Type

Native

Taxonomy

Choristoneura fumiferana complex (Tortricidae: Tortricinae: Archipini)

Common names: spruce budworm

 

Included species:

Choristoneura carnana (Barnes & Busck)

• Subspecies: californica Powell

Choristoneura fumiferana (Clemens)

• Synonyms: nigrida (Tortrix), nigridia (Tortrix)

Choristoneura lambertiana (Busck)

• Subspecies: ponderosana Obraztsov, subretiniana Obraztsov
• Synonyms: lambertianae (Tortrix)

Choristoneura occidentalis Freeman

• Subspecies: biennis Freeman
• Synonyms: freemani (Choristoneura)

Choristoneura orae Freeman

Choristoneura pinus Freeman

• Subspecies: maritima Freeman

Choristoneura retiniana (Walsingham)

• Subspecies: lindseyana Obraztsov
• Synonyms: viridis (Choristoneura)

Choristoneura spaldingana Obraztsov

Overview

The Choristoneura fumiferana complex consists of eight or nine species, characterized primarily by differences in larval host preferences, female sex pheromone chemistry, number of generations per year, and distribution (Dupuis et al. 2017Dupuis et al. 2017:
Dupuis, J. R., Brunet, B. M. T., Bird, H. M., Lumley, L. M., Fagua, G., Boyle, B., Leacute;vesque, R., Cusson, M., Powell, J. A., Sperling, F. A. H. 2017. Genome-wide SNPs resolve phylogenetic relationships in the North American spruce budworm ( Choristoneura fumiferana ) species complex. Molecular Phylogenetics and Evolution. 111: 158-168.). For the purposes of this site, we recognize eight species as listed above, following Dupuis et al. (2017). Choristoneura biennis Freeman is sometimes treated as a distinct species, but we treat it as a subspecies of C. occidentalis Freeman.

This group is widely recognized as North America’s most destructive insect defoliators of living conifers. Species undergo dramatic population oscillations, with outbreaks causing mass tree mortality.

Much recent molecular work has focused on speciation and phylogenetic relationships within this group (Lumley & Sperling 2010, 2011; Brunet et al. 2017Brunet et al. 2017:
Brunet, B. M. T., Blackburn, G. S., Muirhead, K., Lumley, L. M., Boyle, B., Leacute;vesque, R. C., Cusson, M., Sperling, F. A. H. 2017. Tworsquo;s company, threersquo;s a crowd: new insights on spruce budworm species boundaries using genotyping-by-sequencing in an integrative species assessment (Lepidoptera: Tortricidae). Systematic Entomology. 42: 317-328.; Dupuis et al. 2017Dupuis et al. 2017:
Dupuis, J. R., Brunet, B. M. T., Bird, H. M., Lumley, L. M., Fagua, G., Boyle, B., Leacute;vesque, R., Cusson, M., Powell, J. A., Sperling, F. A. H. 2017. Genome-wide SNPs resolve phylogenetic relationships in the North American spruce budworm ( Choristoneura fumiferana ) species complex. Molecular Phylogenetics and Evolution. 111: 158-168.; Fagua et al. 2018Fagua et al. 2018:
Fagua, G., Condamine, F., Dombroskie, J., Byun, B.-K., De Prins, J., Simonsen, T., Baez, M., Brunet, B., Sperling, F. 2018. Genus delimitation, biogeography and diversification of Choristoneura Lederer (Lepidoptera: Tortricidae) based on molecular evidence. Systematic Entomology. 44(1): 19-38.). Despite this species and subspecies boundaries for some taxa remain unclear (e.g. C. orae, C. lambertiana, C. occidentalis, C. carnana), while others are more well-established (C. retiniana, C. fumiferana, C. pinus). A fair amount of hybridization occurs where species’ ranges overlap. We treat all species here as on a single page and provide information on differences in life history and distribution.

The life histories of species in the fumiferana complex are relatively uniform, with differences primarily relating to preferred host plants and number of years required to complete their life cycle. The following life history account is summarized from McKnight (1968)McKnight (1968):
McKnight, M. E. 1968. A literature review of the spruce, western, and 2-year cycle budworms, Choristoneura fumiferana , C . occidentalis , and C . biennis (Lepidoptera: Tortricidae). US For. Serv. Res. Pap. RM-44. Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado. 35 pp..

Eggs are laid in masses on the needles of the host trees in midsummer. The number of eggs per mass depend on the species in question, but average between 20-45. Females lay eggs at all heights of the trees.

