EFFECT OF TEMPERATURE AND EXPOSURE TIME ON TOXICITY OF BACILLUS THURINGIENSIS BERLINER SPRAY DEPOSITS TO SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA CLEMENS (LEPIDOPTERA: TORTRICIDAE)

1990 ◽  
Vol 122 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Kees van Frankenhuyzen
Keyword(s):  
Bacillus Thuringiensis ◽  
Exposure Time ◽  
Choristoneura Fumiferana ◽  
Larval Mortality ◽  
Lethal Dose ◽  
Spruce Budworm ◽  
Fold Increase ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Limited Effect

AbstractExperiments were conducted using balsam fir twigs treated with Bacillus thuringiensis Berliner to examine the influence of temperature and exposure time on mortality of spruce budworm, Choristoneura fumiferana Clemens. Twigs were sprayed with a commercial formulation (8.4 BIU/L) using droplets of 40–70 μm diameter at densities, ranging from 0.5 to 5.5 droplets per needle. Temperature affected progression but not the level of cumulative mortality during 14 days of feeding on sprayed foliage. The LT50 decreased from 12–17 days at 13°C to 2–4 days at 25°C, depending on droplet density. Temperature between 13 and 25°C had a limited effect on dose acquisition because 40–60% of the larvae were able to acquire a lethal dose within 1 day of feeding on foliage with 0.5–1.5 droplets per needle, regardless of temperature. Under these conditions dose acquisition was not limited by temperature-dependent consumption of foliage, but rather by feeding inhibition associated with the dose initially ingested. This also limited the influence of exposure time; a 7- or 14-fold increase in exposure time increased larval mortality at most by 25%. Implications of these findings for improving efficacy of B. thuringiensis in forestry applications are discussed.

EFFECT OF TEMPERATURE ON THE PATHOGENESIS OF BACILLUS THURINGIENSIS BERLINER IN LARVAE OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA CLEM. (LEPIDOPTERA: TORTRICIDAE)

1994 ◽  
Vol 126 (4) ◽  
pp. 1061-1065 ◽  
Author(s):  
Kees van Frankenhuyzen
Keyword(s):  
Bacillus Thuringiensis ◽  
Bacterial Growth ◽  
Choristoneura Fumiferana ◽  
Larval Mortality ◽  
Lethal Dose ◽  
Spruce Budworm ◽  
Effect Of Temperature ◽  
Vegetative Cells ◽  
Time Required ◽  
Peak Abundance

AbstractThe relationship between temperature and pathogenesis of Bacillus thuringiensis Berliner var. kurstaki in infected larvae of the eastern spruce budworm, Choristoneura fumiferana Clem., was investigated to determine if more rapid death of larvae with an increase in temperature could be accounted for by enhanced bacterial growth. Cumulative mortality of larvae force-fed with a lethal dose of HD-1-S-1980 peaked within 2 days at 25 °C, 3 days at 19 °C, 7 days at 16 °C, and 21 days at 13 °C. The progress of bacterial growth in the larvae was followed from spore germination to cell lysis, and was completed within 4 days at 25 °C, 6 days at 22 °C, 12 days at 19 °C, 14 days at 16 °C, and > 28 days at 13 °C. Peak abundance of vegetative cells in the larvae was observed after 1 day at 25 °C, 2 days at 22 °C, 3 days at 19 °C, 7 days at 16 °C, and 21 days at 13 °C, and thus coincided almost exactly with the time required for maximum larval mortality. This correlation suggests that the observed effect of temperature on progression of larval mortality was due to its effect on the proliferation of vegetative cells in the infected larvae, and that bacterial septicemia makes an important contribution to death.

