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Showing papers on "Bacillus thuringiensis published in 1977"


Journal ArticleDOI
TL;DR: Chemical modification of the sulfhydryl groups inhibits the proteolytic and insecticidal activities of the proendotoxin, suggesting that cysteine residues may be present in the active site of the protein.
Abstract: The parasporal crystalline protoxin of Bacillus thuringiensis contains a single glycoprotein subunit that has a molecular weight of approximately 1.2 X 10(5). The carbohydrate consists of glucose (3.8%) and mannose (1.8%). At alkaline pH, the proendotoxin is apparently solubilized and activated by an autolytic mechanism involving an inherent sulfhydryl protease that renders the protoxin insecticidal. Activation generates protons, degraded polypeptides, sulfhydryl group reactivity, proteolytic activity, and insect toxicity. Chemical modification of the sulfhydryl groups inhibits the proteolytic and insecticidal activities, suggesting that cysteine residues may be present in the active site of the protein.

141 citations


Journal ArticleDOI
TL;DR: Results from experiments in which larvae were stressed by exposure to NPV for 24-96 hr prior to exposure to B. thuringiensis showed that increased mortality was an additive effect of the two pathogens.

76 citations


Journal ArticleDOI
TL;DR: The use of both mortality and weight loss data have provided a highly sensitive and reproducible bioassay that can be used to compare relative toxicities of crystals from other subspecies as well as toxic components contained therein.
Abstract: A method for determining the toxicity of Bacillus thuringiensis subsp. kurstaki parasporal crystal to the tabocco hornworm, Manduca sexta, is described. The use of both mortality and weight loss data have provided a highly sensitive and reproducible bioassay that can be used to compare relative toxicities of crystals from other subspecies as well as toxic components contained therein.

62 citations



Journal ArticleDOI
TL;DR: The LC50 of a standard preparation of B. thuringiensis Berliner var.
Abstract: The LC50 of a standard preparation of B. thuringiensis Berliner var. kurstaki against 1-day-old larvae of Trichoplusiani (Hubner) was 90 ng/cm2 of diet surface. One-day-old larvae of Anticarsia gemmatalis Hubner and Plathypena scabra (F.) were > 10 × more susceptible than T. ni; Pseudoplusia includens (Walker) was equally susceptible, and Spodoptera exigua (Hubner) and Heliothis zea (Boddie) were ca. 3 × less susceptible. The LC50 against 4-day-old T. ni was 1800 ng/cm2 of diet surface, and the relative ranking for susceptibility of 4-day-old larvae of the other species was similar to that for 1-day-old larvae. Also ranking for susceptibility based on weight of larvae that survived was identical to that based on larval mortality.

31 citations


Journal ArticleDOI
TL;DR: The existence of a mechanism regulating the level of intracellular proteases during the sporulation phase is postulated and a chymotrypsin-like specificity is deduced from the esterolytic activity of the enzyme.
Abstract: The level of intracellular proteolytic activities was measured in Bacillus thuringiensis sporulating cells and it is shown that the maximum is reached after 4 h from onset of sporulation (t4). A purification procedure using cells harvested at t5 is reported, which leads to the isolation of an intracellular protease totally different from the extracellular enzymes and from another intracellular fraction detected in crude extracts. The homogeneity of the purified enzyme was verified using immunological techniques, electrophoretic migration and kinetics of thermodenaturation. Its molecular weight was estimated to be about 23000. This enzyme was characterized as a seryl protease, totally inhibited by phenylmethylsulfonyl fluoride or EDTA and requiring Ca2+ ions for activity. From the esterolytic activity of the enzyme we deduce a chymotrypsin-like specificity. The pure protease was able to cleave specifically the β' subunit of the form II of B. thuringiensis RNA polymerase purified from t5 sporulating cells. The vegetative holoenzyme and core enzyme appear much less susceptible to the action of the protease. Moreover the σ and α subunits do not seem to be altered by similar treatments. The existence of a mechanism regulating the level of intracellular proteases during the sporulation phase is postulated.

31 citations


Journal ArticleDOI
O. N. Morris1
TL;DR: The compatibility of Bacillus thuringiensis (B.t.) with 27 chemical insecticides representing organophosphorus and carbamate insecticides, pyrethrins, chlordimeform, urea derivative, and antifeedant were studied by way of their effects on germination of the bacterial spores, replication of vegetative cells and spore staining as discussed by the authors.
Abstract: The compatibility of Bacillus thuringiensis (B.t.) with 27 chemical insecticides representing organophosphorus and carbamate insecticides, pyrethrins, chlordimeform, urea derivative, and antifeedant were studied by way of their effects on germination of the bacterial spores, replication of vegetative cells and spore staining, and refractive index characteristics.The results showed that: (1) Carbamates were generally more compatible with Bacillus thuringiensis than were the other insecticide groups tested. (2) Technical formulations were less harmful to the bacteria than wettable powders which were less harmful than emulsifiable concentrates. (3) Of the 27 pesticides, those most compatible with B.t. were Orthene®, Dylox®, Lannate®, Sevin®, Zectran®, and Dimilin®. These insecticides are considered recommendable for use in integrated control operations with Bacillus thuringiensis if the target insects are susceptible to them and provided that due regard is given to the environmental implications of their use.

