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1
Nawrot-Esposito, Marie-Paule, Aurélie Babin, Matthieu Pasco, Marylène Poirié, Jean-Luc Gatti e Armel Gallet. "Bacillus thuringiensis Bioinsecticides Induce Developmental Defects in Non-Target Drosophila melanogaster Larvae". Insects 11, n. 10 (13 ottobre 2020): 697. http://dx.doi.org/10.3390/insects11100697.
Abstract (sommario):
Bioinsecticides made from the bacterium Bacillus thuringiensis (Bt) are the bestselling bioinsecticide worldwide. Among Bt bioinsecticides, those based on the strain Bt subsp. kurstaki (Btk) are widely used in farming to specifically control pest lepidopteran larvae. Although there is much evidence of the lack of acute lethality of Btk products for non-target animals, only scarce data are available on their potential non-lethal developmental adverse effects. Using a concentration that could be reached in the field upon sprayings, we show that Btk products impair growth and developmental time of the non-target dipteran Drosophila melanogaster. We demonstrate that these effects are mediated by the synergy between Btk bacteria and Btk insecticidal toxins. We further show that Btk bioinsecticides trigger intestinal cell death and alter protein digestion without modifying the food intake and feeding behavior of the larvae. Interestingly, these harmful effects can be mitigated by a protein-rich diet or by adding the probiotic bacterium Lactobacillus plantarum into the food. Finally, we unravel two new cellular mechanisms allowing the larval midgut to maintain its integrity upon Btk aggression: First the flattening of surviving enterocytes and second, the generation of new immature cells arising from the adult midgut precursor cells. Together, these mechanisms participate to quickly fill in the holes left by the dying enterocytes.
2
Mastore, Maristella, Sara Caramella, Silvia Quadroni e Maurizio Francesco Brivio. "Drosophila suzukii Susceptibility to the Oral Administration of Bacillus thuringiensis, Xenorhabdus nematophila and Its Secondary Metabolites". Insects 12, n. 7 (13 luglio 2021): 635. http://dx.doi.org/10.3390/insects12070635.
Abstract (sommario):
Drosophila suzukii, Spotted Wing Drosophila (SWD), is a serious economic issue for thin-skinned fruit farmers. The invasion of this dipteran is mainly counteracted by chemical control methods; however, it would be desirable to replace them with biological control. All assays were performed with Bacillus thuringiensis (Bt), Xenorhabdus nematophila (Xn), and Xn secretions, administered orally in single or combination, then larval lethality was assessed at different times. Gut damage caused by Bt and the influence on Xn into the hemocoelic cavity was also evaluated. In addition, the hemolymph cell population was analyzed after treatments. The data obtained show that the combined use of Bt plus Xn secretions on larvae, compared to single administration of bacteria, significantly improved the efficacy and reduced the time of treatments. The results confirm the destructive action of Bt on the gut of SWD larvae, and that Bt-induced alteration promotes the passage of Xn to the hemocoel cavity. Furthermore, hemocytes decrease after bioinsecticides treatments. Our study demonstrates that combining bioinsecticides can improve the efficacy of biocontrol and such combinations should be tested in greenhouse and in field in the near future.
3
Rajan, Vidya. "An Alkaline Foregut Protects Herbivores from Latex in Forage, but Increases Their Susceptibility to Bt Endotoxin". Life 13, n. 11 (11 novembre 2023): 2195. http://dx.doi.org/10.3390/life13112195.
Abstract (sommario):
About 10% of angiosperms, an estimated 20,000 species, produce latex from ubiquitous isoprene precursors. Latex, an aqueous suspension of rubber particles and other compounds, functions as an antifeedant and herbivory deterrent. It is soluble in neutral to alkaline pH, and coagulates in acidic environments. Here, I propose that foregut-fermenting herbivores such as ruminants, kangaroos, sloths, insect larvae, and tadpoles have adapted to latex in forage with the evolution of alkaline anterior digestive chamber(s). However, they consequently become susceptible to the action of Bacillus thuringiensis (Bt) δ-endotoxin and related bioinsecticides which are activated in alkaline environments. By contrast, hindgut-fermenting herbivores, such as horses and rabbits, have acidic anterior digestive chambers, in which latex coagulates and may cause gut blockage, but in which Bt is not activated. The latex-adapted foregut herbivore vs. latex-maladapted hindgut herbivore hypothesis developed in this paper has implications for hindgut-fermenting livestock and zoo animals which may be provided with latex-containing forage that is detrimental to their gut health. Further, ruminants and herbivorous tadpoles with alkaline anterior chambers are at risk of damage by the supposedly “environmentally friendly” Bt bioinsecticide, which is widely disseminated or engineered into crops which may enter animal feed streams.
4
K, LENIN, UDAYASURIYAN V e KANNAIYAN S. "Bacillus thuringiensis and its use in agriculture". Madras Agricultural Journal 88, june (2001): 187–97. http://dx.doi.org/10.29321/maj.10.a00317.
Abstract (sommario):
Bacillus thuringiensis (Bt) is an ubiquitous Gram positive, spore forming bacterium that forms parasporal crystal inclusions. These proteinaceous inclusions are called crystal (Cry) proteins or delta- endotoxins, which are toxic to insects. Hence preparations of Bt are being used as bioinsecticides for the past four decades in commercial agriculture and forest management for the control of certain insect species belonging to the orders of Lepidoptera, Diptera and Coleoptera. Bt is a major source for transfer of genes into plants to impart insect resistance. Since 1996 millions of hectares are grown with insect resistant transgenic plants containing Bt genes, in different parts of the world. Commercial release of transgenic Bt cotton in India is expected soon.
5
Souza, C. S. F., L. C. P. Silveira, R. M. Pitta, J. M. Waquil, E. J. G. Pereira e S. M. Mendes. "Response of field populations and Cry-resistant strains of fall armyworm to Bt maize hybrids and Bt-based bioinsecticides". Crop Protection 120 (giugno 2019): 1–6. http://dx.doi.org/10.1016/j.cropro.2019.01.001.
6
Xiong, Lei, Zhaoxia Liu, Jingge Li, Shuyuan Yao, Zeyun Li, Xuanhao Chen, Lingling Shen et al. "Analysis of the Effect of Plutella xylostella Polycalin and ABCC2 Transporter on Cry1Ac Susceptibility by CRISPR/Cas9-Mediated Knockout". Toxins 15, n. 4 (6 aprile 2023): 273. http://dx.doi.org/10.3390/toxins15040273.
Abstract (sommario):
Many insects, including the Plutella xylostella (L.), have developed varying degrees of resistance to many insecticides, including Bacillus thuringiensis (Bt) toxins, the bioinsecticides derived from Bt. The polycalin protein is one of the potential receptors for Bt toxins, and previous studies have confirmed that the Cry1Ac toxin can bind to the polycalin protein of P. xylostella, but whether polycalin is associated with the resistance of Bt toxins remains controversial. In this study, we compared the midgut of larvae from Cry1Ac-susceptible and -resistant strains, and found that the expression of the Pxpolycalin gene was largely reduced in the midgut of the resistant strains. Moreover, the spatial and temporal expression patterns of Pxpolycalin showed that it was mainly expressed in the larval stage and midgut tissue. However, genetic linkage experiments showed that the Pxpolycalin gene and its transcript level were not linked to Cry1Ac resistance, whereas both the PxABCC2 gene and its transcript levels were linked to Cry1Ac resistance. The larvae fed on a diet containing the Cry1Ac toxin showed no significant change in the expression of the Pxpolycalin gene in a short term. Furthermore, the knockout of polycalin and ATP-binding cassette transporter subfamily C2 (ABCC2) genes separately by CRISPR/Cas9 technology resulted in resistance to decreased susceptibility to Cry1Ac toxin. Our results provide new insights into the potential role of polycalin and ABCC2 proteins in Cry1Ac resistance and the mechanism underlying the resistance of insects to Bt toxins.
7
Kovalenko, T. K., S. D. Grishechkina e N. S. Kocheneva. "Protection of soybean plants from phytophages under conditions of the Primorsky Territory". Siberian Herald of Agricultural Science 53, n. 11 (13 dicembre 2023): 46–52. http://dx.doi.org/10.26898/0370-8799-2023-11-5.
Abstract (sommario):
The effectiveness of pre-sowing treatment of soybean seeds and application of biorational insecticides in reducing the number of major pests of soybean in the conditions of the Primorsky Territory have been studied. The results of using insecticides and biopreparations to regulate the number of dominant pests of soybean have been presented. The studies were conducted in 2020 and 2021. The efficiency of insecticidal protectants Imidor Pro, SC (2 l/t) and Tabu, WSC (1.0 l/t), bioinsecticides Fitoverm, EC (0, 16 l/ha), Proclaim, WSG (0.3 kg/ha), Batsikol, L (15 l/ha), Biosleep BW, L (2 l/ha), Biosleep BT, P (2 kg/ha) against two-striped leaf beetle (Medythia nigrobilineatus Motsch.) and soybean pod borer (Leguminivora glycinivorella Mats.) were studied. Pre-sowing seed treatment with insecticides Imidor Pro and Tabu reduced damage of soybean plants in the sprouting phase by Medythia nigrobilineatus beetles compared to the control by 94.0–98.2%. Seed dressing with imidacloprid-based preparations provided effective protection of crops against the pest in the sprouting – branching phase. Biorational insecticides based on avermectin C and Bacillus thuringiensis showed high biological efficacy (71.1–98.8%) on the 5–10th day after treatment against the two-striped leaf beetle. Soybean seed damage when bioinsecticides were used against Leguminivora glycinivorella was 1.9–3.0% compared to 5.6% in the control. The conducted studies testify to the prospect of using the preparations of biological origin to control the number of dominant pests in soybean crops.
8
Magalhães, G. O., A. M. Vacari, C. P. DE Bortoli, A. F. Pomari, S. A. DE Bortoli e R. A. Polanczyk. "Interactions Between Bt-Bioinsecticides and Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae), a Predator of Plutella xylostella (L.) (Lepidoptera: Plutellidae)". Neotropical Entomology 44, n. 5 (16 agosto 2015): 521–27. http://dx.doi.org/10.1007/s13744-015-0314-5.