LONG TERM STUDY OF THE EFFECTIVENESS OF AERIAL APPLICATION OF BACILLUS THURINGIENSIS – ACEPHATE COMBINATIONS AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)

1977 ◽  
Vol 109 (9) ◽  
pp. 1239-1248 ◽  
Author(s):  
O. N. Morris
Keyword(s):  
Bacillus Thuringiensis ◽  
Choristoneura Fumiferana ◽  
Larval Mortality ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
Population Densities ◽  
Long Term Study

AbstractBacillus thuringiensis (Dipel® 36B) mixed with a sublethal concentration of acephate (Orthene®) (O, S-dimethyl acetylphosphoramidothioate), an organophosphorous insecticide, was applied at 2.35–14 l./ha to white spruce (Picea glauca) and balsam fir (Abies balsamea) trees infested with spruce budworm, Choristoneura fumiferana (Clem.). The treatment rate was 20 Billion International Units of B. thuringiensis (B.t.) activity with or without 42 g of active ingredient of acephate/ha.The ground deposit of the standard Dipel wettable powder formulation was 12% of emitted volume compared with 21–32% for the Dipel 36B flowable. The viability of B.t. spores was drastically reduced after 1 day of weathering but a high level of biological activity by the spore–crystal complex persisted for up to 20 days post-spray due probably to crystal activity.The addition of about 10% of the recommended operational rate of acephate to the B.t. suspension increased larval mortality by 34% when applied at 4.7 l./ha. Reductions in budworm populations were 97–99% in B.t. + acephate plots and 86–90% in B.t. alone plots.Plots with moderate budworm densities of up to 27 larvae/100 buds on white spruce and 36/100 on balsam fir were satisfactorily protected from excessive defoliation in the year of spray by B.t. with or without acephate. Plots with higher population densities were not satisfactorily protected based on the branch sample examination but aerial color photographs indicated good protection to the top third of the trees. Population declines were greater and defoliation and oviposition were lower in the treated plots than in the untreated checks 1 year later without further treatment. Two years later the larval population densities in all plots were low but the density was twice as high in the untreated check as in the treated plots, indicating long term suppression by the treatments. Defoliation was negligible in all plots.The treatments had no deleterious effect on spruce budworm parasitism. The data indicate that the integrated approach using Bacillus thuringiensis – chemical pesticide combinations is a viable alternative to the use of chemical pesticides alone in spruce budworm control. Large scale testing is now warranted.

FORECASTING THE EFFICACY OF OPERATIONAL BACILLUS THURINGIENSIS BERLINER APPLICATIONS AGAINST SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA CLEMENS (LEPIDOPTERA: TORTRICIDAE), USING DOSE INGESTION DATA: INITIAL MODELS

1992 ◽  
Vol 124 (6) ◽  
pp. 1101-1113 ◽  
Author(s):  
Richard A. Fleming ◽  
Kees van Frankenhuyzen
Keyword(s):  
Bacillus Thuringiensis ◽  
Population Density ◽  
Choristoneura Fumiferana ◽  
Lethal Dose ◽  
Spruce Budworm ◽  
Initial Application ◽  
Eastern Spruce Budworm ◽  
Population Reduction ◽  
Support Tools ◽  
Image Position

AbstractSingle aerial applications of Bacillus thuringiensis Berliner (Bt) to control infestations of the eastern spruce budworm (Choristoneura fumiferana Clemens) have had varied operational success. Double applications are too expensive for general use, but might prove useful if directed to areas where the initial application was unsuccessful. This requires forecasts of the efficacy of the initial application in operational spray blocks within 4–5 days.Data were collected in 30 spray blocks in 1989 in a feasibility study to determine if such forecasts of spray efficacy could be made from the prespray budworm population density, N0, and from the proportion of the population that had ingested a lethal dose Bt within 2 days of application, M. A mathematical model forecasting the postspray budworm population density, NF, was derived from population-dynamic considerations and fitted (r2 = 0.48, p < 0.0001):The proportion of current foliage defoliated, D, depended (r = 0.81) on N0 and on whether the block was sprayed (I = 0) or not (I = 1):Only one measure of defoliation involved M in any statistically significant way. The predicted (from values of N0) proportion of defoliation prevented by Bt application, dD, was weakly (r2 = 0.25, p = 0.002) related to M:The large proportion of the variation in efficacy that remains unexplained by the models involving M limits the operational utility of this approach as it now stands for specific sites. The potential for further development of these models as decision support tools for fairly large spray blocks is discussed in terms of improving the sampling plan and including additional predictor variables.Methods are also presented that reduce bias in calculations of population reduction (Abbott 1925) and foliage protection when data are available from few control and many treatment blocks.

scholarly journals Bacillus Thuringiensis: a Logical Weapon for Spruce Budworm Control

