Showing papers on "Bacillus thuringiensis published in 1973"

Insecticidal activity of recent bacterial isolates and their toxins against mosquito larvae.

Abstract: ALTHOUGH Bacillus thuringiensis is proving to be a useful pathogen against insect pests of field crops1–3, there has been no equivalent bacterium that might be used in the control of insects, such as mosquitoes, that carry disease. Since 1966, however, the World Health Organization (WHO) has been seeking such a bacterium. Field workers in various parts of the world collect infected insects4 and send them to an International Reference Center (IRC) at Ohio State University. Here the causative agent of infection is investigated and material is distributed for research on potential control organisms. I have examined bacteria isolated from infected larval mosquitoes collected in Delhi, India (accession WHO/ IRC No. 1321); those of the Bacillus sphaericus group had higher insecticidal activity than previously reported5, and those of the Bacillus alvei-circulans group had never before been implicated in disease of mosquito larvae. Either or both may eventually be useful in the biological control of mosquitoes.

Production of δ-Endotoxin by Bacillus thuringiensis as a Function of Glucose Concentrations

Abstract: The insect pathogen Bacillus thuringiensis was cultured at different glucose concentrations. Size, protein content, and insecticidal activity of the parasporal inclusions, which are formed during the sporulation process, were measured. Increased glucose concentrations led to bigger crystalline inclusions with a higher content of protein and insecticidal activity. Maximum yields of protein and endotoxin were obtained in a semisynthetic medium that contained glucose concentrations of 6 to 8 g/liter.

B. thuringiensis U. S. Assay Standard: Report on the Adoption of a Primary U.S. Reference Standard for Assay of Formulations Containing the δ-Endotoxin of Bacillus thuringiensis

Abstract: A meeting was held on 15 May 1972, at Brownsville, TX, to discuss the adoption of a Primary U.S. Reference Standard for use in the standardization of formulations of the δ -endotoxin produced by Bacillus thuringiensis . The meeting was attended by representatives of the U.S. manufacturers of these formulations, by representatives from the USDA, and by a representative of the Pesticides Regulation Division of the EPA. At this meeting, a formulation of the δ -endotoxin produced by the HD-1 isolate of B. thuringiensis var. kurstaki was adopted as the Primary U. S. Reference Standard. This formulation, designated HD-1-S-1971, was assigned a potency of 18,000 international units (IU)/mg, based on the international standard, E-61.

The germfree culture of three species of Triatominae: Triatoma protracta (Uhler), Triatoma rubida (Uhler) and Rhodnius prolixus Stål.

Abstract: Triatoma protracta protracta, Triatoma rubida rubida , and 2 strains of Rhodnius prolixus were successfully reared germfree into the 4th generation. Triatomine eggs were disinfected externally with iodine and the nymphs reared in vinyl plastic gernifree modules. Gernifrce mice were used as hosts. This is the first report of Triatominae having been reared in a germfree environment. These bugs were never exposed to bacteria internally or externally to the 4th generation. Comparisons of conventional control bugs with replicate germfree groups in the first 2 generations revealed but slight differences in developmental periods. The mean adult longevity of all germfree groups was as long as, or longer than, that of the conventional adults. Fecundity and fertility of mated pairs were quite similar between germfree and control groups within a species. Evaluation of all differences in these various categories resulted in the conclusion that germfree Triatominae of these species develop in a normal manner in the absence of bacteria within or upon them when nourished by a suitable host (mouse). I found, as did Wigglesworth and others, that germfree Rhodnius prolixus did not develop to the adult stage when fed on a rabbit. The critical factor in the normal development of germfree R. prolixus evidently was the nutrition received from the mouse host. Nocardia rhodnii, Escherichia coli , and Streptococcus faecalis fed to germfree T. protracta resulted in the establishment of N. rhodnii and S. faecalis within the alimentary tracts of these bugs and the complete elimination of E. coli from the tracts of those bugs infected with this bacterium. When placed in a germfree module, bugs carrying S. faecalis and N. rhodnii readily transmitted these bacteria to previously germfree bugs maintained in the module. Bacillus thuringiensis var. thuringiensis fed to T. protracta and R. prolixus resulted in the death of all specimens ingesting this bacterial species.

Biosynthesis of the Crystal Protein of Bacillus thuringiensis var. tolworth

Abstract: Our previous work showed that the crystal protein of Bacillus thuringiensis var. tolworth, a highly potent toxin for Lepidopteran larvae consists of two polypeptide components of molecular weights 55000 (“component A”) and 120000 (“component B”) in the molar ratio 2:1. In this study we demonstrate by several criteria that A and B are synthesized de novo, synchronously, for a predetermined and relatively brief period, during the 24-h growth cycle in culture, about 17 h after innoculation of the culture, midway between the cessation of growth and cell lysis. This conclusion is supported by the results of the following types of experiments: 1. pulse-labelling of cultures of B. thuringiensis with radioactive amino acids and subsequent analysis of the radioactivity in the separated crystal protein components; 2. antigenic analysis of protein isolated from cultures at different times, both by precipitin reactions and immunodiffusion in Ouchterlony plates, using antiserum against purified crystal protein and 3. bioassay of the toxicity of similar protein preparations to the larvae of Pieris brassicae.

Evaluation of Bacillus thuringiensis for Gypsy Moth Suppression

Abstract: A formulation of Bacillus thuringiensis Berliner was effective against larvae of Porthetria dispar (L.) when applied at rates of 16×109 and 8×109 international units (IU) per acre. Defoliation caused by the gypsy moth in unsprayed areas approached 100%, indicating an adequate larval population for evaluation. Three applications of the lower dosage produced both foliage protection and larval mortality. Partial defoliation was noted in the treated areas and may have resulted from incomplete coverage or the presence of other forest defoliators not susceptible to the spray. Bioassays demonstrated the residues of the spray to be toxic to early-stage larvae for one month following the last application. In a laboratory bioassay using 2nd instars, the median lethal concentration was 96.2 IU/ml diet. Since postspray egg masses were not reduced, the possibility of a feeding inhibition phenomena is suggested.

