SUSCEPTIBILITY AND VULNERABILITY OF THIRD-INSTAR LARVAE OF THE SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) TO BACILLUS THURINGIENSIS SUBSP. KURSTAKI

2000 ◽  
Vol 132 (5) ◽  
pp. 573-580 ◽  
Author(s):  
Aurélie Massé ◽  
Kees van Frankenhuyzen ◽  
John Dedes
Keyword(s):  
Bacillus Thuringiensis ◽  
Feeding Habits ◽  
Larval Density ◽  
Lethal Dose ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Instar Larva ◽  
Published Data ◽  
Spray Chamber ◽  
Third Instar Larvae

AbstractA droplet-imbibing assay was used to assess the susceptibility of third-instar larvae of the spruce budworm, Choristoneura fumiferana Clemens, to Foray 48B, a commercial formulation of Bacillus thuringiensis subsp. kurstaki containing 12.7 billion international units (IU) per litre. We observed an LD50 of 1.17 IU/larva for third instars, as compared with 3.96 IU/larva for fifth instars. Comparison with previously published data on susceptibility of later instars revealed that third instars were two-to three-fold more susceptible to Foray 48B than fourth and fifth instars and about eightfold more susceptible than sixth instars. Vulnerability of third instars to simulated aerial spray deposits was investigated by using potted balsam firs, Abies balsamea L. Potted trees were infested in the greenhouse when the buds were starting to swell, using a density of about one newly emerged second-instar larva per bud. When 90% of the larvae had reached the third instar and 52% of the buds were breaking (4 d after infesting), infested twigs were harvested and sprayed with undiluted Foray 48B in a spray chamber. Spray droplets on the buds measured between 25 and 125 μm in diameter, with 80% having a diameter of 80 μm or less. A density of 4.2 ± 1.0 droplets per bud resulted in spruce budworm mortality of 83.4 ± 4.0% and a corresponding reduction in larval density of 86.5 ± 3.9% (means ± SD, n = 6) after 5 d at 25 °C. Results of the spray chamber test suggest that third-instar spruce budworms were able to acquire a lethal dose, despite their concealed feeding habits.

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.

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.

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.

Stochastic simulation of growth loss in thinned balsam fir stands defoliated by the spruce budworm in Newfoundland

1998 ◽  
Vol 28 (5) ◽  
pp. 703-710 ◽  
Author(s):  
Erhard John Dobesberger
Keyword(s):  
Stochastic Simulation ◽  
Larval Density ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Damage Function ◽  
Balsam Fir ◽  
Negative Exponential Function ◽  
Attack Pattern ◽  
Growth Loss ◽  
The Impact

A stochastic simulation model was developed to derive a damage function for the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), and balsam fir, Abies balsamea (L.) Mill., herbivore interaction at the stand level for open-grown trees. Both aggregated and uniform models of attack pattern by late-instar larvae based on k of the negative binomial were evaluated to determine the impact of larval density and attack pattern on the loss in stemwood volume increment of young, thinned balsam fir stands in Newfoundland. Percentage loss in stemwood increment was a nonlinear, negative exponential function of initial larval density. Implementation of control measures to prevent 50% defoliation that is caused by about 14 larvae/branch tip would result in saving 24% of the annual stemwood increment after 1 year of defoliation and about 32% after 2 years of cumulative defoliation. Aggregation of spruce budworm larvae among trees within a forest stand results in less growth loss compared with a uniform pattern of attack. The nonlinear damage function may suggest tolerance and possibly compensatory growth after herbivory by low population levels of the spruce budworm.

FIELD RESPONSE OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE), TO DOSAGE AND VOLUME RATES OF COMMERCIAL BACILLUS THURINGIENSIS

1984 ◽  
Vol 116 (7) ◽  
pp. 983-990 ◽  
Author(s):  
O. N. Morris
Keyword(s):  
Bacillus Thuringiensis ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Forest Stands ◽  
Effective Application ◽  
Field Response

AbstractThuricide and Dipel, formulations of Bacillus thuringiensis (B.t.), were applied aerially against the spruce budworm, Choristoneura fumiferana (Clem.), in forest stands of balsam fir, Abies balsamea L. A dosage of 30 Billion International Units (BIU) of B.t./ha applied in 2.4 to 4.7 L of spray/ha was most effective. Application of 20 BIU/ha was marginally effective against a population of 12 to 36 larvae/45 cm of branch.

Notes upon the biology and morphology of the immature stages of Neottiophilum praeustum (Meigen, 1926)(Diptera: Neottiophilidae) parasitic on birds

Parasitology ◽  
1954 ◽  
Vol 44 (1-2) ◽  
pp. 111-119 ◽  
Author(s):  
P. Tate
Keyword(s):  
Feeding Habits ◽  
Instar Larva ◽  
Rhagoletis Pomonella ◽  
Immature Stages ◽  
Primitive Character ◽  
Prepupal Stage ◽  
Calliphora Erythrocephala ◽  
The Third ◽  
Third Instar Larvae

1. The feeding habits of second- and third-instar larvae of Neottiophilum praeustum have been observed and show that this species is a true parasite of birds and feeds by sucking the blood of nestlings.2. If they are too numerous the larvae may kill the nestlings. Although they will continue to feed upon dead birds, and even penetrate into the viscera, such food is unsuitable for the development of the larvae and they become greatly distended and die within a few days.3. The morphology of the hitherto unknown second-instar larva is described and is compared with that of the third instar.4. Within the puparium of Neottiophilum praeustum there is a fourth moult resulting in the formation of a cast prepupal cuticle which resembles that described by Snodgrass in Rhagoletis pomonella and is much better developed than the prepupal cuticle in Calliphora erythrocephala.5. The better development of the prepupal cuticle in the acalypterates than in calypterates indicates that the presence of a prepupal stage in the cyclorrhaphous Diptera is a primitive character and is progressively reduced until in the higher families it is almost vestigial.