1978 ◽  
Vol 54 (6) ◽  
pp. 309-312 ◽  
Author(s):  
W.A. Smirnoff
Keyword(s):  
Bacillus Thuringiensis ◽  
Environmental Variables ◽  
Choristoneura Fumiferana ◽  
Larval Mortality ◽  
Field Tests ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Insect Density ◽  
Different Levels ◽  
Methods Of Application

Action of Bacillus thuringiensis (B.t.) on spruce budworm, Choristoneura fumiferana Clem., was found to be attributable to septicemia with some enterotoxicosis. Development of a compact economical B.t. formulation, with addition of the enzyme chitinase, increased its efficiency by accelerating larval mortality. Between 1971 and 1975 field tests were conducted in balsam fir stands with different levels of insect density to select the best formulation and methods of application and to identify the major influencing environmental variables. Variability in the results prior to 1975 is attributable to difficulties with calibration of spray systems. With accurate calibration in 1976 and 1977, good results in terms of larval mortality and foliage protection were obtained, thus confirming the value of B.t. for control of spruce budworm.

A 2-YEAR STUDY OF THE EFFICACY OF BACILLUS THURINGIENSIS – CHITINASE COMBINATIONS IN SPRUCE BUDWORM (CHORISTONEURA FUMIFERANA) CONTROL

1976 ◽  
Vol 108 (3) ◽  
pp. 225-233 ◽  
Author(s):  
O. N. Morris
Keyword(s):  
Bacillus Thuringiensis ◽  
Direct Relationship ◽  
Choristoneura Fumiferana ◽  
Larval Mortality ◽  
Residual Activity ◽  
Spruce Budworm ◽  
Time Deposit ◽  
Delayed Mortality ◽  
Carry Over

AbstractSpruce budworm infested balsam fir trees were aerially sprayed with Bacillus thuringiensis – chitinase combinations at the rate of 4 Billion International Units of B.t. and 18 mg of enzyme in 0.5 gal/acre. Larvae were peak third instar at spray time. Deposit rates ranged from 1.07 to 3.26 BIU/acre. Efficacy of the treatments was assessed in the year of treatment and carry-over effects were assessed 1 year later.Results in the year of treatment indicated that: (1) Residual activity of B. thuringiensis was drastically reduced after 15 days’ exposure to weathering. (2) Larval mortality alone is not a suitable criterion of efficacy. (3) Dipel and Dipel + chitinase (but not Thuricide 16B or Thuricide + chitinase) were highly effective in reducing budworm densities. (4) Thuricide + chitinase treatment resulted in significant foliage protection. The treatments inhibited feeding in the following order of efficiency: Thuricide + chitinase > Dipel + chitinase > Dipel alone > chitinase alone > Thuricide alone. (5) There was no direct relationship between larval mortality and foliage protection in any of the treatments, likely due to delayed mortality effects. (6) No direct relationship exists between viable spore deposits and deposit of active ingredient (IUs). (7) B.t. treatments retarded development of the spruce budworm and reduced pupal weights, oviposition rates, and egg viability.Assessment of the plots 1 year after spray showed that the treatments apparently gave no long term protection from defoliation, but this was likely due in part to mass invasion of the test plots by moths from immediately surrounding untreated areas.

EFFECT OF TEMPERATURE ON MORTALITY AND RECOVERY OF SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) EXPOSED TO BACILLUS THURINGIENSIS BERLINER

1987 ◽  
Vol 119 (10) ◽  
pp. 941-954 ◽  
Author(s):  
Kees van Frankenhuyzen ◽  
Carl W. Nystrom
Keyword(s):  
Single Dose ◽  
Bacillus Thuringiensis ◽  
Metabolic Rate ◽  
Time Course ◽  
Spruce Budworm ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Influence Of Temperature ◽  
Feeding Inhibition ◽  
Influence Of Temperature On

AbstractSpruce budworm larvae were bioassayed against Bacillus thuringiensis Berliner to study the effect of temperature on the expression of toxicity. Temperatures between 16 and 28°C did not affect the ultimate level of toxicity (LC50). However, LT50’s increased from 2–8 days at 28°C to 11–20 days at 16°C, depending on concentration of the pathogen. When larvae were force-fed with a single dose, temperature had a similar effect on the time course of mortality without affecting the level of mortality. Feeding inhibition of force-fed larvae commenced immediately after dosing. Larvae that did not recover died without further feeding, even at lower temperatures when death occurred 2–3 weeks after dosing. Recovering larvae resumed feeding after 2 (28°C) to 6 (13°C) days. Recovered larvae took longer to develop and produced lighter pupae than untreated larvae. Our data suggest that temperature-dependent feeding and recovery did not contribute to quicker death at higher temperatures. Expression of the toxin itself appears to depend on temperature, possibly through the influence of temperature on metabolic rate of affected gut cells. Implications of these findings for the efficacy of spruce budworm control operations are discussed.

