endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (<100-250 square km (less than about 40-100 square miles)) Restricted to Waianae Mountain Range on the island of Oahu.
Comments: Restricted to the natural distribution of its host plant, Urera glabra. The larvae of D. aglaia develop in the decomposing bark and stem of U. glabra, which is scattered throughout slopes and valley bottoms in mesic and wet forest habitat on Oahu. In the Waianae Mountains on the west side of Oahu, this tree occurs infrequently in mesic forest (USFWS, 2006a). Adults can be collected using baits such as fermenting banana or mushroom.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 5
Comments: Drosophila aglaia is historically known from five localities in the Waianae Mountains of Oahu. During 50 survey dates between 1966 and 1990, 28 individuals were observed (Kaneshiro in litt., 2005a in USFWS, 2006a). The 5 sites include: One lowland mesic Diospyros sp. and Metrosideros sp. (ohia) forest site in Makaleha Valley; two lowland mesic Acacia koa (koa) and ohia forest sites at Peacock Flats (Kapuahikahi Gulch) and Palikea; one site in diverse mesic forest at Puu Kaua; and a lowland, dry to mesic forest site at Puu Pane (K. Kaneshiro, in litt., 2005a in USFWS, 2006a).
The last observation of this species occurred in 1997 during the last survey of the Palikea site. The species has not been observed at the other four historic sites since 1970 or 1971 despite subsequent surveys. However, two of the sites (Kapuahikahi Gulch and Makaleha Valley) have not been surveyed since the 1970s and one site, Puu Pane, was surveyed only once again in 1991 (K. Kaneshiro, in litt., 2005a in USFWS, 2006a). It is not possible to estimate current population levels without further surveys.
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G1 - Critically Imperiled
Reasons: This species is known from five mesic native forest localities in the Waianae Mountains of Oahu. The last observation of this species occurred in 1997 at Palikea and it has not been observed at the other four historical sites since 1970 or 1971 despite subsequent surveys. However, three of the sites have not been surveyed since the 1970s and the fourth site, Puu Pane, was surveyed only once again in 1991 (USFWS, 2006a). D. aglaia has continued to experience a significant amount of habitat loss and degradation throughout its range and the host plant species is rare or sparsely distributed and threatened by ongoing habitat degradation. More efforts are needed to relocate this species and as of now, it is in danger of extinction.
Date Listed: 05/09/2006
Lead Region: Pacific Region (Region 1)
Population location: Entire
Listing status: E
For most current information and documents related to the conservation status and management of Drosophila aglaia , see its USFWS Species Profile
Global Short Term Trend: Decline of 10-30%
Degree of Threat: Very high - high
Comments: Species of Drosophila on the island of Oahu are threatened by the following (from USFWS, 2006a; USFWS, 2006b; USFWS, 2006c and sources cited therein):
(1) Habitat degradation by introduced ungulates, such as pigs and goats. Feral pigs and goats have dramatically altered the native vegetation by feeding upon its host plants, and contributing to erosion on some steeper slopes where the host plants occur. They destroy host plant seedlings and habitat by the trampling of their hooves and through the spread of seeds of nonnative plants. On Oahu, goat populations are increasing and spreading in the dry upper slopes of the Waianae Mountains, becoming an even greater threat to the native habitat. Goats directly feed upon the host plant of D. aglaia.
(2) The invasion of several nonative plants, particularly Psidium cattleianum, Lantana camara, Melinis minutiflora, Schinus terebinthifolius, and Clidemia hirta, further contributes to the degradation of native forests and the host plants of picture-wing flies. Also, M. minutiflora has the ability to spread wildlfire.
(4) Predation by nonnative ants and wasps. At least 44 species of ants are known to be established on the Hawaiian Islands and 4 particularly aggressive ant species have severely affected the native insect fauna. And while there is no documentation that conclusively ties the decrease in picture-wing fly observations at historical sites with the establishment of yellow-jacket wasps within their habitats, the concurrent arrival of wasps and decline of picture-wing fly observations for all 11 picture-wing flies on all islands (Kauai, Oahu, Maui, Molokai, and Hawaii) suggests that the wasps may have played a significant role in the decline of some picture-wing fly populations.
(7) Competition at the larval stage from nonnative tipulid flies.
Furthermore, the host plant species for D. aglaia, Urera glabra, is rare or sparsely distributed and threatened by ongoing habitat degradation.
Also, Drosophila aglaia occurs at Puu Pane, located above the United States Army's Schofield Barracks Military Reservation. The gently sloping lands below Puu Pane are used as a live firing range, and ordinance-induced fires have been a common occurrence in this area (U.S. Army, in litt., 2005 in USFWS 2006a). Although the the U.S. Army recently completed and is implementing an Integrated Wildfire Management Plan to reduce the risk and improve control of training-related fires in this area, wildfires caused by the Army and other sources, and which may escape control, remain a potential threat to this species and its habitat located in gullies up-slope from the firing ranges (Kaneshiro and Kaneshiro 1995; U.S. Army, in litt., 2005 in USFWS, 2006a).
Biological Research Needs: A better understanding of distribution and population size and distribution of host plant is needed. Assess genetic variability in extant population with long term monitoring using modern molecular tools (DNA sequencing).
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