Solanum Alkaloids as Larval Feeding Deterrents for Spruce Budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae)

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.

Download Full-text

Population genetic structure of the spruce budworm (Choristoneura fumiferana) across North America: Are SNP markers valuable for the detection of migrants?

10.1603/ice.2016.95065 ◽

2016 ◽

Author(s):

Lisa Lumley

Keyword(s):

Genetic Structure ◽

North America ◽

Population Genetic Structure ◽

Population Genetic ◽

Choristoneura Fumiferana ◽

Spruce Budworm ◽

Snp Markers

Download Full-text

Derivation of Pheromone-Based Larval Thresholds in Spruce Budworm Accounting for Distance to Defoliated Forest Stands

Journal of Economic Entomology ◽

10.1093/jee/toaa275 ◽

2021 ◽

Author(s):

Marc Rhainds ◽

Ian DeMerchant ◽

Pierre Therrien

Keyword(s):

Boreal Forests ◽

Large Scale ◽

Choristoneura Fumiferana ◽

Intervention Strategy ◽

Spruce Budworm ◽

Interactive Effects ◽

The Novel ◽

Forest Stands ◽

General Guideline ◽

Number Of Males

Abstract Spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is the most severe defoliator of Pinaceae in Nearctic boreal forests. Three tools widely used to guide large-scale management decisions (year-to-year defoliation maps; density of overwintering second instars [L2]; number of males at pheromone traps) were integrated to derive pheromone-based thresholds corresponding to specific intergenerational transitions in larval densities (L2i → L2i+1), taking into account the novel finding that threshold estimates decline with distance to defoliated forest stands (DIST). Estimates of thresholds were highly variable between years, both numerically and in terms of interactive effects of L2i and DIST, which limit their heuristic value. In the context of early intervention strategy (L2i+1 > 6.5 individuals per branch), however, thresholds fluctuated within relatively narrow intervals across wide ranges of L2i and DIST, and values of 40–200 males per trap may thus be used as general guideline.

Download Full-text

Weather and Outbreaks of the Spruce Budworm in the Province of Quebec from 1939 to 1956

The Canadian Entomologist ◽

10.4039/ent93118-2 ◽

1961 ◽

Vol 93 (2) ◽

pp. 118-123 ◽

Cited By ~ 22

Author(s):

J. G. Pilon ◽

J. R. Blais

Keyword(s):

Choristoneura Fumiferana ◽

Abies Balsamea ◽

Spruce Budworm ◽

Balsam Fir ◽

The Past ◽

Forest Regions ◽

Tree Component ◽

Gaspe Peninsula ◽

Gaspé Peninsula

Nearly all forest regions in the Province of Quebec where balsam fir (Abies balsamea (L.) Mill.) is an important tree component have been subjected to severe defoliation by the spruce budworm, Choristoneura fumiferana (Clem.), during the past 20 years. These outbreaks have followed an easterly direction beginning near the Ontario-Quebec border in 1939 and ending in the Gaspé Peninsula in 1958.

Download Full-text

GROUND RELEASES OF TRICHOGRAMMA MINUTUM RILEY (HYMENOPTERA: TRICHOGRAMMATIDAE) AGAINST THE SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE)

The Canadian Entomologist ◽

10.4039/ent119251-3 ◽

1987 ◽

Vol 119 (3) ◽

pp. 251-263 ◽

Cited By ~ 7

Author(s):

S.M. Smith ◽

M. Hubbes ◽

J.R. Carrow

Keyword(s):

Optimal Strategy ◽

Choristoneura Fumiferana ◽

Spruce Budworm ◽

Egg Mass ◽

Northern Ontario ◽

Inundative Release ◽

Egg Masses ◽

Trichogramma Minutum ◽

Spruce Stands ◽

Natural Parasitism

AbstractDuring 1982 and 1984, ground releases of Trichogramma minutum Riley were assessed for control of the spruce budworm, Choristoneura fumiferana (Clemens), on 12- to 20-year-old, white spruce stands in northern Ontario. Maximum parasitism of susceptible egg masses was 16 and 87% following the release of 480 000 and 12 million female T. minutum per hectare, respectively. Releases at intervals of 1 week maintained parasitism of susceptible egg masses at constant levels throughout the oviposition period of spruce budworm. When parasitism of susceptible egg masses was maintained above 78.2% during the ovipositional period, total egg mass parasitism averaged 58.0% and resulted in an 80.3% reduction of overwintering 2nd-instar larvae. The optimal strategy for reducing spruce budworm was two releases of T. minutum at an interval of 1 week in the ovipositional period. This allowed a second generation of parasitoids to emerge from the spruce budworm eggs that were more efficient in maintaining high levels of parasitism than those emerging from the standard rearing host. Natural parasitism of spruce budworm egg masses was less than 4% and there was no carryover of parasitism in the years following inundative release. The rate of T. minutum release necessary to achieve effective mortality of spruce budworm during outbreak populations is discussed briefly.

