Microlepidoptera on Solanaceae

Phthorimaea operculella

Name

Phthorimaea operculella (Zeller, 1873)

Common names: potato tuber moth, potato tuberworm; tobacco splitworm

Original combination: Gelechia operculella Zeller, 1873

Synonyms:

  • Gelechia terrella Walker, 1864
  • Bryotropha solanella Boisduval, 1874
  • Gelechia tabacella Ragonot, 1879
  • Gelechia sedata Butler, 1880
  • Phthorimaea argentinae Povolný, 1989
  • Gelechia piscipellis Howard, 1897, (nec Zeller, 1873), misidentification
  • Phthorimaea epicentra auctt., (nec Meyrick, 1909), misidentification

Classification: Gelechioidea: Gelechiidae: Gelechiinae: Gnorimoschemini

Adult recognition

Adults are about 5.5-7.2 mm in forewing length. They are variably light brown and gray. The forewing fold has light yellow scales between grayish-black spots, and the apical area has many white-based black scales. The labial palpus is upturned. The hindwing is gray, trapezoidal, and modified with a hair-pencil from the base of the costa in males. The abdomen is gray with two lateral hair-pencils near the apex in males. The male genitalia have an oval gnathos, and the valva has a dilated, curved apex. Females have segment eight with a distinct transverse zone of foam-like texture in the medial part of the sternum, a broadly funnel-shaped antrum leading into a very short ductus bursae, and a small sickle-shaped signum.

Immature stages

The prothoracic shield of P. operculella lacks a dark band on the posterior margin and the abdominal SD pinaculum is about as large as the spiracle of the corresponding segment. In addition, the line joining setae L1 and S2 runs posterior to stemma one, all thoracic legs are pigmented, SD1 on A9 is hairlike, and the three L setae of A9 are in a triangular arrangement.

PDF - Dichotomous key to Gelechiid larvae

Similar species

This species is superficially similar to Scrobipalpa aptatella (Walker) and S. ergasima (Meyrick), but it differs by the forewing having the light brown fold with light yellow scales between grayish-black spots, the spots in the middle of the wing indistinct, the male uncus broadly rounded, and the gnathos not hook-shaped.

As with many Gelechioidea, no one larval character of P. operculella is totally diagnostic; this species is recognized by the combination of characters. Unlike Keiferia lycopersicella and Tuta absoluta, the prothoracic shield is uniformly colored. The pigmented legs of P. operculella are also unusual. The trisetose L group on A9 separates P. operculella from Symmetrischema tangolias and Tecia solanivora which have a bisetose L group on that segment.

Behavior

Eggs are laid on the hairy underside of leaves. Larvae mine leaves and stems in various solanaceous plants, but they act primarily as tuber borers in potato and as leaf miners in tobacco. When they are fully grown, larvae pupate in the soil near the base of host-plants, in leaf remains, or in some other suitably sheltered site. Pupae are enclosed in a white silken cocoon. They are multivoltine occurring about five or six generations per year.

Distribution

Native to South America, introduced worldwide. USA (widely in the United States, particularly California and southeastern states north to Maryland). Throughout the New World. New Zealand, South Africa.

Hosts

Nicotiana glauca Graham (Tree tobacco)

Nicotiana tabacum L. (Cultivated tobacco)

Solanum dulcamara L. (Climbing nightshade)

Solanum lycopersicum L. (Garden tomato)

Solanum melongena L. (Eggplant)

Solanum nigrum L. (Black nightshade)

Solanum tuberosum L. (Irish potato)

Comments

This species occurs in almost all potato production areas in the world. It also feeds on other Solanaceae including important weeds in potato fields (e.g., black nightshade, Solanum nigrum L.).

Literature

Carter, 1984.

Hilje, 1994.

Huemer and Karsholt, 2010.

MacKay, 1972.

Rondon, 2010.

Weisman, 1986.

Zeller, 1873.