23 citations


Journal ArticleDOI
TL;DR: Thirteen strains of Bacillus thuringiensis were bioassayed against late-instar larvae of field-collected Simulium vittatum and all 13 strains caused significant blackfly mortality.

23 citations



Journal ArticleDOI
TL;DR: Dipel®, a commercial formulation of Bacillus thuringiensis Berliner, was combined with 7 pesticides, and their effects against 3rd instars of Plutella xylostella (L.) were determined by using a leaf-dip method.
Abstract: Dipel®, a commercial formulation of Bacillus thuringiensis Berliner, was combined with 7 pesticides, and their effects against 3rd instars of Plutella xylostella (L.) were determined by using a leaf-dip method. Binapacryl, tricyclohexyltin hydroxide, chlordimeform, and fentin hydroxide synergised B. thuringiensis by factors of 5.5, 4.2, 4.2, and 3.7, respectively, at the LC50 level; demeton-S-methyl and dimethoate were highly antagonistic. When the synergistic mixtures were tested against Thyraeella collaris Gravely, a parasite of P. xylostella , those containing binapacryl, tricyclohexyltin hydroxide, and fentin hydroxide were not toxic; the chlordimeform mixture displayed some vapor and stomach activity but no contact toxicity.

19 citations


Journal ArticleDOI
TL;DR: The exosporium in Bacillus thuringiensis appears to be synthesised during stages II and III of sporulation although uptake of [35S]cysteine occurs much later.
Abstract: Two membrane fractions, F1 and F2, have been purified from the outer layers of spores of Bacillus thuringiensis. Both fractions contain 6-7% cysteine and appear to be similar in composition. Amino acids account for about 75% of the dry weight, carbohydrate for about 2% and lipids for about 25%. The fractions are both toxic to Pieris brassicae and the toxicity is inactivated by antiserum to the toxic crystal of Bacillus thuringiensis. The fractions can be distinguished by examination under the electron microscope; both fractions show similar hexagonal patterns but with different spacings. The same fractions from an acrystaliferous mutant (cr) were prepared. These were identical in density and in appearance under the electron microscope; the amino acid analysis of fraction F2 from both strains was identical. However, the spores and fractions F1 and F2 from this strain lacked toxicity. Fraction F2 from the cr strain was used to prepare antiserum specific to fraction F2. Using this antiserum and anticrystal serum, crystal and F2 antigens were shown to appear simultaneously in sporulating cultures. Crystal and F2 antigens appeared some time before the maximum rate of uptake of [35S]cysteine. It is concluded that fraction F2 is derived from the exosporium and that fraction F1 probably originates from the spore coat. The exosporium in Bacillus thuringiensis appears to be synthesised during stages II and III of sporulation although uptake of [35S]cysteine occurs much later.





Journal ArticleDOI
TL;DR: In this paper, the authors conducted extensive and systematic laboratory studies conducted under various experimental conditions (larval stage, physiological condition of the insect, temperature, formulation) revealed that non-crystalliferous strains of Bacillus thuringiensis Berliner and B. fumiferana were equally pathogenic for larvae of Choristoneura fumarana Clemens as the crystalliferous strain of B. thuringiansis tested.
Abstract: Intensive and systematic laboratory studies conducted under various experimental conditions (larval stage, physiological condition of the insect, temperature, formulation) revealed that non-crystalliferous strains of Bacillus thuringiensis Berliner and B. cereus Frankland and Frankland were equally pathogenic for larvae of Choristoneura fumiferana Clemens as the crystalliferous strain of B. thuringiensis tested. Also the addition of minute quantities of chitinase (10,000 UN/ha) considerably increased the efficiency of commercial preparation of B. thuringiensis against C. fumiferana.At 20°C, B. thuringiensis var. kurstaki provoked a slow septicemia in 3rd instar larvae of C. fumiferana which resulted in 90% larval mortality in 27 days. Under the same experimental conditions, a non-crystalliferous strain of B. thuringiensis (No. 17) and two strains of B. cereus, entomopathogens isolated from C. fumiferana and from a Tachinidae, also caused a slow septicemia resulting in 90% mortality of 3rd instar larvae after 30 to 32 days.Experiments revealed that the symptoms of infection (lethargy, loss of weight) caused by B. thuringiensis + chitinase were far more rapid and pronounced than those provoked by B. thuringiensis alone The commercial preparation 26B prepared by Sandoz-Wander, applied at a rate of 16.8 × 109 BIU/ha caused only 80% mortality of 3rd and 4th stage larvae, while the complex Sandoz + chitinase N.B.C. provoked 100% larval mortality between 9 and 27 days depending upon the experimental conditions used Similar results were obtained with Dipel 36B. For instance, at 20°C Dipel + chitinase N.B.C. provoked 100% mortality of 3rd stage larvae in 9 days, while with Dipel alone, the same level of mortality was reached after 24 days. Also, it was established that C. fumiferana larvae reared on Abies balsamea were far more susceptible to the action of the bacillus than those reared on artificial diet.These results confirmed that addition of chitinase considerably increased the pathogenic properties of B. thuringiensis on C. fumiferana and the low efficiency of the bacillus alone. The addition of chitinase to commercial B. thuringiensis preparations is required and of prime importance in future use of B. thuringiensis for the control of this insect pest.