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Duarte, Adriane da Fonseca, Juliano Lessa Pinto Duarte, Liliane Nachtigall Martins, Lucas Raphael da Silva, Nycole de Souza Cunha, Fábio Pereira Leivas Leite, Uemerson Silva da Cunha e Daniel Bernardi. "Toxicity of Bacillus sp. (Bacillales: Bacillaceae) on the fungus gnats, Bradysia aff. ocellaris larvae (Diptera: Sciaridae)". Bioscience Journal 39 (18 agosto 2023): e39089. http://dx.doi.org/10.14393/bj-v39n0a2023-59878.
Abstract (sommario):
Bacillus thuringiensis (Bt) Berliner has potential for use in insect management. Its use can be an alternative for the management of Bradysia aff. ocellaris (Comstock), considered one of the main strawberry pests in a soilless system. Therefore, the objective of this work was to evaluate the toxicity of different bacteria on B. aff. ocellaris in laboratory and greenhouse bioassays. The following isolates were used in the experiments: Bacillus circulans (Bc), B. thuringiensis var. oswaldo cruzi (Bto) or B. thuringiensis var. israelensis (Bti) and B. thuringiensis var. kurstaki (Btk) In the laboratory, B. aff. ocellaris larvae showed high susceptibility to Bti isolate (92 % mortality) 14 days after treatment exposure (DAET). In contrast, the isolates Bc, Bto, and Btk showed less than 32 % mortality, not differing from the control treatment (water – 22 % mortality). According to the concentration-response curves the values of lethal concentration LC50 and LC90 were 4 x 106 CFU.mL-1 and 4 x 1015 CFU.mL-1. By applying Bti (4 × 1012 CFU.mL-1) at the base of strawberry plants growing in plastic pots containing commercial plant substrate, a reduction of 26 % in the emergence of B. aff. ocellaris was observed. According to these results, the Bti isolate is considered promising for the formulation of bioinsecticides based on Bt for the management of B. aff. ocellaris in strawberry culture.
10
Dias, Felipe Cordeiro, Jaqueline Fernanda Dionísio, Daniel Ricardo Sosa-Gómez e Renata Da Rosa. "Molecular Characterization of Mutations in Anticarsia gemmatalis Cadherin Gene and their Relation to Bacillus thurigiensis Resistance". Global Journal of Agricultural Innovation, Research & Development 9 (28 aprile 2022): 54–60. http://dx.doi.org/10.15377/2409-9813.2022.09.5.
Abstract (sommario):
Anticarsia gemmatalis Hübner, 1818 is the main soybean defoliating pest in Brazil. The biological control of the species is done with products based on toxins produced by Bacillus thurigiensis (Bt), as bioinsecticides, or in transgenic plants. After activation by intestinal proteases, these toxins interact with receptors, especially cadherin, leading to death due to the formation of cellular pores. In recent years resistant populations have been identified in the laboratory, which can be a problem if the same patterns are found in crops, reducing their control effect. In this paper, we performed a comparative structural analysis of a mutation region for the gene of this receptor in A. gemmatalis, among resistant and susceptible strains treated with a toxin produced by Bt (Cry1Ac). The HaCad fragment of the cadherin gene was amplified by PCR, sequenced, and analyzed by bioinformatics tools. The PCR results were positive for resistant specimens but not for susceptible strains, suggesting the presence of a mutation in the resistant strain. In the sequenced fragments of the resistant insects, six haplotypes were found, and the originated amino acid sequences demonstrated the modification in four sites, which did not interfere with the three-dimensional shape of the protein. These data showed considerable variation taking into account the size of the fragment, even if they do not affect the final structure of the protein. The results allowed a better understanding of the mechanisms of resistance to Cry1Ac in the species, mainly in the involvement of cadherin in this process.
11
Shikov, Anton E., Yury V. Malovichko, Rostislav K. Skitchenko, Anton A. Nizhnikov e Kirill S. Antonets. "No More Tears: Mining Sequencing Data for Novel Bt Cry Toxins with CryProcessor". Toxins 12, n. 3 (23 marzo 2020): 204. http://dx.doi.org/10.3390/toxins12030204.
Abstract (sommario):
Bacillus thuringiensis (Bt) is a natural pathogen of insects and some other groups of invertebrates that produces three-domain Cry (3d-Cry) toxins, which are highly host-specific pesticidal proteins. These proteins represent the most commonly used bioinsecticides in the world and are used for commercial purposes on the market of insecticides, being convergent with the paradigm of sustainable growth and ecological development. Emerging resistance to known toxins in pests stresses the need to expand the list of known toxins to broaden the horizons of insecticidal approaches. For this purpose, we have elaborated a fast and user-friendly tool called CryProcessor, which allows productive and precise mining of 3d-Cry toxins. The only existing tool for mining Cry toxins, called a BtToxin_scanner, has significant limitations such as limited query size, lack of accuracy and an outdated database. In order to find a proper solution to these problems, we have developed a robust pipeline, capable of precise 3d-Cry toxin mining. The unique feature of the pipeline is the ability to search for Cry toxins sequences directly on assembly graphs, providing an opportunity to analyze raw sequencing data and overcoming the problem of fragmented assemblies. Moreover, CryProcessor is able to predict precisely the domain layout in arbitrary sequences, allowing the retrieval of sequences of definite domains beyond the bounds of a limited number of toxins presented in CryGetter. Our algorithm has shown efficiency in all its work modes and outperformed its analogues on large amounts of data. Here, we describe its main features and provide information on its benchmarking against existing analogues. CryProcessor is a novel, fast, convenient, open source (https://github.com/lab7arriam/cry_processor), platform-independent, and precise instrument with a console version and elaborated web interface (https://lab7.arriam.ru/tools/cry_processor). Its major merits could make it possible to carry out massive screening for novel 3d-Cry toxins and obtain sequences of specific domains for further comprehensive in silico experiments in constructing artificial toxins.
12
Shipsheva, Z. L., L. Kh Shidova e L. M. Khromova. "Expediency of protecting corn crops from progressive phytophages". Siberian Herald of Agricultural Science 53, n. 7 (22 agosto 2023): 57–63. http://dx.doi.org/10.26898/0370-8799-2023-7-7.
Abstract (sommario):
Monitoring of phytophages of corn crops in the conditions of Kabardino-Balkaria in the steppe arid zone for 2000–2021 was carried out in dynamics. It was noted that climate change in the direction of warming and significant increase in the areas of corn crops changed the phytosanitary situation, which led to the formation of foci of high numbers and harmfulness of cotton budworm. Control agents against cotton budworm and corn borer from different groups of chemical and biological compounds were studied. Protective measures were planned and implemented based on the predicted and actual phytosanitary situation in order to obtain ecologically cleaner and biologically nutritious grain products. Based on long-term observations, the outbreak of cotton budworm and corn borer was found to be periodic for 5 ± 1 years. This will allow timely spraying in years of maximum outbreaks of these pests. Determination of biological efficacy and competent rotation of the group of chemical insecticides will reduce their resistance to progressive pests on corn crops. Values of biological efficiency of insecticides in the variants of Voliam Flexi, SC and Avant, EC preparations corresponded to 97.1 and 95.6 %. The economic efficiency of the insecticides was evaluated by grain yield increment, where Voliam Flexi, SC, Avant, EC and Lepidocid, SC and had the values of 1.1; 1.0 and 0.5 t/ha, respectively. Long-term studies have established that yields depend on the degree of damage to cobs and corn grain by cotton budworm caterpillars. The reserve of significant increase of corn grain yield by 0.5–1.1 t/ha is the use of effective insecticides of chemical origin with low rates of consumption (Voliam Flexi, SC, Avant, EC). It has been revealed that 2-fold spraying with bioinsecticides Lepidocid, SC and Bioslip BT, P on the beginning and mass hatching of caterpillars significantly reduced the harmfulness of these pests, the biological efficiency of which amounted to 77.9 and 73.5 %, respectively.
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Sukirno, Fiola Siregar, Aryo Seto Pandu Wiranto, Suparmin Suparmin, Siti Sumarmi, Hari Purwanto, Ignatius Sudaryadi, R. C. Hidayat Soesilohadi e Abdulrahman Saad Aldawood. "Synergism of Turmeric, Moringa, Clove, and Red Betel Extracts with Bacillus thuringiensis var. kurstaki Berl. against Taro Caterpillar (Spodoptera litura Fab.) (Lepidoptera: Noctuidae) at the Laboratory Scale". Berkala Ilmiah Biologi 13, n. 3 (15 dicembre 2022): 36–42. http://dx.doi.org/10.22146/bib.v13i3.4718.
Abstract (sommario):
Bacillus thuringiensis is known as a bioinsecticide for controlling taro caterpillar, Spodoptera litura Fab. in cabbage plants. However, Bt. is easily degraded by ultraviolet (UV), so it needs UV protectant. This research aimed to study the synergism of extract of turmeric, moringa, cloves, and red betel as UV protectants for Bt. and to measure the Bt. half lifes. As much as 25 (w/v) of turmeric, moringa, cloves, and red betel extracts was used to make Bt. suspension. The Bt. suspension then was exposed to sunlight for 0, 1, 3, 7, 14, 21, and 28 days then it was tested againts 25 individuals of 1st larval instar of taro caterpillar and each treatment was using three replicates. Pathogenicity of each formulation was observed by calculating larval mortality up to the 7th day after treatment. The results showed that the highest larval mortality was found in the Bt. formulation added extracts at 0-day exposure. Mortality data for each Bt. treatment. showed a decrease from the treatment of 0 to 28-day exposures. After 28 days of exposure, Bt. without extract addition had a pathogenicity of 15.2%, whereas Bt. with clove extract had pathogenicity about 56.4%, which is higher than those on turmeric, moringa, and red betel. The first half life of Bt. added with clove was 32.3 days, while the second half life was 50.7 days. Based on this research, it can be concluded that clove has synergism affect when applied with Bt.
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Djunaedy, Achmad, Syaiful Khoiri, Nuriya Firdaus, Dita Megasari e Giyanto. "Field trial of new Bt-base bioinsecticide formula, Bashield®, for controlling Spodoptera frugiperda J.E. Smith on maize". E3S Web of Conferences 499 (2024): 01031. http://dx.doi.org/10.1051/e3sconf/202449901031.
