Comparing the efficacy of various aerial spraying scenarios using Bacillus thuringiensis to protect trees from spruce budworm defoliation

Fuentealba, Álvaro; Dupont, Alain; Hébert, Christian; Berthiaume, Richard; Quezada-García, Roberto; Bauce, Éric

doi:10.1016/j.foreco.2018.10.034

Cited by 20 publications

(24 citation statements)

References 31 publications

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“…These sociopolitical dynamics can be difficult to quantify, but are nonetheless a key determinant of whether an EIS program can work. In Foliage Protection these issues tend to be less prominent as the majority of treatments take place on Crown Lands [11]. In contrast, an area-wide management program such as EIS aims to control all areas with hotspots and thus must account for the values of a diverse range of affected stakeholders.…”

Section: Sociopoliticalmentioning

confidence: 99%

A Conceptual Framework for the Spruce Budworm Early Intervention Strategy: Can Outbreaks be Stopped?

Johns

Bowden

Carleton³

et al. 2019

Forests

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The spruce budworm, Choristoneura fumiferana, Clem., is the most significant defoliating pest of boreal balsam fir (Abies balsamea (L.) Mill.) and spruce (Picea sp.) in North America. Historically, spruce budworm outbreaks have been managed via a reactive, foliage protection approach focused on keeping trees alive rather than stopping the outbreak. However, recent theoretical and technical advances have renewed interest in proactive population control to reduce outbreak spread and magnitude, i.e., the Early Intervention Strategy (EIS). In essence, EIS is an area-wide management program premised on detecting and controlling rising spruce budworm populations (hotspots) along the leading edge of an outbreak. In this article, we lay out the conceptual framework for EIS, including all of the core components needed for such a program to be viable. We outline the competing hypotheses of spruce budworm population dynamics and discuss their implications for how we manage outbreaks. We also discuss the practical needs for such a program to be successful (e.g., hotspot monitoring, population control, and cost-benefit analyses), as well as the importance of proactive communications with stakeholders.

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Section: Sociopoliticalmentioning

confidence: 99%

A Conceptual Framework for the Spruce Budworm Early Intervention Strategy: Can Outbreaks be Stopped?

Johns

Bowden

Carleton³

et al. 2019

Forests

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“…Fuentealba et al. () suggested that RPC could be used to better estimate the effects of damage by SBW than the measures of defoliation used in short‐term studies because RPC is less sensitive to fluctuations in SBW population (Hardy and Dorais ). We did not observe a direct relationship between AD and NEP; however, there was a clear inverse relationship between AD DS1 and NEP DS1 for all forest types early (Table ).…”

Section: Discussionmentioning

confidence: 99%

“…The delayed effects of spray on defoliation, carbon fluxes, or stocks, 1–3 yr (i.e., the period for which foliage protection is considered efficacious, Fuentealba et al. ) after the application, were compared to the immediate effect numerically by calculating the delayed effect X DS n on variable X as follows Eq. 3:

X_{{DS}_{n}} = [\sum_{i = 1}^{p} {false({\overset{false¯}{X}}_{normalDSi normalspray} - {\overset{false¯}{X}}_{normalDSi normalno normalspray} false)}_{n > 0} - {false({\overset{false¯}{X}}_{normalDSi normalspray} - {\overset{false¯}{X}}_{normalDSi normalno normalspray} false)}_{n = - 1}] / p

where X is AD, carbon fluxes, or stocks (e.g., GPP, NEP, and aboveground biomass).…”

Section: Methodsmentioning

confidence: 99%

“…, Fuentealba et al. ). The main objective of Btk application is to maintain 50% or more of current‐year foliage on trees in order to reduce timber losses during outbreaks (Carisey et al.…”

Section: Introductionmentioning

confidence: 99%

“…Fuentealba et al. () reported that without Btk protection, coniferous forests lose much of their residual photosynthetic capacity (RPC). However, it is still unknown how much C could be maintained in forest by aerial spraying programs during a SBW outbreak.…”

Section: Introductionmentioning

confidence: 99%

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Aerial spraying of bacterial insecticides to control spruce budworm defoliation leads to reduced carbon losses

et al. 2020

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Spruce budworm (SBW) outbreaks are a major natural disturbance in boreal forests of eastern North America. During large-scale infestations, aerial spraying of bacterial insecticides is used to suppress local high-density SBW populations. While the primary goal of spraying is the protection of wood volume for later harvest, it should also maintain carbon stored in trees. This study provides the first quantitative analysis of the efficacy of aerial spraying against SBW on carbon dynamics in balsam fir, spruce, and mixed fir-spruce forests. In this study, we used the TRIPLEX-Insect model to simulate carbon dynamics with and without spray applications in 14 sites of the boreal forest located in various regions of Qu ebec. We found that the efficacy of aerial spraying on reducing annual defoliation was greater in the early stage (<5 yr since the outbreak began) of the outbreak than in later (5-10 yr since the outbreak began) stage. Our results showed that more net ecosystem productivity is maintained in balsam fir (the most vulnerable species) than in either spruce or mixed fir-spruce forests following spraying. Also, average losses in aboveground biomass due to the SBW following spraying occurred more slowly than without spraying in balsam fir forests. Our findings suggest that aerial spraying could be used to maintain carbon in conifer forests during SBW disturbances, but that the efficacy of spray programs is affected by host species and stage of the SBW outbreak.

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Impacts of spruce budworm defoliation on the habitat of woodland caribou, moose, and their main predators

Chagnon

Bouchard

Pothier

2022

Ecology and Evolution

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Forest logging has contributed to the decline of several woodland caribou populations by causing the fragmentation of mature coniferous stands. Such habitat alterations could be worsened by spruce budworm (SBW) outbreaks. Using 6201 vegetation plots from provincial inventories conducted after the last SBW outbreak (1968–1992) in boreal forests of Québec (Canada), we investigated the influence of SBW‐caused tree defoliation and mortality on understory vegetation layers relevant to woodland caribou and its main predators. We found a positive association between severe outbreaks and the cover of most groups of understory plant species, especially in stands that were dominated by balsam fir before the outbreak, where a high canopy openness particularly benefited relatively fast‐growing deciduous plants. Such increases in early successional vegetation could provide high‐quality forage for moose, which is likely to promote higher wolf densities and increase predation pressure on caribou. SBW outbreaks may thus negatively affect woodland caribou by increasing predation risk, the main factor limiting caribou populations in managed forests. For the near future, we recommend updating the criteria used to define critical caribou habitat to consider the potential impacts of spruce budworm defoliation.

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Comparing the efficacy of various aerial spraying scenarios using Bacillus thuringiensis to protect trees from spruce budworm defoliation

Cited by 20 publications

References 31 publications

A Conceptual Framework for the Spruce Budworm Early Intervention Strategy: Can Outbreaks be Stopped?

A Conceptual Framework for the Spruce Budworm Early Intervention Strategy: Can Outbreaks be Stopped?

Aerial spraying of bacterial insecticides to control spruce budworm defoliation leads to reduced carbon losses

Impacts of spruce budworm defoliation on the habitat of woodland caribou, moose, and their main predators

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