This study investigated the eco-biocontrol potential of indigenous isolates obtained from agricultural soils in WarboVillage, Papua, Indonesia, targeting the highly destructive fall armyworm (Spodoptera frugiperda) in...This study investigated the eco-biocontrol potential of indigenous isolates obtained from agricultural soils in WarboVillage, Papua, Indonesia, targeting the highly destructive fall armyworm (Spodoptera frugiperda) in corn agroecosystems.A total of 58 bacterial colonies were isolated, of which 18 were morphologically confirmed as Bacillus thuringiensis basedon endospore and parasporal crystal protein characteristics. These isolates were cultured in Tryptose Phosphate Broth andtested for larvicidal activity against second-instar larvae under controlled conditions. Toxicity tests revealed that isolate 18exhibited the highest efficacy, causing 100% larval mortality, followed by isolates 12 and 13 with 93.3%, confirming astrong entomopathogenic potential. The most toxic isolates were further verified by the presence of cry1F and cry2Aagenes through PCR analysis, indicating the molecular basis of their virulence. The innovation of this research lies in thecombination of morphological, toxicological, and molecular characterizations of locally adapted Bacillus thuringiensisstrains, which offers a sustainable, environmentally friendly alternative to chemical pesticides. These findings provide ascientific foundation for developing region-specific bioinsecticides, reducing dependence on synthetic inputs, and supportingsustainable pest management strategies in tropical corn production systems.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
[Objective] This study was conducted to isolate and screen new Bacillus thuringiensis （Bt） strains against Lepidoptera insecticides. [Method] Bt strains were isolated from soil of Changbai Mountain area by temperatu...[Objective] This study was conducted to isolate and screen new Bacillus thuringiensis （Bt） strains against Lepidoptera insecticides. [Method] Bt strains were isolated from soil of Changbai Mountain area by temperature screening method, and highly-toxic Bt stains were then selected by biological determination and toxicity de- termination. [Result] From 150 soil samples, 18 Bt isolates were isolated, with an average isolation rate of 12.0%. Specifically, the isolation rate from mountain field was 8.5 %, and the isolation rate from farmland was 16.2%. The results of activity determination showed that there were17, 5 and 4 strains showing lethality rate over 90% against Plutel/a xylosrel/a, Spodoptera litura and Spodptera exigua, respectively, and among them, strain YNI-1 exhibited high activity against all the 3 kinds of in- sects. The results of toxicity determination showed that strain YNl-lhad the best fast-acting property against S.litura and S. exigua; strains with high toxicity against S. exigua were YN6-2〉YN1-1〉YN4-2〉YN2-6 sequentially; and toxicity of strains against S. /itura was in order of YN4-4〉YN1-1 〉YN6-1 〉YN4-1 〉YN2-1. [Conclusion] According to activity determination and toxicity determination, strain YN1-1 was screened as the target strain with wide spectrum, fast-acting property and high toxi- city.展开更多
Cry toxins produced by Bacillus thuringiensis（Bt） are effective biological insecticides against certain insect species.In this study,bioassay results indicated that Cry1B and Cry1C were toxic to Spodoptera exigua.We...Cry toxins produced by Bacillus thuringiensis（Bt） are effective biological insecticides against certain insect species.In this study,bioassay results indicated that Cry1B and Cry1C were toxic to Spodoptera exigua.We also identified a cadherin-like gene in S.exigua that could enhance the toxicity of Cry1B and Cry1C.The cadherin-like gene identified from the larvae midgut tissue was cloned by reverse transcription polymerase chain reaction（RT-PCR） and rapid amplification of cDNA ends（RACE）.The full-length cDNA of the gene consisted of 5 220 bp encoding 1 740 amino acid with a predicted molecular mass of 196 kD.BLAST search analysis showed that the predicted amino acid sequence had a high sequence identity to the published sequences of cadherin-like proteins from other Lepidoptera insects.Spatial expression of the cadherin-like gene detected by qRT-PCR analysis revealed that the cadherin-like gene was mainly present in the gut of 4th instar larvae and during different life stages.The results suggested that the commercial development of this synergist has the potential to enhance Cry1B and Cry1C toxicity against Lepidoptera insects.展开更多