EFFICACY OF FORAY 48B (BACILLUS THURINGIENSIS BERLINER) APPLICATIONS AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEMENS) (LEPIDOPTERA: TORTRICIDAE), TIMED FOR PHENOLOGICAL DEVELOPMENT OF BALSAM FIR AND BLACK SPRUCE

1993 ◽  
Vol 125 (3) ◽  
pp. 479-488 ◽  
Author(s):  
Beresford L. Cadogan ◽  
Roger D. Scharbach
Keyword(s):  
Bacillus Thuringiensis ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Larval Survival ◽  
Balsam Fir ◽  
Early Instar ◽  
Respective Species ◽  
Respective Host

AbstractThe insecticide Foray 48B (Bacillus thuringiensis var. kurstaki Berliner) was applied undiluted at 30 BIU per ha to control spruce budworm, Choristoneura fumiferana (Clem.), in a mixed boreal forest stand of balsam fir, Abies balsamea (L.) Mill., and black spruce, Picea mariana (Mill.) B.S.P. When the treatment was timed to coincide with the early flushing of balsam fir shoots, the corrected budworm population reductions were 74 and 52% on balsam fir and black spruce, respectively. This treatment resulted in 19 and 8% defoliation on the two respective species. When the insecticide application was timed later to coincide with the late flushing of black spruce shoots the corrected population reductions were 93% on balsam fir and 72% on black spruce. Defoliation of the two species was 29 and 10% respectively, following this treatment. Larval survival on both species after the spray timed for black spruce (0.8 and 2.2 larvae per 45-cm branch on balsam fir and black spruce, respectively) was significantly less (P = 0.05) than that observed after the spray timed for balsam fir (4.6 and 4.2 larvae per 45-cm branch on the respective host species).The data indicate that the spray timed to correspond with the flushing of black spruce was generally more efficacious than the spray timed to impact on newly flushed balsam fir; nevertheless, the results raise the question as to how B. thuringiensis insecticides impact on early-instar budworm larvae when there is no preferred current year foliage on which the insects can feed.

scholarly journals Relationship of spruce budworm (Choristoneura fumiferana) emergence and balsam fir (Abies balsamea) bud flush to climate indices

2009 ◽  
Vol 85 (4) ◽  
pp. 625-630 ◽  
Author(s):  
Alan J Thomson
Keyword(s):  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Climate Indices ◽  
Published Data ◽  
Eastern Canada ◽  
The Pacific ◽  
Larval Emergence ◽  
Temperature Records

Temperature records from weather stations across eastern Canada were used with published data on degree-day requirements for spruce budworm larval emergence and balsam fir bud flush to estimate historical patterns of larval emergence and timing of bud flush. The pattern of association was studied using Response Surface Analysis and was found to vary from west to east. April values of the Pacific/North American (PNA) pattern, Pacific Decadal Oscillation (PDO) and Northern Annular Mode (NAM) climate indices showed the most significant relationship to both emergence and bud flush in the 2 Ontario stations, while May values of the PDO and Eastern Pacific (EP) indices were most significant in the 4 Quebec and New Brunswick locations. Key words: phenology, balsam fir, teleconnections

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.

EFFECT OF SPRAY DROPLET SIZE AND DENSITY ON EFFICACY OF BACILLUS THURINGIENSIS BERLINER AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE)

1995 ◽  
Vol 127 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Nicholas J. Payne ◽  
Kees van Frankenhuyzen
Keyword(s):  
Bacillus Thuringiensis ◽  
Droplet Size ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Application Rate ◽  
Larval Feeding ◽  
Droplet Sizes ◽  
Sublethal Doses ◽  
Overall Mortality

AbstractBecause microbial insecticides based on Bacillus thuringiensis subsp. kurstaki cause temporary cessation of larval feeding at sublethal doses, we hypothesized that the delivery of a given dose in a single droplet is more efficacious than delivery of the same dose in multiple smaller droplets. We tested this hypothesis by exposing larvae of the spruce budworm, Choristoneura fumiferana (Clem.), to an LD50 of a commercial product (Dipel 8L) in combinations of droplet sizes and densities that are commonly observed on coniferous foliage after aerial application. A nominal dose of 5.2 International Units (IU) was presented to fifth-instar larvae on one, two, or four balsam fir, Abies balsamea L., needles in the form of one, two, or four droplets with diameters of 84, 66, or 52 μm, respectively. The combinations of droplet size and density were chosen to represent an increasing degree of dose dispersion. Overall mortality after a 24-h exposure was significantly reduced with increasing dose dispersion from an average of 66% when the dose was presented in one 84-μm droplet on one needle to 40% when presented in multiple droplets on several needles. Increased dose dispersion reduced the proportion of larvae that were able to ingest the full dose, presumably because of feeding inhibition caused by ingestion of sublethal droplets. In addition, mortality of fully dosed larvae declined significantly with increasing dispersion, implying a reduction in the effectiveness of the ingested dose. When compared with operational spray deposits, our results suggest that efficacy of spruce budworm sprays may be improved by increasing the proportion of needles receiving a lethal spray deposit by increasing product potency and possibly the active ingredient application rate.

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