[ Objective] The paper was to study pathogenic mechanism and action mode of Bacillus thuringiensis （Bt） 00-50-5 strain against Trichoplusia ni Hub- ner. [Method] The crystals and spores of B. thuringiensis 00-50-5 s...[ Objective] The paper was to study pathogenic mechanism and action mode of Bacillus thuringiensis （Bt） 00-50-5 strain against Trichoplusia ni Hub- ner. [Method] The crystals and spores of B. thuringiensis 00-50-5 strain were first isolated and purified, and their insecticidal activities against T. ni were com- pared. [ Result] Either the mixture of pure crystals and pure spores of 00-50-5 strain, or only pure crystals could kill T. n/larvae under the concentration of 100 p.g/mL after 48 h, and the mortality rate reached 100% ; pure spores could not kill the larvae. Determination results of median lethal concentration showed that in- secticidal activity of pure crystal of Bt 00-50-5 strain （LGs0 =0.32 p~/mL） was higher than the mixture of crystals and spores （LCs0 =0.48）, but the insecticidal acti^ty of pure spores was very low （LC50 〉 500.00）. Therefore, the crystals were primarily responsible for causing death of larvae. [ Conclusion] The paper provides theoretical basis for application of Bt 00-50-5 strain.展开更多
Eight insecticidal crystal proteins of Bacillus thuringiensis, CrylAa, CrylAb, CrylAc, CrylB, Cry2Aa, CrylC, CrylDa and Cry 1Ea were assessed for toxicity against 1 st instar larvae of rice leaf folder, Cnaphalocrocis...Eight insecticidal crystal proteins of Bacillus thuringiensis, CrylAa, CrylAb, CrylAc, CrylB, Cry2Aa, CrylC, CrylDa and Cry 1Ea were assessed for toxicity against 1 st instar larvae of rice leaf folder, Cnaphalocrocis medinalis （Guenee） at 48 HAT and 72 HAT. Bioassay results depicted CrylAa was the most toxic （LCso 2.35 ppm） followed by CrylBa （LCso 8,50 ppm） and CrylAb （LCso 8.73 ppm） at 48 HAT, whereas, at 72 HAT CrylAb proved to be highly toxic （LC50 0.50 ppm） followed by CrylAa （LCso 4.07 ppm）, CrylAc （LCso 4,84 ppm） and CrylBa （LCso 6.42 ppm）. Toxins Cry2Aa, CrylCa, CrylDa and CrylEa did not resulted in any mortality at 48 HAT and 72 HAT, respectively. Baseline estimates for CrylAb against 1st instar larvae of C. medinalis sampled from seven geographical locations revealed variation in LC50＇s from 0.37 ppm to LC50 16.25 ppm at 48 HAT and LC50 0.50 ppm to LC50 6.49 ppm 72 HAT, respectively with relative resistance ratios of 44-fold and 13-fold at 48 HAT and 72 HAT over the susceptible population.展开更多
[Objective] This study aimed to investigate the biological characteristics of a Bacillus thuringiensis strain YNI-1, which has high virulence to Lepidoptera spp. [Method] The crystal protein of YNI-1 was analyzed by S...[Objective] This study aimed to investigate the biological characteristics of a Bacillus thuringiensis strain YNI-1, which has high virulence to Lepidoptera spp. [Method] The crystal protein of YNI-1 was analyzed by SDS-PAGE, and its indoor and field efficacy for Lepidoptera spp. was investigated. [Result] The parasporal crystal of YNI-1 has a diamond-like structure. The molecular weight of the original toxin protein is 136 kDa. After trypsin treatment, the original toxin protein was hy- drolyzed into active toxin protein with molecular weight of 63 kDa. For Plutella xy- Iostella and Pieris rapae, the indoor efficacy of B. thuringiensis was better than that of commercial B. thuringiensis （WP）. In view of field efficacy, rate of YNI-1 strain was higher than that of commercial B [Conelusion] YNI-1 strain has excellent development potential. the insects reduced thuringiensis （WP）.展开更多
Bacillus thuringiensis strains isolated from Madurai, TamilNadu, India were evaluated for their mosquitocidal activity, as well as cry and cyt genes diversity. It revealed that 99% of the parasporal crystal morphology...Bacillus thuringiensis strains isolated from Madurai, TamilNadu, India were evaluated for their mosquitocidal activity, as well as cry and cyt genes diversity. It revealed that 99% of the parasporal crystal morphology of these isolates was spherical in nature and a variable percentage (0% - 100%) of toxicity was observed against Culex quinquefasciatus and Aedes aegypti. PCR analysis revealed that 53% of the isolates were positive for the various cry and cyt genes tested, whereas 47% did not produce any PCR product for the cry gene analyzed. Diverse pattern of cry and cyt genes distribution was observed even in the isolates from the same sample. B. thuringienis subsp. LDC-9 showed three-fold higher toxicity against Culex quinquefasciatus than that of B. thuringiensis var israelensis which might be used as a potential strain to control mosquitoes in near future after field evaluation.展开更多
