Inheritance Patterns, Dominance, Stability, and Allelism of Insecticide Resistance and Cross-Resistance in Two Colonies of Culex quinquefasciatus (Diptera: Culicidae) Selected With Cry Toxins From Bacillus thuringiensis subsp. israelensis

2010 ◽  
Vol 47 (5) ◽  
pp. 814-822 ◽  
Author(s):  
Margaret C. Wirth ◽  
William E. Walton ◽  
Brian A. Federici
Keyword(s):  
Bacillus Thuringiensis ◽  
Insecticide Resistance ◽  
Culex Quinquefasciatus ◽  
Cross Resistance ◽  
Cry Toxins ◽  
Inheritance Patterns

scholarly journals Lack of Cross-Resistance to Cry19A from Bacillus thuringiensis subsp. jegathesan in Culex quinquefasciatus (Diptera: Culicidae) Resistant to Cry Toxins from Bacillus thuringiensis subsp.israelensis

2001 ◽  
Vol 67 (4) ◽  
pp. 1956-1958 ◽  
Author(s):  
Margaret C. Wirth ◽  
Armelle Delécluse ◽  
William E. Walton
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Quinquefasciatus ◽  
Cross Resistance ◽  
Cry Toxins ◽  
Bacillus Thuringiensis Subsp

ABSTRACT Culex quinquefasciatus mosquitoes with high levels of resistance to single or multiple toxins from Bacillus thuringiensis subsp. israelensis were tested for cross-resistance to the Bacillus thuringiensis subsp.jegathesan polypeptide Cry19A. No cross-resistance was detected in mosquitoes that had been selected with the Cry11A, Cry4A and Cry4B, or Cry4A, Cry4B, Cry11A, and CytA toxins. A low but statistically significant level of cross-resistance, three to fourfold, was detected in the colony selected with Cry4A, Cry4B, and Cry11A. This cross-resistance was similar to that previously detected with B. thuringiensis subsp.jegathesan in the same colony. These data help explain the toxicity of B. thuringiensis subsp.jegathesan against the resistant colonies and indicate that the Cry19A polypeptide might be useful in managing resistance and/or as a component of synthetic combinations of mosquitocidal toxins.

scholarly journals Use of Bacillus thuringiensis Toxins for Control of the Cotton Pest Earias insulana (Boisd.) (Lepidoptera: Noctuidae)

2006 ◽  
Vol 72 (1) ◽  
pp. 437-442 ◽  
Author(s):  
María A. Ibargutxi ◽  
Anna Estela ◽  
Juan Ferré ◽  
Primitivo Caballero
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Sites ◽  
Specific Binding ◽  
Significant Inhibition ◽  
The Other ◽  
Cross Resistance ◽  
Earias Insulana ◽  
Cry Proteins ◽  
Cry Toxins ◽  
Laboratory Colony

ABSTRACT Thirteen of the most common lepidopteran-specific Cry proteins of Bacillus thuringiensis have been tested for their efficacy against newly hatched larvae of two populations of the spiny bollworm, Earias insulana. At a concentration of 100 μg of toxin per milliliter of artificial diet, six Cry toxins (Cry1Ca, Cry1Ea, Cry1Fa, Cry1Ja, Cry2Aa, and Cry2Ab) were not toxic at all. Cry1Aa, Cry1Ja, and Cry2Aa did not cause mortality but caused significant inhibition of growth. The other Cry toxins (Cry1Ab, Cry1Ac, Cry1Ba, Cry1Da, Cry1Ia, and Cry9Ca) were toxic to E. insulana larvae. The 50% lethal concentration values of these toxins ranged from 0.39 to 21.13 μg/ml (for Cry9Ca and Cry1Ia, respectively) for an E. insulana laboratory colony originating from Egypt and from 0.20 to 4.25 μg/ml (for Cry9Ca and Cry1Da, respectively) for a laboratory colony originating from Spain. The relative potencies of the toxins in the population from Egypt were highest for Cry9Ca and Cry1Ab, and they were both significantly more toxic than Cry1Ac and Cry1Ba, followed by Cry1Da and finally Cry1Ia. In the population from Spain, Cry9Ca was the most toxic, followed in decreasing order by Cry1Ac and Cry1Ba, and the least toxic was Cry1Da. Binding experiments were performed to test whether the toxic Cry proteins shared binding sites in this insect. 125I-labeled Cry1Ac and Cry1Ab and biotinylated Cry1Ba, Cry1Ia, and Cry9Ca showed specific binding to the brush border membrane vesicles from E. insulana. Competition binding experiments among these toxins showed that only Cry1Ab and Cry1Ac competed for the same binding sites, indicating a high possibility that this insect may develop cross-resistance to Cry1Ab upon exposure to Cry1Ac transgenic cotton but not to the other toxins tested.

scholarly journals Mtx Toxins Synergize Bacillus sphaericus and Cry11Aa against Susceptible and Insecticide-Resistant Culex quinquefasciatus Larvae

