Showing papers on "Bacillus thuringiensis published in 1972"

Effects of Bacillus thuringiensis β-exotoxin on Larval Maturation, Adult Longevity, Fecundity, and Egg Viability in Several Species of Lepidoptera

Abstract: Prevention of mouthpart development after feeding Bacillus thuringiensis Berliner β-exotoxin was demonstrated in Heliothis zea (Boddie), H. Virescens (F.), Trichoplusia ni (Hubner), Spodoptera exigua (Hubner), Estigmene acrea (Drury), and Pectinophora gossypiella (Saunders). Development of neonatal H. zea or mature T. ni larvae was affected by exposure to diets surface treated with β-exotoxin. Mortality in many cases resulted from failure to molt and/or to discard exuvia. Fecundity and longevity were reduced for moths which developed from mature larvae fed diets surface treated with β-exotoxin. Topical treatment of T. ni eggs did not interfere with hatching but did affect subsequent survival and development of neonatal larvae. Dephosphorylation of free-acid β-exotoxin completely destroyed its per os or injected activity.

Control of the Cabbage looper and the Imported Cabbage worm by Viruses and Bacteria

Abstract: The nuclear-polyhedrosis virus of the cabbage looper, Trichoplusia ni (Hubner), the granulosis virus of the imported cabbage worm, Pieris rapae (L.), formulations or Bacillus thuringiensis Berliner, and chemical insecticides were compared for control of T. ni and P. rapae larvae on cabbage in plot tests in southern Ontario in 1969 and 1970. In 1970, 4 applications of mixtures of the viruses (6×1012 T. ni polyhedra and 1 × 1013 P. rapae granules/ha) controlled the respective hosts as well as did 4 applications of endosulfan (0.84 kg/ha) or of Thuricide 90TS® (5.6 l/ha), a formulation of B. thuringiensis . Experimental formulations of B. thuringiensis (Thuricide HP® and Dipel HD-l®) were more effective than the Thuricide 90TS formulation. Tests in large plots in growers fields also demonstrated efficacy of the viruses. The combination of viruses with chemical insecticides in the spray program was especially effective.

Inhibitory effects of foliage extracts of some forest trees on commercial bacillus thuringiensis

Abstract: The antibiotic effects of foliage extracts of some forest trees on commercial Bacillus thuringiensis (Berliner) var. galleriae were studied with a view to determining whether or not such substances might be inhibitory to development and multiplication of ingested bacteria. The results indicate that ethyl acetate and petroleum or ethyl ether extracts of the trees tested were particularly inhibitory to the bacteria. Of 24 pure terpenes tested, pinene, pulegone, menthone, 4-terpineol, citral, citronellol, and linalool were highly inhibitory to the production of spores and crystals by the bacteria.

Susceptibility of some forest insects to mixtures of commercial bacillus thuringiensis and chemical insecticides, and sensitivity of the pathogen to the insecticides

Abstract: Experiments were designed to determine the effects of low doses of some insecticides on the viability and physiological characteristics of commercial Bacillus thuringiensis (Berliner) as a prelude to studies on the susceptibility of lepidopterous forest defoliators to mixtures of bacteria and insecticides.The results show that the insecticides tested had no effect on viability or physiological integrity of the bacteria.Bacteria–insecticide combination effects varied from strongly antagonistic to strongly supplemental depending on insecticide or Thuricide® formulations and concentrations and on the relative susceptibility of the test species to either agent applied separately. Pyrethrum at 10−3 was highly potentiating to BT at 10−1 against third instar Halisidota argentata. Among Hyphantria cunea, a supplemental effect always resulted from combining Thuricide® at 10−2 with low concentrations of malathion, phosphamidon, or pyrethrum.There was generally a drastic reduction in feeding activity among BT-treated insects and a further reduction among BT-chemical-insecticide-treated ones compared with controls.

Control of the European Corn Borer with Two Varieties of Bacillus thuringiensis

Abstract: Bacillus thuringiensis var. thuringiensis Berliner and B. thuringiensis var. kurstaki De Barjac & Le Mille were evaluated as biological insecticides for control of Ostrinia nubilalis (Hubner). The varieties were compared in 6 field experiments during 1969–70. Various rates, formulations, and numbers of applications of the bacterial varieties were compared with DDT and diazinon for control of the European corn borer. Data indicated that both varieties of B. thuringiensis were as effective as DDT or diazinon.