Aerial spraying of a bacillus thuringiensis — chitinase formulation for control of the spruce budworm (lepidoptera: tortricidae)

Abstract: A 10,000 acre stand of mature balsam fir, in Temiscouata County, Quebec, which had a spruce budworm population of about 21 larvae/18 in. branch-tip was sprayed with a Bacillus thuringiensis + chitinase formulation. Aerial spraying was carried out by three TBM aircraft between 4 and 7 June 1972, when insect development was at the peak of the third instar. Where the quantity of B. thuringiensis colonies per square centimeter was higher than 77 and spray deposit higher than 0.4 gal/acre (U.S.), larval mortality was between 84% and 93% compared with between 39% and 53% in the check plot. Foliage protection was 47%. The results indicate the possibilities of using B. thuringiensis + chitinase to control spruce budworm infestations.

Microbial Control of the Grape Leaffolder with Different Formulations of Bacillus thuringiensis

Abstract: The effectiveness of three commercial preparations of Bacillus thuringiensis Berliner was compared with the standard insecticide carbaryl for control of Desmia funeralis (Hubner). Both spray and dust treatments of all 3 preparations of B. thuringiensis obtained good control. The chemicals tested included Biotrol® XK, wettable; Dipel®, wettable; Thuricide® HPC, aqueous concentrate; carbaryl 50, wettable; Dipel, 2% dust; Thuricide 150M, dust; and carbaryl, 10% dust.

Tobacco Budworm: Control On Flue-Cured Tobacco with Certain Microbial Pesticides

Abstract: In advanced field test during 1964–72, certain commercial formulations of Bacillus thuringiensis Berliner and a nuclear polyhedrosis virus of Heliothis zea (Boddie) were applied with a power sprayer to flue-cured tobacco at dosages suggested by the manufacturers for tobacco budworm, H. virescens (F.), control. The lower dosages of B. thuringiensis and the virus were usually as effective as the higher dosages, and addition of certain insecticidal and non-insecticidal products to B. thuringiensis spray did not increase its effectiveness. Thuricide®, Biotrol® BTB-183, and Dipel® brands of B. thuringiensis were usually as effective as 1.5 lb/acre of TDE or carbaryl and sometimes as effective as 0.5 lb of methomyl. Biotrol® VHZ and Viron® /H brands of the virus were usually less effective than TDE or methomyl. In a preliminary test, a noncommercial preparation of Nosema necatrix Kramer provided significant but less control than methomyl.

Sod Webworm Control in Florida Turfgrass

Abstract: Insecticides were evaluated for control of sod webworms, Herpetogramma and Crambus spp., on Tifgreen bermudagrass in Florida. Akton, 0-2-chloro-1-(2,5-dichlorophenyl)vinyl) 0,0-diethyl phosphorothioate, provided excellent control for at least 5 weeks or 2 generations of the larvae, and gave significantly better control than any of the other 14 insecticides tested. Formulations of Bacillus thuringiensis provided control of larvae for 1-2 weeks.

Some Biological Effects of a Bacillus thuringiensis Product on the Gypsy Moth Larvae

Abstract: Bacillus thuringiensis製剤のマイマイガ幼虫に対する殺虫作用は,一般の化学殺虫剤とは異なり,非常に遅効的であるが,処理後の日数の経過にともない,致死率が漸次増大し,処理後の日数とLC50の関係は,3∼7日の間では,ほぼ直線関係を示した。しかし,7と8日目のLC50値の間の差は少なく,全体として両者の関係は,むしろ放物線に適合するものの様である。B. t.製剤の食下による摂食量の減少は,処理1日後から顕著にあらわれ,いずれの処理区も致死にさきだってあらわれた。それ故,外観上は正常個体となんら変わりがなくても,摂食は著しく抑制されており,なかには全く摂食活動を停止した個体もみられた。B. t.製剤で処理した葉を連続して与えている限り,この摂食抑制はつづくが,3日目に無処理葉に移すと摂食活動が回復し,6日後にはほとんど正常な摂食量に戻る。それ故,B. t.製剤による初期の摂食抑制は,回復性のある一時的な作用であると考えられる。B. t.製剤による処理葉と無処理葉を同時に与えた時も摂食量が減少する。またこの条件下では両者に対する幼虫の摂食度合の差異や,処理葉から無処理葉への忌避行動が観察されたが,これらは幼虫の処理葉にたいする臭覚や視覚によるものではなく,B. t.製剤を食下した結果生じた幼虫の反応であると考えられる。

Field Effectiveness of the Granulosis Virus of the Green Cloverworm as Compared with Bacillus thuringiensis and Selected Chemical Insecticides on Soybean

Abstract: On Aug. 16, 1972, a granulosis virus was field-tested at 1 × 1011 capsules/acre against Plathypena scabra (F.) larval populations in a soybean field near Cambridge, Iowa. Bacillus thuringiensis Berliner and selected chemical insecticides were applied to small plots in a complete randomized-block design for comparison. No significant differences existed between the check and virus-treated plots for the first 4 days after application, whereas all plots treated with chemical insecticides R. thuringiensis were significantly different from the check. Larval numbers in virus-treated plots differed significantly from those of the check, beginning with the 6th day after treatment, with no significant differences between virus, B. thuringiensis , and 5 out of 6 chemical insecticide treatments on that date.