Author: (Hübner, 1799)
Acorn moth
Chestnut fruit tortrix
Species Overview:
Adult: 14-22 mm wingspan; forewing ground colour grey or whitish grey; basal patch indistinct; terminal part of wing with a conspicuous blackish triangular pre-tornal marking, extending around ocellus to subapical area. This pre-tornal marking and the purplish ocellus distinguish Cydia splendana from Cydia fagiglandana. Hindwing fuscous, lighter basally and on inner margin.
Egg: about 150-200 eggs are deposited singly on the upper or underside of the leaves, usually along a vein and always in the vicinity of the fruit [Cydia splendana egg ].
Larva: 13-15 mm; head light yellowish brown; prothoracic plate paler, weakly sclerotized; abdomen greyish green or yellowish white, sometimes tinged with purplish grey posteriorly; pinacula concolorous with integument; anal plate weakly sclerotized, yellowish white, faintly mottled with brown; anal comb present. Prolegs of third to sixth abdominal segments presenting 14 to 21 microscopic hooks (crochets) in a circumference. Anal proleg with only 7 to 9 crochets [C. splendana larva 1 ].
Pupa: 9-10 mm long, brown; two transversal series of short stout spines present on second to seventh abdominal tergites, and only one series on eighth to tenth. Usually spun up in a tough, brown silken cocoon (hibernaculum) in the earth (5 to 8 cm under the soil surface) or amongst litter, but sometimes under moss or in a crevice in the bark of the tree and very occasionally in old Cynipid or other galls.
Taxonomic Description:
Male:
Cydia splendana male
Cydia splendana adults
External characters: 14-22 mm wingspan; forewing ground colour white or greyish white, suffused with grey and sparsely strigulated with brown, the whole wing including fasciate markings finely irrorate (tips of scales) with pale yellow-ochreous, producing a pronounced farinose effect, costa strigulated with black-brown, most strongly in apical half, the interspaces producing two long plumbeous striae, edged with yellow-ochreous, and sometimes one or two shorter striae; fasciate markings grey-brown with a black admixture; basal and sub-basal fasciae forming an indistinct basal patch, its outer edge somewhat irregular, acutely angulated medially and sometimes produced; median fascia narrow, outward-oblique on costa and diffusely edged with ochreous, obsolescent or obsolete dorsally; a well-developed, conspicuous, blackish triangular pre-tornal marking extending around ocellus to subapical area; ocellus large, containing four or five black dashes and edged laterally with metallic purplish plumbeous striae, the inner stria being thickest; an admixture of black above ocellus often forming striae and extending into subapical area; cilia concolorous with wing basally, otherwise grey, with an indistinct dark brown sub-basal line irrorate with white and sometimes interrupted subapically. Hindwing fuscous, lighter basally and on inner margin; cilia grey, with a fuscous sub-basal line (Bradley et al., 1979).
male genitalia C. splendana
Genitalia: Uncus and socii absent. Ventral margin of valva with slight notch; costal margin of valva curved; cucullus elongated. Sclerotized ridge across neck of valva extending from ventral angle of cucullus and merging into margin of basal opening, below its apex. Entire surface between ridge and basal opening covered with dense bristles. Aedeagus G-shaped.
Female:
External characters: Similar to male.
female genitalia C. splendana
detail f. gen. C. splendana
Genitalia: Sterigma with distinct contours, consisting of two regions which differ in structure and are separated by a transverse groove; anterior region oblong, smooth; distal region inversely trapezoidal, covered with theca of scales. Lateral margins of 7th sternite distinct. Papilla analis narrow. Ductus seminalis originates close to corpus bursae, the latter with two signa. Small sclerites present in ductus bursae.
Variation:
Minor variation is found in the forewing colouration and markings; in well-marked specimens the markings contrast with the light ground colour. A dark form occurs with the markings obliterated except the pre-tornal marking and ocellus (Bradley et al., 1979).
Biology
C. splendana larva 2
Cydia splendana is a univoltine species. The flight period is in June to July (Central Europe) or in August to September (Southern Europe and Hungary). The biological activity of Cydia splendana is synchronized with ripening and natural fall of fruits. During the day adults remain inactive under the leaves, branches and trunk, being difficult to spot. The swarming starts at dusk. It is most intensive during the hours before midnight. The males live 10-12 days, maximally 21 days, without any food supply. Female lifespan shorter than males. They start to lay their eggs 24 hours after mating. The average fecundity is 60 eggs and egg-laying extends for a period of 10 days. The eggs are deposited singly on the young fruits, in case of Castanea sativa mainly on the veins of leaves near fruit. Neither leaf side is favoured. The larvae hatch after 10-15 days, bore into the fruits (they never feed on the leaves), and eat these more or less empty, filling them with faeces. The coexistence of several larvae of this species on the same fruit is extremely rare due to larval intraspecific competition. The larva can complete its development using only one fruit. Externally the fruits do not appear to be damaged. Infested fruits drop prematurely. They are left by the full-grown larvae before the end of November. The larva undergoes 5 larval stages during a period of 35-45 days. Full-grown larvae overwinter inside a cocoon in bark crevices or in the soil at a depth of 5-10 cm. The maximum duration of winter diapause (at 17°C) is of 144 days; and the minimum (at 20°C) 96 days. Pupation takes place in the next spring (May to June in Madeira). The pupal stage lasts 2-4 weeks (Bogenschütz, 1991; Aguiar, p.c.).
Host plants:
The larvae feed inside the fruits of Castanea and Quercus (preferred), and also those of Fagus and Juglans.
Damage:
C. splendana damage 1
C. splendana damage 2
The larvae bore into the fruits, eat these more or less empty and fill them with faeces. Infested fruits drop prematurely. The economic damage is great, in particular to Castanea sativa. If the larva is not fully grown when the nuts are harvested, it will continue its development inside the nuts in the place of storage.
Distribution:
Europe to Asia Minor, Northern Iran, Russia (Ural Mountains); Madeira.
In Southern Europe, an aberration is found (ab. reaumurana Heinrich), mainly on Castanea sativa.
Pheromone:
E 8Z 10-12Ac : 0.08 *
E 8E 10-12Ac : 0.01 *
E 8Z 10-12OH : 0.01
E 9-12Ac : 0.01
12Ac : 0.14
12OH : 0.01
14Ac : 0.07
16Ac : 0.01
18Ac : 0.04
Components marked with * are involved in attraction (Witzgall et al., 1996b).
or
E 8E 10-12Ac : 9
E 8E 10-12Al : 1
(Frérot et al., 1995)
Parasitoids:
Itoplectis maculator (Fabricius) (Ichneumonidae)
Pristomerus vulnerator (Panzer) (Ichneumonidae)
Epirus ventricosus Tschek (Ichneumonidae)
Ascogaster quadridentata (Braconidae)
Phancrotoma dentata (Panzer) (Braconidae)
Microdus tumidulus Nees (Braconidae)
Trichogramma sp. (Trichogrammatidae)
Elachertus sp. (Eulophidae)
Bessa selects (Meigen) (Tachinidae)
Zenillea roseanae (Brauer and Bergenstamm) (Tachinidae)
Pathogens:
Paecilomyces farinosus (Holm. Gray)