Journal ArticleDOI
TL;DR: Bacillus thuringiensis products (Dipel and Thuricide HPC) were standardized against the European corn borer by using standard bioassay techniques and gave better control of thecorn borer than did the spray formulations.

Patent
27 Jun 1977
TL;DR: In this article, an improved insecticidal composition and a method for its use are disclosed, which comprises from 25 to 75 weight percent (by weight of the total active materials) of Bacillus thuringiensis and 75 to 25 weight percent of 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea.
Abstract: An improved insecticidal composition and a method for its use are disclosed. The improved insecticidal composition comprises from 25 to 75 weight percent (by weight of the total active materials) of Bacillus thuringiensis and 75 to 25 weight percent (by weight of the total active materials) of 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea.





Journal ArticleDOI
TL;DR: At 20 degrees C, aflatoxin B1, at a sublethal dose, decreases the activity of alkaline phosphatase, alpha-glucosidase, and phosphoamidase in Bacillus thuringiensis (Berliner), while at 41 degrees C no significant decrease was observed.
Abstract: At 20 degrees C, aflatoxin B1, at a sublethal dose, decreases the activity of alkaline phosphatase (EC 3.1.3.1), alpha-glucosidase (EC 3.2.1.20), esterase (EC 3.1.1.1), chymotrypsin (EC 3.4.21.1), leucine aminopeptidase (EC 3.4.11.1), and phosphoamidase (EC 3.9.1.1) biosynthesis in Bacillus thuringiensis (Berliner). In contrast, at 41 degrees C no significant decrease was observed. At this temperature, the mycotoxin is not destroyed or metabolized and bacterial cells are resistant to the toxin.



Journal ArticleDOI
TL;DR: Field trials with Bacillus thuringiensis Berliner for control of paramyelois transitella (Walker) were conducted in commercial almond orchards in California and the highest level of control was obtained with 4 applications of Thuricide HPC at a rate of 1 qt/25 trees.
Abstract: Field trials with Bacillus thuringiensis Berliner for control of paramyelois transitella (Walker) were conducted in commercial almond orchards in California. B. thuringiensis formulated as Dipel® (2% dust and WP), Thuricide® HPC (EC), and Biotrol® XK (WP) was applied starting at about the onset of hullcrack for 4–5 applications at 3–10 day intervals. A synthetic feeding stimulant, Mo-Bait,® also was tested. The highest level of control (44.8% damage reduction) was obtained with 4 applications of Thuricide HPC at a rate of 1 qt/25 trees. The addition of the feeding stimulant did not increase the effectiveness of the treatments. Navel orangeworms are difficult to control because they apparently move to the deeper areas of the hull-shell interspace that are not penetrated by the treatments.

Journal Article
TL;DR: Electron microscopy of the cultural fluid of the Bac.
Abstract: The culture of Bacillus thuringiensis var. galleriae was shown to be polylysogenic. As has been found earlier, the culture has a phage with the original structure of particles whose tail possesses a special substructure called a "collar". The phage was described in detail as a phage of Bac. thuringiensis 1-97 with a "collar". Further studies of the culture of Bac. thuringiensis var. galleriae 1-97 has shown that it also contains another phage which differs sharply from the first one in the morphology of particles, the spectrum of lytic action, and other properties. Electron microscopy of the cultural fluid of the Bac. thuringiensis var. galleriae cultures has revealed in them the presence of different amounts of the particles of both morphological types found in the strain 1-97. These data suggest that the cultures of Bac. thuringiensis var. galleriae are polylysogenic. The methods for the isolation of the new phage are described.