Aspila molesta

Status

ADVENTIVE

PORT INTERCEPT | DOMESTIC SURVEY

Taxonomy

Aspila molesta (Busck) (Tortricidae: Olethreutinae: Grapholitini)

Common names: oriental fruit moth

Note: Aspila molesta was formerly known as Grapholita molesta until recently (Hu et al. 2023Hu et al. 2023:
Hu, G.-L., Brown, J.W., Heikkilä, M., Aarvik, L., Mutanen, M. 2023. Molecular phylogeny, divergence time, biogeography and trends in host plant usage in the agriculturally important tortricid tribe Grapholitini (Lepidoptera: Tortricidae: Olethreutinae). Cladistics. 39(5): 359-381.). Komai (1999) provides a taxonomic history for the Grapholitini.

Adult Recognition

FWL: 5.0–6.5 mm

Forewings are dull grayish brown with a row of black dots near the apex and termen. The ocellus is obsolete. Males lack a forewing costal fold. Hindwings are dark brown.

Male genitalia are characterized by the absence of an uncus and elongate valvae with rounded cucullus and strongly constricted neck. Female genitalia are characterized by rectangular lateral extensions of the sterigma with sharply pointed posterolateral projections and two curved, thorn-like signa in the corpus bursae.

Larval Morphology

The following account is summarized from MacKay (1959)MacKay (1959):
MacKay, M. R. 1959. Larvae of the North American Olethreutidae (Lepidoptera). Canadian Entomologist, Supplement 10: 1-338..

Last instar larvae are approximately 10–12 mm in length with a pinkish abdomen and large pale pinacula. The head and prothoracic shield are yellowish brown. The anal shield is light brown without mottling. An anal comb is present with ca. 5 teeth. Early instars are assumed to be whitish with a black head and prothoracic shield.

Detailed figures of larval chaetotaxy are available in MacKay (1959)MacKay (1959):
MacKay, M. R. 1959. Larvae of the North American Olethreutidae (Lepidoptera). Canadian Entomologist, Supplement 10: 1-338..

Larvae may appear similar to those of many other species of Aspila, Grapholita and Cydia. Aspila pomonella larvae can be separated from A. molesta by the absence of an anal fork. Other species of Aspila cannot be reliably separated from A. molesta based solely on larval morphology.

Chen and Dorn (2009)Chen and Dorn (2009):
Chen, M. H., Dorn, S. 2009. Reliable and efficient discrimination of four internal fruit-feeding Cydia and Grapholita species (Lepidoptera: Tortricidae) by polymerase chain reaction-restriction fragment length polymorphism. Journal of Economic Entomology. 102: 2209-2216. provide a molecular assay to distinguish A. molesta larvae from similar species using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

Similar Species

Adults are similar to other species of Aspila, including A. funebrana, A. libertina, A. tenebrosana, and several others. A genitalic dissection may be necessary to confirm species identity, especially if individuals are recovered from sticky traps. Males of A. funebrana can be distinguished by the thornlike projection off the ventral margin of the valva, which is lacking in A. molesta. Gilligan et al. (2008)Gilligan et al. (2008):
Gilligan, T. M., Wright, D. J., Gibson, L. D. 2008. Olethreutine moths of the midwestern United States, an identification guide. Ohio Biological Survey, Columbus, Ohio. 334 pp. provide illustrations of male and female genitalia for many common Nearctic Aspila (then Grapholita). A key is also available here with photos of adults and male genitalia.

Synthetic pheromones are not species-specific, and A. molesta lures will attract other species of Aspila, including A. funebrana.

Distribution

Aspila molesta is thought to have originated in northwest China. The first North American records are from 1913 to 1915. It is currently widely distributed on all continents where stone fruit is grown.

Biology

The following account is summarized from Dustan (1960)Dustan (1960):
Dustan, G. G. 1960. The oriental fruit moth, Grapholitha molesta (Busck) (Lepidoptera: Olethreutidae) in Ontario. Proceedings of the Entomological Society of Ontario. 91: 215-227. and Rothschild and Vickers (1991)Rothschild and Vickers (1991):
Rothschild, G. H. L., Vickers, R. A. 1991. Biology, ecology and control of the oriental fruit moth, pp. 389-412. In : van der Geest, L. P. S., Evenhuis, H. H. (eds.), Tortricid pests, their biology, natural enemies and control. Elsevier, Amsterdam, The Netherlands..

Aspila molesta completes 3–7 annual generations; the exact number depends on temperature (latitude). In midwestern North America, adults are present from early May to late September. In southern locations, adults may be present year-round.

Females lay eggs singly on smooth surfaces of the host plant, which usually includes leaves, shoots, and twigs. Early instars tunnel into shoots or pedicels. Later instars continue feeding in shoots or tunnel into fruit. The final instar leaves the fruit or shoot and constructs a cocoon on the tree or in leaf litter. Larvae complete 4–5 instars. Overwintering occurs as a prepupa and pupation occurs in the spring for the overwintering generation.

Larval damage is characterized by dead and wilting shoots and injured fruit. Injured fruit may fall early and is more prone to secondary infection by fungus.

Aspila molesta is an important pest of stone fruit crops throughout the world. Most economic damage occurs in peach and nectarine, or when other fruit crops are grown adjacent to peach. In addition to the Rosaceae, larvae have been recorded feeding on plants in several families.

Plant Associations

View full screen host table here

Links

Additional photos and a distribution map of this species in North America are available at Moth Photographers Group.