General evaluation of isolate Bacillus thuringiensis （Bt-ASF-1） used as biocide in meddle scale application was conducted. Some morphological and confirmation tests were achieved. The sensitivity tests had been acco...General evaluation of isolate Bacillus thuringiensis （Bt-ASF-1） used as biocide in meddle scale application was conducted. Some morphological and confirmation tests were achieved. The sensitivity tests had been accomplished by diffusion and dilution techniques to determine the response of isolate against the antibiotics. The results of diffusion tests showed to the sensitivity of bacteria to antibiotics of cefixime, erythromycin, gentamicin and tetracycline respectively. It was resistant to trimethoprim sulfonamide （TMP）, bacitracin, penicillin and all its generations, and moderate resistance to nalidixic acid. Minimum Inhibitory Concentration （MIC） for amoxicillin was ranged between 30-40 pg/mL and these results are an approximation of the universal findings. Curing experiments showed the effective role of sodium dodecyl sulfate （SDS） （1.5%） comparing with temperature. The bacterial cells became sensitive to amoxicillin and TMP. The curing by temperature did not differ significantly from control treatment in plasmid pattern or antibiotics response. Plasmid profile referring that curing by SDS has been caused disturbance in beta -lactamase genes through the sensitivity to amoxicillin and remaining resistance to ampicillin. Curing isolate by SDS also became more sensitive to nalidixic acid, erythromycin and tetracycline respectively. It was found from the curing treatments the complexity distribution of r-genes between different plasmid size and chromosome but not effect on their insecticidal ability.展开更多
The research cxamined the effects of microbial and novel insecticidal control strategies and also Irichogramma pretiosum on the I,epidoptera： Crambidae, the European corn borer （ECB）, （Ostrinia nubilalis）. The tr...The research cxamined the effects of microbial and novel insecticidal control strategies and also Irichogramma pretiosum on the I,epidoptera： Crambidae, the European corn borer （ECB）, （Ostrinia nubilalis）. The treatments included ~ino^d, from bacteria the entomopathogenic fungus Beauveria bassiana, the egg parasitoid Trichogramma pretiosum, and foliar applied Bt spray, and t^vo combinations Bearveria bassiana plus Bt spray and Trichogramma pretiosum and spinosad. The infestations by the European corn borer larvae on stalks of corn were very＂ severe in all the control treatments both 2006 and 2007. The microbial treatments caused various levels of European corn borer mortality. In all the parameters there was a significant difference between the control and other treatments with a P 〈 0.00 l. In this research, treatment with spinosad emerged as the most effective biological agent in the control of the European corn borer. The treatments had no significant effects on the relative abundance and composition of non-target arthropods （P 〉 0.05）. This research is relevant in boosting underutilized control strategies and increasing stakeholder adoption of integrated pest management practices and thereby＇ reducing the use of conventional insecticides especially for orgamc thrmers. This is very important especially in certain countries where the commumities are skeptical about consuming transgenic crops.展开更多
[Objective] This study aimed to screen the best synergistic material for Bt wettable powder and evaluate their synergistic effect. [Method] The synergism of six different kinds of additives for Bacillus thuringiensis ...