scholarly journals Isolation of Bacillus thuringiensis strains from Saudi Arabia soil and study of their potential efficiency against the lepidopteran pest Ephestia kuehniella

2021 ◽  
Vol 12 (2) ◽  
pp. 238-245
Author(s):  
Fidaa Ibrahim Kallaf ◽  
Hanen Boukedi ◽  
Dalel Daâssi ◽  
Lobna Abdelkefi-Mesrati
Keyword(s):  
Saudi Arabia ◽  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Ephestia Kuehniella ◽  
Environment Friendly ◽  
Insecticidal Proteins ◽  
Insect Pathogens ◽  
Bacterium Bacillus ◽  
Parasporal Crystals ◽  
Lepidopteran Pest

Insect pests represent a major threat to food crops and human health, and therefore have to be combated in several ways, including chemical methods. However, researchers demonstrated that these molecules are dangerous for the farmers, consumers and the environment in general. For this reason, scientists permanently searched environment friendly alternatives such as the use of the bacterium Bacillus thuringiensis classified as one of the best insect pathogens. This microorganism is known by its ability to produce two types of insecticidal proteins, Vegetative insecticidal proteins (Vip) and delta-endotoxins produced during vegetative and sporulation stages of growth, respectively. In the present study, 15 B. thuringiensis strains were isolated from soil collected from different regions in Saudi Arabia (Al Baha, Jeddah, Khulis and Yanbu). B. thuringiensis isolates were then classified according to the shape of their parasporal crystals identified under microscope and proteins content of these crystals. Delta-endotoxins efficiency of the different isolates was investigated and promising strains were identified as very active. After 5 days-treatment, B. thuringiensis isolates 14 and 7 killed Ephestia kuehniella larvae with low LC50 of about 59.18 and 65.67 mg/cm2, respectively. The results described in the present study proved that the new B. thuringiensis isolates could be of a great interest in the control of lepidopteran pests by using their delta-endotoxins in bioinsecticide formulations.

scholarly journals Fatores de virulência de Bacillus thuringiensis: o que existe além das proteínas Cry

2012 ◽  
Vol 5 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Gislayne Trindade Vilas-Bôas ◽  
Rita C. Alvarez ◽  
Clelton A. Dos Santos ◽  
Laurival A. Vilas-Boas
Keyword(s):  
Biological Control ◽  
Bacillus Thuringiensis ◽  
Virulence Factors ◽  
Insect Pests ◽  
Cry Proteins ◽  
Control Programs ◽  
Wide Range ◽  
Vip Proteins ◽  
Bacterium Bacillus ◽  
And Control

As proteínas Cry produzidas pela bactéria entomopatogênica Bacillus thuringiensis Berliner são bem conhecidas devido a alta citotoxicidade que exibem a uma variedade de insetos-alvo. O modo de ação destas proteínas é específico e torna os produtos à base de B. thuringiensis os mais amplamente utilizados em programas de controle biológico de pragas na agricultura e de importantes vetores de doenças humanas. Contudo, embora as proteínas Cry sejam os fatores de virulência inseto-específico mais conhecidos, linhagens de B. thuringiensis apresentam também uma ampla gama de fatores de virulência, os quais permitem à bactéria atingir a hemolinfa e colonizar eficientemente o inseto hospedeiro. Dentre estes fatores, destacam-se as proteínas Vip, Cyt, enterotoxinas, hemolisinas, fosfolipases, proteases, enzimas de degradação, além das recentemente descritas parasporinas. Essa revisão aborda a ação desses fatores de virulência, bem como a caracterização e o controle da expressão de seus genes. Adicionalmente, são discutidos aspectos relacionados ao nicho ecológico da bactéria com ênfase nas características envolvidas com a biossegurança da utilização dos produtos à base de B. thuringiensis para o controle biológico de insetos-alvo. Virulence Factors of Bacillus thuringiensis Berliner: Something Beyond of Cry Proteins? Abstract. The Cry proteins produced by the entomopathogenic bacterium Bacillus thuringiensis Berliner are widely known due to its high toxicity against a variety of insects. The mode of action of these proteins is specific and becomes B. thuringiensis-based products the most used in biological control programs of insect pests in agriculture and of important human disease vectors. However, while the Cry proteins are the best-known insect-specific virulence factor, strains of B. thuringiensis show also a wide range of other virulence factors, which allow the bacteria to achieve the hemolymph and colonize efficiently the insect host. Among these factors, we highlight the Vip proteins, Cyt, enterotoxins, hemolysins, phospholipases, proteases and enzymes of degradation, in addition to the recently described parasporin. This review explores the action of these virulence factors, as well as, the characterization and control of expression of their genes. Additionally, we discuss aspects related to the ecological niche of the bacteria with emphasis on the characteristics involved in the biosafety of the use of B. thuringiensis-based products for biological control of target insects.

scholarly journals Cry75Aa (Mpp75Aa) Insecticidal Proteins for Controlling the Western Corn Rootworm, Diabrotica virgifera virgifera, (Coleoptera: Chrysomelidae), Isolated from the Insect Pathogenic Bacteria Brevibacillus laterosporus.