Resistance in insect pests against the endotoxin of Bacillus thuringiensis （Berliner） （Bt） is a major threat to the usefulness of this biopesticide, both used as traditional formulations and in transgenic crops. A...Resistance in insect pests against the endotoxin of Bacillus thuringiensis （Berliner） （Bt） is a major threat to the usefulness of this biopesticide, both used as traditional formulations and in transgenic crops. A crucial requirement for the development of successful resistance management strategies is a molecular understanding of the nature and inheritance of resistance mechanisms. This information can be used to design management strategies that will delay or counteract Bt resistance. The best known Bt resistance mechanism is inactivation of brush border membrane receptors. This type of resistance has a largely recessive mode of inheritance, which has enabled the design of resistance management approaches involving high dose and refuge strategies. Recent observations suggest that other resistance mechanisms are possible, including a mechanism that sequesters the toxin in the gut lumen through inducible immune reactions. The elevated immune status associated with tolerance to the toxin can be transmitted to subsequent generations by a maternal effect, which has implications for resistance management in the field. The high dose/refuge strategy may not be appropriate for the management of these alternative resistance mechanisms and other strategies have to be developed if inducible dominant resistance or tolerance mechanisms occur frequently in the field.展开更多
In this study, we rapidly identified Bacillus thuringiensis 4.0718 strain that harbored the known cry1 and cry2 type genes by a PCR strategy. Three pairs of universal oligonucleotide primers were designed to detect al...In this study, we rapidly identified Bacillus thuringiensis 4.0718 strain that harbored the known cry1 and cry2 type genes by a PCR strategy. Three pairs of universal oligonucleotide primers were designed to detect all known cry1, cry2 and cry3 type gene sequences. Then the DNA of the positive strain 4.0718 was probed with a set of specific primers. One feacture of this screening method was that each gene was expected to produce a PCR product having a precise molecular weight. PCR products having different sizes probably represented the gene was a potentially novel gene. Differentiations among these genes was determined on the basis of the electrophoresis patterns of PCR products. Finally, five cry1 type genes (cry1Aa, cry1Ab, cry1Ac, cry1Cb, a novel cry4.5 type genes) and one cry2Ac type gene had been detected from Bacillus thuringiensis 4.0718 strain.展开更多
基金supported by Project for Introduced Talents in Environment and Plant Protection Institute of Chinese Academy of Tropical Agriculture(HZS1101)Fundamental Research Special Project for Central Public-interest Scientific Institutes(2012hzs1 J038,2012hzs1 J016)
文摘[ Objective] The paper was to study pathogenic mechanism and action mode of Bacillus thuringiensis （Bt） 00-50-5 strain against Trichoplusia ni Hub- ner. [Method] The crystals and spores of B. thuringiensis 00-50-5 strain were first isolated and purified, and their insecticidal activities against T. ni were com- pared. [ Result] Either the mixture of pure crystals and pure spores of 00-50-5 strain, or only pure crystals could kill T. n/larvae under the concentration of 100 p.g/mL after 48 h, and the mortality rate reached 100% ; pure spores could not kill the larvae. Determination results of median lethal concentration showed that in- secticidal activity of pure crystal of Bt 00-50-5 strain （LGs0 =0.32 p~/mL） was higher than the mixture of crystals and spores （LCs0 =0.48）, but the insecticidal acti^ty of pure spores was very low （LC50 〉 500.00）. Therefore, the crystals were primarily responsible for causing death of larvae. [ Conclusion] The paper provides theoretical basis for application of Bt 00-50-5 strain.