Ninety-two Bacillus thuringiensis isolates were screened from 683 soil samples collected from tropical and semitropical primeval forests in Yunnan and Hainan provinces of China. Several shapes of crystals, including b...Ninety-two Bacillus thuringiensis isolates were screened from 683 soil samples collected from tropical and semitropical primeval forests in Yunnan and Hainan provinces of China. Several shapes of crystals, including bipyramidal, square, ovoid, spherical, and amorphous, were observed in the B. thuringiensis isolates. Twenty-six pairs of primers were used to identify 31 holotype cry genes at primary rank of the B. thuringiensis cry gene nomenclature system. The cry gene-types of 92 B. thuringiensis isolates and 33 B. thuringiensis isolates screened from Northeast region of China were identified by PCR-RFLP and SDS-PAGE methods. Fifty-eight isolates harbored cry1 genes, 32 isolates cry2 genes, 12 isolates cry8 genes, 3 isolates cry9 genes, 12 isolates cry11 genes, and 13 isolates cry30 genes. Of the tested isolates, 42 produced no reaction product with 26 pairs of primers and also exhibited no toxicity against 8 insect species tested. The isolate Z2-34 harbored a novel cry30 gene, exhibited insecticidal activity against Aedes albopictus of Dipterans. The accession number of the novel genes in this study is AY916046. Isolation and identification of B. thuringiensis and cry gene are important for investigating the diversity of B. thuringiensis resources and cloning new cry gene.展开更多
The adsorption and desorption of the toxin from Bacillus thuringiensis strain WG-001 on rectorite were studied at different toxin and/or rectorite concentrations, pH values and temperatures. The insecticidal activity ...The adsorption and desorption of the toxin from Bacillus thuringiensis strain WG-001 on rectorite were studied at different toxin and/or rectorite concentrations, pH values and temperatures. The insecticidal activity of the adsorbed toxin was evaluated by determining the lethal concentration to kill 50% of the larvae of Heliothis armigera （LC50）. The adsorption of the toxin on rectorite in sodium carbonate buffer （pH 9） reached equilibrium within 0.5-1.0 h and the adsorption isotherm of the toxin followed the Langmuir equation （R^2 〉 0.99）. In the pH range from 9 to 11 （carbonate buffer）, the adsorbed toxin decreased with increasing pH. The adsorption amounts decreased with increasing rectorite：toxin ratio. The adsorption was not significantly affected by the temperature between 10 and 50 ℃. The X- ray diffraction analysis indicated occurrence of the intercalation of the rectorite by the toxin. The infrared absorption spectrum showed that the binding of the toxin did not alter its structure. The LC50 wlues of the adsorbed toxin were smaller than those of the free toxin. The rectorite protected the toxin from ultraviolet irradiation damage. The desorption of the adsorbed toxin in water ranged from 37.5% to 56.4% and from 27.4% to 41.8% in a carbonate buffer. The desorption percentage also decreased with increasing rectorite：toxin ratio.展开更多
In order to find and identify more targets species of pests for toxic insecticidal Bacillus thuringiensis(Bt)strains,a toxicity survey was carried out of two strains h3 and Ly30 against diamondback moth(Lepidoptera),C...In order to find and identify more targets species of pests for toxic insecticidal Bacillus thuringiensis(Bt)strains,a toxicity survey was carried out of two strains h3 and Ly30 against diamondback moth(Lepidoptera),Culex pipiens pallens and Musca domestica(Diptera),Blattella germanica(Coleoptera),which were respectively isolated from Lianyungang oceans with excellent characteristic of high salt tolerance,and from insect Componotus iaponicu Mayr larvae,respectively.Bioassay showed that h3 and Ly30 have efficient insecticidal activity against diamondback moth(Lepidoptera),Culex pipiens pallens and Musca domestica(Diptera)by 99%-100%mortality at 3 d-5 d,while only have 30%mortality at 5 d against coleoptera pests.It provided strong evidence for the insecticidal role of autotrophic Bt strains h3 and Ly30 against pests populations of lepidoptera and diptera and coleoptera,and aslo evidence for the application in the fields of agriculture and forest and public health.Furthermore,high salt tolerance of h3 could provide great benefit not only in expanding the application fields of biological insecticides,but also increasing the applicable object,and enhancing the efficacy of Bt.展开更多
基金funded by the Directorate General of Higher Education(DRPM),Ministry of Education,Culture,Research,and Technology of Indonesia,under the auspices of the Research Grant Scheme 2024.