Abstract (sommario):
Maize is one of the important staple crops. The process of cultivating corn cannot be separated from pests and plant diseases, one of the attacking pests is Spodoptera frugiperda, which can attack the growing points of plants causing a decrease in corn production. Based on previous research conducted in vitro, bioinsecticide of Bacillus thuringiensis-base (Bt-base) liquid formula (namely Bashield®) was able to reduce pupal weight, the proportion of larvae-pupae, and pupal becomes abnormal. Action that can be taken to control this attack is by utilizing biological agent, B. thuringiensis strain BT2, as an alternative control. This research aims to evaluate or to determine the effectiveness of a new bioinsecticide of Bt-base liquid formula (Bashield®), as a control agent for S. frugiperda on maize in the field. This research was prepared at the Laboratory of Plant Protection and Environment, Universitas Trunojoyo Madura, and was conducted at the Horticultural Seed Garden, Socah District, Bangkalan Regency, East Java, Indonesia (7°05'17.2"S 112°42'32.0"E). The design used was a complete randomized block design (CRBD) with 4 treatments and 6 replications. The data were analyzed using 5% ANOVA and if there was a significant effect, then a DMRT follow-up test was carried out with a 5% level. The results showed that the 15% treatment was able to kill test larvae up to 78% with a high virulence level, and reduced damage up to 100%. In conclusion, the new Bt-base liquid formula, Bashield®, has good potential for effective biocontrol and contributed as a new biopesticide for S. frugiperda.
15
Marzban, Rasoul. "INVESTIGATION ON THE SUITABLE ISOLATE AND MEDIUM FOR PRODUCTION OF BACILLUS THURINGIENSIS". Journal of Biopesticides 05, n. 02 (1 dicembre 2011): 144–47. http://dx.doi.org/10.57182/jbiopestic.5.2.144-147.
Abstract (sommario):
ABSTRACT Bacillus thuringiensis bioinsecticide has been widely used on crops worldwide to replace chemical pesticides. B. thuringiensis production by solid-state fermentation requires less capital investment and modest technical skills. The method is often considered unsuitable for growth of aerobic organisms. However, optimization of Bt production using solid-state fermentation can effectively contribute to promote use of this bacterium in insect pest management programs. Research into suitable nutrient concentrations of different media and characteristics of bacterial growth on these has enabled use of several agricultural or industrial by-products for mass production of several Bt strains. These materials include wheat bran, rice bran, rice crumb, and remaining barley from feeding of Sitotroga serealella. Wheat bran was the best of media for production of B. thuringiensis.
16
Tetreau, Guillaume, Elena A. Andreeva, Anne-Sophie Banneville, Elke De Zitter e Jacques-Philippe Colletier. "Can (We Make) Bacillus thuringiensis Crystallize More Than Its Toxins?" Toxins 13, n. 7 (26 giugno 2021): 441. http://dx.doi.org/10.3390/toxins13070441.
Abstract (sommario):
The development of finely tuned and reliable crystallization processes to obtain crystalline formulations of proteins has received growing interest from different scientific fields, including toxinology and structural biology, as well as from industry, notably for biotechnological and medical applications. As a natural crystal-making bacterium, Bacillus thuringiensis (Bt) has evolved through millions of years to produce hundreds of highly structurally diverse pesticidal proteins as micrometer-sized crystals. The long-term stability of Bt protein crystals in aqueous environments and their specific and controlled dissolution are characteristics that are particularly sought after. In this article, we explore whether the crystallization machinery of Bt can be hijacked as a means to produce (micro)crystalline formulations of proteins for three different applications: (i) to develop new bioinsecticidal formulations based on rationally improved crystalline toxins, (ii) to functionalize crystals with specific characteristics for biotechnological and medical applications, and (iii) to produce microcrystals of custom proteins for structural biology. By developing the needs of these different fields to figure out if and how Bt could meet each specific requirement, we discuss the already published and/or patented attempts and provide guidelines for future investigations in some underexplored yet promising domains.
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Loureiro, Elisângela De Souza, Luis Gustavo Amorim Pessoa, Thayla Christiane Putrick, Ariane De Andréa Pantaleão e Pamella Mingotti Dias. "IN VITRO COMPATIBILITY BETWEEN INSECTICIDES AND THE COMMERCIAL BIOINSECTICIDE AGREE® WG". JOURNAL OF NEOTROPICAL AGRICULTURE 7, n. 1 (3 aprile 2020): 49–52. http://dx.doi.org/10.32404/rean.v7i1.3597.
Abstract (sommario):
Compatibility studies are essential for the integration and simultaneous use of chemical and biological pest control methods since they are necessary for an Integrated Pest Management (IPM) program. In this work, the aim was to evaluate the compatibility of insecticides used in soybean and cotton crops for pest control with Bacillus thuringiensis (Bt). The in vitro inoculation technique was used with B. thuringiensis var. kurstaki and B. thuringiensis var. aizawai, in culture medium containing the following insecticides: beta-cyfluthrin (Bulldock®), methomyl (Bazuka®), thiamethoxam + lambda-cialotrina (Engeo Pleno®), zeta-cypermethrin (Fury 200®), acetamiprid (Saurus®), bifenthrin + carbosulfano (Talisman®) and bifenthrin (Talstar®), in Petri dishes. The Petri dishes were taken to the B.O.D. (Biological Oxygen Demand), at a temperature of 30 ± 1 ºC, 70 ± 10% RH (relative humidity) and a photophase of 12 h, for 24 hours. Colony growth was measured, and Colony Forming Units (CFU) counted in the total area of the Petri dish. The product that allowed growth to be significantly equal to or higher than the control was established as compatible, and the one that did not allow growth or was significantly less than the control was incompatible. It was found that all insecticides were classified as incompatible with the bioinsecticide.
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Flores P, Abad, Rosa M. Egúsquiza Ch., Mario Alcarraz C., Juan C. Woolcott H., Elena Benavides R, Juan Godoy A., Doris Huerta C., Yisella Jesus M. e Alejandro Patiño G. "Biodiversidad de Bacillus thuringiensis aislados de agroecosistemas peruanos y evaluación del potencial bioinsecticida". Ciencia e Investigación 14, n. 1 (13 giugno 2011): 30–35. http://dx.doi.org/10.15381/ci.v14i1.3235.
Abstract (sommario):
El control de plagas en la agricultura peruana se ha caracterizado por el uso intensivo de plaguicidas químicos; sin embargo, las pérdidas en el rendimiento y la aparición de resistencia en las plagas han llevado a los productores a incrementar el uso de plaguicidas. Este uso indiscriminado genera problemas de contaminación ambiental, muerte de la fauna benéfica, presencia de residuos químicos en los frutos, riesgo de intoxicaciones agudas y crónicas; además, incremento en los costos de producción. Los objetivos propuestos fueron aislar y caracterizar cepas de Bacillus thuringiensis de interés biotecnológico de suelos agrícolas peruanos, y evaluar su potencial entomotóxico frente a Spodoptera frugiperda. Se aislaron 54 cepas de Bacillus thuringiensis de 385 muestras de suelo agrícola de diferentes partes del país. Las observaciones microscópicas mostraron la presencia de cristales parasporales característicos. Las cepas aisladas fueron evaluadas y confirmadas en sus características culturales y bioquímicas. Los bioensayos realizados sobre Spodoptera frugiperda, mostraron que la cepa Bt-UNMSM-42 posee una toxicidad superior al resto de las cepas con una media de mortalidad de 39,73% con 50 μg/mL y de 71,93% para 250 μg/mL, con una desviación estándar de 11,30 y 9,98; respectivamente.
19
S., Khasanov,, e Muminov, R. "Use of Microbiological Preparations in the Fight Against Tetranychus urticae Koch on Roses, in the Conditions of the Protected Ground of the Tashkent Region". Bulletin of Science and Practice, n. 1 (15 gennaio 2023): 144–48. http://dx.doi.org/10.33619/2414-2948/86/19.
Abstract (sommario):
Presents data on the effect, under protected ground conditions of the Tashkent region, on the number of spider mites (Tetranychus urticae Koch) on roses, safe preparations for the environment. Microbiological preparations were used: Bitoxibacillin P, Bioslip BV, Bioslip BT, bioinsecticide Fitoverm 5% a. e. As a result, the best biological efficiency was in the variant when using Fitoverm 5% a. e., at consumption rate of 0.8 l/ha and ranged from 84.7% to 85.9%. In order to increase the effectiveness of the fight to reduce the number of spider mites (T. urticae), applied combined options: Fitoverm 5% a. e. 0.4 l/ha + Bitoxibacillin P 2 l/ha, and Fitoverm 5% a. e. 0.8 l/ha + Bitoxibacillin P 3 l/ha, where biological efficiency was obtained in the Fitoverm variant 5% a. e. 0.8 l/ha + Bitoxibacillin P 3 l/ha, up to 98.2% already on the third day and 98.6% lasted until the 14th day of observations.
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Zaiets, S., A. Kovalenko, L. Onufran, S. Yuzyuk e K. Fundirat. "Efficiency of biological insecticides against the main pests of winter wheat in the system of organic farming". Karantin i zahist roslin, n. 4 (30 dicembre 2023): 9–14. http://dx.doi.org/10.36495/2312-0614.2023.4.9-14.
Abstract (sommario):
Goal. To investigate the pest infestation of soft winter wheat (Triticum aestivum L.) crops and to determine the technological effectiveness of biological products against them in the system of organic farming.
Methods. Field studies to record the number of major pests of winter wheat before and after 10 days after treatment with biological insecticides were laid out and conducted in a six-man rotation of organic farming: peas — soft winter wheat — chickpeas — hard winter wheat — oil flax — millet. The winter wheat crops were treated twice in BBCH 31 and BBCH 59. The technical effectiveness of biological insecticides was determined and compared with chemical insecticides, and the reliability of the results obtained was determined using the mathematical and statistical method in the Agrostat program.
Results. The studies of 2021—2023 on the control variant (without treatment) of winter wheat observed an average of 1.1 copies/ m2 of the shell bug (Eurygaster integriceps Put.), 17.4 copies/stem of cereal aphids (Schizaphis graminum F.), 7.7 copies/ear of wheat thrips (Haplothrips tritici Kurd) and 4.5 copies/ m2 of bread beetle (Anisoplia austriaca Hrbst.), and on variants treated with biological insecticides — by 27.3—36.4%, respectively, 36.8—39.5, 40.6—50.7 and 33.3—46.7% less. The technical efficiency of biological preparations against the indicated pests in the years of research ranged from 10.0 to 68.8%, and that of chemical insecticides from 55.6 to 100.0% and depended on both the conditions of the year and the type of pest and the preparation. Among biological insecticides, the highest technical efficiency against the turtle bug and wheat thrips on winter wheat crops was provided by Bitoxybacillin-BTU, r. (10 l/ ha) — 31.6 and 53.2%, respectively, and against cereal aphids (37.5%) and bread beetle (47.5%) — Biospectr BT, r. (3 l/ha) with Metarizin BT, r. (3 l/ ha). Bioinsecticide Phytoimun Sintez, r. (1 + 1 l/ha) against the specified pests had somewhat lower technical efficiency — 23.3 and 45.3% and 33.8 and 33.0%, respectively.