2020 ◽  
Author(s):  
David Bowen ◽  
Yong Yin ◽  
Stanislaw Flasinski ◽  
Catherine Chay ◽  
Gregory Bean ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Pathogenic Bacteria ◽  
Insect Pests ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
Cross Resistance ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Insecticidal Proteins ◽  
Brevibacillus Laterosporus

This study describes three closely related proteins, cloned from Brevibacillus laterosporus strains, that are lethal upon feeding to Diabrotica virgifera virgifera LeConte, the western corn rootworm (WCR). Mpp75Aa1, Mpp75Aa2 and Mpp75Aa3 were toxic to WCR larvae when fed purified protein. Transgenic plants expressing each mMpp75Aa protein were protected from feeding damage and showed significant reduction in adult emergence from infested plants by both susceptible and Cry3Bb1 and Cry34Ab1/Cry35Ab1-resistant WCR. These results demonstrate that proteins from B. laterosporus are as efficacious as the well-known Bacillus thuringiensis (Bt) insecticidal proteins in controlling major insect pests such as WCR. The deployment of transgenic maize expressing mMpp75Aa along with other active molecules lacking cross-resistance have the potential to be a useful tool for control of WCR populations resistant to current Bt traits. IMPORTANCE Insects feeding on roots of crops can damage the plant roots resulting in yield loss due to poor water and nutrient uptake and plant lodging. In maize the western corn rootworm (WCR) can cause severe damage to the roots resulting in significant economic loss for farmers. Genetically modified (GM) expressing Bacillus thuringiensis (Bt) insect control proteins, has provided a solution for control of these pests. In recent years populations of WCR resistant to the Bt proteins in commercial GM maize have emerged. There is a need to develop new insecticidal traits for the control of WCR populations resistant to current commercial traits. New proteins with commercial level efficacy on WCR from sources other than Bt are becoming more critical. The Mpp75Aa proteins, from B. laterosporus, when expressed in maize, are efficacious against the resistant populations of WCR and have the potential to provide solutions for control of resistant WCR.

Mechanisms of Resistance to Insecticidal Proteins from Bacillus thuringiensis

2021 ◽  
Vol 66 (1) ◽  
pp. 121-140
Author(s):  
Juan Luis Jurat-Fuentes ◽  
David G. Heckel ◽  
Juan Ferré
Keyword(s):  
Bacillus Thuringiensis ◽  
Current Knowledge ◽  
Mechanisms Of Resistance ◽  
Insecticidal Proteins ◽  
Bt Toxins ◽  
Evolution Of Resistance ◽  
Synthetic Pesticides ◽  
Bacterium Bacillus ◽  
High Level ◽  
Level Resistance

Insecticidal proteins from the bacterium Bacillus thuringiensis ( Bt) are used in sprayable formulations or produced in transgenic crops as the most successful alternatives to synthetic pesticides. The most relevant threat to sustainability of Bt insecticidal proteins (toxins) is the evolution of resistance in target pests. To date, high-level resistance to Bt sprays has been limited to one species in the field and another in commercial greenhouses. In contrast, there are currently seven lepidopteran and one coleopteran species that have evolved practical resistance to transgenic plants producing insecticidal Bt proteins. In this article, we present a review of the current knowledge on mechanisms of resistance to Bt toxins, with emphasis on key resistance genes and field-evolved resistance, to support improvement of Bt technology and its sustainability.

Discovery of crystalline inclusions in Bacillus licheniformis that resemble parasporal crystals of Bacillus thuringiensis

2007 ◽  
Vol 53 (9) ◽  
pp. 1111-1115 ◽  
Author(s):  
Ming Yan ◽  
Michael H. Roehrl ◽  
Julia Y. Wang
Keyword(s):  
Bacillus Thuringiensis ◽  
Bacillus Licheniformis ◽  
Rrna Gene ◽  
Bacterial Cells ◽  
Insecticidal Toxin ◽  
Crystalline Inclusions ◽  
Large Size ◽  
Protein Toxins ◽  
Bacterium Bacillus ◽  
Parasporal Crystals

Crystalline inclusions were discovered in stationary and sporulating cells of the spore-forming bacterium Bacillus licheniformis ATCC 9945a. As detected by electron microscopy, dying or sporulating bacterial cells contain a single crystal of strikingly large size. The crystals in sporulating cells are located next to nascent spores and can be several times larger than the spores. Morphologically, most crystals are rhomboid with uniformly spaced grids. These newly discovered crystalline inclusions of B. licheniformis closely resemble parasporal crystals of Bacillus thuringiensis that are formed by insecticidal toxin proteins and used widely as biopesticides. The taxonomic identity of this strain was verified by its 16S rRNA gene sequence and its fatty acid profile. The finding of crystal proteins in B. licheniformis may lead to the discovery of new protein toxins and may expand our pool of biopesticides.

