Amorbia cuneanum

Status

NATIVE

PORT INTERCEPT | DOMESTIC SURVEY

Taxonomy

Amorbia cuneanum (Walsingham) (Tortricidae: Tortricinae: Sparganothini)

Common names: western avocado leafroller

Synonyms: adumbrana (Amorbia), essigana (Amorbia), synneurana (Amorbia)

Note: preliminary studies on the pheromone composition and COI sequence data suggests that A. cuneanum species may be two distinct species (Powell and Brown 2012Powell and Brown 2012:
Powell, J. A., Brown, J. W. 2012. Tortricoidea, Tortricidae (part): Tortricinae (part): Sparganothini and Atteriini. In: Hodges, R. W. (ed.). The Moths of North America, fascicle 8.1. Wedge Entomological Research Foundation, Washington, D.C., 230 pp.).

Adult Recognition

FWL: 10.0–14.5 mm (males); 13.5–17.5 mm (females)

Male forewing color varies from pale tan to rust to dark gray-brown. Many individuals have a dark costal spot that is a remnant of the median fascia or more well-defined transverse markings. Females have a more uniform rust to tan forewing with obscured marking. Males lack a forewing costal fold. A dorsal pit is present on the second abdominal segment and ocelli are absent.

Male genitalia are characterized by a long, thin uncus; large, setose socii; and large, membranous valvae. Female genitalia are characterized by a sterigma with well-developed lateral lobes and a band-like signum on the wall of the corpus bursae.

Larval Morphology

The following account is summarized from MacKay (1962a)MacKay (1962a):
MacKay, M. R. 1962a. Larvae of the North American Tortricinae (Lepidoptera: Tortricidae). Canadian Entomologist, Supplement 28: 1-182. and Powell and Brown (2012)Powell and Brown (2012):
Powell, J. A., Brown, J. W. 2012. Tortricoidea, Tortricidae (part): Tortricinae (part): Sparganothini and Atteriini. In: Hodges, R. W. (ed.). The Moths of North America, fascicle 8.1. Wedge Entomological Research Foundation, Washington, D.C., 230 pp..

Mature larvae approximately 25 mm in length; width of head 2.1–2.9 mm; head yellowish brown; prothoracic shield concolorous but with dark brown lateral bands; legs brown; body pale yellow or green; SV group on A1, 2, 7, 8, 9 numbering 3:3:3:2:2. 

For more information on Amorbia larvae, including a more detailed account of chaetotaxy, please consult the fact sheet and keys on LepIntercept.

Similar Species

Few other North American tortricids are similar in size or appearance to Amorbia, and this is one of the few tortricid genera in which the adults lack ocelli. The three Amorbia species treated on this site can be separated by the combination of two characters: forewing color and number of median dorsal pits on the abdomen. Amorbia humerosana is gray, oftentimes with a brownish band on the inner margin and has a single median dorsal pit on the second abdominal segment. Both A. emigratella and A. cuneanum are yellow-orange or yellow-brown, but A. cuneanum has a median dorsal pit on segment 2 whereas A. emigratella has median dorsal pits on segments 2–6. 

The lateral bands on the prothoracic shield can be used to distinguish late instar Amorbia larvae from those of many other tortricids. Early instars lack the distinctive dark bands, and morphological identification of early instar larvae may be difficult or impossible.

Distribution

Amorbia cuneanum is found along the Pacific Coast from southwestern Canada south to Baja California and east to Arizona and Idaho. Isolated records exist from Montana and Utah. 

Biology

The following account is summarized from Phillips-Rodríguez and Powell (2007)Phillips-Rodríguez and Powell (2007):
Phillips-Rodríguez, E., Powell, J. A. 2007. Phylogenetic relationships, systematics, and biology of the species of Amorbia Clemens (Lepidoptera: Tortricidae: Sparganothini). Zootaxa. 1670: 1-109. and Powell and Brown (2012)Powell and Brown (2012):
Powell, J. A., Brown, J. W. 2012. Tortricoidea, Tortricidae (part): Tortricinae (part): Sparganothini and Atteriini. In: Hodges, R. W. (ed.). The Moths of North America, fascicle 8.1. Wedge Entomological Research Foundation, Washington, D.C., 230 pp..

Amorbia cuneanum completes two generations per year in northern California, where adults are present in May through June and again in October. In southern California, A. cuneanum is multivoltine and adults have been recorded every month of the year.

Larvae feed on leaves, skeletonizing them in early instars and consuming the entire leaf in later instars. Larvae also web leaves to fruit and feed on the skin of fruit in a cluster, sometimes causing economic damage.

Amorbia cuneanum can be a significant pest of avocado (Persea americana) in California. Its putative synonym, A. essigana Busck, was described as an avocado pest in southern California in 1929, and it is possible that avocado-feeding populations may represent this "pheromone race."

Amorbia cuneanum feeds on plants in several families although it is usually recognized as a pest of avocado.

Plant Associations

View full screen host table here

Links

Additional photos and distribution map in North America available at Moth Photographers Group.