Different Mechanisms of Resistance to
            <i>Bacillus thuringiensis</i>
            Toxins in the Indianmeal Moth

Herrero, Salvador; Oppert, Brenda; Ferré, Juan

doi:10.1128/aem.67.3.1085-1089.2001

Cited by 89 publications

(66 citation statements)

References 29 publications

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“…Our results with labeled toxins show that among the toxins tested, Cry1Ab was the only one that shared common binding sites with Cry1Ac. This is a feature observed in all lepidopterans (3,8,9,14,19,20), and it explains the basis of many cases of resistance to more than one B. thuringiensis toxin (12). It is interesting that Cry1Ac, in addition to the shared sites, also seems to have binding sites not shared with Cry1Ab in E. insulana, a feature not particularly common among lepidopteran species.…”

Section: Discussionmentioning

confidence: 96%

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

Ibargutxi

Estela

Ferré

et al. 2006

Appl Environ Microbiol

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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 g 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 g/ml (for Cry9Ca and Cry1Ia, respectively) for an E. insulana laboratory colony originating from Egypt and from 0.20 to 4.25 g/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.125 I-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.

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Section: Discussionmentioning

confidence: 96%

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

Ibargutxi

Estela

Ferré

et al. 2006

Appl Environ Microbiol

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“…In addition to high levels of resistance produced by receptor insensitivity (5, 16, 17), several cases of tolerance to low to medium levels of toxin have been reported in laboratory colonies of lepidopteran species (3,18). Because the molecular basis of some of these cases of tolerance to the toxin are not known, we explored alternative mechanisms.…”

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confidence: 99%

Induction and transmission of Bacillus thuringiensis tolerance in the flour moth Ephestia kuehniella

Rahman

Roberts

Sarjan

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

157

120

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The use of Bacillus thuringiensis (Bt) endotoxins to control insect vectors of human diseases and agricultural pests is threatened by the possible evolution of resistance in major pest species. In addition to high levels of resistance produced by receptor insensitivity (5, 16, 17), several cases of tolerance to low to medium levels of toxin have been reported in laboratory colonies of lepidopteran species (3, 18). Because the molecular basis of some of these cases of tolerance to the toxin are not known, we explored alternative mechanisms. Here, we present evidence that tolerance to a Bt formulation in a laboratory colony of the flour moth Ephestia kuehniella can be induced by preexposure to a low concentration of the Bt formulation and that the tolerance correlates with an elevated immune response. The data also indicate that both immune induction and Bt tolerance can be transmitted to offspring by a maternal effect and that their magnitudes are determined by more than one gene.coagulation ͉ endotoxin tolerance ͉ immune induction ͉ maternal effect ͉ melanization

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“…B. thuringiensis is a Gram-positive bacteria that brings forth crystal inclusions during sporulation, made up of Cry proteins (19,33). They are highly toxic and specific and that is why they are harmless for most non-target organisms (18,30). These toxins are codified by cry genes, and their toxicity has a relationship with the C-terminal section of polypeptidical chains, while the N-terminal section is determinant for crystal structure shape (23 The growth of B. thuringiensis thuringiensis 407 (pH 408) and B. thuringiensis kurstaki HD-73 strains, which synthesize Cry1Ab and Cry1Ac proteins, respectively, was carried out in Glucose medium, at 28±2ºC and 180 rpm, until 90% of cell lyses was achieved.…”

mentioning

confidence: 99%

In vitro effect of Bacillus thuringiensis strains and Cry proteins in phytopathogenic fungi of paddy rice-field

Knaak¹,

Rohr²,

Fiúza³

2007

Braz. J. Microbiol.

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Cry1Ab and Cry1Ac strains and proteins synthesized by Bacillus thuringiensis thuringiensis and B. thuringiensis kurstaki were assessed in the following phytopathogens: Rhizoctonia solani, Pyricularia grisea, Fusarium oxysporum and F. solani, which had their micelial growth decreased after incubation in the presence of the bacterial strains. As to Cry proteins, there were no inhibition halo development in the assessed concentrations.

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Different Mechanisms of Resistance to Bacillus thuringiensis Toxins in the Indianmeal Moth

Cited by 89 publications

References 29 publications

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

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

Induction and transmission of Bacillus thuringiensis tolerance in the flour moth Ephestia kuehniella

In vitro effect of Bacillus thuringiensis strains and Cry proteins in phytopathogenic fungi of paddy rice-field

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