scholarly journals Improving the Insecticidal Activity against Resistant Culex quinquefasciatus Mosquitoes by Expression of Chitinase Gene chiAC in Bacillus sphaericus

2007 ◽  
Vol 73 (23) ◽  
pp. 7744-7746 ◽  
Author(s):  
Yajun Cai ◽  
Jianpin Yan ◽  
Xiaomin Hu ◽  
Bei Han ◽  
Zhiming Yuan
Keyword(s):  
Bacillus Thuringiensis ◽  
Insecticidal Activity ◽  
Culex Quinquefasciatus ◽  
Recombinant Strain ◽  
Bacillus Sphaericus ◽  
Chitinase Gene ◽  
Binary Toxin

ABSTRACT Expression of a chitinase gene, chiAC, from Bacillus thuringiensis in B. sphaericus 2297 using the binary toxin promoter yielded a recombinant strain that was 4,297-fold more toxic than strain 2297 against resistant Culex quinquefasciatus. These results show that this chitinase can synergize the toxicity of the binary toxin against mosquitoes and thus may be useful in managing mosquito resistance to B. sphaericus.

scholarly journals Recombinant Strain of Bacillus thuringiensis Producing Cyt1A, Cry11B, and the Bacillus sphaericus Binary Toxin

2003 ◽  
Vol 69 (2) ◽  
pp. 1331-1334 ◽  
Author(s):  
Hyun-Woo Park ◽  
Dennis K. Bideshi ◽  
Brian A. Federici
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Quinquefasciatus ◽  
Recombinant Strain ◽  
Bacillus Sphaericus ◽  
Fourth Instar ◽  
Lethal Concentration ◽  
Binary Toxin

ABSTRACT A novel recombinant Bacillus thuringiensis subsp. israelensis strain that produces the B. sphaericus binary toxin, Cyt1Aa, and Cry11Ba is described. The toxicity of this strain (50% lethal concentration [LC50] = 1.7 ng/ml) against fourth-instar Culex quinquefasciatus was higher than that of B. thuringiensis subsp. israelensis IPS-82 (LC50 = 7.9 ng/ml) or B. sphaericus 2362 (LC50 = 12.6 ng/ml).

The Introduction into Bacillus sphaericus of the Bacillus thuringiensis subsp. medellin cyt1Ab1 Gene Results in Higher Susceptibility of Resistant Mosquito Larva Populations to B. sphaericus

1998 ◽  
Vol 64 (10) ◽  
pp. 3910-3916 ◽  
Author(s):  
I. Thiéry ◽  
S. Hamon ◽  
A. Delécluse ◽  
S. Orduz
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Recombinant Strain ◽  
Mosquito Larva ◽  
Shuttle Vector ◽  
Bacillus Sphaericus ◽  
The Other ◽  
Binary Toxin ◽  
Gene Encoding ◽  
Flanking Sequences

ABSTRACT The fragment containing the gene encoding the cytolytic Cyt1Ab1 protein from Bacillus thuringiensis subsp.medellin and its flanking sequences (I. Thiery, A. Delécluse, M. C. Tamayo, and S. Orduz, Appl. Environ. Microbiol. 63:468–473, 1997) was introduced into Bacillus sphaericus toxic strains 2362, 2297, and Iab872 by electroporation with the shuttle vector pMK3. Only small amounts of the protein were produced in recombinant strains 2362 and Iab872. The protein was detected in these strains only by Western blotting and immunodetection with antibody raised against Cyt1Ab1 protein. Large amounts of Cyt1Ab1 protein were produced in B. sphaericus recombinant strain 2297, and there was an additional crystal, other than that of the binary toxin, within the exosporium. The production of the Cyt1Ab1 protein in addition to the binary toxin did not increase the larvicidal activity of theB. sphaericus recombinant strain against susceptible mosquito populations of Culex pipiens orAedes aegypti. However, it partially restored (10 to 20 times) susceptibility of the resistant mosquito populations of C. pipiens (SPHAE) and Culex quinquefasciatus (GeoR) to the binary toxin. The Cyt1Ab1 protein produced in recombinantB. thuringiensis SPL407(pcyt1Ab1) was synthesized in two types of crystal—one round and with various dense areas, surrounded by an envelope, and the other a regular cuboid crystal, very similar to that found in the B. sphaericus recombinant strain.

scholarly journals Production of Cry11A and Cry11Ba Toxins in Bacillus sphaericus Confers Toxicity towards Aedes aegyptiand Resistant Culex Populations

