007a,b). Comparative assessment: Comparative analyses of data from field trials located at representative sites and environments in the USA and Europe indicate that maize MON810 is agronomically and phenotypically equivalent to the conventional counterpart and commercially available reference varieties, with the exception of the lepidopteran-protection trait, conferred by the expression of the Cry1Ab protein. The field evaluations support a conclusion of no phenotypic changes indicative of increased plant weed/pest potential of MON810 compared to conventional maize. Evaluations of ecological interactions between maize MON810 and the biotic and abiotic environment indicate no unintended effects of the introduced trait on agronomic and phenotypic characteristics. Environmental risk: There are no reports of the target lepidopteran species attaining pest status on maize in Norway. Since there are no Bt-based insecticides approved for use in Norway, and lepidopteran pests have not been registered in maize, issues related to resistance evolution in target pests are not relevant at present for Norwegian agriculture. Published scientific studies show no or negligible adverse effects of Cry1Ab protein on non-target arthropods that live on or in the vicinity of maize plants. Cultivation of maize MON810 is not considered to represent a threat to the prevalence of red-listed species in Norway. Few studies have been published examining potential effects of Cry1Ab toxin on ecosystems in soil, mineralization, nutrient turnover and soil communities. Some field studies have indicated that root exudates and decaying plant material containing Cry proteins may affect population size and activity of rhizosphere organisms (soil protozoa and microorganisms). Most studies conclude that effects on soil microorganisms and microbial communities are transient and minor compared to effects caused by agronomic and environmental factors. However, data are only available from short term experiments and predictions of potential long term effects are difficult to deduce. Few studies have assessed the impact of Cry proteins on non-target aquatic arthropods and the fate of these proteins in senescent and decaying maize detritus in aquatic environments. However, exposure of non-target organisms to Cry proteins in aquatic ecosystems is likely to be very low, and potential exposure of Bt toxins to non-target organisms in aquatic ecosystems in Norway is considered to be negligible. Maize is the only representative of the genus Zea in Europe, and there are no cross-compatible wild or weedy relatives outside cultivation with which maize can hybridise and form backcross progeny. Vertical gene transfer in maize therefore depends on cross-pollination with other conventional or organic maize varieties. In addition, unintended admixture of genetically modified material in seeds represents a possible way for gene flow between different crop cultivations. The risk of pollen flow from maize volunteers is negligible under Norwegian growing conditions. In addition to the data presented by the applicant, the VKM GMO Panel is not aware of any scientific report of increased establishment and spread of maize MON810 and any change in survival (including over-wintering), persistence and invasiveness capacity. Because the general characteristics of maize MON810 are unchanged, insect resistance are not likely to provide a selective advantage outside cultivation in Norway. Since MON810 has no altered agronomic and phenotypic characteristics, except for the specific target pest resistance, the VKM GMO Panel is of the opinion that the likelihood of unintended environmental effects due to the establishment and survival of maize MON810 will be no different to that of conventional maize varieties in Norway. Overall conclusion: The VKM GMO Panel concludes that cultivation of maize MON810 is unlikely to have any adverse effect on the environment in Norway.

3.
Rev. bras. entomol ; 62(3): 198-204, July-Sept. 2018. tab
Article in English | LILACS | ID: biblio-1045513

ABSTRACT

ABSTRACT The coffee berry borer Hypothenemus hampei Ferrari, 1876 (Coleoptera: Curculionidae: Scolytinae) is considered the most serious pest of the coffee crop and is controlled primarily with the use of chemical insecticides. An alternative to this control method is the use of the entomopathogenic bacterium, Bacillus thuringiensis Berliner, 1911. Therefore, the objective of this work was to select strains of B. thuringiensis virulent against H. hampei and characterize them by morphological and molecular methods to identify possible genes for the production of genetically modified plants. To achieve this objective, 34 strains of B. thuringiensis underwent a selective bioassay to evaluate their toxicity to H. hampei first-instar larvae. Among the strains tested, 11 and the standard B. thuringiensis subspecies israelensis (IPS-82) caused mortality above 90%. Then, the median lethal concentration (LC50) was estimated for these strains followed by characterization using morphological, biochemical and molecular methods. The lowest LC50 was obtained for strain BR58, although this concentration did not differ significantly from that of the standard strain IPS-82 or from that of strains BR137, BR80 and BR67. The molecular characterization detected cry4A, cry4B, cry10, cry11 and cyt1 genes in 10 of the most virulent strains (BR58, BR137, BR80, BR81, BR147, BR135, BR146, BR138, BR139, BR140). Strain BR67 differed completely from the others and amplified only the cry3 gene. This strain was more virulent than BR135, BR146, BR138, BR139 and BR140, but it did not differ from BR58, BR137, BR80, BR81 and BR147. The protein profile revealed proteins of 28, 65, 70 and 130 kDa, and the morphological analysis identified spherical crystalline inclusions in all strains. The results showed that the 11 strains studied have potential for use as a gene source for insertion into coffee plants for the control H. hampei, especially the cry3, cry4A, cry4B, cry10, cry11 and cyt1 genes, that were repeated in the most virulent isolates.

