Author: (Denis and Schiffermüller, 1775)
Fruittree tortrix
Rhomboid tortrix moth
Species Overview:
Adult: 13-21 mm wingspan; forewings with a subfalcate tip, varying from dark reddish-brown to greyish-brown or ochreous, with darker markings, a reticulate pattern and, sometimes, a distinct central scale tuft; the median fascia is comparatively conspicuous. Hindwings whitish-grey to brownish-grey, greyer in females. A very variable species.
Egg: 0.8 x 0.5 mm, flat and oval, yellow-green; deposited singly or in small batches on the bark of the branches or trunk of the food plant.
Larva: 12-14 mm long; head and prothoracic plate black, towards maturity changing to brown or yellow-brown or prothoracic plate sometimes changing to green; abdomen light green or yellowish green; pinacula paler than integument; anal plate green; anal comb present, yellowish; thoracic legs black [Acleris rhombana larva].
Pupa: 8-9 mm, reddish brown or dark brown, wings paler; cremaster short and broad, with obtuse corners behind, eight slender cremaster bristles (no hooks); no anal bristles or hook. In a silken cocoon in the larval habitation or between spun leaves of the food plant or in the soil [details pupa A. rhombana ].
Taxonomic Description:
Male:
Acleris rhombana adults 1
Acleris rhombana adults 2
External characters: head, thorax and antenna dark brown; abdomen brownish-grey. Forewing slightly expanding distally; costa bent outwards in basal third; apex of forewing subfalcate; termen sinuate, oblique. Ground colour varying from dark reddish-brown to greyish-brown or ochreous (see 'variation'). A common form: ground colour dark ferruginous brown, variably suffused with fuscous, indistinctly strigulated with ferruginous, veins lined with fuscous and combining with strigulation to form a reticulate pattern; markings reduced, dark fuscous-brown; basal and sub-basal fasciae diffuse, often discernible only on costa; median fascia narrow, comparatively conspicuous, angulate outwards above and inwards below middle, narrowing and often obsolescent towards dorsum; discocellular scale-tuft moderately developed when present; pre-apical spot small, diffuse, usually shallowly excised on costa; cilia on costa before apex ferruginous, grey along termen except apices of those in upper half which are white, a rather conspicuous black sub-basal line, often edged with plumbeous inwardly. Hindwing whitish grey to brownish-grey, indistinctly strigulated with grey; cilia whitish grey, with a dark grey sub-basal line around apex, obsolescent towards tornus (Bradley et al., 1973; Razowski, 1984).
male gen. A. rhombana
Genitalia: Tegumen small with delicate posterior lobes; socii long, slightly broader anteriorly than posteriorly, base of socius situated medially. Valva broad; sacculus strong, broad anteriorly, strongly concave beyond base ventrally, then curved outwards to broad spined termination; brachiola triangular; an additional weakly sclerotized pocket in posterior part of valva ventrally to brachiola. Aedeagus elongate, bent; four long cornuti present in vesica.
Female:
External characters: Forewing not expanding distally; apex of forewing more prominent, costa shallowly concave beyond middle; termen less oblique than in male. Hindwing greyer than in males.
female gen. A. rhombana
Genitalia: Apophyses long; sterigma with fairy long antero-lateral projections which are pointed terminally; antrum weakly sclerotized, broad, ductus bursae proportionately long, provided with elongate median and small subterminal sclerites.
Variation:
Acleris rhombana is a very variable species. A common form occurs in which the forewing markings are relatively conspicuous, the ground colour being light ochreous-yellow; in this form the median fascia is produced medially and joins the pre-apical spot. In another common form the markings are conspicuous, the ground colour is dark orange and strongly reticulate, but the median fascia is separate from the pre-apical spot which is usually small and in some specimens may be obsolete; the median fascia is often dilated and strong on the dorsum but weak on the costa. In another common form, the forewing ground colour varies from light to dark ochreous-brown, and the median fascia is usually well developed only in the costal half. Occasionally specimens are found with a median fascia that is well developed only in the costal half, and with the ground colour light ochreous-yellow and strongly reticulate. Least common is a dark form in which the forewing ground colour is dark fuscous-brown with the markings obsolescent (Bradley et al., 1973).
Biology:
Eggs are laid singly or in small batches on the bark of trunks and branches of the food plant during late summer and early autumn, overwintering and hatching the following spring. Larvae then invade the opening buds. Later, they feed in webbed leaves, usually at the tips of young shoots. They may also feed on blossom trusses. Pupation takes place in June or early July, usually in a cocoon in the soil. The pupal stage is protracted, lasting for six to eight weeks or more. Moths fly from August to October, frequenting especially hedgerows in which hawthorn and blackthorn grow, and also on scrubby downland and in orchards. They often occur in numbers (Alford, 1995; Bradley et al., 1973).
Host plants:
Crataegus, Prunus (ornamental cherry, plum), Malus, Pyrus and Rosa ; also occasionally on Prunus laurocerasus, Corylus, Sorbus and Quercus.
Damage:
A. rhombana damage to plum
The young larvae eat into the buds of the food plant, later feeding externally and spinning the leaves, usually those of the terminal shoots, and flowerheads. Acleris rhombana is not an important fruit pest, since damage is mainly restricted to the loss or distortion of younger leaf tissue, with little or no effect on tree growth (Alford, 1995).
Distribution:
Northern and Central Europe to Asia Minor. Records from North America are doubtful.
Pheromone:
Pheromone unknown.
Attractantia:
E 11-14Ac : 8
Z 11-14Ac : 2 (Frérot et al., 1979b)
or
E 11-14Ac : 9
Z 11-14Ac : 1 (Voerman, 1979)
Parasitoids:
Derostenus sp. (Eulophidae)
Glypta pictipes (Ichneumonidae)
Campoplex mutabilis (Ichneumonidae)
Trichomma enecator (Ichneumonidae)
Meteorus confinis (Bracomidae)
Apanteles sp. (Bracomidae)
Nemorilla floralis (Tachinidae)
Acleris notana Donovan
Acleris notana Donovan (= tripunctana Hübner) has been recorded from Pyrus, Prunus and Quercus, Alnus, Betula, Myrica, Fagus, Populus and Rubus, but because of the confusion of this species with Acleris ferrugana Denis and Schiffermüller (= tripunctulana Haworth), it is doubtful whether these records are entirely correct.
Both species can be reliably separated from Acleris rhombana by examination of the genitalia. In Acleris rhombana, the male genitalia have the socii relatively long. Acleris notana can be separated from Acleris ferrugana by examining the aedeagus. In Acleris notana, the aedeagus has a small sclerite, from which a short projection extends, and the vesica contains two comparatively stout, unequal cornuti [male genitalia A. notana ]. In Acleris ferrugana the aedeagus has a very long and prong-like lateral projection on the right, and the vesica contains one needle-like cornutus [male genitalia A. ferrugana ].
Females can be distinguished by examining the ductus, sterigma and antrum. In Acleris rhombana, the ductus bursae is provided with an elongate median and a small subterminal sclerite and the sterigma has fairly long antero-lateral projections. In Acleris notana, the sterigma has long antero-lateral projections, and the antrum is weakly sclerotized, cylindrical and narrow [female gen. A. notana ]. In Acleris ferrugana the sterigma has short antro-lateral projections and the antrum is strongly sclerotized and dilated laterally [female gen. A. ferrugana ].
Note: Razowski, 1984, accidentally exchanged the drawings of both male and female genitalia of Acleris notana and Acleris ferrugana .