1999 ◽  
Vol 65 (7) ◽  
pp. 3021-3026 ◽  
Author(s):  
Pascale Servant ◽  
Marie-Laure Rosso ◽  
Sylviane Hamon ◽  
Sandrine Poncet ◽  
Armelle Delécluse ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Recombinant Strain ◽  
Bacillus Sphaericus ◽  
Binary Toxin ◽  
Protease Gene ◽  
Gene Encoding ◽  
In Vivo Recombination ◽  
Target Sites

ABSTRACT Cry11A from Bacillus thuringiensis subsp.israelensis and Cry11Ba from Bacillus thuringiensis subsp. jegathesan were introduced, separately and in combination, into the chromosome of Bacillus sphaericus 2297 by in vivo recombination. Two loci on theB. sphaericus chromosome were chosen as target sites for recombination: the binary toxin locus and the gene encoding the 36-kDa protease that may be responsible for the cleavage of the Mtx protein. Disruption of the protease gene did not increase the larvicidal activity of the recombinant strain against Aedes aegyptiand Culex pipiens. Synthesis of the Cry11A and Cry11Ba toxins made the recombinant strains toxic to A. aegyptilarvae to which the parental strain was not toxic. The strain containing Cry11Ba was more toxic than strains containing the added Cry11A or both Cry11A and Cry11Ba. The production of the two toxins together with the binary toxin did not significantly increase the toxicity of the recombinant strain to susceptible C. pipiens larvae. However, the production of Cry11A and/or Cry11Ba partially overcame the resistance of C. pipiens SPHAE andCulex quinquefasciatus GeoR to B. sphaericus strain 2297.

scholarly journals Conjugal Transfer of a Toxin-Coding Megaplasmid from Bacillus thuringiensis subsp. israelensis to Mosquitocidal Strains of Bacillus sphaericus

2006 ◽  
Vol 72 (3) ◽  
pp. 1766-1770 ◽  
Author(s):  
Katherine Gammon ◽  
Gareth W. Jones ◽  
Steven J. Hope ◽  
Cláudia M. F. de Oliveira ◽  
Lêda Regis ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Culex Quinquefasciatus ◽  
Vegetative Growth ◽  
Bacillus Sphaericus ◽  
Conjugal Transfer ◽  
Large Plasmid ◽  
Erythromycin Resistance ◽  
Plasmid Loss ◽  
The Stability

ABSTRACT Both Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis produce mosquitocidal toxins during sporulation and are extensively used in the field for control of mosquito populations. All the known toxins of the latter organism are known to be encoded on a large plasmid, pBtoxis. In an attempt to combine the best properties of the two bacteria, an erythromycin resistance-marked pBtoxis plasmid was transferred to B. sphaericus by a mating technique. The resulting transconjugant bacteria were significantly more toxic to Aedes aegypti mosquitoes and were able to overcome resistance to B. sphaericus in a resistant colony of Culex quinquefasciatus, apparently due to the production of Cry11A but not Cry4A or Cry4B. The stability of the plasmid in the B. sphaericus host was moderate during vegetative growth, but segregational instability was observed, which led to substantial rates of plasmid loss during sporulation.

scholarly journals Eficiência e Persistência de Três Produtos Comerciais à Base de Bacillus thuringiensis israelensis e Bacillus sphaericus no controle de Culicidae (Diptera) em Lagoas de Tratamento de Efluentes

2010 ◽  
Vol 3 (3) ◽  
pp. 85-88
Author(s):  
Jose Lopes ◽  
Fernando Pereira dos Santos ◽  
João Antonio Cyrino Zequi ◽  
Denise Miguel Petroni
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Quinquefasciatus ◽  
Bacillus Sphaericus ◽  
Pathogen Transmission ◽  
Effluent Treatment ◽  
Alternative Methods ◽  
Liquid Formulation ◽  
Bacillus Thuringiensis Israelensis ◽  
Commercial Products ◽  
Culex Nigripalpus