Conclusions. The use of biological insecticides Bitoxybacillin-BTU, p. (10 l/ha), Biospectr BT, p. (3 l/ ha) with Metarizin BT, p. (3 l/ ha) and Phytoimun Sintez, p. (1 + 1 l/ha) on soft winter wheat crops in organic farming rotation makes it possible to reduce the number of shell bugs and cereal aphids by 1.4—1.6 times, and wheat thrips and bread beetle by 1.7—2.0 and 1.5—1.9 times compared to the control.
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Wang, Yaqin, Yan Zhang, Fang Wang, Chao Liu e Kede Liu. "Development of transgenic Brassica napus with an optimized cry1C* gene for resistance to diamondback moth (Plutella xylostella)". Canadian Journal of Plant Science 94, n. 8 (novembre 2014): 1501–6. http://dx.doi.org/10.4141/cjps-2014-099.
Abstract (sommario):
Wang, Y., Zhang, Y., Wang, F., Liu, C. and Liu, K. 2014. Development of transgenic Brassica napus with an optimized cry1C* gene for resistance to diamondback moth (Plutella xylostella). Can. J. Plant Sci. 94: 1501–1506. Bacillus thuringiensis (Bt) cry1Ac gene has been transformed into rapeseed to control diamondback moth (DBM, Plutella xylostella), which is one of the major lepidopteran pests of rapeseed (Brassica napus). However, Cry1A-resistant DBM populations have already developed in the field. Cry1C* is a new synthetic Bt gene based on the original cry1Ca5 sequence through optimizing its codons as well as removing AT-rich sequences and inverted repeats. In our present study, the cry1C* gene was introduced into rapeseed via Agrobacterium-mediated transformation, and a total of 42 transgenic lines were recovered. The results of polymerase chain reaction (PCR) and Southern blot both confirmed the expression of the cry1C* gene in the genomes of the transformants. We also assessed the expression of this foreign gene at the mRNA level in some selected transgenic lines by real-time reverse transcription (RT) PCR analysis. Enzyme-linked immunosorbent assay (ELISA) showed that the Cry1C* expression at the protein level greatly varied among individual transgenic plants, and transgenic line 1C-8 had the highest protein level of 799.32 ng g−1. The transgenic rapeseed plants expressing cry1C* gene showed a high efficacy against DBM. Taken together, the cry1C*-transgenic rapeseed could be employed as a useful germplasm in pest management and in the broad bioinsecticidal spectrum to prevent and postpone the development of pest resistance.
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TORRES, YOLIMA, SONIA BEJARANO, DANIEL URIBE e JAIRO CERÓN. "Análisis de algunas características asociadas a la actividad bioinsecticida de poblaciones obtenidas por curado de plásmidos de la cepa de Bacillus thuringiensis IBUN 28.5". Revista Colombiana de Entomología 27, n. 2 (31 dicembre 2001): 193–99. http://dx.doi.org/10.25100/socolen.v27i2.9687.
Abstract (sommario):
Spodoptera frugiperda (J. E Smith) es una plaga que representa pérdidas económicas para diferentes cultivos en nuestro país. El Instituto de Biotecnología de la Universidad Nacional, interesado en desarrollar estrategias para el control biológico de esta plaga, ha venido evaluando la actividad biopesticida de cepas nativas de Becillús thuringiensis (Berliner) sobre este insecto plaga. Dentro del proceso de caracterización de cepas nativas cabe destacar la cepa IBUN28.5 por presentar una mayor actividad biopesticida contra S. frugiperda, que la cepa estándar Bt subsp. aizawai HD137. Con el objeto de obtener colonias con diferente contenido de genes cry y evaluar la incidencia de éstos en la actividad insecticida, se aplicó la técnica de curado de plásmidos. Se emplearon naranja de acridina, bromuro de etidio, SOS, temperatura y en algunos casos subcultivos, como agentes para inducir curado de plásmidos en la cepa nativa IBUN28.5 y en la cepa estándar HD137. La selección de colonias curadas de plásrnldcs se realizó aplicando las técnicas de observación microscópica, perfil plasmídico, análisis electroforético de proteínas y PCR; las colonias seleccionadas se sometieron a ensayos de actividad biológica contra larvas de primer ínstar de S. frugiperda evaluando dos concentraciones de proteína liofilizada: 240 y 480 ng/cm2 observando como respuesta el porcentaje de mortalidad. Se obtuvieron colonias que presentaban la pérdida de un plásmido de aproximadamente 80 MDa para la cepa nativa y de 77 MDa para la cepa de referencia, 1 s cuales portan el gen cry1Ab. Otras poblaciones perdieron los genes cry1Ab, cry1C y cry1D, sin determinarse en cual(es) plásmido(s) se encuentran estos dos últimos genes. Los resultados obtenidos sugieren que todos los genes curados participan de forma importante en la actividad insecticida de la cepa IBUN 28.5 y de la cepa de referencia Bt aizawai HD137 y además que la diferencia de actividad presentada entre estas dos cepas reside principalmente en las características intrínsecas de los genes cry1C y cry1D.
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Ren, Xiang-Liang, Rui-Rui Chen, Ying Zhang, Yan Ma, Jin-Jie Cui, Zhao-Jun Han, Li-Li Mu e Guo-Qing Li. "A Spodoptera exigua Cadherin Serves as a Putative Receptor for Bacillus thuringiensis Cry1Ca Toxin and Shows Differential Enhancement of Cry1Ca and Cry1Ac Toxicity". Applied and Environmental Microbiology 79, n. 18 (8 luglio 2013): 5576–83. http://dx.doi.org/10.1128/aem.01519-13.
Abstract (sommario):
ABSTRACTCrystal toxin Cry1Ca fromBacillus thuringiensishas an insecticidal spectrum encompassing lepidopteran insects that are tolerant to current commercially usedB. thuringiensiscrops (Bt crops) expressing Cry1A toxins and may be useful as a potential bioinsecticide. The mode of action of Cry1A is fairly well understood. However, whether Cry1Ca interacts with the same receptor proteins as Cry1A remains unproven. In the present paper, we first cloned a cadherin-like gene,SeCad1b, fromSpodoptera exigua(relatively susceptible to Cry1Ca).SeCad1bwas highly expressed in the larval gut but scarcely detected in fat body, Malpighian tubules, and remaining carcass. Second, we bacterially expressed truncated cadherin rSeCad1bp and its interspecific homologue rHaBtRp fromHelicoverpa armigera(more sensitive to Cry1Ac) containing the putative toxin-binding regions. Competitive binding assays showed that both Cry1Ca and Cry1Ac could bind to rSeCad1bp and rHaBtRp, and they did not compete with each other. Third, Cry1Ca ingestion killed larvae and decreased the weight of surviving larvae. Dietary introduction ofSeCad1bdouble-stranded RNA (dsRNA) reduced approximately 80% of the target mRNA and partially alleviated the negative effect of Cry1Ca on larval survival and growth. Lastly, rSeCad1bp and rHaBtRp differentially enhanced the negative effects of Cry1Ca and Cry1Ac on the larval mortalities and growth ofS. exiguaandH. armigera. Thus, we provide the first lines of evidence to suggest that SeCad1b fromS. exiguais a functional receptor of Cry1Ca.
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Fonseca G., Alicia, Guadalupe Peña Ch., Adriana G. Trejo L., Laura P. Lina G., Luis Á. Rodríguez B. e Víctor M. Hernández V. "PATOGENICIDAD Y VIRULENCIA DE CEPAS DE BACILLUS THURINGIENSIS NATIVAS DEL ESTADO DE MORELOS SOBRE DIATRAEA MAGNIFACTELLA (LEPIDOPTERA: CRAMBIDAE)". ACTA ZOOLÓGICA MEXICANA (N.S.) 29, n. 3 (21 maggio 2013): 534–44. http://dx.doi.org/10.21829/azm.2013.2931596.
Abstract (sommario):
La caña de azúcar representa uno de los cultivos industriales más importantes en México, diversos insectos se alimentan de ésta, provocando pérdidas económicas considerables. Para el estado de Morelos se reporta la presencia de los barrenadores Diatraea magnifactella y Eoreuma loftini. Para su control se han usado insecticidas químicos, a la fecha no existen bioinsecticidas a base de bacterias entomopatógenas. Existen reportes de evaluaciones in vitro y en campo contra otras especies de barrenadores, por lo que en el presente trabajo se aislaron cepas de Bacillus thuringiensis (Bt) a partir de cadáveres de D. magnifactella. Se evaluó la patogenicidad y virulencia de las cepas bacterianas sobre larvas neonatas del barrenador para lo cual se estableció un pie de cría de D. magnifactella en laboratorio, garantizando así la sanidad de las larvas usadas en los bioensayos. Se obtuvo un total de 118 cepas de B. thuringiensis. Los cuales se agruparon en tres categorías, dependiendo del peso molecular de las proteínas mayoritarias (perfil proteico) producidas por la bacteria. De los bioensayos de patogenicidad realizados, seis de las 118 cepas evaluadas fueron las que ocasionaron una mortalidad mayor al 50% en las larvas neonatas de D. magnifactella. Se determinó la Concentración Letal 50 de éstas seis cepas, la que presentó mejores resultados fue la cepa B148 con CL50 de 254.01 ng/cm2 de dieta, menor a la de la cepa comercial HD1 417.61 ng/cm2, evaluada como testigo positivo. Las cinco cepas restantes presentaron CL50 superiores a la de la cepa testigo.
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Verdugo-Fuentes, Abel Alberto, Luciano Castro Espinoza, Marco A. Gutiérrez-Coronado e José Luis Martínez-Carrillo. "Metodologías para el análisis de expresión y cuantificación de proteínas conferidas en tejidos de cultivos GM". Revista Mexicana de Ciencias Agrícolas 10, n. 4 (21 giugno 2019): 815–28. http://dx.doi.org/10.29312/remexca.v10i4.1666.