文摘Eight insecticidal crystal proteins of Bacillus thuringiensis, CrylAa, CrylAb, CrylAc, CrylB, Cry2Aa, CrylC, CrylDa and Cry 1Ea were assessed for toxicity against 1 st instar larvae of rice leaf folder, Cnaphalocrocis medinalis （Guenee） at 48 HAT and 72 HAT. Bioassay results depicted CrylAa was the most toxic （LCso 2.35 ppm） followed by CrylBa （LCso 8,50 ppm） and CrylAb （LCso 8.73 ppm） at 48 HAT, whereas, at 72 HAT CrylAb proved to be highly toxic （LC50 0.50 ppm） followed by CrylAa （LCso 4.07 ppm）, CrylAc （LCso 4,84 ppm） and CrylBa （LCso 6.42 ppm）. Toxins Cry2Aa, CrylCa, CrylDa and CrylEa did not resulted in any mortality at 48 HAT and 72 HAT, respectively. Baseline estimates for CrylAb against 1st instar larvae of C. medinalis sampled from seven geographical locations revealed variation in LC50＇s from 0.37 ppm to LC50 16.25 ppm at 48 HAT and LC50 0.50 ppm to LC50 6.49 ppm 72 HAT, respectively with relative resistance ratios of 44-fold and 13-fold at 48 HAT and 72 HAT over the susceptible population.
基金Supported by Natural Science Foundation of Yanbian University(2011-34)~~
文摘[Objective] This study aimed to investigate the biological characteristics of a Bacillus thuringiensis strain YNI-1, which has high virulence to Lepidoptera spp. [Method] The crystal protein of YNI-1 was analyzed by SDS-PAGE, and its indoor and field efficacy for Lepidoptera spp. was investigated. [Result] The parasporal crystal of YNI-1 has a diamond-like structure. The molecular weight of the original toxin protein is 136 kDa. After trypsin treatment, the original toxin protein was hy- drolyzed into active toxin protein with molecular weight of 63 kDa. For Plutella xy- Iostella and Pieris rapae, the indoor efficacy of B. thuringiensis was better than that of commercial B. thuringiensis （WP）. In view of field efficacy, rate of YNI-1 strain was higher than that of commercial B [Conelusion] YNI-1 strain has excellent development potential. the insects reduced thuringiensis （WP）.
文摘Bacillus thuringiensis strains isolated from Madurai, TamilNadu, India were evaluated for their mosquitocidal activity, as well as cry and cyt genes diversity. It revealed that 99% of the parasporal crystal morphology of these isolates was spherical in nature and a variable percentage (0% - 100%) of toxicity was observed against Culex quinquefasciatus and Aedes aegypti. PCR analysis revealed that 53% of the isolates were positive for the various cry and cyt genes tested, whereas 47% did not produce any PCR product for the cry gene analyzed. Diverse pattern of cry and cyt genes distribution was observed even in the isolates from the same sample. B. thuringienis subsp. LDC-9 showed three-fold higher toxicity against Culex quinquefasciatus than that of B. thuringiensis var israelensis which might be used as a potential strain to control mosquitoes in near future after field evaluation.
文摘Resistance in insect pests against the endotoxin of Bacillus thuringiensis （Berliner） （Bt） is a major threat to the usefulness of this biopesticide, both used as traditional formulations and in transgenic crops. A crucial requirement for the development of successful resistance management strategies is a molecular understanding of the nature and inheritance of resistance mechanisms. This information can be used to design management strategies that will delay or counteract Bt resistance. The best known Bt resistance mechanism is inactivation of brush border membrane receptors. This type of resistance has a largely recessive mode of inheritance, which has enabled the design of resistance management approaches involving high dose and refuge strategies. Recent observations suggest that other resistance mechanisms are possible, including a mechanism that sequesters the toxin in the gut lumen through inducible immune reactions. The elevated immune status associated with tolerance to the toxin can be transmitted to subsequent generations by a maternal effect, which has implications for resistance management in the field. The high dose/refuge strategy may not be appropriate for the management of these alternative resistance mechanisms and other strategies have to be developed if inducible dominant resistance or tolerance mechanisms occur frequently in the field.
文摘In this study, we rapidly identified Bacillus thuringiensis 4.0718 strain that harbored the known cry1 and cry2 type genes by a PCR strategy. Three pairs of universal oligonucleotide primers were designed to detect all known cry1, cry2 and cry3 type gene sequences. Then the DNA of the positive strain 4.0718 was probed with a set of specific primers. One feacture of this screening method was that each gene was expected to produce a PCR product having a precise molecular weight. PCR products having different sizes probably represented the gene was a potentially novel gene. Differentiations among these genes was determined on the basis of the electrophoresis patterns of PCR products. Finally, five cry1 type genes (cry1Aa, cry1Ab, cry1Ac, cry1Cb, a novel cry4.5 type genes) and one cry2Ac type gene had been detected from Bacillus thuringiensis 4.0718 strain.
