Author: (Hübner, 1799)
Cereal leafroller
Species Overview:
Adult: 15-20 mm wingspan; forewings greyish brown or greyish ochreous, markings obscurely indicated and sometimes almost indiscernible in males, markings stronger in females. Hindwings greyish-brown.
Egg: white, turning orange-red during development; deposited on the rough surface of the bark of a tree.
Larva: head light yellowish brown, marked with black laterally; prothoracic plate light yellowish brown, spotted with black; abdomen variable, yellowish brown or light greenish grey, translucent; pinacula black; anal plate yellowish brown, sometimes paler than head and indistinct; anal comb black; thoracic legs yellowish brown, terminal segments black.
Pupa: dark shining blackish brown, in the folded edge of a leaf or in debris on the ground.
Taxonomic Description:
Male:
Cnephasia pasiuana male
C. pasiuana male
External characters: Antenna very shortly ciliate. Costal margin of forewing slightly arced, apex delicately rounded; termen oblique. Ground colour greyish brown or greyish ochreous finely irrorate with fuscous, the irroration usually not very apparent; markings obscurely indicated and sometimes almost indiscernible; when discernible in well-marked specimens, sub-basal fascia obtusely angled outwards at middle and obsolescent towards the dorsum; median fascia moderately broad throughout, its inner margin most strongly defined and usually slightly sinuous; cilia concolorous. Hindwing grey; cilia paler (Bradley et al., 1973).
male genitalia C. pasiuana
Genitalia: Length of sacculus and place of attaching of sacculus to valva variable. Socii short; gnathos arms broad, terminal plate big; aedeagus bent, acuminate terminally.
Female:
Cnephasia pasiuana female
C. pasiuana females
External characters: Similar to male but forewing markings frequently stronger.
female gen. C. pasiuana
Genitalia: Lamella antevaginalis broad; its caudal margin deeply incised medially, its proximal margin rounded; antrum more sclerotized than ductus, ductus bursae short; signum fairly long and slender.
Biology:
Adults emerge from the middle of June to the beginning of August. The moths have a presexual period of about 1-5 days after emergence on their host plants. Copulation takes place in the early twilight inside the fields. One day after copulation the females fly to nearby wood (forest, wind shelters, solitary trees etc.), where they deposit their eggs on the rough surface of the bark until midnight. The eggs are white, but later change to orange-red. Eggs hatch after about 14 days and the neonate larvae (about 1 mm long) first crawl over the bark for a period of about 2 days. They then conceal themselves in crevices of the bark or moss and weave a small white cocoon (the hibernaculum). They stay inside the cocoon for the rest of the summer, autumn and winter in a state of dormancy, first an obligate diapause until mid to late December and later a quiescence that lasts until the beginning of the spring. The quiescence ends when the maximum daily temperature exceeds 8 °C (as the climate is in March in Central Europe). The larvae then leave their hibernacula. Migration on a massive scale starts on sunny days, when the average temperature reaches 13 °C (usually from mid to late April). The larvae move on the surface of the bark and then descend on threads on which they are carried by the wind. Larvae that land on suitable host plants start to feed on the leaves. The larvae mine in narrow oblong passages, feeding on the parenchyma tissue between the upper and lower epidermis. Late third instar larvae leave the mines and continue to feed on the leaves in the typical manner of leafrollers, by folding and spinning the leaf margins towards the central veins. Pupation commences in June and lasts 9-25 days, depending on the ambient temperature. Pupation always occurs on the host plant, mainly in the sheath of the flag leaf or between the grains and the awns (Glas, 1991).
Host plants:
This species is a pests and of certain economical importance on wheat (Triticum), barley (Hordeum), rye (Secale) and oat (Avena). Host plants also include Aster, Anthemis, Achillea, Artemisia, Centaurea, Chrysanthemum, Circium, Colchicum, Erigeron, Echium, Hyochoeris, Ranunculus and Thalictrum.
Damage:
Larvae cause yield-reducing damage to cereal crops. From the beginning of the formation of the ears, the sheath of the flag leaf is penetrated by the larvae and stamens and pistils are destroyed. In some cases, even stalks are cut. They feed in the developing grain until milky-ripeness.
The causes of outbreaks of Cnephasia pasiuana seem to be climatic factors (probably dry periods during larval dispersion) and the high proportion of cereals in crop rotations. Populations may be effectively controlled by natural enemies. Economic damage is now only reported from Germany and France (Glas, 1991).
Distribution:
Europe and Palaearctic Asia.
Pheromone:
Pheromone:
E 9-12Ac : 6
Z 9-12Ac : 4
12Ac : <4
(Biwer et al., 1977: pheromone of Cnephasia pumicana).
Attractantia:
Z 5-10Ac : 1
Z 7-12Ac : 1 (Tòth et al., 1992)
Parasitoids:
of egg:
Trichogramma euproctidis (Girault) (Trichogrammatidae)
Trichogramma evanescens (Westwood) (Trichogrammatidae)
of larva:
Hypomicrogaster tiro (Reinhard) (Braconidae)
Itoplectis maculator (Fabricius) (Ichneumonidae)