Resumo. A ação hematofágica exercida por fêmeas de algumas espécies de Culicidae sobre o homem e outros animais pode estar diretamente relacionada à transmissão de patógenos, além de provocar reações alérgicas e causar incômodo. O aparecimento de populações resistentes aos inseticidas químicos impulsiona o uso de métodos de controle alternativos, principalmente o biológico. Objetivando testar a eficiência e persistência de produtos comerciais com principio ativo a base de Bacillus thuringiensis israelensis Berliner e Bacillus sphaericus Neide foram realizados experimentos em três lagoas de tratamento de efluentes, sobre larvas de Culicidae. Testou-se Vectolex (formulação granulada de B. sphaericus), Sphaericus (Formulação líquida de B. sphaericus) e Bt-horus (formulação líquida de B. thuringiensis). As aplicações foram realizadas quinzenalmente com avaliações realizadas a 0, 24, 48, 72 e 120 horas após a aplicação. As lagoas estavam colonizadas por Culex nigripalpus Theobald (1,5%), Culex saltanensis Dyar (2,25%) e Culex quinquefasciatus Say (96,25%). Com o produto Bt horus, registrou-se redução larval de 89,06%, 83,97% e 89,96% respectivamente a 24, 48 e 72 horas após a aplicação. Nos produtos contendo B. sphaericus, respectivamente na formulação granulada e líquida observou-se uma redução de 98,89 % e 98,34%, após 24 horas da aplicação e de 99,79% e 99,78% após 48 horas. Os produtos e as diferentes formulações foram eficientes no controle de larvas das três espécies de culicídeos em lagoas com grande quantidade de matéria orgânica, porém a persistência verificada foi de dois e três dias para produtos contendo respectivamente B. sphaericus e B. thuringiensis israelensis. Efficiency and Persistence of Three Commercial Products Based on Bacillus thuringiensis israelensis and Bacillus sphaericus in Controlling Culicidae (Diptera) in Effluent Treatment Lagoons Abstract. The hematofagic effect caused by females belonging to some species of Culicidae on humans and animals can be directly related to pathogen transmission, allergic reactions and uneasiness. The emergence of populations resistant to chemical insecticides has fostered the use of alternative methods, mainly biological control. The trials were conducted in three effluent treatment lagoons, on larvae of Culicidae to test the efficiency and persistence of commercial products whose active principles are based on Bacillus thuringiensis israelensis Berliner and Bacillus sphaericus Neide. The products tested were Vectolex (a granulated formulation of B. sphaericus), Sphaericus (a liquid formulation of B. sphaericus) and Bt-horus (a liquid formulation of B. thuringiensis). The products were applied biweekly and evaluations were conducted 0, 24, 48, 72, and 120 hours after each application. The lagoons were colonized by Culex nigripalpus Theobald (1.5%), Culex saltanensis Dyar (2.25%), and Culex quinquefasciatus Say (96.25%). Bt-horus reduced larvae by 89.06%, 83.97% and 89.96% at 24, 48 and 72 hours after product application, respectively. The granulated and the liquid formulations containing B. sphaericus reduced larvae by 98.89 % and 98.34% 24 hours after application, and by 99.79% and 99.78% after 48 hours, respectively. The products and the different formulations were effective in controlling larvae of all three Culicidae species in lagoons with high levels of organic matter, but the persistence was recorded in two and three days for products containing respectively B. sphaericus and B. thuringiensis israelensis.

A second independent resistance mechanism to Bacillus sphaericus binary toxin targets its alpha-glucosidase receptor in Culex quinquefasciatus

FEBS Journal ◽  
2006 ◽  
Vol 273 (7) ◽  
pp. 1556-1568 ◽  
Author(s):  
Tatiany Patricia Romao ◽  
Karlos Diogo de Melo Chalegre ◽  
Shana Key ◽  
Constancia Flavia Junqueira Ayres ◽  
Claudia Maria Fontes de Oliveira ◽  
...  
Keyword(s):  
Culex Quinquefasciatus ◽  
Resistance Mechanism ◽  
Bacillus Sphaericus ◽  
Binary Toxin ◽  
Alpha Glucosidase

scholarly journals A 1.1-Kilobase Region Downstream of the bin Operon in Bacillus sphaericus Strain 2362 Decreases Bin Yield and Crystal Size in Strain 2297

2008 ◽  
Vol 75 (3) ◽  
pp. 878-881 ◽  
Author(s):  
Hyun-Woo Park ◽  
Mujin Tang ◽  
Yuko Sakano ◽  
Brian A. Federici
Keyword(s):  
Homologous Recombination ◽  
Culex Quinquefasciatus ◽  
Crystal Size ◽  
Toxin Production ◽  
Bacillus Sphaericus ◽  
Fourth Instar ◽  
Binary Toxin ◽  
Size Characteristic

ABSTRACT The 2297 strain of Bacillus sphaericus produces a crystal of the Bin (binary) toxin that is approximately fourfold larger than that of strain 2362, the strain currently used in VectoLex, a commercial mosquito larvicide. Comparison of the regions downstream from the bin operon in these two strains showed that strain 2362 contained a 1.6-kb region with four orf genes not found in strain 2297. Insertion of a 1.1-kb portion of this region from strain 2362 by homologous recombination downstream from the bin operon in strain 2297 reduced Bin toxin production by 50 to 70% and toxicity to fourth-instar larvae of Culex quinquefasciatus by 68%. These results suggest that the 1.6-kb region downstream from the bin operon in B. sphaericus 2362 is responsible for the lower Bin yield and smaller crystal size characteristic of this strain.

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