Sand-verbena moth (Copablepharon fuscum) COSEWIC assessment and status report: chapter 2

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Species Information

The Sand-verbena Moth (Copablepharon fuscum) is a noctuid moth. It was described in 1996 from specimens collected near Sidney, B.C. and Whidbey Island, Washington. Although the species was recently described, its specific habitat requirements and apparently poor dispersal abilities indicate that it was not recently introduced to Canada. Adults are dark to golden brown with distinctive black and pale yellow forewing lines. There are no superficially similar moth species in British Columbia, and the Sand-verbena Moth is the only species of Copablepharon found west of the Cascade Mountains. Most species in the genus are found in arid, sandy or dune environments.

Distribution

The Sand-verbena Moth has been recorded from eight sites globally. Three occurrences are in Canada in the Strait of Georgia region of southwestern British Columbia. Five occurrences are in the Puget Sound region of Washington. Each location is believed to encompass one population. The most northern occurrence is in the Comox area in B.C. and the most southern is near Port Townsend, Washington. Populations are spatially isolated.

Habitat

The Sand-verbena Moth occurs in association with its host-plant, yellow sand-verbena, in spits, dunes and other sand-dominated coastal sites. It has consistently been found in close spatial association with large, dense patches of yellow sand-verbena. The Sand-verbena Moth and the yellow sand-verbena appear to have a parasite/host relationship. The yellow sand-verbena is dependent on open sand habitats and declines in vigour where competition from other vascular plants and bryophytes occurs.

Biology

The Sand-verbena Moth is dependent on the yellow sand-verbena for all phases of its lifecycle. Adult moths fly once per year between mid-May and early July during dusk and early evening. They feed on the nectar of yellow sand-verbena flowers. Mating peaks in mid-June. Eggs are laid singly or in groups on yellow sand-verbena leaves and flowers. Larvae feed nocturnally on yellow sand-verbena during July and August before a period of fall and winter dormancy. Pupation occurs in late April and May.

Population Sizes and Trends

There is no quantitative information on population sizes and trends for the Sand-verbena Moth. Changes in the distribution and abundance of yellow sand-verbena may be useful in inferring Sand-verbena Moth population trends. This extrapolation relies on the assumption that Sand-verbena Moth population size is related to the quantity and quality of yellow sand-verbena. Occurrences of yellow sand-verbena in British Columbia are generally stable. However, the size of yellow sand-verbena populations in many sites has likely declined substantially in the past 50 years because of vegetation changes.

Limiting Factors and Threats

The primary threat to the Sand-verbena Moth is the reduction in the quantity and quality of host-plant resources as a result of loss or change to open sand habitats. This is primarily caused by vegetation stabilization. Stabilization occurs as a result of natural succession in sand-dominated coastal sites. However, anthropogenic impacts, particularly exotic species invasion, have increased the rate of successional change. Direct disturbance from human development and recreational use are considered secondary threats. Other potential threats include the use of Btk, a pest control product that was developed to control moth and butterfly pests, and climate change, which could eliminate habitat through rising sea-level.

Special Significance of the Species

The Sand-verbena Moth is endemic to coastal sites in the Strait of Georgia region of British Columbia and adjacent areas in the Puget Sound region of Washington. It is a monophagous species that relies exclusively on yellow sand-verbena, a regionally rare plant species of coastal dunes and beaches, for food and reproduction. While this type of parasite/host relationship is not unique in moths, the habitat specialization of both species increases its conservation significance. It may also mean that the Sand-verbena Moth is not resilient to anthropogenic or stochastic change.

Existing Protection or Other Status Designations

No national, provincial, or state jurisdictions have designated the protection status of the Sand-verbena Moth. It is not listed in the BC Conservation Data Centre’s database or in the international conservation database maintained by NatureServe.

The host-plant, yellow sand-verbena, is designated by the BC Conservation Data Centre as vulnerable, which indicates it is sensitive to human activities or natural events. It is not listed by the Washington Natural Heritage Program. Dune plant communities were recently designated by the BC Conservation Data Centre as endangered/threatened, which indicates they are critically imperiled or imperiled. They are included under the plant association “Carex macrocephala Herbaceous Vegetation”.