2007 ◽  
Vol 73 (19) ◽  
pp. 6066-6071 ◽  
Author(s):  
Margaret C. Wirth ◽  
Yangkun Yang ◽  
William E. Walton ◽  
Brian A. Federici ◽  
Colin Berry
Keyword(s):  
Escherichia Coli ◽  
Bacillus Thuringiensis ◽  
Insecticide Resistance ◽  
Culex Quinquefasciatus ◽  
Vegetative Growth ◽  
Bacillus Sphaericus ◽  
Highly Active ◽  
Level Of Activity ◽  
Low Concentrations ◽  
High Level

ABSTRACT Two mosquitocidal toxins (Mtx) of Bacillus sphaericus, which are produced during vegetative growth, were investigated for their potential to increase toxicity and reduce the expression of insecticide resistance through their interactions with other mosquitocidal proteins. Mtx-1 and Mtx-2 were fused with glutathione S-transferase and produced in Escherichia coli, after which lyophilized powders of these fusions were assayed against Culex quinquefasciatus larvae. Both Mtx proteins showed a high level of activity against susceptible C. quinquefasciatus mosquitoes, with 50% lethal concentrations (LC50) of Mtx-1 and Mtx-2 of 0.246 and 4.13 μg/ml, respectively. The LC50s were 0.406 to 0.430 μg/ml when Mtx-1 or Mtx-2 was mixed with B. sphaericus, and synergy improved activity and reduced resistance levels. When the proteins were combined with a recombinant Bacillus thuringiensis strain that produces Cry11Aa, the mixtures were highly active against Cry11A-resistant larvae and resistance was also reduced. The mixture of two Mtx toxins and B. sphaericus was 10 times more active against susceptible mosquitoes than B. sphaericus alone, demonstrating the influence of relatively low concentrations of these toxins. These results show that, similar to Cyt toxins from B. thuringiensis subsp. israelensis, Mtx toxins can increase the toxicity of other mosquitocidal proteins and may be useful for both increasing the activity of commercial bacterial larvicides and managing potential resistance to these substances among mosquito populations.

scholarly journals Evaluating Cross-resistance Between Vip and Cry Toxins of Bacillus thuringiensis

2019 ◽  
Vol 113 (2) ◽  
pp. 553-561 ◽  
Author(s):  
Bruce E Tabashnik ◽  
Yves Carrière
Keyword(s):  
Bacillus Thuringiensis ◽  
Genetically Engineered ◽  
Cross Resistance ◽  
Published Data ◽  
Data Sets ◽  
Cry Proteins ◽  
Cry Toxins ◽  
Bt Crops ◽  
Resistant Strains ◽  
Bacterium Bacillus

Abstract Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized control of some major pests. Some recently introduced Bt crops make Vip3Aa, a vegetative insecticidal protein (Vip), which reportedly does not share binding sites or structural homology with the crystalline (Cry) proteins of Bt used widely in transgenic crops for more than two decades. Field-evolved resistance to Bt crops with practical consequences for pest control includes 21 cases that collectively reduce the efficacy of nine Cry proteins, but such practical resistance has not been reported yet for any Vip. Here, we review previously published data to evaluate cross-resistance between Vip and Cry toxins. We analyzed 31 cases based on 48 observations, with each case based on one to five observations assessing cross-resistance from pairwise comparisons between 21 resistant strains and 13 related susceptible strains of eight species of lepidopteran pests. Confirming results from previous analyses of smaller data sets, we found weak, statistically significant cross-resistance between Vip3 and Cry1 toxins, with a mean of 1.5-fold cross-resistance in 21 cases (range: 0.30–4.6-fold). Conversely, we did not detect significant positive cross-resistance between Vip3 toxins and Cry2Ab. Distinguishing between weak, significant cross-resistance, and no cross-resistance may be useful for better understanding mechanisms of resistance and effectively managing pest resistance to Bt crops.

scholarly journals Cyt1Ab1 and Cyt2Ba1 from Bacillus thuringiensis subsp. medellin and B. thuringiensis subsp. israelensis Synergize Bacillus sphaericus against Aedes aegypti and Resistant Culex quinquefasciatus (Diptera: Culicidae)

2001 ◽  
Vol 67 (7) ◽  
pp. 3280-3284 ◽  
Author(s):  
Margaret C. Wirth ◽  
Armelle Del�cluse ◽  
William E. Walton
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Culex Quinquefasciatus ◽  
Bacillus Sphaericus ◽  
Bacillus Thuringiensis Subsp

ABSTRACT The interaction of two cytolytic toxins, Cyt1Ab fromBacillus thuringiensis subsp. medellinand Cyt2Ba from Bacillus thuringiensis subsp.israelensis, with Bacillus sphaericus was evaluated against susceptible and resistant Culex quinquefasciatus and the nonsensitive species Aedes aegypti. Mixtures of B. sphaericus with either cytolytic toxin were synergistic, and B. sphaericusresistance in C. quinquefasciatus was suppressed from >17,000- to 2-fold with a 3:1 mixture of B. sphaericusand Cyt1Ab. This trait may prove useful for combating insecticide resistance and for improving the activity of microbial insecticides.