Abstract (sommario):
Las toxinas Cry de Bacillus thuringiensis (Bt) son utilizadas como bioinsecticidas en la agricultura. Se precisa de métodos confiables que permitan analizar las características que se confieren a las plantas genéticamente modificadas (GM) durante su desarrollo, antes de su comercialización. El objetivo del trabajo fue estandarizar metodologías para el análisis de la expresión de genes y proteínas conferidas al algodonero GM durante sus diferentes etapas fenológicas en campo. Como principal aplicación práctica del estudio realizado, las metodologías estandarizadas se podrán emplear en la caracterización de cultivos GM que se desarrollen y para los cuales sea necesario realizar su análisis de riesgo. Para ello se procesaron muestras de tejido vegetal en diferentes etapas fenológicas obtenidas de predios comerciales de algodonero GM en el Valle del Yaqui. En los diferentes tejidos se cuantificó la expresión génica y proteica mediante análisis RTq-PCR y Elisa, respectivamente. Los resultados obtenidos muestran variación en la expresión de los genes conferidos a lo largo del desarrollo de la misma variedad y entre los diferentes sitios donde se ubicaron los cultivos. Los mayores niveles de expresión se identificaron, como se esperaba, en las etapas tempranas del cultivo (valores medios de 8.5 μg g-1 para Cry1Ac y 63.1 μg g-1 para Cry2Ab) comparados con lo observado en etapas tardías o maduras (valores medios de 0.05 y 0.3 μg g-1 para Cry1Ac y Cry2Ab, respectivamente). Por lo tanto, se concluye que las técnicas de RTq-PCR y ELISA son adecuadas para evaluar la expresión espacial y temporal de genes que se confieran a plantas GM, información requerida para caracterizar la exposición al peligro y poder realizar el análisis de riesgo.
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Le, Thanh, Ngoc Le, Ngoc Pham, Ha Trinh, Dong Quyen, Binh Ngo, Ha Chu, Ha Hoang e Dong Nguyen. "Detection of a novel Cry2Ab toxin against Etiella zinckenella Treitschke from the Bacillus thuringiensis serovar canadensis SP142 strain". Plant Protection Science 58, No. 2 (28 marzo 2022): 158–69. http://dx.doi.org/10.17221/59/2021-pps.
Abstract (sommario):
The soybean (Glycine max) is an important crop. The pod borer (Etiella zinckenella) is one of the most serious insects that attacks various Leguminosae. Common insecticidal controls are ineffective because of the insect’s growth properties. Use of resistant crop varieties offers stabilisation of the yield and has benefits over the use of insecticides. Bacillus thuringiensis is widely used as a bioinsecticide for pest control and a genetic material for pest-resistant transgenic plants. However, the resistance evolution of target insects is emerging as a major threat to the long-term efficacy of these applications. Studies on the detection of novel highly host-specific pesticidal proteins have been in urgent demand. A search for the source of Bt Cry toxins against E. zinckenella in the Vietnamese B. thuringiensis strain collection has been performed. The B. thuringiensis serovar canadensis SP142 is one of strains that resulted in more than 80% mortality to this pod borer. Its genome was estimated about 7.1 Mb and revealed a putative novel cry2Ab gene. The sequence analysis of cry2Ab gene revealed an open reading frame of 1 899 bp encoding a 633-amino acid protein with a calculated molecular mass of 70 kDa and 99.05% to 99.21% homology to known cry2Ab genes in the GenBank. There are eighteen different nucleotide sites which lead to five amino acid changes in Domain I and II. This gene was expressed in Escherichia coli BL21(DE3) and the purified Cry2Ab was toxic to E. zinckenella larvae with an LC<sub>50</sub> value of 1.74 µg/g diet. The novel Cry2Ab was designated as Cry2Ab39 by the Bacterial Pesticidal Protein Resource Center and its sequence was deposited in the GenBank (MN319700.1). This is a type of novel Cry2 toxin from B. thuringiensis against E. zinckenella, and it is important for breeding E. zinckenella-resistant soybeans.
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Cloutier, Conrad, e France Bauduin. "BIOLOGICAL CONTROL OF THE COLORADO POTATO BEETLE LEPTINOTARSA DECEMLINEATA (COLEOPTERA: CHRYSOMELIDAE) IN QUEBEC BY AUGMENTATIVE RELEASES OF THE TWO-SPOTTED STINKBUG PERILLUS BIOCULATUS (HEMIPTERA: PENTATOMIDAE)". Canadian Entomologist 127, n. 2 (aprile 1995): 195–212. http://dx.doi.org/10.4039/ent127195-2.
Abstract (sommario):
AbstractField plot tests during two seasons show that augmentative releases of Perillus bioculatus can control first-generation eggs and larvae of the Colorado potato beetle (CPB) under Quebec short-season conditions. Stinkbugs mass-reared on CPB were introduced manually as 2nd- and 3rd-stage nymphs during spring oviposition of the beetle at densities of one nymph per 50–225 CPB eggs recruited per plant, in 0.025-ha plots. Sampling at intervals of 1–3 days measured predator establishment, CPB egg and larval mortality, and foliage protection level. Direct observations were used to document predator-prey relationships and to determine weather conditions favourable to P. bioculatus.In the 1 st-year test, with predators released over all plants within plots, CPB control was compared among: (1) stinkbugs alone, (2) the bioinsecticide Bacillus thuringiensis (BT) as Trident™, (3) a combination of both control alternatives, and (4) no protection against the CPB. BT and stinkbugs, both alone and in combination, produced significant control as measured by percentage reductions in prepupal drop to the ground, new adult emergence, and foliage protection. Only treatments involving P. bioculatus reduced CPB egg eclosion which was the key control factor; it is strongly correlated with overall control level.In the 2nd-year test, predators were released in a central area comprising only 25% of all plants within plots. Predator and CPB egg mass densities were manipulated to produce predator: prey ratios of 0:1, 0:2, 1.5:2, 1.5:1, 3:2, and 3:1, representing average ratios of 0, 1.5,or 3 P. bioculatus per plant, and 1 or 2 CPB egg masses per plant at release time. As expected, central release produced complex interactions between control, and predator and prey densities. High beetle density slowed predator emigration from the centre, more so at low predator density than at high predator density. Predators moved more quickly within the same row than across rows. CPB eggs were destroyed in large numbers in both years but in 1993, final control correlated with larval rather than egg predation. A maximum 80% reduction in prepupal drop to the ground was obtained at the 3:1 predator:prey ratio (1 P. bioculatus:95 CPB eggs recruited per plant).The results prove the efficacy of P. bioculatus for biological control of first-generation L. decemlineata populations, at densities resulting in approximately 300 eggs laid per plant during spring oviposition in the study area. Despite low natural populations of P. bioculatus and unclear prospects for commercial availability at reasonable cost, it is evident that stinkbug releases have potential as a non-chemical control measure within an IPM program in Quebec potato production.
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Babin, Aurélie, Marie-Paule Nawrot-Esposito, Armel Gallet, Jean-Luc Gatti e Marylène Poirié. "Differential side-effects of Bacillus thuringiensis bioinsecticide on non-target Drosophila flies". Scientific Reports 10, n. 1 (1 ottobre 2020). http://dx.doi.org/10.1038/s41598-020-73145-6.
Abstract (sommario):
Abstract Bioinsecticides based on Bacillus thuringiensis (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in the environment on non-target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (~ 106 Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at ≥ 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species-and strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on non-target Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.
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Babin, Aurélie, Jean-Luc Gatti e Marylène Poirié. "Bacillus thuringiensis bioinsecticide influences Drosophila oviposition decision". Royal Society Open Science 10, n. 8 (agosto 2023). http://dx.doi.org/10.1098/rsos.230565.
Abstract (sommario):
Behavioural avoidance has obvious benefits for animals facing environmental stressors such as pathogen-contaminated foods. Most current bioinsecticides are based on the environmental and opportunistic bacterium Bacillus thuringiensis ( Bt ) that kills targeted insect pests upon ingestion. While food and oviposition avoidance of Bt bioinsecticide by targeted insect species was reported, this remained to be addressed in non-target organisms, especially those affected by chronic exposure to Bt bioinsecticide such as Drosophila species. Here, using a two-choice oviposition test, we showed that female flies of three Drosophila species (four strains of D. melanogaster , D. busckii and D. suzukii ) avoided laying eggs in the presence of Bt var. kurstaki bioinsecticide, with potential benefits for the offspring and female's fitness. Avoidance occurred rapidly, regardless of the fraction of the bioinsecticide suspension (spores and toxin crystals versus soluble toxins/compounds) and independently of the female motivation for egg laying. Our results suggest that, in addition to recent findings of developmental and physiological alterations upon chronic exposure to non-target Drosophila , this bioinsecticide may modify the competitive interactions between Drosophila species in treated areas and the interactions with their associated natural enemies.
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Duraisamy, Kalaiselvi, Nan Hee Yu, Seon Hwa Kim, Jong Hwi Baek, Ji Yeon Son, Euna Choi, Min Gu Park et al. "Development of a new broad-spectrum microencapsulation-based spray drying formulation of Bacillus thuringiensis subsp. kurstaki IMBL-B9 for the control of moths". Frontiers in Microbiology 14 (22 novembre 2023). http://dx.doi.org/10.3389/fmicb.2023.1273725.
Abstract (sommario):
Certain Bacillus thuringiensis (Bt) strains such as Bt subsp. kurstaki and Bt subsp. aizawai have been widely used for pest management in agricultural practices. However, each strain only shows high specificity for pest control against a narrow range of lepidopteran species, and numerous lepidopteran pests have developed resistance to commercialized Bt strains. Therefore, there is a need for the development of novel Bt bioinsecticides which allow for potent and broad-spectrum insecticidal activity against lepidopteran species, including Spodoptera spp. (Noctuidae) and Plutella xylostealla (Plutellidae). In order to develop a novel bioinsecticide using Bt subsp. kurstaki IMBL-B9 (Btk IMBL-B9) that exhibits excellent insecticidal activity against three different lepidopteran species, we have developed a viable microencapsulation-based spray drying Btk IMBL-B9 formulation. The spore-crystal complex of Btk IMBL-B9 was microencapsulated using coating materials such as gum arabic, maltodextrin, and corn starch via spray drying. The encapsulated formulation of Btk IMBL-B9 presented an increased survival rate and storage stability at 54 ± 2°C for up to 6 weeks. The formulation showed similar insecticidal activity as the commercial bioinsecticide XenTari® against P. xylostella. Under controlled greenhouse conditions, the Btk IMBL-B9 formulation was more effective against Lepidoptera spp. S. frugiperda and P. xylostella, than XenTari®. These results suggest that the microencapsulation-based spray drying formulation of Btk IMBL-B9 can be used effectively for the control of a wide range of moths.
