Author: (Fabricius, 1794)
Pea moth
Species Overview:
Adult: 12-16 mm wingspan; distinguished by the overall uniform brown or grey-brown appearance of the forewing, which is finely irrorate with pale ochreous distally and has a poorly developed ocellus and usually conspicuous costal strigulae and interspaces. In the hindwing the white or cream-white cilia are characteristic and contrast strongly with the dark fuscous colouration of the wing; the male is further distinguished by the presence of a dorsal fold along the inner margin.
Egg: 0.75 x 0.6 mm; lenticular, at first translucent yellowish white, becoming obscured after 12 to 24 hours by two irregular red streaks which disappear on the sixth day when the outline of the larva can be seen through the chorion; deposited singly or in groups of two or three, usually on the leaves and stipules and occasionally on the sepals or developing pod of the food plant.
Larva: 13 mm long; head yellowish brown, mandibles, adfrontal sutures, ocelli and postero-lateral margin blackish; prothoracic plate weakly sclerotized, light greyish brown, with irregular dark brown or blackish pigmentation posteriorly and medially, medial sulcus moderately well defined; abdomen yellowish white, sometimes with a greenish tinge, spinulation of integument distinct; pinacula greyish, moderately distinct; spiracles very small, peritreme blackish; anal plate weakly sclerotized, rounded caudally, greyish or yellowish brown with scattered blackish spots; anal comb absent; thoracic legs yellowish white [C. nigricana larva in pod ].
Pupa: 8 mm long; dark brown; spun up in a tough silken cocoon or hibernaculum in the earth at a depth of 1-8 cm, or inside the pod (on lentil). When deeply buried in the soil the larva apparently cuts its way out of the hibernaculum and comes up to the surface before pupating.
Taxonomic Description:
Male:
Cydia nigricana adult
Cydia nigricana male
External characters: 12-16 mm wingspan. Labial palpus and irons greyish white, crown of head, thorax and tegula grey-brown. Forewing ground colour white or cream-white, overlaid with brown except interspaces between usually sharply defined black-brown costal strigulae, three of the strigulae beyond middle producing rather indistinct bluish plumbeous striae; basal third of wing suffused with grey and concolorous with thorax and tegulae, distal two-thirds strongly irrorate (tips of scales) with pale ochreous; fasciate markings obsolete; ocellus obscure, containing three or four black dots or dashes and edged laterally with metallic plumbeous striae which sometimes meet the long bluish plumbeous striae from costal strigulae; cilia concolorous with wing at base, otherwise whitish to dark grey, with a black-brown sub-basal line variably interrupted subapically. Hindwing dark fuscous, lighter basally, with a well-developed dorsal fold or pocket on the upperside along the inner margin from base to tornus, fringed with whitish scales; cilia cream-white, with a dark sub-basal line (Bradley et al., 1979).
male genitalia Cydia nigricana
Genitalia: Tegumen fairly blunt apically. Ventral margin of valva with slight notch, and blunt glabrous tooth before cucullus. Cucullus large, with a group of spinescent bristles present along ventral margin of cucullus, extending to basal opening; outer (ventral) margin of cucullus glabrous.
Female:
Cydia nigricana female
External characters: Forewing colouration and markings similar to those of male; hindwing entirely dark fuscous, often with a warm reddish or coppery sheen.
female gen. Cydia nigricana
Genitalia: Median field of seventh sternite separated by distinct grooves, these grooves more or less parallel. Sclerotized region in ductus short. Sterigma relatively long and narrow, with triangular processes posteriorly.
Variation:
Minor variation occurs in the strength and clarity of the costal strigulae and interspaces and in the depth and intensity of the pale ochreous irroration of the forewing.
Biology:
Females deposit their eggs singly or in groups of two or three, usually on the leaves and stipules and occasionally on the sepals or developing pod of the food plant. Eggs hatch in 6-11 days. Larvae of the first generation feed in the stems, tunnelling upwards from the base; those of the second generation usually feed in spun terminal leaves and flowerheads, and also in the pods. When two or more larvae arrive at a pod, they tolerate each other. When one larva is already feeding inside a pod, it is unable to defend itself and may be killed by any larva arriving subsequently. Full-grown larvae hibernate in a cocoon in the soil at a depth of 1-8 cm. On lentil it can also hibernate inside the pod. Pupation occurs the next spring and usually lasts 12-14 days. When deeply buried in the soil the larva apparently cuts its way out of the hibernaculum and comes up to the surface before pupating.
According to Bovey, 1966, moths fly from the end of May till mid or late July (Germany) or from early June till late July or early August (Finland). According to Bradley et al., 1979, moths fly from May to late August in the UK, having a prolonged period of emergence. A small second brood occasionally occurs (Bovey, 1966; Bradley et al., 1979; Geest van der et al., 1991; Bardner, 1978).
Host plants:
Lathyrus spp. (including cultivated or garden pea, Lathyrus sativum), Pisum spp. (including sweet pea, Pisum odoratus), Vicia spp (including broad bean, Vicia falca and common vetch, Vicia sativa), Lens culinaris (lentil).
Damage:
Cydia nigricana is a major pest of cultivated peas, particularly those which are dry-harvested. Larvae bore into developing pods, causing disfigurement of the harvested crop, down-grading and lower prices. Feeding may be followed by fungal infection which spreads to uneaten seeds, resulting in even greater yield loss.
Pea moths damage a mean of about 8.5 % of dried peas, but the actual loss in weight is only about 1 %, so losses are mainly 'cosmetic' (record from UK). Vining peas are less subject to damage, but less damage is tolerated by the buyers. Green peas for market are also not heavily attacked.
Field trials have shown that quickly maturing varieties of peas sown early are less prone to pea moth attack (Bardner, 1978; Geest van der et al., 1991; Bovey, 1966; Koptur, 1998).
Distribution:
Palaearctic, ranging from Europe to Siberia, Mongolia, China, Korea and Japan; introduced into North America.
Pheromone:
12 AC : 2.5
E 9-12Ac : 0.1
E 8E 10-12Ac : 0.8 *
E 8Z 10-12Ac : < 0.04
Z 8E 10-12Ac : < 0.04
Z 8Z 10-12Ac : < 0.04
14AC : 1.7
Z 5-14AC : 0.1
Z 7-14AC : 0.1
16Ac : 1.5
18Ac : 0.3
Component marked with * is involved in attraction (Witzgall et al., 1993).
In the field, males are attracted to fresh dispensers releasing E 8,E 10-12:Ac plus less than 2% of the antagonistic E, Z; Z, E and Z, Z isomers.
Parasitoids:
Pristomerus vulnerator (Ichneumonidae)
Diadegma sp. (Ichneumonidae)
Glypta haesitator (Ichneumonidae)
Hemiteles ridibundus (Ichneumonidae)
Scambus sp. (Ichneumonidae)
Ascogaster quadridentatus (Braconidae)
Cydia nebritana (Treitschke)
Cydia nebritana adult 1
Cydia nebritana adult 2
Another species that incidentally occurs on peas is Cydia nebritana (Treitschke). It occurs from Central and Southern Europe to South-Western Russia.
Adults resemble those of Cydia nigricana (grey-brown forewings, irrorated with reddish-ochreous posteriorly; ocellus edged laterally by plumbeous streaks).
Genitalia:
male gen. Cydia nebritana; female gen. Cydia nebritana
Males can be distinguished by the very large aedeagus and the deep notch in the ventral margin of the valva.
Females can be distinguished by the ring-shaped sterigma and the broad ductus bursae with a partially spined sclerite.