Variable Cross-Resistance to Cry11B from Bacillus thuringiensis subsp. jegathesan in Culex quinquefasciatus (Diptera: Culicidae) Resistant to Single or Multiple Toxins of Bacillus thuringienisis subsp.israelensis

1998 ◽  
Vol 64 (11) ◽  
pp. 4174-4179 ◽  
Author(s):  
Margaret C. Wirth ◽  
Armelle Delécluse ◽  
Brian A. Federici ◽  
William E. Walton
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Quinquefasciatus ◽  
Complex Mixture ◽  
Cross Resistance ◽  
Variable Cross ◽  
Bacterial Strains ◽  
Bacillus Thuringiensis Subsp ◽  
Cry Toxin

ABSTRACT A novel mosquitocidal bacterium, Bacillus thuringiensissubsp. jegathesan, and one of its toxins, Cry11B, in a recombinant B. thuringiensis strain were evaluated for cross-resistance with strains of the mosquito Culex quinquefasciatus that are resistant to single and multiple toxins of Bacillus thuringiensis subsp. israelensis. The levels of cross-resistance (resistance ratios [RR]) at concentrations which caused 95% mortality (LC95) betweenB. thuringiensis subsp. jegathesan and the different B. thuringiensis subsp.israelensis-resistant mosquito strains were low, ranging from 2.3 to 5.1. However, the levels of cross-resistance to Cry11B were much higher and were directly related to the complexity of the B. thuringiensis subsp. israelensis Cry toxin mixtures used to select the resistant mosquito strains. The LC95 RR obtained with the mosquito strains were as follows: 53.1 againstCq4D, which was resistant to Cry11A; 80.7 againstCq4AB, which was resistant to Cry4A plus Cry4B; and 347 against Cq4ABD, which was resistant to Cry4A plus Cry4B plus Cry11A. Combining Cyt1A with Cry11B at a 1:3 ratio had little effect on suppressing Cry11A resistance in Cq4D but resulted in synergism factors of 4.8 and 11.2 against strainsCq4AB and Cq4ABD, respectively; this procedure eliminated cross-resistance in the former mosquito strain and reduced it markedly in the latter strain. The high levels of activity ofB. thuringiensis subsp. jegathesan and B. thuringiensis subsp. israelensis, both of which contain a complex mixture of Cry and Cyt proteins, against Cry4- and Cry11-resistant mosquitoes suggest that novel bacterial strains with multiple Cry and Cyt proteins may be useful in managing resistance to bacterial insecticides in mosquito populations.

scholarly journals ATP-Binding Cassette Subfamily a Member 2 Is a Functional Receptor for Bacillus thuringiensis Cry2A Toxins in Bombyx mori, But Not for Cry1A, Cry1C, Cry1D, Cry1F, or Cry9A Toxins

Toxins ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 104 ◽  
Author(s):  
Xiaoyi Li ◽  
Kazuhisa Miyamoto ◽  
Yoko Takasu ◽  
Sanae Wada ◽  
Tetsuya Iizuka ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Bombyx Mori ◽  
Cell Swelling ◽  
Cross Resistance ◽  
Atp Binding ◽  
Transcription Activator ◽  
Cry Toxins ◽  
Toxin Resistance ◽  
Functional Receptor ◽  
Atp Binding Cassette

Cry toxins are insecticidal proteins produced by Bacillus thuringiensis (Bt). They are used commercially to control insect pests since they are very active in specific insects and are harmless to the environment and human health. The gene encoding ATP-binding cassette subfamily A member 2 (ABCA2) was identified in an analysis of Cry2A toxin resistance genes. However, we do not have direct evidence for the role of ABCA2 for Cry2A toxins or why Cry2A toxin resistance does not cross to other Cry toxins. Therefore, we performed two experiments. First, we edited the ABCA2 sequence in Bombyx mori using transcription activator-like effector-nucleases (TALENs) and confirmed the susceptibility-determining ability in a diet overlay bioassay. Strains with C-terminal half-deleted BmABCA2 showed strong and specific resistance to Cry2A toxins; even strains carrying a deletion of 1 to 3 amino acids showed resistance. However, the C-terminal half-deleted strains did not show cross-resistance to other toxins. Second, we conducted a cell swelling assay and confirmed the specific ability of BmABCA2 to Cry2A toxins in HEK239T cells. Those demonstrated that BmABCA2 is a functional receptor for Cry2A toxins and that BmABCA2 deficiency-dependent Cry2A resistance does not confer cross-resistance to Cry1A, Cry1Ca, Cry1Da, Cry1Fa or Cry9Aa toxins.

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