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Thao, Nguyen Kim Nu, Do Thuy Linh, Dinh Thi Ngoc Mai, Pham The Hai e Nguyen Hong Minh. "Solid Fermentation of Bacillus thuringiensis: Method Development". VNU Journal of Science: Natural Sciences and Technology 37, n. 4 (7 dicembre 2021). http://dx.doi.org/10.25073/2588-1140/vnunst.5335.
Abstract (sommario):
Bacillus thuringiensis (Bt) is a significant bioinsecticidal agent that has been solely produced by liquid fermentation. With the increasing demand of bioinsecticides for organic agriculture, solid fermentation is preferred to enable low-cost and large-scale production of Bt. Therefore, in this study, we attempted to develop a solid state fermentation method to produce Bt by testing different solid substrates and also the effects of water percentage, fermentation time, temperature and seeding rate on the productions of biomass and parasporal crystal bodies (crystal proteins) of the Bt strain PAM33. Corn bran, rice bran and soybean meal are suitable to be utilized as substrates for biomass production. However, crystal proteins are only observed in solid fermentation using soybean meal as the substrate after 6 days of culture. The temperature range of 25-30°C and 10% seeding rate are the most suitable conditions for solid fermentation of strain PAM33 to obtain the bacterial density of approximate 109 CFU/g and the highest quantity of crystal proteins. This study shows that solid fermentation of Bt is feasible and effective to obtain bacterial biomass and crytal proteins by using cheap and available agricultural wastes. Thus, it can be a potential approach to produce the important Bt-based insecticide products for use in organic agriculture.
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Pereira, Jonathan, Lino Bittencourt Monteiro e Daniel Ricardo Sosa Gómez. "MORTALITY OF APPLE LEAFROLLER EXPOSED TO DIFFERENT Bacillus thuringiensis SUBSPECIES IN ARTIFICIAL DIET, IN THREE ASSESSMENT PERIODS". Revista Brasileira de Fruticultura 40, n. 1 (8 febbraio 2018). http://dx.doi.org/10.1590/0100-29452018732.
Abstract (sommario):
ABSTRACT Bioinsecticides based on Bacillus thuringiensis are the entomopathogen most marketed worldwide. The aim of this study was to evaluate the bioactivity of kurstaki, aizawai subspecies and kurstaki x aizawai hybrid on B. salubricola larvae fed on artificial diet in different assessment periods. Mortality was assessed on the seventh, tenth and fifteenth days after treatment. Microplates containing 150 µl of diet in each cell were used. Suspensions containing Bt subspecies was deposited on the surface of the diet, then neonate larvae were released. The mortality assessment performed after fifteen days of treatment was significant for all three subspecies. Bt kurstaki was more efficient in all assessment periods, except for fifteen days, which was similar to Bt aizawai. Assessments performed up to seven days were more efficient to determine mortality. The three subspecies have influenced the ability for instar change, regardless of concentration. The LC50 of Bt kurstaki on the seventh and tenth days of assessment was from three to six times smaller than that observed in Bt aizawai x kurstaki, and Bt aizawai, respectively.
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DAHIPHALE K D, S V WAGMARE, A K GHOTMUKALE e D P DESHPANDE. "Bio-rational management of groundnut defoliators (Spodoptera litura and Helicoverpa armigera) in kharif season". Journal of Oilseeds Research 40, Specialissue (14 dicembre 2023). http://dx.doi.org/10.56739/jor.v40ispecialissue.145294.
Abstract (sommario):
Field trial was laid at ORS, Latur (MS, India) to evaluate insecticides for the management of Helicoverpa armigera (Hubner) and Spodoptera litura (Fabricius) infesting groundnut. Insecticides/bioinsecticides evaluated were Bt-127 SC @3ml/lit, Delfin (Bt commercial formulation) @1g/lit, Quinalphos 25 EC @ 2ml/lit and Chlorantraniliprole 18.5 SC @ 0.3ml/lit. The results revealed that insecticidal treatments were significantly superior over untreated control in reducing the infestation groundnut defoliators. However, chlorantraniliprole 18.5 SC was significantly most effective as well as safer to natural enemies. Significantly higher pod yield (1672 kg/ha) of groundnut was recorded in treatment Chlorantraniliprole 18.5 SC @ 0.3ml/lit, and it was at par with treatment Bt127 SC @3ml/lit (1559 kg/ha).
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Libardoni, Gabriela, Pedro Manuel Oliveira Janeiro Neves, Raiza Abati, Amanda Roberta Sampaio, Fabiana Martins Costa-Maia, Edgar de Souza Vismara, Everton Ricardi Lozano e Michele Potrich. "Possible interference of Bacillus thuringiensis in the survival and behavior of Africanized honey bees (Apis mellifera)". Scientific Reports 11, n. 1 (10 febbraio 2021). http://dx.doi.org/10.1038/s41598-021-82874-1.
Abstract (sommario):
AbstractBacillus thuringiensis (Bt), an entomopathogenic bacterium, has been used as bioinsecticides for insect pest control worldwide. Consequently, the objective of this work was to evaluate the possible effects of commercial formulations of Bt products, Dipel and Xentari, on the survival and behavior of Africanized honey bees (Apis mellifera). Bioassays were performed on foragers and newly emerged (24-h-old) bees that received the products mixed in the food. Their survival and behavior were evaluated through the vertical displacement tests and the walk test, analyzed using software Bee-Move. Then, histological analysis of the mesenterium was performed. As control treatment was used sterile water. The honey bees’ survival was evaluated for between 1 and 144 h. No interference of B. thuringiensis, Dipel and Xentari, in the survival of Africanized honey bees were found. Only Xentari interfered with vertical displacement behavior of newly emerged (24-h-old) bees. Both the products tested were selective and safe for A. mellifera.
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RASHID, YUSDAYATI, CIK MOHD RIZUAN ZAINAL ABIDIN, KEK HO THEN e NOOR HISHAM HAMID. "GLASSHOUSE EVALUATION ON THE EFFICACY OF BACILLUS THURINGIENSIS (BT) AGAINST BAGWORM, METISA PLANA AND NON-TARGET EFFECT ON OIL PLAM POLLINATOR, ELAEIDOBIUS KAMERUNICUS (FAUST)". Planter 97, n. 1148 (25 novembre 2021). http://dx.doi.org/10.56333/tp.2021.018.
Abstract (sommario):
Evaluations on the performance of selected bioinsecticides and recommended chemical insecticides to suppress the bagworm, Metisa plana (Walker) infesting oil palm, were carried out in a glasshouse environment. The results showed that a series of biological products using Bacillus thuringiensis (Bt) is effective in killing 80 per cent of bagworm larvae within 7 to 15 days after application (DAA). Among the biological products, the Bt1 product showed the highest efficacy, killing 99.72 per cent of the bagworm population at 7 DAA. Although slow in reacting, Bt products were highly toxic to the adults, and less effective on the emergence of pollinator weevil,Elaeidobius kamerunicus (Faust). The chemical insecticide, cypermethrin was the most effective compared to all other treatments (p<0.05), killing 100 per cent of the bagworm larvae in only 3 DAA. All non-Bt based insecticides, including cypermethrin, were toxic to both adults and emergence of the weevils. There was no significant difference in the number of adult emergence between the non-treated (control) and Bt-insecticides, but significantly was lower when treated with other insecticides (F= 93.75 p<0.05). Based on its high performance, the biopesticide Bt1 product has a higher potential to be tested in the field for integrated leaf-eating caterpillar management programme. To ensure consistency in their efficacy, these bio-insecticides need further evaluation in large-scale trials, especially in oil palm fields infested with bagworms in epidemic proportions. Keywords: Bagworms, Bacillus thuringiensis, non-target effect, pollinator, oil palm
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Khurshid, Huma, Hafsa Zaheer, Fakhar-un-Nisa Yunus, Farkhanda Manzoor, Aasma Abdul Latif e Farzana Rashid. "Site-directed mutagenesis in Cry proteins of Bacillus thuringiensis to demonstrate the role of domain II and domain III in toxicity enhancement toward Spodoptera litura". Egyptian Journal of Biological Pest Control 33, n. 1 (30 agosto 2023). http://dx.doi.org/10.1186/s41938-023-00731-x.
Abstract (sommario):
Abstract Background Bacillusthuringiensis (Bt) is a gram-positive bacterium responsible for the production of a wide variety of insecticidal Cry, Cyt, and Vip proteins with distinct insect specificities. The bioinsecticides derived from Bt Cry proteins account for > 95% of the microbial biopesticide market to combat a variety of pest species belonging to the order Lepidoptera (including Spodoptera spp.), Coleoptera, Diptera, etc. Cry proteins are engineered by using different molecular techniques to control the development of multiple insecticide resistance problems in major insect pests using bio-toxicity assays. Main body It is common knowledge that the Cry proteins domain II and III are involved in pore formation or interaction between several insect larval receptors and the membranes of epithelial cells. In the present research, the PCR site-directed mutagenesis technique was used to introduce a total of four mutations into the cry genes (cry1 and cry2) near key regions of active proteins. The diet overlay bioassay was used to test the efficacy of expressed mutant Cry proteins against Spodopteralitura (Fabricius) (Lepidoptera: Noctuidae), one of the most damaging bollworms to cotton, causing severe output losses. Results Two amino acid replacements in the receptor binding domain of Cry1Ac toxins (S573, L588) showed decrease in activity for Cry1Ac mutants. However, amino acid substitutions in the receptor binding/pore formation domain of Cry2Aa (T325, S445) were to some extent proved more toxic than wild-type recombinant Cry2Aa protein, with an increase in mortality percentage from 3.33 to 6.66% after 24 to 72 h of treatment, respectively, against 2nd instar larvae of S.litura. Conclusion A comparison of activity demonstrated that larvae of S.litura were more susceptible to Cry2Aa toxins than those of Cry1Ac toxins after being treated with Bt toxins. The LC50 values of Cry2Aa mutants were slightly reduced for S.litura larvae than those of Cry1Ac mutants.