MORTALITY, FEEDING INHIBITION, AND RECOVERY OF SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) LARVAE FOLLOWING AERIAL APPLICATION OF A HIGH-POTENCY FORMULATION OF BACILLUS THURINGIENSIS SUBSP. KURSTAKI

2000 ◽  
Vol 132 (4) ◽  
pp. 505-518 ◽  
Author(s):  
Kees van Frankenhuyzen ◽  
Carl Nystrom ◽  
John Dedes ◽  
Vern Seligy
Keyword(s):  
Bacillus Thuringiensis ◽  
Spray Deposition ◽  
Larval Mortality ◽  
Lethal Dose ◽  
Spruce Budworm ◽  
Limiting Factor ◽  
Larval Feeding ◽  
Spray Application ◽  
Aerial Application ◽  
Feeding Inhibition

AbstractA larval population of spruce budworm, Choristoneura fumiferana (Clemens), was monitored for 5 d following aerial application of a commercial formulation of Bacillus thuringiensis Berliner subsp. kurstaki to investigate dose acquisition and expression (larval mortality, recovery, feeding, and growth) in relation to spray deposition and persistence of spray deposits. The main objective was to test if previous laboratory observations on how B. thuringiensis affects feeding and dose ingestion by spruce budworm larvae hold true under field conditions. About 40% of the treated population ingested a lethal dose within 1 d after spray application. Lethally dosed larvae died without further feeding upon transfer from treated foliage to (untreated) artificial diet. Resumption of feeding by larvae that survived the treatment was delayed relative to larvae from the control population during 3 d following spray application; during that time, normal feeding activity and larval weight gain were suppressed. Inhibited feeding by survivors appeared to prevent further dose uptake because the proportion of lethally dosed larvae in daily collections did not increase despite significant residual spray deposits in budworm feeding sites. Restoration of "normal" recovery times by the fourth day coincided with a 65–85% reduction in persistence of the pathogen on the foliage and did not result in further lethal dose acquisition, as treatment-induced mortality dropped to about 20% on the 4th and 5th days. The observations are consistent with previous laboratory observations of how B. thuringiensis affects larval feeding and with the hypothesis that feeding inhibition may be a limiting factor in the acquisition of a lethal dose.

INTERACTIONS BETWEEN BACILLUS THURINGIENSIS BERLINER AND APANTELES FUMIFERANAE VIER. (HYMENOPTERA: BRACONIDAE), A PARASITOID OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE)

1990 ◽  
Vol 122 (4) ◽  
pp. 585-594 ◽  
Author(s):  
Vincent Nealis ◽  
Kees van Frankenhuyzen
Keyword(s):  
Bacillus Thuringiensis ◽  
Negative Impact ◽  
Choristoneura Fumiferana ◽  
Management Strategies ◽  
Lethal Dose ◽  
Spruce Budworm ◽  
Fourth Instar ◽  
Mortality Factors ◽  
Commercial Formulation ◽  
Beneficial Effects

AbstractInteractions between Bacillus thuringiensis Berliner and Apanteles fumiferanae Viereck as mortality factors of the spruce budworm, Choristoneura fumiferana (Clemens), were investigated by placing parasitized and nonparasitized budworm larvae on foliage with and without spray deposits of a commercial formulation of B. thuringiensis. The effect of larval age (and, thus, the timing of spray applications) was examined by using peak third-instar and peak fourth-instar larvae. We demonstrated that parasitized larvae are more likely to survive exposure to B. thuringiensis because they feed less than non-parasitized larvae and are thus less likely to acquire a lethal dose of the bacterium. Bacillus thuringiensis nevertheless reduced parasitoid populations by 50–60% by killing their hosts before parasitoid emergence. This negative impact of B. thuringiensis on parasitoid survival was decreased when exposure of budworm larvae to spray deposits was delayed from peak third to peak fourth instar. The enhanced survival of parasitoids offset the lower mortality as a result of B. thuringiensis in the delayed sprays. We conclude that B. thuringiensis applied when budworm larval populations are at peak fourth instar or later would complement rather than interfere with the beneficial effects of A. fumiferanae. The implications for budworm management strategies are discussed.

