Rapid assessment of invertebrate fauna of the Kona Forest Unit of Hakalau National Wildlife Refuge.















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This report details a large, but preliminary, collection of insects from the Kona Forest Unit of the Hakalau National Wildlife Refuge. Visits to the Refuge were carried out by vehicle from July 1999 until October 2000 when the survey was interrupted by loss of road access to the Refuge. The purpose of this survey was to inventory endemic insect taxa likely to respond to future forest restoration efforts, including the removal of feral ungulates from the Refuge. Additionally, selected alien insect species were also collected. Before the inventory was undertaken, 296 historical species records were compiled for the South Kona region. Using this list and other summaries for the Island of Hawai‘i, nine groups of endemic insects were targeted, including 4 genera of beetles; pomace flies; yellow-faced bees; 2 genera of moths; and Hawaiian damselflies. These target groups were chosen because species richness within these taxa increases the opportunity for documenting changes in native insect communities as a consequence of resource management activities. Many of these groups also contain Fish and Wildlife Species of Concern or Candidate Endangered Species. Survey work was initiated over 750 m long contour transects at 500 m intervals between 762 m and 1,676 m elevation. A total of 1,683 specimen lots comprising a total of 9,330 individual specimens were collected and analyzed. Among alien invertebrates of concern that were detected, yellowjacket wasps were widely established in the refuge and their populations underwent seasonal outbreaks typical of other mesic forest populations on the island. Three scientific publications so far have directly resulted from the analysis of native insect taxa from the Refuge and specimen data has also contributed to one comprehensive taxonomic monograph. One interesting finding is the occurrence of the ‘ohe leafroller, Omiodes asaphombra, at light traps on the refuge. This endemic moth was once thought to be extinct and has only been found breeding on ‘ohe, or Joinvillea ascendens. This indigenous plant is very rare on the island of Hawaii and has not been recorded from the refuge or anywhere on the west side of the island. The most significant finding of this project was the discovery of a population of the rare picture-wing pomace fly, Drosophila heteroneura. Drosophila heteroneura is a Candidate Endangered Species found only on the Island of Hawai‘i. Images of the hammer-headed males of this pomace fly have frequently been used to illustrate the uniqueness of Hawai‘i’s insect fauna and D. heteroneura has been one of the most intensively researched native insects in the state. However, the fly now appears to be extirpated from all of its previously known historical range. The observations of D. heteroneura on the Refuge are the first observations of this species in the wild in approximately ten years. As of 1999, the Refuge supported the only known extant population of this unique Hawaiian picture-wing fly. It is recommended that management of the Kona Forest Unit to foster preservation of this and other rare Hawaiian insects should include suppression of alien yellowjacket wasps.







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