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E Senewe, Rein, F. X. Wagiman e Soekadar Wiryadiputra. "Effectiveness of Bioinsecticide Bacillus thuringiensisFormulation Against Cocoa Pod Borer in Field Condition". Pelita Perkebunan (a Coffee and Cocoa Research Journal) 29, n. 2 (31 agosto 2013). http://dx.doi.org/10.22302/iccri.jur.pelitaperkebunan.v29i2.58.
Abstract (sommario):
Field trial of Bt insecticide formulation with a code of formulation-A +1WP against cocoa pod borer (CPB) (Conopomorpha cramerella) has been conducted at the heavily infested cocoa area in Holo village, Amahai sub district, Central Maluku regency. Formulation-B 2.5 WP as a commercial Bt insecticide which has been distributed widely in the market was used as a comparison Bt insecticide. The results of the trial revealed that compared with untreated treatment, Bt insecticide formulation-A +1WP significantly reduced infestation of CPB, CPB population, and yield losses of dry cocoa bean caused by CPB. At the same concentration (2.5 g/L), the effectiveness of formulation-A +1WP was not significantly different with formulation-B 2.5WP. In the case of production increase, at the same concentration (2.5 g/L) formulation-A +1WP caused higher yield than formulation-B 2.5WP, i.e. 39.9% compared with 35.1%, respectively. Both Bt insecticide formulations tried did not caused phytotoxic against cocoa plant. It is recommended that controling of CPB should use concentration of 2.5 g/L Bt insecticide formulation/L of water, and should be applied at around early morning until 09.00 AM and / or at the afternoon after 15.00 PM. Spraying targets should be cocoa pods at the length of less than 8.0 cm which is not laid eggs of CPB yet. Key words: Cocoa, cocoa pod borer, Conopomorpha cramerella, control, effectiveness, microbial insecticide, Bacillus thuringiensis
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Fernandes, F. O., T. D. Souza, A. C. Sanches, I. R. Carvalho, N. P. Dias, J. A. Desiderio e R. A. Polanczyk. "Phenotypic plasticity in adults of Anticarsia gemmatalis exposed to sub-doses of Bt-based bioinsecticide". Brazilian Journal of Biology 84 (2024). http://dx.doi.org/10.1590/1519-6984.256933.
Abstract (sommario):
Abstract Anticarsia gemmatalis Hünber, 1818 is one of the main defoliating species in the soybean crop. Bacillus thuringiensis Berliner, 1915, is a bacterium used in the biological control of this pest species. Resistant populations and their sublethal effects caused by the use of the bacteria have already been reported; however, there are no studies on phenotypic plasticity in adulthood exposed to Bt-based bioinsecticide sub-doses. This study aimed to evaluate the morphometry of A. gemmatalis adults under laboratory conditions submitted to the Bt-based bioinsecticide Dipel® over the three generations. The body segments mensuread were width, length, and area of the anterior and posterior wings, the weight of the integument, chest, abdomen, wings, and the whole adult of males and females. Among the treatments, LC5 in the first generation and LC10 in the second generation were those with lower thresholds in relation to the weight of the chest and abdomen, considering the proportions of the body smaller than the females. The female’s weight adulthood was reduced by 10% about males, and, only in the first generation. Males have larger body size and more pronounced phenotypic plasticity than females. Here, we demonstrate the first study assessing the phenotypic plasticity of A. gemmatalis adults.
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Baranek, Jakub, Bartłomiej Pogodziński, Norbert Szipluk e Andrzej Zielezinski. "TOXiTAXi: a web resource for toxicity of Bacillus thuringiensis protein compositions towards species of various taxonomic groups". Scientific Reports 10, n. 1 (13 novembre 2020). http://dx.doi.org/10.1038/s41598-020-75932-7.
Abstract (sommario):
AbstractBioinsecticides consisting of different sets of Bacillus thuringiensis (Bt) Cry, Cyt and Vip toxins are broadly used in pest control. Possible interactions (synergistic, additive or antagonistic) between these proteins can not only influence the overall efficacy of certain Bt-based bioinsecticide, but also raise questions regarding environmental safety. Here, we assemble, summarize and analyze the outcomes of experiments published over 30 years, investigating combinatorial effects among Bt Cry, Cyt and Vip toxins. We collected the results on 118 various two-to-five-component combinations that have been bioassayed against 38 invertebrate species. Synergism, additive effect and antagonism was indicated in 54%, 32% and 14% of experiments, respectively. Synergism was noted most frequently for Cry/Cyt combinations, followed by Cyt/Vip and Cry/Cry. In Cry/Vip combinations, antagonism is more frequent and higher in magnitude compared to other categories. Despite a significant number of tested Bt toxin combinations, most of them have been bioassayed only against one pest species. To aid the research on Bt pesticidal protein activity, we present TOXiTAXi (https://www.combio.pl/toxitaxi/), a universal database and a dedicated web tool to conveniently gather and analyze the existing and future bioassay results on biocidal activity of toxins against various taxonomic groups.
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Santos, Cicero Antônio Mariano dos, Renata Thaysa da Silva Santos, Jaqueline Franciosi Della’Vechia, Fabiano Griesang, Ricardo Antônio Polanczyk e Marcelo da Costa Ferreira. "Effect of addition of adjuvants on physical and chemical characteristics of Bt bioinsecticide mixture". Scientific Reports 9, n. 1 (29 agosto 2019). http://dx.doi.org/10.1038/s41598-019-48939-y.
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Pereira, Adriano E., Man P. Huynh, Alvar R. Carlson, Alexandra Haase, Robert M. Kennedy, Kent S. Shelby, Thomas A. Coudron e Bruce E. Hibbard. "Assessing the Single and Combined Toxicity of the Bioinsecticide Spear and Cry3Bb1 Protein Against Susceptible and Resistant Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae)". Journal of Economic Entomology, 28 agosto 2021. http://dx.doi.org/10.1093/jee/toab160.
Abstract (sommario):
Abstract The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), poses a serious threat to maize (Zea mays L.) growers in the U.S. Corn Belt. Transgenic corn expressing Bacillus thuringiensis (Bt) Berliner is the major management tactic along with crop rotation. Bt crops targeting WCR populations have been widely planted throughout the Corn Belt. Rootworms have developed resistance to nearly all management strategies including Bt corn. Therefore, there is a need for new products that are not cross-resistant with the current Bt proteins. In this study, we evaluated the susceptibility of WCR strains resistant and susceptible to Cry3Bb1 to the biological insecticide Spear-T (GS-omega/kappa-Hexatoxin-Hv1a) alone and combined with Cry3Bb1 protein. The activity of Hv1a alone was similar between Cry3Bb1-resistant and susceptible strains (LC50s = 0.95 mg/cm2 and 1.50 mg/cm2, respectively), suggesting that there is no cross-resistance with Cry3Bb1 protein. Effective concentration (EC50), molt inhibition concentration (MIC50), and inhibition concentration (IC50) values of Hv1a alone were also similar between both strains, based on non-overlapping confidence intervals. Increased mortality (64%) was observed on resistant larvae exposed to Hv1a (0.6 mg/cm2) + Cry3Bb1 protein (170.8 µg/cm2) compared to 0% mortality when exposed to Cry3Bb1 alone and 34% mortality to Hv1a alone (0.3 mg/cm2). The time of larval death was not significantly different between Hv1a alone (3.79 mg/cm2) and Hv1a (0.6 mg/cm2) + Cry3Bb1 (170.8 µg/cm2). New control strategies that are not cross-resistant with current insecticides and Bt proteins are needed to better manage the WCR, and Hv1a together with Cry3Bb1 may fit this role.
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Fernandes, Fabrício Oliveira, Tamires Doroteo de Souza, Ariadne Costas Sanches, Naymã Pinto Dias, Janete Apparecida Desiderio e Ricardo Antonio Polanczyk. "Sub-lethal effects of a Bt-based bioinsecticide on the biological conditioning of Anticarsia gemmatalis". Ecotoxicology, 21 settembre 2021. http://dx.doi.org/10.1007/s10646-021-02476-5.
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Chung, Taejung, Abimel Salazar, Grant Harm, Sophia Johler, Laura M. Carroll e Jasna Kovac. "Comparison of the performance of multiple whole-genome sequence-based tools for the identification of Bacillus cereus sensu stricto biovar Thuringiensis". Applied and Environmental Microbiology, 12 marzo 2024. http://dx.doi.org/10.1128/aem.01778-23.
Abstract (sommario):
ABSTRACT The Bacillus cereus sensu stricto ( s.s .) species comprises strains of biovar Thuringiensis ( Bt ) known for their bioinsecticidal activity, as well as strains with foodborne pathogenic potential. Bt strains are identified (i) based on the production of insecticidal crystal proteins, also known as Bt toxins, or (ii) based on the presence of cry , cyt , and vip genes, which encode Bt toxins. Multiple bioinformatics tools have been developed for the detection of crystal protein-encoding genes based on whole-genome sequencing (WGS) data. However, the performance of these tools is yet to be evaluated using phenotypic data. Thus, the goal of this study was to assess the performance of four bioinformatics tools for the detection of crystal protein-encoding genes. The accuracy of sequence-based identification of Bt was determined in reference to phenotypic microscope-based screening for the production of crystal proteins. A total of 58 diverse B. cereus sensu lato strains isolated from clinical, food, environmental, and commercial biopesticide products underwent WGS. Isolates were examined for crystal protein production using phase contrast microscopy. Crystal protein-encoding genes were detected using BtToxin_Digger, BTyper3, IDOPS (identification of pesticidal sequences), and Cry_processor. Out of 58 isolates, the phenotypic production of crystal proteins was confirmed for 18 isolates. Specificity and sensitivity of Bt identification based on sequences were 0.85 and 0.94 for BtToxin_Digger, 0.97 and 0.89 for BTyper3, 0.95 and 0.94 for IDOPS, and 0.88 and 1.00 for Cry_processor, respectively. Cry_processor predicted crystal protein production with the highest specificity, and BtToxin_Digger and IDOPS predicted crystal protein production with the highest sensitivity. Three out of four tested bioinformatics tools performed well overall, with IDOPS achieving high sensitivity and specificity (>0.90). IMPORTANCE Strains of Bacillus cereus sensu stricto ( s.s .) biovar Thuringiensis ( Bt ) are used as organic biopesticides . Bt is differentiated from the foodborne pathogen Bacillus cereus s.s . by the production of insecticidal crystal proteins. Thus, reliable genomic identification of biovar Thuringiensis is necessary to ensure food safety and facilitate risk assessment. This study assessed the accuracy of whole-genome sequencing (WGS)-based identification of Bt compared to phenotypic microscopy-based screening for crystal protein production. Multiple bioinformatics tools were compared to assess their performance in predicting crystal protein production. Among them, identification of pesticidal sequences performed best overall at WGS-based Bt identification.
