Author: (Walker, 1863)
Hemp moth
Species Overview:
Adult: 10-14 mm wingspan; forewing greyish ochreous, more reddish-ochreous on apical half of costa; dorsum with yellowish semi-square patch, edged by brown streaks and divided by three parallel brown lines; costal strigulae brown; fourth and fifth strigula from termen give rise to pale greyish oblique striae towards tornus. Hindwing brown-grey.
Egg: deposited singly on the stalk and leaves of the host plant.
Larva: head yellowish brown, with black pigmentation in region of stemmata; prothoracic and anal shields and thoracic legs pale, with occasionally some slight brownish pattern on shields; body colour pale; anal fork absent.
Pupa: in the stalk, on curled leaves, in cocoons at the base of the stalk and on the surface of the soil.
Taxonomic Description:
Male:
Grapholita delineana adult 1
Grapholita delineana adult 2
External characters: 10-14 mm wingspan. Head yellowish, thorax brown-grey, abdomen greyish brown. Forewing greyish ochreous, more reddish-ochreous on apical half of costa; apex with blackish spot; dorsum with yellowish semi-square patch, edged by brown streaks and divided by three parallel brown lines; above this a distinct longitudinal dark streak; costa with about six brown strigulae and some additional weak strigulae anterior to these; fourth and fifth strigulae from termen give rise to pale greyish oblique striae towards tornus; cilia greyish-yellowish with a fine sub-basal line. Hindwing brown-grey; cilia whitish with brownish-grey sub-basal line.
male gen. G. delineana (aedeagus and valva)
Genitalia: Tegumen without bristles. Aedeagus tapered unevenly. Notch in ventral margin of valva evenly rounded, symmetrical. Apex of sacculus protruding at angle.
Female:
External characters: Similar to male.
female gen. G. delineana
Genitalia: Seventh sternite with a ventro-lateral pair of sclerotized patches near anterior edge. Cingulum long and large. Signa unequal in size and shape, the smaller one being spinescent.
Biology:
The species has two generations per year, plus a partial third. It overwinters in the larval stage, on the remains of hemp roots in the soil at a depth of 5 cm, on the stalks, at the threshing sites and where the straw and seeds are kept. The adults of the overwintered generation begin to emerge in the beginning of May. Females lay up to 500 eggs each, singly on the stalk and leaves. On hatching, the larvae skeletonize the leaves and subsequently penetrate the petioles and stalks. The larvae later attack the inflorescences and damage the seeds. Pupation takes place in the stalk, on curled leaves, in a cocoon at the base of the stalk and on the surface of the soil. The egg, larval and pupal stages last 7-10, 22-29 and 10-21 days respectively (Sandru, 1972; Shutova and Strygina, 1969).
Host plants:
Cannabis sativa, Humulus japonicus, Humulus lupulus.
Damage:
This species is a pest of fiber hemp production.
In the Ukraine, this species has been known to be responsible for 30-40 % loss of hemp seed, up to 100 % damage to the stalks and severe impairment of fibre quality.
Larvae feed in stems, inflorescences and developing seeds (Shutova and Strygina, 1969; Miller, 1982).
Distribution:
Germany, Poland, France, Italy, Greece, Austria, Czech Republic, Slovakia, Romania, Hungary, Ukraine, Soviet Armenia, Moldavia, Russia, China, Korea, Japan; also recorded from North America.
Pheromone:
Pheromone unknown.
Parasitoids:
The dominant parasites of this species in Hungary (in 1978) were Scambus spp., they made up 80% of the parasite complex. Parasitism averaged 30% (Scheibelreiter, 1978).
In Romania, experiments have shown that the egg parasite Trichogramma evanescens Westw. can considerably reduce populations of Grapholita delineana. The species is not a natural host of Grapholita delineana (Peteanu, 1970; Peteanu, 1980)
In China, the braconid Phanerotoma planifrons is record as a parasitoid of Grapholita delineana, the rate of parasitism being 20-45% (Wang and Rong, 1992).