4.
Arq. Inst. Biol ; 85: e0132018, 2018. ilus, tab
Article in English | LILACS, VETINDEX | ID: biblio-999204

ABSTRACT

Bacillus thuringiensis subsp. israelensis has been used to control the Aedes aegypti (Diptera: Culicidae) mosquito larvae, the vector of virus diseases such as dengue, Chikungunya and Zika fever, which have become a major public health problem in Brazil and other tropical countries since the climate favors the proliferation and development of the transmitting vector. Because B. thuringiensis has shown potential for controlling insects of the Diptera order, this work aimed at testing the Bacillus thuringiensis subsp. thuringiensis strain T01-328 and its proteins Cry2Aa and Cry2Ab for control A. aegypti and at comparing the results to the B. thuringiensis subsp. israelensis specific dipteran strain. To this end, bioassays using spore-crystal of both strains, and Cry2Aa and Cry2Ab proteins from the heterologous expression in Escherichia coli, were performed against A. aegypti larvae. The results showed that the B. thuringiensis thuringiensis ­T01-328 has insecticidal activity against the larvae, but it is less toxic than B. thuringiensis subsp. israelensis. Cry2Aa and Cry2Ab proteins expressed heterologously were effective for controlling A. aegypti larvae. Therefore, the results indicate that the Cry2Aa and Cry2Ab proteins of the B. thuringiensis thuringiensis T01-328 can be used as an alternative to assist in the control of A. aegypti.(AU)


Bacillus thuringiensis subsp. israelensis vem sendo empregada no controle do díptero Aedes aegypti, vetor do vírus causador de doenças como dengue, febre Chikungunya e Zika, que se tornou um dos grandes problemas de saúde pública no Brasil e em outros países de clima tropical, que favorece a proliferação e o desenvolvimento do transmissor. Em virtude do potencial de B. thuringiensis no controle de dípteros, a proposta deste trabalho foi testar as proteínas Cry2Aa e Cry2Ab da linhagem de Bacillus thuringiensis subsp. thuringiensis T01-328 no controle de A. aegypti, em comparação à linhagem díptero específica B. thuringiensis subsp. israelensis. Para tanto, foram realizados bioensaios com larvas de A. aegypti com o esporo-cristal de ambas as linhagens, bem como com as proteínas Cry2Aa e Cry2Ab com expressão heteróloga em Escherichia coli. A linhagem B. thuringiensis thuringiensis T01-328 apresentou atividade inseticida contra as larvas, porém foi menos tóxica que a B. thuringiensis subsp. israelensis. As proteínas Cry2Aa e Cry2Ab expressas de forma heteróloga foram eficazes no controle de A. aegypti. Os resultados obtidos sugerem as proteínas Cry2Aa e Cry2Ab da linhagem B. thuringiensis thuringiensis T01-328 como alternativas para contribuir no controle do A. aegypti.(AU)


Subject(s)
Bacillus thuringiensis , Pest Control, Biological , Aedes/microbiology , Dengue , Disease Vectors , Chikungunya Fever , Zika Virus Infection
5.
Braz. j. microbiol ; 43(2): 618-626, Apr.-June 2012. ilus, tab
Article in English | LILACS | ID: lil-644478

ABSTRACT

The screening of Bacillus thuringiensis (Bt) Cry proteins with high potential to control insect pests has been the goal of numerous research groups. In this study, we evaluated six monogenic Bt strains (Bt dendrolimus HD-37, Bt kurstaki HD-1, Bt kurstaki HD-73, Bt thuringiensis 4412, Bt kurstaki NRD-12 and Bt entomocidus 60.5, which codify the cry1Aa, cry1Ab, cry1Ac, cry1Ba, cry1C, cry2A genes respectively) as potential insecticides for the most important insect pests of irrigated rice: Spodoptera frugiperda, Diatraea saccharalis, Oryzophagus oryzae, Oebalus poecilus and Tibraca limbativentris. We also analyzed their compatibility with chemical insecticides (thiamethoxam, labdacyhalothrin, malathion and fipronil), which are extensively used in rice crops. The bioassay results showed that Bt thuringiensis 4412 and Bt entomocidus 60.5 were the most toxic for the lepidopterans, with a 93% and 82% mortality rate for S. frugiperda and D. saccharalis, respectively. For O. oryzae, the Bt kurstaki NRD-12 (64%) and Bt dendrolimus HD-37 (62%) strains were the most toxic. The Bt dendrolimus HD-37 strain also caused high mortality (82%) to O. poecilus, however the strains assessed to T. limbativentris caused a maximum rate of 5%. The assays for the Bt strains interaction with insecticides revealed the compatibility of the six strains with the four insecticides tested. The results from this study showed the high potential of cry1Aa and cry1Ba genes for genetic engineering of rice plants or the strains to biopesticide formulations.


