Author: Yasuda and Suzuki, 1987
Todo-fir budworm
Species Overview:
Adult: 15-23 mm wingspan (males smaller than females); forewings yellowish ochre with ochreous brown to chocolate-brown more or less developed markings and darker transverse, usually obliterate, lines in interspaces.
Egg: deposited in overlapping linear clusters of 1-8 eggs.
Larva: 18-21 mm long; head dark brown; body greyish white to yellowish green; prothoracic plate dark brown; thoracic legs black; spiracles pale brown, indistinct; pinacula not visible; anal plate yellowish orange. Ventral prolegs usually with 53-62 crochets.
Taxonomic Description:
Male:
Choristoneura jezoensis male
External characters: 15-20 mm wingspan. Antennae dark ochreous brown, densely ciliated. Labial palpi, head and thorax ochreous brown to pale ochreous tan. Forewing elongate, moderately broad, somewhat paler than body; costa gently arced, without costal fold; apex rounded; termen oblique; pale yellowish ochreous to pale greyish ochreous, with markings more or less developed, concolorous with thorax or slightly more chocolate-brown. Basal blotch about one-quarter of wing length; a rather broad oblique median fascia from about middle of costa to dorsum just before tornus, dilated dorsally and completely dividing it in two parts along distal cell; a small costal spot about midway between median fascia and wing apex, followed by a distinct shadow; some inconstant, usually obliterate, interrupted, transverse lines in interspaces; along external part of costa, and in apical wing area, with concolorous dashes (Yasuda and Suzuki, 1987).
male genitalia C. jezoensis
apex of sacculus C. jezoensis
apex aedeagus C. jezoensis
8th sternite in Choristoneura spp.
Genitalia: Uncus spatulate, rather elongate, gradually dilated towards rounded apex, broadened at three-quarters from base; socii band-like, rather broad and long. Valvae subtriangular; sacculus as long as ventral margin of valva, rather broad with upcurved pointed tip. Aedeagus with a pointed carina penis and with minute dents on distal end. Eighth sternite with a short median process.
Female:
Choristoneura jezoensis female
External characters: 21-23 mm wingspan. Similar to male, but ground colour of forewings darker; markings less distinct.
female gen. C. jezoensis
antrum in C. jezoensis
Genitalia: Caudal margin of sterigma with small incision; ostium a simple broad funnel, little sclerotized. Antrum wide and broadly rounded anteriorly; sclerite in it large, with dentate edge.
Biology:
Choristoneura jezoensis has an univoltine life cycle. The eggs are laid in mid July to late June. They are deposited in an overlapping linear cluster mainly on the current year's needles of the host plant. The number of eggs per cluster varies from 1 to 20, and approximately 8 on average. The larva hatches in late July or early August; the newly hatched larvae disperse to protected situations on the basal part of branch or on trunk (mostly to cracks on branch) where the larva makes a silken hibernaculum, and the larva moults after construction of the hibernaculum. In the early spring of the next year, the larva emerges from the hibernaculum and enters vegetative buds, which just begin to swell. There are six instars in the larval stage. The larva matures within six to eight weeks after spring emergence; pupation takes place at or near the larval feeding site. Emergence of adults starts in early July and lasts throughout July (Yasuda and Suzuki, 1987).
Host plants:
Abies sachalinensis, Larix leptolepis and Picea jezoensis.
Damage:
During outbreaks, Choristoneura jezoensis can cause severe damage to Abies sachalinensis. It feeds not only on buds and needles, but also on young shoots, and causes all the needles on the shoots to wither. The entire stand turns red in mid or late June when the density of Choristoneura jezoensis is high, and trees in the stand suffer great damage. Defoliation by Choristoneura jezoensis results in loss in growth, and, after defoliation for three or more years, tree tops are killed over a length of 30-40 cm. Such heavy defoliation occurs when fifteen larvae or more feed on a 50 cm long branch.
Distribution:
Japan: Hokkaido only
Pheromone:
Pheromone unknown.
Parasitoids:
Of egg:
Ascogaster reticulatus Watanabe (Braconidae)
Ascogaster sp. (Braconidae)
Trichogramma sp. (Trichogrammatidae)
Of larva:
Acropimpla jezoensis Matsumura (Ichneumonidae)
Acropimpla pictipes Gravenhorst (Ichneumonidae)
Apohita tobensis Uchida (Ichneumonidae)
Campoplex spp. (Ichneumonidae)
Cephaloglypta laricis Momoi (Ichneumonidae)
Diadegma sp. (Ichneumonidae)
Lissonota sp. (Ichneumonidae)
Scambus spp. (Ichneumonidae)
Teleutaea brischkei Holmgren (Ichneumonidae)
Tranosema arenicola albula Momoi (Ichneumonidae)
Tranosema nigricans Momoi (Ichneumonidae)
Trichionotus sp.(Ichneumonidae)
Apanteles sp. (Braconidae)
Meteorus adoxophyesi Minamikawa (Braconidae)
Meteorus sp. (Braconidae)
Rogas sp. (Braconidae)
Sympiesis sp. (Chalcidoidea)
Actia maksymovi Mesnil (Tachinidae)
Bessa fugax Rondani (Tachinidae)
Elodia tragicta Meigen (Tachinidae)
Eumea spernanda Zetterstedt (Tachinidae)
Nemorilla floralis Fallén (Tachinidae)
Pseudoperichaeta insidiosa Robineau-Desvoidy (Tachinidae)
Tachinid sp. (Tachinidae)
Of pupa:
Coccygomimus aquilonius japonicus Momoi (Ichneumonidae))
Coccygymimus disparis Viereck (Ichneumonidae)
Coccygymimus turioinellae Linnaeus (Ichneumonidae)
Coccygymimus sp. (Ichneumonidae)
Dirophanes yezoensis Uchida (Ichneumonidae)
Itoplectis alternans spectabilis Matsumura (Ichneumonidae)
Theronia atalantae gestator Thunberg (Ichneumonidae)
Mesopolobus subfumatus (Ratzeburg) (Pteromalidae)
Mesopolobus tortricidis Kamijo (Pteromalidae)
Cyclogastrella deplanata (Nees) (Pteromalidae)