Properties of the β-Exotoxin of Bacillus thuringiensis IMC 10,001 Against the Tobacco Budworm

Abstract: When a new formulation of the β-exotoxin of Bacillus thuringiensis Berliner of the International Minerals and Chemical Corporation (IMC 10,001) was tested against Heliothis virescens (F.), it was about 1/5 as toxic to neonate larvae as a preparation of the θ-endotoxin that had a potency of 16,000 international units/mg. Its primaly anion against larvae less than 4 days old was insecticidal; larvae that survived emerged as normal adults. However, when IMC 10,001 was incorporated into the diet of 4- or 8-day-old larvae, the length of the proboscis was reduced in those animals surviving to adulthood. When a spray of the formulation containing 40,000 μg/ml was applied to leaves of cotton plants the biological activity persisted between 6 and 12 days after application.

A new medium for Bacillus thuringiensis Berliner.

Abstract: SUMMARYA. new solid medium for culturing Bacillus thuringiensis consists of groundnut cake, 10%; tamarind kernel powder, 1.5% and agar, 0.5%. The quantity of agar in the medium could be decreased from 1.5 to 0.5 % by adding tamarind kernel powder. A spore yield (85 % sporulation) of 3.2 g/l was obtained. Bacterial sporesproduced on the new solid medium were pathogenic to the larvae of the almond moth, Cadru mutellu.

Effect of Bacillus thuringiensis and Carbaryl on an Elm Spanworm Egg Parasite Telenomus alsophilae

Abstract: Immature stages of Telenomus alsophilae Viereck, an egg parasite of the elm span worm, Ennomos subsignarius (Hubner), were unaffected by field application of Bacillus thuringiensis Berliner and carbaryl in early June. Immature parasites were killed when the host’s eggs were dipped in 0.2 lb/gal of carbaryl 7 days before adult emergence.

Control of Four Species of Caterpillars on Cabbage with Bacillus thuringiensis var. alesti, 1969-70

Abstract: An experimental wettable powder formulation of Bacillus Thuringiensis var. alesti Berliner applied as a spray in field tests at Charleston, South Carolina, gave control of the populations of cabbage looper, Trichoplusia ni (Hubner), on spring and fall cabbage. Also, it was as effective in producing marketable cabbage heads as sprays containing endosulfan (1 lb), methomyl (0.4 lb), or endosulfan (1 lb) + parathion (0.5 lb), whether it was used at 0.1 or 0.5 lb/acre. However, applications of bacillus at 1 lb/acre were necessary to produce as many plants with completely uninjured heads as were produced by the spray mixture of endosulfan + parathion. Mixtures of bacillus + endosulfan or methomyl sometimes gave more effective control of the loopers than the same doses of the same materials used alone, and no synergism or antagonism was observed between the bacillus and the chemicals. As little as 0.1 lb/acre of the bacillus formulated as a spray gave good control of the diamondback moth, Plutella xy/ostella (L.); the imported cabbageworm, Pieris rapae (L.); and the fall armyworm, Spodoplera frugiperda (J. E. Smith). A bacillus dust tested only one season was not so effective as the spray in controlling the cabbage looper. However, it was moderately effective against the diamondback moth and highly effective against the imported cabbageworm.

Sensibilité de archips cerasivoranus (lepidoptera-tortricidae) à l’infection par bacillus thuringiensis

Abstract: Infectivity tests revealed that sensitivity of larvae of Archips cerasivoranus Fitch to infection by a commercial preparation of Bacillus thuringiensis Berliner depends on the physiological condition of the insects (determined by age and nutrition), and temperature, but mostly on the presence or absence of infection by the microsporidia Plisliphora sp. and Nosema cerasivoranus Thomson. Mortality attributable to the bacillus was 90, 40, and 30% for healthy third-, fifth-, and seventh-instar larvae after 20 days, mortality reached 90% after 3, 9, and 19 days for larvae of the same ages naturally infected by microsporidia. Also, low temperatures decreased the effect of the pathogen and starvation reduced the resistance of larvae to infection. The results obtained suggest the action of B . thuringiensis in this tortricid is to provoke generalized septicemia rather than toxemia. Other infectivity tests made with cultures of B . thuringiensis and Bacillus cereus Frankland and Frankland confirmed these results. The action of the two bacteria was similar, both provoking septicemia in the insect. This effect was considerably increased by the presence of protozoan diseases. Analyses of unsaturated lipids by the iodine number method showed that infection by a microsporidian or B . thuringiensis lowered considerably the energy value index. The index reached 13.0, 25.5, and 27.0 in healthy larvae of third-, fifth-, and seventh-instar, was reduced to 5.2, 17.0, and 15.0 by a microsporidian infection, and to 7.5, 18.0, and 22.5 by a B . thuringiensis infection. When an infection with both pathogens was induced, the value decreased to 4.0, 8.0, and 7.5.