文摘This study investigated the eco-biocontrol potential of indigenous isolates obtained from agricultural soils in WarboVillage, Papua, Indonesia, targeting the highly destructive fall armyworm (Spodoptera frugiperda) in corn agroecosystems.A total of 58 bacterial colonies were isolated, of which 18 were morphologically confirmed as Bacillus thuringiensis basedon endospore and parasporal crystal protein characteristics. These isolates were cultured in Tryptose Phosphate Broth andtested for larvicidal activity against second-instar larvae under controlled conditions. Toxicity tests revealed that isolate 18exhibited the highest efficacy, causing 100% larval mortality, followed by isolates 12 and 13 with 93.3%, confirming astrong entomopathogenic potential. The most toxic isolates were further verified by the presence of cry1F and cry2Aagenes through PCR analysis, indicating the molecular basis of their virulence. The innovation of this research lies in thecombination of morphological, toxicological, and molecular characterizations of locally adapted Bacillus thuringiensisstrains, which offers a sustainable, environmentally friendly alternative to chemical pesticides. These findings provide ascientific foundation for developing region-specific bioinsecticides, reducing dependence on synthetic inputs, and supportingsustainable pest management strategies in tropical corn production systems.
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 Natural Science Foundation of Yanbian University(2011-34)~~
文摘[Objective] This study was conducted to isolate and screen new Bacillus thuringiensis （Bt） strains against Lepidoptera insecticides. [Method] Bt strains were isolated from soil of Changbai Mountain area by temperature screening method, and highly-toxic Bt stains were then selected by biological determination and toxicity de- termination. [Result] From 150 soil samples, 18 Bt isolates were isolated, with an average isolation rate of 12.0%. Specifically, the isolation rate from mountain field was 8.5 %, and the isolation rate from farmland was 16.2%. The results of activity determination showed that there were17, 5 and 4 strains showing lethality rate over 90% against Plutel/a xylosrel/a, Spodoptera litura and Spodptera exigua, respectively, and among them, strain YNI-1 exhibited high activity against all the 3 kinds of in- sects. The results of toxicity determination showed that strain YNl-lhad the best fast-acting property against S.litura and S. exigua; strains with high toxicity against S. exigua were YN6-2〉YN1-1〉YN4-2〉YN2-6 sequentially; and toxicity of strains against S. /itura was in order of YN4-4〉YN1-1 〉YN6-1 〉YN4-1 〉YN2-1. [Conclusion] According to activity determination and toxicity determination, strain YN1-1 was screened as the target strain with wide spectrum, fast-acting property and high toxi- city.
基金supported by the National Basic Research Program of China(2012CB114104)the National Natural Science Foundation of China (31071694 and 31171858)
文摘Cry toxins produced by Bacillus thuringiensis（Bt） are effective biological insecticides against certain insect species.In this study,bioassay results indicated that Cry1B and Cry1C were toxic to Spodoptera exigua.We also identified a cadherin-like gene in S.exigua that could enhance the toxicity of Cry1B and Cry1C.The cadherin-like gene identified from the larvae midgut tissue was cloned by reverse transcription polymerase chain reaction（RT-PCR） and rapid amplification of cDNA ends（RACE）.The full-length cDNA of the gene consisted of 5 220 bp encoding 1 740 amino acid with a predicted molecular mass of 196 kD.BLAST search analysis showed that the predicted amino acid sequence had a high sequence identity to the published sequences of cadherin-like proteins from other Lepidoptera insects.Spatial expression of the cadherin-like gene detected by qRT-PCR analysis revealed that the cadherin-like gene was mainly present in the gut of 4th instar larvae and during different life stages.The results suggested that the commercial development of this synergist has the potential to enhance Cry1B and Cry1C toxicity against Lepidoptera insects.