[Objective] This study aimed to screen the best synergistic material for Bt wettable powder and evaluate their synergistic effect. [Method] The synergism of six different kinds of additives for Bacillus thuringiensis wettable powder （Bt WP） on the 2^nd instar larvae of Plutella xylostella was tested by method of leaf dipping in labora- tory. [Result] The mixtures of Bt with 0.1% ZnCl2, 0.5% ZnCl2, 1.0% ZnCl2, 1.0% MgCI2, 0.5% boric acid, 1.0% boric acid, 0.5% citric acid or 1.0% citric acid all ex- hibited synergistic effect, in which the synergistic effect of mixture containing 0.5% boric acid was the highest, with 17.2 synergistic ratio; followed by the mixture containing 1.0% ZnCl2, with 15.6 synergistic ratio. Moreover, addition of 0.5% boric acid could shorten the median lethal time of Bt wettable powder by about 10 h. After the mixtures of Bt with 0.5% boracic acid or 1.0% ZnCl2 was stored for 15 d at room temperature, toxicities of the two mixtures did not change significantly. [Conclusion] Boracic acid as the synergist of Bt wettable powder could not only increase insecti- cidal effect of Bt, but also accelerate its insecticidal rate. So, boracic acid could improve the disadvantages of Bt wettable powder such as poor insecticidal effect and slow insecticidal speed in a certain degree.展开更多
Chemical reactions and fate of the toxins of Bacillus thuringiensis （Bt） in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants. In this study, the effect ...Chemical reactions and fate of the toxins of Bacillus thuringiensis （Bt） in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants. In this study, the effect of ionic strength （0-1 000 mmol kg-1） adjusted by NaCl or CaCl2 on adsorption of Bt toxin by a lateritic red soil, a paddy soil and these soils after chemical removal of organic-bound or free Fe and Al oxides, as well as by pure minerals （goethite, hematite and gibbsite） which are widespread in these soils, were studied. The results indicated that when the supporting electrolyte was NaCl, the adsorption of Bt toxin by the lateritic red soil and paddy soil increased rapidly until the ionic strength reached 250 mmol kg-1 and then gradually slowed down with the increase of ionic strength; while in ease the supporting electrolyte was CaCl2, the adsorption of Bt toxin enhanced significantly at low ionic strength （〈 10 mmol kg-1） and then decreased as the ionic strength increased. The adsorption of Bt toxin by the tested minerals and soils after the removal of organic-bound or free Fe and Al oxides also increased with increasing ionic strength controlled by NaCl. Removing organic-bound Fe and Al oxides obviously increased the adsorption of Bt toxin in the tested soils. Differently, removing free Fe and Al oxides increased the Bt adsorption by the paddy soil, but decreased the adsorption by the lateritic red soil. The study indicated that the varieties of ionic strength and the presence of Ve and Al oxides affected the adsorption of Bt toxin by the soils, which would contribute to the further understanding of the fate of Bt toxin in the soil environment and provide references for the ecological risk assessment of transgenic Bt plants.展开更多
文摘General evaluation of isolate Bacillus thuringiensis （Bt-ASF-1） used as biocide in meddle scale application was conducted. Some morphological and confirmation tests were achieved. The sensitivity tests had been accomplished by diffusion and dilution techniques to determine the response of isolate against the antibiotics. The results of diffusion tests showed to the sensitivity of bacteria to antibiotics of cefixime, erythromycin, gentamicin and tetracycline respectively. It was resistant to trimethoprim sulfonamide （TMP）, bacitracin, penicillin and all its generations, and moderate resistance to nalidixic acid. Minimum Inhibitory Concentration （MIC） for amoxicillin was ranged between 30-40 pg/mL and these results are an approximation of the universal findings. Curing experiments showed the effective role of sodium dodecyl sulfate （SDS） （1.5%） comparing with temperature. The bacterial cells became sensitive to amoxicillin and TMP. The curing by temperature did not differ significantly from control treatment in plasmid pattern or antibiotics response. Plasmid profile referring that curing by SDS has been caused disturbance in beta -lactamase genes through the sensitivity to amoxicillin and remaining resistance to ampicillin. Curing isolate by SDS also became more sensitive to nalidixic acid, erythromycin and tetracycline respectively. It was found from the curing treatments the complexity distribution of r-genes between different plasmid size and chromosome but not effect on their insecticidal ability.
