Journal of Economic Entomology (2021) 114, 769-775

Marc Rhainds, Ian DeMerchant and Pierre Therrien (2021)
Derivation of pheromone-based larval thresholds in spruce budworm accounting for distance to defoliated forest stands
Journal of Economic Entomology 114 (2), 769-775
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 (L2_i -> L2_i+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 L2_i and DIST, which limit their heuristic value. In the context of early intervention strategy (L2_i+1 > 6.5 individuals per branch), however, thresholds fluctuated within relatively narrow intervals across wide ranges of L2_i and DIST, and values of 40–200 males per trap may thus be used as general guideline.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Marc Rhainds

Research topic(s) for pests/diseases/weeds:
damage/losses/economics
thresholds/decision-support systems

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Choristoneura fumiferana		Canada (east)