文摘Ninety-two Bacillus thuringiensis isolates were screened from 683 soil samples collected from tropical and semitropical primeval forests in Yunnan and Hainan provinces of China. Several shapes of crystals, including bipyramidal, square, ovoid, spherical, and amorphous, were observed in the B. thuringiensis isolates. Twenty-six pairs of primers were used to identify 31 holotype cry genes at primary rank of the B. thuringiensis cry gene nomenclature system. The cry gene-types of 92 B. thuringiensis isolates and 33 B. thuringiensis isolates screened from Northeast region of China were identified by PCR-RFLP and SDS-PAGE methods. Fifty-eight isolates harbored cry1 genes, 32 isolates cry2 genes, 12 isolates cry8 genes, 3 isolates cry9 genes, 12 isolates cry11 genes, and 13 isolates cry30 genes. Of the tested isolates, 42 produced no reaction product with 26 pairs of primers and also exhibited no toxicity against 8 insect species tested. The isolate Z2-34 harbored a novel cry30 gene, exhibited insecticidal activity against Aedes albopictus of Dipterans. The accession number of the novel genes in this study is AY916046. Isolation and identification of B. thuringiensis and cry gene are important for investigating the diversity of B. thuringiensis resources and cloning new cry gene.
基金the National Natural Science Foundation of China (Nos.40271064 and 30170032)the Natural Science Foundation of Tianjin,China (No.05YFJMJC05100)+1 种基金the Scientific Research Project of the Education Administration of Hubei Province,China (No.Q200611007)the Key Research Program of Wuhan University of Science and Technology,China (No.2006XZ4).
文摘The adsorption and desorption of the toxin from Bacillus thuringiensis strain WG-001 on rectorite were studied at different toxin and/or rectorite concentrations, pH values and temperatures. The insecticidal activity of the adsorbed toxin was evaluated by determining the lethal concentration to kill 50% of the larvae of Heliothis armigera （LC50）. The adsorption of the toxin on rectorite in sodium carbonate buffer （pH 9） reached equilibrium within 0.5-1.0 h and the adsorption isotherm of the toxin followed the Langmuir equation （R^2 〉 0.99）. In the pH range from 9 to 11 （carbonate buffer）, the adsorbed toxin decreased with increasing pH. The adsorption amounts decreased with increasing rectorite：toxin ratio. The adsorption was not significantly affected by the temperature between 10 and 50 ℃. The X- ray diffraction analysis indicated occurrence of the intercalation of the rectorite by the toxin. The infrared absorption spectrum showed that the binding of the toxin did not alter its structure. The LC50 wlues of the adsorbed toxin were smaller than those of the free toxin. The rectorite protected the toxin from ultraviolet irradiation damage. The desorption of the adsorbed toxin in water ranged from 37.5% to 56.4% and from 27.4% to 41.8% in a carbonate buffer. The desorption percentage also decreased with increasing rectorite：toxin ratio.
文摘In order to find and identify more targets species of pests for toxic insecticidal Bacillus thuringiensis(Bt)strains,a toxicity survey was carried out of two strains h3 and Ly30 against diamondback moth(Lepidoptera),Culex pipiens pallens and Musca domestica(Diptera),Blattella germanica(Coleoptera),which were respectively isolated from Lianyungang oceans with excellent characteristic of high salt tolerance,and from insect Componotus iaponicu Mayr larvae,respectively.Bioassay showed that h3 and Ly30 have efficient insecticidal activity against diamondback moth(Lepidoptera),Culex pipiens pallens and Musca domestica(Diptera)by 99%-100%mortality at 3 d-5 d,while only have 30%mortality at 5 d against coleoptera pests.It provided strong evidence for the insecticidal role of autotrophic Bt strains h3 and Ly30 against pests populations of lepidoptera and diptera and coleoptera,and aslo evidence for the application in the fields of agriculture and forest and public health.Furthermore,high salt tolerance of h3 could provide great benefit not only in expanding the application fields of biological insecticides,but also increasing the applicable object,and enhancing the efficacy of Bt.