Effectiveness of Purified Bacillus thuringiensis Berliner Insecticidal Proteins in Controlling Three Insect Pests of Australian Eucalypt Plantations

1996 ◽  
Vol 89 (6) ◽  
pp. 1392-1398 ◽  
Author(s):  
Rebecca L. Harcourt ◽  
Danny Llewellyn ◽  
Richard Morton ◽  
Elizabeth S. Dennis ◽  
W. Jim Peacock
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Insecticidal Proteins ◽  
Eucalypt Plantations

scholarly journals Study on the combined action of the entomopathogenic bacterium Bacillus thuringiensis subsp. kurstaki and the entomopathogenic nematode Heterorhabditis bacteriophora

2017 ◽  
Vol 23 (2) ◽  
pp. 74 ◽  
Author(s):  
I. Zampara ◽  
C. Zamparas ◽  
S. Mantzoukas ◽  
E. Karanastasi
Keyword(s):  
Bacillus Thuringiensis ◽  
Entomopathogenic Nematode ◽  
Heterorhabditis Bacteriophora ◽  
Post Treatment ◽  
Ephestia Kuehniella ◽  
Laboratory Conditions ◽  
Bacillus Thuringiensis Subsp ◽  
Lepidoptera Pyralidae ◽  
Combined Action ◽  
Bacterium Bacillus

The interaction between the entomopathogenic bacterium Bacillus thuringiensis subsp. Kurstaki and the entomopathogenic nematode Heterorhabditis bacteriophora (Heterorhabditidae) was examined against larvae of Ephestia kuehniella (Lepidoptera: Pyralidae) at 7, 14, 21 and 28 days post treatment, in laboratory conditions. Three different combinations of the aforementioned pathogens were tested on 4th instar larvae, namely 500ppm B. thuringiensis subsp. kurstaki (B.t.k.) and H. bacteriophora infective Juveniles (1000IJs/ml), 1500ppm B.t.k. and H. bacteriophora (1000IJs/ml) and 3000ppm B.t.k. and H. bacteriophora (1000IJs/ml). At 7, 14 and 21 days, the interaction between the pathogens was additive in two of the treatments and synergistic in one, whereas at 28 days, it was negative in two of the treatments and synergistic in one. Overall, the application of the lowest dose of B.t.k. (500ppm) in combination with H. bacteriophora (1000IJs/ml), turned out to be highly effective. The interaction between B. thuringiensis and H. bacteriophora is to be further examined.

scholarly journals Response Mechanisms of Invertebrates to Bacillus thuringiensis and Its Pesticidal Proteins

2021 ◽  
Vol 85 (1) ◽  
Author(s):  
Daniel Pinos ◽  
Ascensión Andrés-Garrido ◽  
Juan Ferré ◽  
Patricia Hernández-Martínez
Keyword(s):  
Bacillus Thuringiensis ◽  
Pest Control ◽  
Insect Pests ◽  
Relevant Literature ◽  
Nematode Species ◽  
Biological Pest Control ◽  
Insecticidal Proteins ◽  
Content Type ◽  
Resistance Evolution ◽  
Control Insect

SUMMARY Extensive use of chemical insecticides adversely affects both environment and human health. One of the most popular biological pest control alternatives is bioinsecticides based on Bacillus thuringiensis. This entomopathogenic bacterium produces different protein types which are toxic to several insect, mite, and nematode species. Currently, insecticidal proteins belonging to the Cry and Vip3 groups are widely used to control insect pests both in formulated sprays and in transgenic crops. However, the benefits of B. thuringiensis-based products are threatened by insect resistance evolution. Numerous studies have highlighted that mutations in genes coding for surrogate receptors are responsible for conferring resistance to B. thuringiensis. Nevertheless, other mechanisms may also contribute to the reduction of the effectiveness of B. thuringiensis-based products for managing insect pests and even to the acquisition of resistance. Here, we review the relevant literature reporting how invertebrates (mainly insects and Caenorhabditis elegans) respond to exposure to B. thuringiensis as either whole bacteria, spores, and/or its pesticidal proteins.

scholarly journals Retargeting of the Bacillus thuringiensis toxin Cyt2Aa against hemipteran insect pests

2013 ◽  
Vol 110 (21) ◽  
pp. 8465-8470 ◽  
Author(s):  
N. P. Chougule ◽  
H. Li ◽  
S. Liu ◽  
L. B. Linz ◽  
K. E. Narva ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Bacillus Thuringiensis Toxin ◽  
Hemipteran Insect
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