Author: (Clerck, 1759)
Fruitlet-mining tortrix
Species Overview:
Adult: 9-12 mm wingspan; forewings dark metallic purplish with a ferruginous-orange tip; hindwings fuscous, in males with an elongate patch of blackish scales along vein A 1 towards termen.
Egg: 0.7 x 0.6 mm; flat and oval; translucent whitish; deposited singly on the underside of a leaf of the food plant near an inflorescence.
Larva: 5-6 mm long; rather plump; head brown (black in early instars), prothoracic plate brown, sometimes yellowish brown with dark mottling; abdomen cream-white; pinacula pale brown, moderately conspicuous; anal plate greyish brown.
Pupa: 4-5 mm long; light brown; in a silken cocoon in bark or dead wood, or sometimes in the soil.
Taxonomic Description:
Male:
Pammene rhediella adult 1
Pammene rhediella adult 2
Pammene rhediella adults
External characters: 9-12 mm wingspan. Forewing ground colour cream-white, whole of basal area to median fascia overlaid with dark purplish brown, distal area overlaid with ferruginous-orange except interspaces between rather indistinct brown costal strigulae, the interspaces producing obscure violet metallic striae; basal and sub-basal fasciae obsolete; median fascia deep chestnut-brown, moderately distinct or obscure, confluent dorsally with pre-tornal marking, bordered distally by a metallic stria from costa; ocellus obsolescent, indicated by metallic striae; cilia greyish ochreous, with a dark brown or blackish basal line; hindwing fuscous or dark fuscous, with an elongate patch of blackish scales along vein A 1 towards termen; cilia cream-white, with brown basal line (Bradley et al., 1979).
male gen. Pammene rhediella
Genitalia: Cucullus broad; ventral margin of valva with small process; cornuti longer than diameter of aedeagus but shorter than width of neck of valva.
Female:
External characters: Similar to male but usually larger and lacking the patch of blackish scales in the vannal area of the hindwing.
female gen. Pammene rhediella
Genitalia: Cingulum more or less conical, narrowing in direction of ostium. Corpus bursae with two signa. Signa large; diameter of basal plate equal to diameter of cingulum.
Biology:
Pammene rhediella is an univoltine species. The adult is active in daylight and is on wing at blossom time (May-June). Infestation therefore commences very early. Eggs are laid singly on the undersurface of leaves near flowers or clusters of young fruitlets. They hatch in about two weeks. The larvae then attack the fruitlets, although they may firstly feed on the stamens and calyxes of the flowers, webbing them together with silk. If isolated fruitlets are attacked, the larva attaches a leaf to the surface as a shelter. Larvae feed within the fruitlets until late June or early July and then, on becoming full-grown, wander away to spin cocoons under loose bark on the trunks or larger branches. Here, they overwinter, pupating in the spring (Dickler, 1991; Alford, 1984).
Host plants:
Normally associated with hawthorn (Crataegus), but sometimes an important pest of cultivated apple (Malus) and, less frequently, plum (Prunus domestica), pear (Pyrus) and cherry (Prunus cerases). Also known from Swida sanguinea and Sorbus torminalis.
Damage:
Apple:
damaged apple shoot
P. rhediella damage on apple
P. rhediella tunneling in apple
P. rhediella damage on cherries
Fruitlets are usually attacked when about 2 cm in diameter. Initially, the young larvae feed within the eye (calyx), forming a strong, external web in which brown frass soon accumulates. Feeding also occurs around the stalk and at the sides where adjacent fruits are touching. One larva may damage several fruitlets in a cluster. The stalk of an attacked fruitlet is often loosened following the loss of flesh around the base; such fruitlets, and those with major flesh injury, will drop prematurely but they sometimes remain in situ, held by the web. The main gallery formed in the flesh of a bored fruit characteristically runs from the stalk to the core and then outwards to the shoulder; the tunnel is usually no more than 2 mm wide, virtually frass-free and is often lined with a whitish, sugary secretion upon which yeasts develop. Superficially damaged fruitlets often possess holes in the sides, each up to 2 mm deep; these eventually heal and at maturity the apples bear one or more irregular pits with corky scar tissue at their bases. Such fruits also tend to become misshapen (Alford, 1984).
Plum:
Larvae form galleries in the flesh of fruitlets, causing considerable weeping of gum which then accumulates in the surrounding webbing. As on apple, very little frass remains within in larval gallery, and attacked fruitlets either drop prematurely or, if superficially damaged, survive to maturity with the wounds healed over (Alford, 1984).
Distribution:
Europe to Asia Minor and Central Asia.
Pheromone:
Pheromone unknown.
Attractantia:
Z 8E 10-12OH
(Guerin et al., 1983)