Results of the 2007-2008 alien species and wekiu bug (Nysius Wekiuicola) surveys on the summit of Mauna Kea, Hawaii Island, final report

Author:: Englund, R. A., Preston, D.J., Vorsino, A. E., Evenhuis, N.L., Myers, S., Englund, L. L.
Title:: Results of the 2007-2008 alien species and wekiu bug (Nysius Wekiuicola) surveys on the summit of Mauna Kea, Hawaii Island, final report
Year:: 2009
Subject:: Wekiu bug surveys Nysius wekiuicola
Summary:: As part of a continuing long-term study, the Hawaii Biological Survey of the Bishop Museum was contracted by the Office of Mauna Kea Management (OMKM) to monitor for alien arthropod species and to continue monitoring populations of the wekiu bug (Nysius wekiuicola Ashlock & Gagne), which is endemic to the Mauna Kea summit area. Ten day field trips were conducted in June 2007 and July 2008 to provide a baseline of introduced arthropod species found at the Mauna Kea summit, and to continue monitoring wekiu bug populations within critical core habitats. Forty-seven data loggers that were placed at the summit in 2006 to monitor soil temperatures and relative humidity were removed in July 2008. Data were successfully downloaded from 24 operating loggers that provided new information related to wekiu bug soil temperature preferences. The objective of the alien arthropod baseline and monitoring surveys was to provide information to managers on any potential threats to endemic Mauna Kea arthropod species such as the wekiu bug. Intensive surveys for ants were conducted to assess if any populations are currently found within any areas in close proximity to wekiu bugs. Ants are already well-established at the summit regions of Haleakala National Park, and this elevational range is well within that of lowest elevation that wekiu bugs have been found. Because of the predatory and social nature of ants, and because ants have caused the extinction and decline of native arthropods throughout Hawaii, it was imperative to search high risk areas around the Mauna Kea summit region. This included public roadways, picnic areas, and around buildings. During the course of this study we did not see or collect any ants at the summit region, and in fact obtained the highest wekiu bug captures since the 1997 - 1998 field season during trapping in the 2007 field season. Of concern was the finding of several predatory species of alien beetles, with the major new finding of a predatory carabid beetle that so far appears to be restricted to just around the Lake Waiau shoreline area. Data downloaded from temperature loggers was analyzed using the GIS ArcMap Inverse Distance Weighted model that predicted mean yearly soil surface temperatures. The upper regions of all slopes on Puu Hau Oki and the north slope of Puu Hau Kea were predicted to have the coldest annual temperatures of less than 5 degrees C, and these two areas also generally have the highest wekiu bug captures at the summit. The warmest region was found to be the Lake Waiau area, where wekiu bugs have not been captured during the past ten years of study.
URL:: http://hbs.bishopmuseum.org/publications/pdf/wekiu-rep12-09.pdf
Date:: December 2009
Collection:: Monographs