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Eniya, Arumugam, Venkatasamy Balasubramani, Marimuthu Murugan, Muthurajan Raveendran, Lakshmanan Pugalendhi, Ravikumar Caroline Nirmala, Rajasekaran Raghu e Gothandaraman Rajadurai. "In silico Analysis and Molecular Docking of Cry3Aa Toxin with Coleopteran Specific Midgut Receptor of ADAM10/APN Receptors". Agricultural Science Digest - A Research Journal, Of (3 aprile 2024). http://dx.doi.org/10.18805/ag.d-5955.
Abstract (sommario):
Background: Bacillus thuringiensis (Bt) is widely recognized as a safe and effective bioinsecticide, with Cry toxins targeting pests of various insect orders. The present study focuses on the modeling and validation of the Cry3Aa protein (deduced amino acid sequence of cry3Aa gene cloned from native Bt isolate, T121) and its interaction with midgut receptor proteins (ADAM10 and APN). Methods: The three-dimensional structures of Cry3Aa protein and the midgut receptors ADAM10 and APN were predicted using the SWISS model server. Functional domain analysis of Cry3Aa revealed three distinct domains: N-terminal (Domain I), Central (Domain II) and C-terminal (Domain III), providing insights into their structural organization. The predicted models of Cry3Aa, ADAM10 and APN were validated using the Ramachandran plot which demonstrated structural integrity. Result: Primary structure analysis of Cry3Aa revealed a 652 amino acid protein with a theoretical isoelectric point of 5.59, a molecular weight of 74 kDa and stable characteristics. Protein-protein docking analysis using ClusPro 2.0 showed that Cry3Aa exhibited higher level of interaction with the ADAM10 receptor than with the APN receptor. The Cry3Aa-ADAM10 docked complex demonstrated 23 hydrogen bonds, reasoning for its stability and binding affinity. These findings revealed that the Cry3Aa protein has a strong affinity against coleopteran specific midgut receptors and hence Cry3Aa has a potential to be an effective coleopteran specific insecticidal protein.
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dos Santos, Hister M. M., Camila de S. Varize, Camilla A. S. Valença, Fábio C. A. Dossi, Marcus V. de Aragão Batista, Roberta P. M. Fernandes, Patricia Severino et al. "Use of agro-industrial bio-waste for the growth and production of a previously isolated Bacillus thuringiensis strain". Beni-Suef University Journal of Basic and Applied Sciences 13, n. 1 (4 gennaio 2024). http://dx.doi.org/10.1186/s43088-023-00461-x.
Abstract (sommario):
Abstract Background Bacillus thuringiensis (Bt) is a widely used biopesticide. The bioinsecticide based on Bt is obtained by fermentation, but the substrates currently used for its production constitute ingredients of high commercial value. In this context, the use of agro-industrial residues as substrates is an alternative to make the fermentation process viable on a large scale, in addition to minimizing environmental problems and contributing to the destination of these residues for biotechnological purposes. Results In the first part of this study, a previously isolated spore forming soil bacteria (Bv5) harboring and expressing a novel cry 8A gene was confirmed as B. thuringiensis based on its morphological characteristics, Gram staining, scanning electron microscopy (SEM) and genome sequencing. Bv5 was established as a Gram-positive spore forming bacteria with ellipsoidal spores and small round toxins. Bv5 genome comprised of the 5.30 Mb chromosome and two megaplasmids of 450 kb and 261 kb, respectively, with cry 8A gene located on the smallest megaplasmid. In the second part of the study, the physiological profile of the Bv5 strain during fermentation in different agro-industrial biowastes (cassava wastewater, orange pulp wash and whey) was analyzed. The fermentation experiment was divided into two stages. In the first stage, the agro-industrial waste with or without salts with the best results for biomass, spores and proteins production was selected. In the second stage, the effect of the selected medium in original and diluted form with the C:N balance was evaluated, in two different fermentation times (72 h and 96 h). Pulp wash enriched with salts was selected as the most suitable medium for the growth of Bv5 strain in the first stage. In the second stage pulp wash (without dilution) with the addition of salts, and with nitrogen supplementation, was considered the best for cell growth, spore and toxin production by Bv5. Conclusions To conclude, our study provide a new alternative for bio-waste from the orange juice industry, as well as potential culture medium for the Bt commercial scale production.
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WIDIASTUTI, Happy, TRI PANJI, Ciptadi Achmad YUSUP, Iman RUSMANA e Tri Eko WAHYONO. "Formulasi bioinsektisida Bacillus thuringiensis isolat indigenos untuk pengendalian Hyposidra talaca pada tanaman teh (Formulation of indigenous isolate of Bacillus thuringiensis bioinsecticide to control Hyposidra talaca on tea)". E-Journal Menara Perkebunan 87, n. 1 (7 maggio 2019). http://dx.doi.org/10.22302/iribb.jur.mp.v87i1.329.
Abstract (sommario):
A study has been conducted to develop indigenousBacillusthuringiensisbioinsecticide. Preliminary study has been conducted to explore B. thuringiensisfrom sample of soil, leaf, and infected larvae from selected tea area as well as another area such as cocoa, and acasia. The result showed that based on the colony morphology, it was found 10 isolateswith the characteristics of B. thuringiensis colony. Assessed of the ability to formed crystal using phase contrast microscope and staining revealed that 4 isolates as crystal protein forming isolates. The four isolates used as active coumpound of bioinsecticide. The best formula based on the viability of bacteria was the one withwhite clay as a carrier. While the best liquid formula based on the similar characteristic was using maltosa as osmoprotectant. Theassessment ofthetoxisity B. thuringiensistowards Hyposidra talacalarvae showed that B. thuringiensiscould control H. talacalarvaeup to 37.5%. However, the toxicity need longer periode compared to that commercial B. thuringiensisbioinsecticide. [Keywords:Bt insecticide, cypermethrine, integrated pest management, Tea looper].AbstrakPenelitian telah dilakukan untuk mengembangkan bioinsektisida berbahan aktif B. thuringiensisdari isolat asli Indonesia. Eksplorasi B. thuringiensisdari contoh berupa tanah, daun, dan ulat dari kebun teh telah dilakukan demikian pula dari habitat lain seperti kebun kakao dan akasia. Berdasarkan morfologi koloni diperoleh 10 isolat yang menunjukkan ciri-ciri koloni B. thuringiensis. Selanjutnyaisolat yang diperoleh diuji kemampuan pembentukan kristal protein dengan pewarnaan dan pengamatan mikroskop phase kontras dan menghasilkan 4 isolat yang mampu membentuk kristal protein. Selanjutnya keempat isolat yang diperoleh digunakan sebagai bahan aktif dalam formulasi bioinsektisida. Formula terbaik berdasarkan kriteria viabilitas bakteri adalah formula yang menggunakan bahan pembawa berupa white clay. Formula terbaik untuk bioinsektida cair berdasarkan kriteria viabilitas B. thuringiensisdan kejernihan bioinsektisida adalah menggunakan maltosesebagai osmoprotektan.Pada pengujian toksisitas isolat B. thuringiensisterhadap larvaulat jengkal(Hyposidra talaca)menunjukkan bahwa B. thuringiensishasil percobaan dapat mengen-dalikan larva ulat jengkalhingga 37,5%. Namun demikian toksisitasnya memerlukan waktu yang lebih lama dibandingkan dengan bioinsektisida berbahan aktif B. thuringiensiskomersial. [Kata kuci: Bioinsektisida Bt, pengendalian hama terpadu, sipermetrin, ulat jengkal teh].
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Sharif, Muhammad Nauman, Muhammad Shahzad Iqbal, Rukkaya Alam, Mudassar Fareed Awan, Muhammad Tariq, Qurban Ali e Idrees Ahmad Nasir. "Silencing of multiple target genes via ingestion of dsRNA and PMRi affects development and survival in Helicoverpa armigera". Scientific Reports 12, n. 1 (21 giugno 2022). http://dx.doi.org/10.1038/s41598-022-14667-z.
Abstract (sommario):
AbstractRNA interference (RNAi) triggered by exogenous double-stranded RNA (dsRNA) is a powerful tool to knockdown genetic targets crucial for the growth and development of agriculturally important insect pests. Helicoverpa armigera is a pest feeding on more than 30 economically important crops worldwide and a major threat. Resistance to insecticides and Bt toxins has been gradually increasing in the field. RNAi-mediated knockdown of H. armigera genes by producing dsRNAs homologous to genetic targets in bacteria and plants has a high potential for insect management to decrease agricultural loss. The acetylcholinesterase (AChE), ecdysone receptor (EcR) and v-ATPase-A (vAA) genes were selected as genetic targets. Fragments comprising a coding sequence of < 500 bp were cloned into the L4440 vector for dsRNA production in bacteria and in a TRV-VIGS vector in antisense orientation for transient expression of dsRNA in Solanum tuberosum leaves. After ingesting bacterial-expressed dsRNA, the mRNA levels of the target genes were significantly reduced, leading to mortality and abnormal development in larva of H. armigera. Furthermore, the S. tuberosum plants transformed with TRV-VIGS expressing AChE exhibited higher mortality > 68% than the control plants 17%, recorded ten days post-feeding and significant resistance in transgenic (transient) plants was observed. Moreover, larval lethality and molting defects were observed in larva fed on potato plants expressing dsRNA specific to EcR. Analysis of transcript levels by quantitative RT–PCR revealed that larval mortality was attributable to the knockdown of genetic targets by RNAi. The results demonstrated that down-regulation of H. armigera genes involved in ATP hydrolysis, transcriptional stimulation of development genes and neural conduction has aptitude as a bioinsecticide to control H. armigera population sizes and therefore decreases crop loss.