Subject(s)
Biological Assay , Bacillus thuringiensis/genetics , Bacillus thuringiensis/isolation & purification , In Vitro Techniques , Insect Vectors , Oryza/genetics , Proteins/analysis , Agricultural Pests , Methods , Virulence
6.
Braz. j. biol ; 70(3): 677-684, Aug. 2010. tab
Article in English | LILACS | ID: lil-555282

ABSTRACT

Among the phytophagous insects which attack crops, the fall armyworm, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera, Noctuidae) is particularly harmful in the initial growth phase of rice plants. As a potential means of controlling this pest, and considering that the entomopathogen Bacillus thuringiensis Berliner demonstrates toxicity due to synthesis of the Cry protein, the present study was undertaken to evaluate this toxic effect of B. thuringiensis thuringiensis 407 (pH 408) and B. thuringiensis kurstaki HD-73 on S. frugiperda. The following method was used. Both bacterial strains were evaluated in vitro in 1st instar S. frugiperda caterpillars, by means of histopathological assays. The Cry1Ab and Cry1Ac proteins, codified by the respective strains of B. thuringiensis, were evaluated in vivo by bioassays of 1st instar S. frugiperda caterpillars in order to determine the Mean Lethal Concentration (LC50). The results of the histopathological analysis of the midget of S. frugiperda caterpillars demonstrate that treatment with the B. thuringiensis thuringiensis strain was more efficient, because the degradations of the microvilosities started 9 hours after treatment application (HAT), while in the B. thuringiensis kurstaki the same effect was noticed only after 12 HAT. Toxicity data of the Cry1Ab and Cry1Ac proteins presented for the target-species LC50 levels of 9.29 and 1.79 μg.cm-2 respectively. The strains and proteins synthesised by B. thuringiensis thuringiensis and B. thuringiensis kurstaki are effective in controlling S. frugiperda, and may be used to produce new biopesticides or the genes may be utilised in the genetic transformation of Oryza sativa L.


Entre os insetos fitófagos que atacam as culturas, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera, Noctuidae) destaca-se como uma praga polífaga que causa prejuízos na fase inicial da cultura do arroz. No seu controle, o entomopatógeno Bacillus thuringiensis Berliner revela-se tóxico devido à síntese de proteínas Cry. Nesse contexto, o objetivo deste trabalho foi avaliar a toxicidade das cepas e proteínas Cry de B. thuringiensis thuringiensis 407 (pH 408) e B. thuringiensis kurstaki HD-73 sobre S. frugiperda. As duas cepas bacterianas foram avaliadas, in vitro, em lagartas de 1º instar de S. frugiperda, através de ensaios de histopatologia. As proteínas Cry1Ab e Cry1Ac, codificadas pelas respectivas cepas de B. thuringiensis, foram avaliadas in vivo, através de bioensaios com lagartas de 1º instar de S. frugiperda para determinação da Concentração Letal Média (CL50). Os resultados da análise histopatológica do intestino médio das lagartas S. frugiperda mostram que o tratamento com a cepa B. thuringiensis thuringiensis foi mais eficiente e a degradação das microvilosidade iniciou-se 9 horas após a aplicação dos tratamentos (HAT). Para B. thuringiensis kurstaki, o mesmo efeito foi observado, 12 HAT. Os dados de toxicidade das proteínas de Cry1Ab e Cry1Ac revelaram para a espécie-alvo uma CL50 de 9,29 e 1,79 μg.cm-2, respectivamente. As cepas e proteínas sintetizadas por B. thuringiensis thuringiensis e B. thuringiensis kurstaki são eficientes no controle de S. frugiperda, e poderão ser usadas na produção de novos biopesticidas ou a utilização dos genes na transformação genética de Oryza sativa L.


Subject(s)
Animals , Bacillus thuringiensis/chemistry , Bacterial Proteins/toxicity , Endotoxins/toxicity , Hemolysin Proteins/toxicity , Insecticides/toxicity , Spodoptera/drug effects , Bacillus thuringiensis/classification , Pest Control, Biological
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