Several, see text
Spruce budworms and relatives are a group of closely related insects in the genus Choristoneura. Most are serious pests of conifers. There are nearly forty Choristoneura species, and even more subspecies, or forms, with a complexity of variation among populations found throughout much of the United States and Canada, and about again this number in Eurasia.
- Choristoneura adumbratanus (Walsingham, 1900)
- Choristoneura africana Razowski, 2002
- Choristoneura albaniana (Walker, 1863)
- Choristoneura argentifasciata Heppner, 1989
- Choristoneura biennis Freeman, 1967
- Choristoneura bracatana (Rebel, in Rebel & Rogenhofer, 1894)
- Choristoneura carnana (Barnes & Busck, 1920)
- Choristoneura chapana Razowski, 2008
- Choristoneura colyma Razowski, 2006
- Choristoneura conflictana (Walker, 1863)
- Choristoneura diversana (Hubner, [1814-1817])
- Choristoneura evanidana (Kennel, 1901)
- Choristoneura expansiva X.P.Wang & G.J.Yang, 2008
- Choristoneura ferrugininotata Obraztsov, 1968
- Choristoneura fractivittana (Clemens, 1865)
- Choristoneura freemani Razowski, 2008, western spruce budworm
- Choristoneura fumiferana (Clemens, 1865), eastern spruce budworm
- Choristoneura griseicoma (Meyrick, 1924)
- Choristoneura hebenstreitella (Muller, 1764), mountain-ash tortricid
- Choristoneura heliaspis (Meyrick, 1909)
- Choristoneura improvisana (Kuznetsov, 1973)
- Choristoneura irina Syachina & Budashkin, 2007
- Choristoneura jecorana (Kennel, 1899)
- Choristoneura jezoensis Yasuda & Suzuki, 1987
- Choristoneura lafauryana (Ragonot, 1875)
- Choristoneura lambertiana (Busck, 1915)
- Choristoneura longicellanus (Walsingham, 1900)
- Choristoneura luticostana (Christoph, 1888)
- Choristoneura metasequoiacola Liu, 1983
- Choristoneura murinana (Hubner, [1796-1799])
- Choristoneura neurophaea (Meyrick, 1932)
- Choristoneura obsoletana (Walker, 1863)
- Choristoneura occidentalis (Walsingham, 1891)
- Choristoneura orae Freeman, 1967
- Choristoneura palladinoi Razowski & Trematerra, 2010
- Choristoneura parallela (Robinson, 1869)
- Choristoneura pinus Freeman, 1953, jack pine budworm
- Choristoneura propensa Razowski, 1992
- Choristoneura psoricodes (Meyrick, 1911)
- Choristoneura quadratica Diakonoff, 1955
- Choristoneura retiniana (Walsingham, 1879)
- Choristoneura rosaceana (Harris, 1841)
- Choristoneura simonyi (Rebel, 1892)
- Choristoneura spaldingana Obraztsov, 1962
- Choristoneura thyrsifera Razowski, 1984
- Choristoneura zapulata (Robinson, 1869)
Budworm populations are usually regulated naturally by combinations of several natural factors such as insect parasites, vertebrate and invertebrate predators, and adverse weather conditions. During prolonged outbreaks when stands become heavily defoliated, starvation can be an important mortality factor in regulating populations.
This species is a favoured food of the Cape May warbler, which is therefore closely associated with its host plant, balsam fir. This bird, and the Tennessee and bay-breasted warblers, which also have a preference for budworm, lay more eggs and are more numerous in years of budworm abundance.
Natural enemies are probably responsible for considerable mortality when budworm populations are low, but seldom have a regulating influence when populations are in epidemic proportions.
Chemical insecticides such as malathion, carbaryl, and acephate can substantially reduce budworm. Microbial insecticides such as bacterium species Bacillus thuringiensis(Bt), a naturally occurring, host-specific pathogen that affects specific insect larvae based on the bacteria strain. Bt insecticides are often used in sensitive areas such as campgrounds or along rivers and streams, where it may not be desirable to use chemical insecticides with modes of action that affect fish and mammals.
The eastern spruce budworm is one of the most destructive insects of fir and spruce forests throughout Canada and the eastern United States. In locations such as New Brunswick, pesticides were applied to over 3.6 million hectacres from 1952 to 1958 and 1960 to 1967. This use of chemical control effectively decreased the mortality rate within this area and prevented significant economic impact. For biological methods, birds are important in controlling populations of the eastern spruce budworm below outbreak levels, and the parasitic wasp Trichogramma minutum was investigated as a solution as well.
Appearances in the media
In the Katharine Hepburn/Spencer Tracy film Desk Set, the market cost of the annual depredations of the spruce budworm on United States forests is invoked as an example reference question in comparing the response times of human reference librarians and early computer databases.
- "Out Of Print : Biosystematic Studies of Conifer-Feeding Choristoneura (Lepidoptera Tortricidae) in the Western United States : Edited by Jerry A. Powell - University of California Press". www.ucpress.edu. Retrieved 2017-10-23.
- MacDonald, D.R. 1968. Management of spruce budworm populations. For. Chron. 44(3):33–36 (separate pagination).
- Crawford, Hewlette S.; Jennings, Daniel T. (1989). "Predation by Birds on Spruce Budworm Choristoneura Fumiferana: Functional, Numerical, and Total Responses". Ecology. 70 (1): 152–163. doi:10.2307/1938422.
- Smith, S.M.; Hubbes, M.; Carrow, J.R. 1986. Factors affecting inundative releases of Trichogramma minutum Ril. against the spruce budworm. J. Appl. Entomol. 101(1):29–39.
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- Razowski, J. & P. Trematerra, 2010: Tortricidae (Lepidoptera) from Ethiopia Journal of Entomological and Acarological Research Serie II, 42 (2): 47-79. Abstract: .