Download Full-text

Prescribed Burning for Stand Conversion in Budworm-killed Balsam Fir: An Ontario Case History

The Forestry Chronicle ◽

10.5558/tfc62096-2 ◽

1986 ◽

Vol 62 (2) ◽

pp. 96-100 ◽

Cited By ~ 1

Author(s):

D. J. McRae

Keyword(s):

Fuel Consumption ◽

Prescribed Burning ◽

Choristoneura Fumiferana ◽

Abies Balsamea ◽

Spruce Budworm ◽

Fire Spread ◽

Fire Effects ◽

Balsam Fir ◽

Prescribed Burn ◽

Stand Conversion

Recent spruce budworm (Choristoneura fumiferana [Clem.]) infestations have resulted in widespread areas of balsam fir (Abies balsamea [L.] Mill.) mortality in Ontario, and there is growing interest in reestablishing these areas quickly as productive forests. One technique being used is prescribed fire after a salvage and bulldozer tramping operation. A 445-ha prescribed burn was carried out under moderate fire danger conditions in northern Ontario. The site, which was covered by balsam fir fuel that had been killed by spruce budworm, was tramped to improve fire spread. Weather, fuel consumption, and fire effects are reported. The burn effectively reduced heavy surface fuel loadings and consequently planting on the site was easier. Key words: Prescribed burning, fire, spruce budworm. Choristoneura fumiferana, balsam fir, Abies balsamea, fuel consumption, site preparation, tramping, stand conversion.

Download Full-text

WHITE SPRUCE AND THE SPRUCE BUDWORM: DEFINING THE PHENOLOGICAL WINDOW OF SUSCEPTIBILITY

The Canadian Entomologist ◽

10.4039/ent129291-2 ◽

1997 ◽

Vol 129 (2) ◽

pp. 291-318 ◽

Cited By ~ 79

Author(s):

Robert K. Lawrence ◽

William J. Mattson ◽

Robert A. Haack

Keyword(s):

Picea Glauca ◽

High Performance ◽

Choristoneura Fumiferana ◽

Spruce Budworm ◽

White Spruce ◽

Shoot Elongation ◽

Larval Survival ◽

Strongly Correlated ◽

Negative Effect ◽

Foliar Traits

AbstractSynchrony of insect and host tree phenologies has often been suggested as an important factor influencing the susceptibility of white spruce, Picea glauca (Moench) Voss, and other hosts to the spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae). We evaluated this hypothesis by caging several cohorts of spruce budworm larvae on three white spruce populations at different phenological stages of the host trees, and then comparing budworm performance with host phenology and variation of 13 foliar traits. The beginning of the phenological window of susceptibility in white spruce occurs several weeks prior to budbreak, and the end of the window is sharply defined by the end of shoot growth. Performance was high for the earliest budworm cohorts that we tested. These larvae began feeding 3–4 weeks prior to budbreak and completed their larval development prior to the end of shoot elongation. Optimal synchrony occurred when emergence preceded budbreak by about 2 weeks. Larval survival was greater than 60% for individuals starting development 1–3 weeks prior to budbreak, but decreased to less than 10% for those starting development 2 or more weeks after budbreak and thus completing development after shoot elongation ceased. High performance by the budworm was most strongly correlated with high levels of foliar nitrogen, phosphorous, potassium, copper, sugars, and water and low levels of foliar calcium, phenolics, and toughness. These results suggest that advancing the usual phenological window of white spruce (i.e. advancing budbreak prior to larval emergence) or retarding budworm phenology can have a large negative effect on the spruce budworm’s population dynamics.

Download Full-text

FACTORS AFFECTING ADULT EMERGENCE AND MATING BEHAVIOR OF THE EASTERN SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)

The Canadian Entomologist ◽

10.4039/ent107967-9 ◽

1975 ◽

Vol 107 (9) ◽

pp. 967-977 ◽

Cited By ~ 27

Author(s):

C. J. Sanders

Keyword(s):

Field Experiments ◽

Choristoneura Fumiferana ◽

Adult Emergence ◽

Spruce Budworm ◽

Field Conditions ◽

Continuous Illumination ◽

Degree Days ◽

Factors Affecting ◽

Eastern Spruce Budworm ◽

Duration Of Copulation

AbstractLaboratory and field experiments indicate that the female spruce budworm (Choristoneura fumiferana (Clem.)) pupal stadium requires approximately 122C degree-days above a threshold of 7.2 °C (45°F), the male 124. Emergence time on any given day depends on temperature but is independent of photoperiod. Under field conditions male and female budworm mate only once per 24-h period. In the laboratory under continuous illumination females mate repeatedly and males readily mate a second time within a few hours, but the duration of the second copulation is abnormally long. The probability of multiple matings under field conditions is reduced by the restricted period of sexual activity coupled with the duration of copulation and the lower competitiveness of mated insects. Antennae are essential to the male for successful copulation.

Download Full-text