Baseline survey of arthropods (insects and relatives) of Kahului Airport environs, Maui, Hawaii. Final report

A survey of the arthropod fauna occurring within the Kahului Airport Environs at Kahului, Maui, was conducted between August 1999 and November 2000 to fulfill requirements of the Federal- State Alien Species Action Plan for the Kahului Airport (pursuant to the Memorandum of Understanding signed August 1998). The main objective of the survey was to develop a list of species and set of authoritatively determined specimens of the arthropods collected. The survey was comprehensive, but a few groups (vertebrate parasites, truly aquatic species, and small cryptic species) were excluded. The list and voucher specimens are to provide quarantine officials with information to improve quarantine procedures at the airport, as well as facilitate rapid response efforts that deal with newly recognized harmful alien or non-indigenous species. In addition, we determined the status of the recently listed federally endangered species, Blackburn's sphinx moth (Manduca blackburni) within the Airport Environs and herein make recommendations on its protective management. A total of 624 species were collected during the survey, of which 584, or 94%, could be identified to species. These include 473 adventive species, 47 purposefully introduced species, 59 endemic species, eight indigenous species, and 37 species whose status is unknown. The majority were insects with the beetles, flies, moths, and wasps each represented by 100 species or more. A significant percentage of both the native and alien species represent additions to the known fauna of Maui. Among the 520 recognized alien species, 328 species (63%) were previously reported from Maui; 158 species (30%) were previously known from another island and here reported from Maui for the first time; and 34 species (7%) are new records for the state. At least 23 of the 67 identified native species (34%) represent new island records for Maui, and ten of the 23 are new species. About 40% of the alien species reported as new island records have been in Hawaii for more than 50 years. These data indicate that there is a long lag period between the time that a species becomes established and its eventual recognition and published record. The biologies of most of the species are unknown. However, a few of the new records appear to be potential pests. For example, six new wood boring beetles (an Agrilus species, two Platypodidae and three Scolytidae) could become injurious to native or commercially valuable trees. A new biting midge (Culicoides species) belongs to a group of notorious pests of vertebrates. The predatory assassin bug (Sinea rileyi) and the parasitic and predatory wasps could affect populations of beneficial arthropods. Some of the moths could attack economic crops or native plants. The survey is not yet complete; a few groups have not been identified; and the severe drought preceding and during the survey greatly limited arthropod activity within the study area. Therefore, it is recommended to continue the survey as a monitoring program. Such a survey would concentrate on intercepting newly established species (especially potential pest species) as well as completing the list rather than attempting to process all species. Also recommended is the development of a database to manage more efficiently the information regarding the fauna at Kahului Airport. The database should include computer based identification aids for the species, so that quarantine personnel as well as other stakeholders can identify species unknown to them rapidly on site. We found the endangered Blackburn's sphinx moth on alien tree tobacco plants at the east end of the airport area near Sprecklesville and also determined that it occurs sporadically within the Kanaha Pond Wildlife Sanctuary. The area at the west end of the runway does not appear to provide good habitat for the moth except perhaps temporarily during wet periods even though tree tobacco, an alternate alien host plant, is common there. The east end of the airport appears to provide a refuge habitat important for the long-term survival of the moth. This area is a windswept coastal shrubland containing a mix of native shrubs and alien plants. The area is within the airport safety zone, which requires that the vegetation remain low in stature. Since the native shrubs rarely grow higher than two meters (about six feet), whereas some of the invasive alien species can become trees and since traditional land clearing activities foster the spread of the taller invasive species, we recommend that the area be managed to enhance the native species. This strategy will be beneficial to the endangered moth as well as other native species (some of which may deserve listing) living in the area. In the long-term, such management may prove to be cheaper, easier, safer, and less damaging than periodic land clearing. The US Fish and Wildlife Service and the Native Plant Society of Maui can provide support for the conservation activities. Continuation of the program to enhance the hosts and habitat for the moth within the Kanaha Pond Wildlife Sanctuary is also recommended. Other notable native species included a flightless Acalles weevil, a new species of the endemic Plagithmysus woodborer, six species (probably all new) of the diverse endemic moth genus Hyposmocoma, six other rare moths, two exceptionally rare true bugs, and two predatory wasps. Most native species persist by using one f four strategies: i.e., they have aquatic immature stages, are woodborers or live in other cryptic habitats, or live in windswept coastal habitat.