Interactions between Bacillus thuringiensis and parasitoids of late-instar larvae of the spruce budworm (Lepidoptera: Tortricidae)

2001 ◽  
Vol 79 (9) ◽  
pp. 1697-1703 ◽  
Author(s):  
Astrid Schoenmaker ◽  
Michel Cusson ◽  
Kees van Frankenhuyzen
Keyword(s):  
Bacillus Thuringiensis ◽  
Choristoneura Fumiferana ◽  
Lethal Dose ◽  
Spruce Budworm ◽  
Petri Dish ◽  
Control Treatment ◽  
Eastern Spruce Budworm ◽  
Late Instar ◽  
Host Mortality ◽  
Pathogen Exposure

We investigated interactions between Bacillus thuringiensis Berliner var. kurstaki and parasitoids that attack late instars of the eastern spruce budworm, Choristoneura fumiferana (Clemens). In a petri-dish arena, females of Tranosema rostrale rostrale (Brishke) (Hymenoptera: Ichneumonidae) were able to discriminate between untreated fourth instars and fourth instars that had been given a known dose of a commercial product (Foray 48B). When the choice tests were conducted before host mortality due to B. thuringiensis had occurred among treated larvae (24 h post ingestion), the parasitoid attacked untreated larvae more readily. When females were given a choice between control larvae and treated larvae that were still alive 72 h post ingestion, they were able to discriminate between the two only when the larvae had been treated with at least a 50% lethal dose. Under laboratory conditions, female T. r. rostrale were thus able to detect and avoid treated larvae that exhibited a lethal response to the pathogen, and to a lesser extent larvae that had survived pathogen exposure. The ability of the latter was not apparent under field conditions. When treated and untreated larvae were exposed for 1 week to a complex of indigenous parasitoids in the field, there was no difference between treatments in the rates of parasitism by either T. r. rostrale or Actia interrupta Curran (Diptera: Tachinidae). Parasitism averaged 91% for larvae in the control treatment compared with 92% for larvae treated with Foray 48B. The field data suggest that spruce budworm larvae that survive exposure to B. thuringiensis are just as likely to be parasitized as unexposed, healthy larvae. This means that prolonged development of late-instar spruce budworm larvae after treatment with B. thuringiensis could possibly result in increased attack rates by parasitoids.

FIELD TESTS OF A HIGHLY CONCENTRATED FORMULATION OF BACILLUS THURINGIENSIS AGAINST SPRUCE BUDWORM (CHORISTONEURA FUMIFERANA; LEPIDOPTERA: TORTRICIDAE)

1985 ◽  
Vol 117 (7) ◽  
pp. 877-881 ◽  
Author(s):  
W.A. Smirnoff
Keyword(s):  
Bacillus Thuringiensis ◽  
Choristoneura Fumiferana ◽  
Larval Mortality ◽  
Field Tests ◽  
Spruce Budworm ◽  
The Past ◽  
Final Volume ◽  
New Formula ◽  
Better Than

AbstractDuring the summer of 1982, aerial experimental sprayings were carried out with a new formula of Bacillus thuringiensis named Futura®. This formula provided a treatment of the 20 × 109 IU of B. thuringiensis/ha required for suppression of spruce budworm (Choristoneura fumiferana), in a final volume of 2.5 L/ha. Results of spraying with Grumman AgCat and DC-4G aircraft are presented. These results were compared with those obtained with formulas of B. thuringiensis used in the past at 4.7 L/ha. Futura® caused 91.1 and 88.7% larval mortality and resulted in 86.6 and 75.1% foliage protection with the Grumman AgCat and DC-4G aircraft, respectively. Such results were equal to or better than those obtained with the formulas used earlier at 4.7 L/ha and confirm the feasibility of using B. thuringiensis operationally in an efficient and economical way.

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