文摘The research cxamined the effects of microbial and novel insecticidal control strategies and also Irichogramma pretiosum on the I,epidoptera： Crambidae, the European corn borer （ECB）, （Ostrinia nubilalis）. The treatments included ~ino^d, from bacteria the entomopathogenic fungus Beauveria bassiana, the egg parasitoid Trichogramma pretiosum, and foliar applied Bt spray, and t^vo combinations Bearveria bassiana plus Bt spray and Trichogramma pretiosum and spinosad. The infestations by the European corn borer larvae on stalks of corn were very＂ severe in all the control treatments both 2006 and 2007. The microbial treatments caused various levels of European corn borer mortality. In all the parameters there was a significant difference between the control and other treatments with a P 〈 0.00 l. In this research, treatment with spinosad emerged as the most effective biological agent in the control of the European corn borer. The treatments had no significant effects on the relative abundance and composition of non-target arthropods （P 〉 0.05）. This research is relevant in boosting underutilized control strategies and increasing stakeholder adoption of integrated pest management practices and thereby＇ reducing the use of conventional insecticides especially for orgamc thrmers. This is very important especially in certain countries where the commumities are skeptical about consuming transgenic crops.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(200903042-5)National Apple Industry Technology System Project of China(nycytx-08-04-01)~~
文摘[Objective] This study aimed to screen the best synergistic material for Bt wettable powder and evaluate their synergistic effect. [Method] The synergism of six different kinds of additives for Bacillus thuringiensis wettable powder （Bt WP） on the 2^nd instar larvae of Plutella xylostella was tested by method of leaf dipping in labora- tory. [Result] The mixtures of Bt with 0.1% ZnCl2, 0.5% ZnCl2, 1.0% ZnCl2, 1.0% MgCI2, 0.5% boric acid, 1.0% boric acid, 0.5% citric acid or 1.0% citric acid all ex- hibited synergistic effect, in which the synergistic effect of mixture containing 0.5% boric acid was the highest, with 17.2 synergistic ratio; followed by the mixture containing 1.0% ZnCl2, with 15.6 synergistic ratio. Moreover, addition of 0.5% boric acid could shorten the median lethal time of Bt wettable powder by about 10 h. After the mixtures of Bt with 0.5% boracic acid or 1.0% ZnCl2 was stored for 15 d at room temperature, toxicities of the two mixtures did not change significantly. [Conclusion] Boracic acid as the synergist of Bt wettable powder could not only increase insecti- cidal effect of Bt, but also accelerate its insecticidal rate. So, boracic acid could improve the disadvantages of Bt wettable powder such as poor insecticidal effect and slow insecticidal speed in a certain degree.
基金Supported by the National Natural Science Foundation of China (Nos. 41001140 and 40671087)
文摘Chemical reactions and fate of the toxins of Bacillus thuringiensis （Bt） in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants. In this study, the effect of ionic strength （0-1 000 mmol kg-1） adjusted by NaCl or CaCl2 on adsorption of Bt toxin by a lateritic red soil, a paddy soil and these soils after chemical removal of organic-bound or free Fe and Al oxides, as well as by pure minerals （goethite, hematite and gibbsite） which are widespread in these soils, were studied. The results indicated that when the supporting electrolyte was NaCl, the adsorption of Bt toxin by the lateritic red soil and paddy soil increased rapidly until the ionic strength reached 250 mmol kg-1 and then gradually slowed down with the increase of ionic strength; while in ease the supporting electrolyte was CaCl2, the adsorption of Bt toxin enhanced significantly at low ionic strength （〈 10 mmol kg-1） and then decreased as the ionic strength increased. The adsorption of Bt toxin by the tested minerals and soils after the removal of organic-bound or free Fe and Al oxides also increased with increasing ionic strength controlled by NaCl. Removing organic-bound Fe and Al oxides obviously increased the adsorption of Bt toxin in the tested soils. Differently, removing free Fe and Al oxides increased the Bt adsorption by the paddy soil, but decreased the adsorption by the lateritic red soil. The study indicated that the varieties of ionic strength and the presence of Ve and Al oxides affected the adsorption of Bt toxin by the soils, which would contribute to the further understanding of the fate of Bt toxin in the soil environment and provide references for the ecological risk assessment of transgenic Bt plants.