Eggs hatch in about ten days, after which the larvae disperse, spin hibernacula, molt to the second instar, and cease activity. Larvae overwinter as second instars. Activity begins in the spring when maximum daily temperature reaches about 60ºF, this usually occurring in late April or early May throughout their range.

Larvae will initially mine one or more old needles before moving on to developing needles within buds of the host plant. Fourth, fifth, and sixth instar larvae feed on new growth shoots in loosely constructed silken shelters made from dead and fresh needles, bud scales, and frass. Third and fourth instar larvae feed primarily from within these shelters, but fifth and sixth instar larvae will venture out to establish new shelters and feeding sites.

The pupal stages lasts approximately ten days beginning in mid-July. Larvae pupate within one of their established feeding shelters, often near the main stem of the affected branch. Adults eclose in late July, mate, and lay eggs.

Species or subspecies with 2-year life cycles suspend feeding activity as third instar larvae in July, spin a second hibernaculum, and emerge the following spring to complete development.

Though species seem to have a general host plant preference, like with many other Archipini, it is highly plastic and may vary among populations of the same species.

The following table is modified from Dupuis et al. (2017) with supplementary information from Powell (1980b).

Taxon	Distribution	1º host plant association	Years per generation	Comments
C. fumiferana	Boreal, disjunct population in southern Appalachians	Picea glauca	1
C. pinus pinus	Boreal, but absent from Alaska, Yukon, Northwest Territories, northern Alberta, northern Quebec	Pinus banksiana	1	scattered southeastern US records of what appear to be Choristoneura pinus may be referrable to C. p. maritima, but verification is required.
C. pinus maritima	Several disjunct populations: Atlantic Canada; Pennsylvania east to Massachusetts; southern Appalachians	Pinus rigida	1?
C. retiniana retiniana	Southern Cascade range, Sierra Nevada range, Transverse ranges, Northern Coast range	Abies concolor	1	northern Coast Range population requires verification, as it may be confused with C. carnana californica.
C. retiniana lindseyana	Warner Mountains (California)	Abies spp.	unknown	taxonomic status unclear. May be synonymous with C. r. retiniana.
C. occidentalis occidentalis	New Mexico north through the northern Rocky Mountains to Alberta and British Columbia and south to northern California	Pseudotsuga menziesii	1	Choristoneura freemani was briefly used as a replacement name for this species when Razowski (2008) transferred the African species Cacoecia occidentalis Walsingham to Choristoneura rendering C. occidentalis Freeman a junior homonym. Brunet et al. (2017) rejected the placement made by Razowski (2008) and treated the African species as “Archipini unplaced,” thus making occidentalis available again for the North American species.
C. occidentalis biennis	eastern British Columbia and Alberta	Picea engelmannii	2
C. lambertiana lambertiana	northern Sierra Nevada range; Cascade range; northern Rockies?; New Mexico?	Pinus spp.	1	some of the northern Rockies populations may be C. l. ponderosana. The New Mexico records require verification.
C. lambertiana ponderosana	southern Rockies (Colorado); Black Hills?	Pinus ponderosa	unknown	the Black Hills population was treated as a disjunct population of C. pinus by Dupuis et al. (2017), but are more likely C. l. ponderosana.
C. lambertiana subretiniana	southern Sierra Nevada range	Pinus contorta?	unknown
C. orae	coastal British Columbia and Alaska	Picea sitchensis	1-2
C. carnana carnana	San Gabriel range; southern Arizona?	Pseudotsuga spp.	1	the southern Arizona record included in Dupuis et al. (2017) is dubious and requires verification.
C. carnana californica	North Coast range; southern Cascade range; west slope of Sierra Nevada range	Pinus spp. or Pseudotsuga spp.?	1?	Powell (1980b) suggests Pinus as the preferred host, but Powell (2006)Powell (2006): Powell, J. A. 2006. Database of Lepidoptera rearing lots, 1960-2005. University of California Berkeley, CA. suggests Pseudotsuga. The Pinus records may be based on a misidentification.
C. spaldingana	Utah; eastern Nevada; California?	Abies concolor?	unknown	the California records are dubious and require verification. This species may prove to be a synonym of C. retiniana or C. occidentalis.

Host plant table (embedded)

View full screen host table here

Links

Additional photos and distribution maps for species in this complex in the United States and Canada are available at Moth Photographers Group.