Monday, December 10, 2007 - 9:05 AM

Life history of the wekiu bug and its implications for conservation of this unique alpine species from Hawaii's Mauna Kea Volcano (Lygaeidae: Nysius)

Jesse A. Eiben,, University of Hawaii - Manoa, Plant and Environmental Protection Sciences, 3050 Maile Way, Gilmore Hall 607A, Honolulu, HI and Daniel Z Rubinoff,, University of Hawaii at Manoa, Plant and Environmental Protection Sciences, 3050 Maile Way, Gilmore Hall 607A, Honolulu, HI.

A quarter of the world’s Nysius species are endemic to the Hawaiian Islands, with the wekiu bug, N. wekiuicola, (and its sister species the Mauna Loa bug, N. aa) showing extreme differences in ecology and morphology. While all other Nysius are seed-feeders, the wekiu bug is a flightless, micropterous, cold tolerant, scavenger-predator of moribund insects on the summit of the 4,205 meter volcano of Mauna Kea on the island of Hawaii. The wekiu bug is a candidate for listing under the Endangered Species Act, due to its decreasing numbers, limited range, specialized habitat requirements, isolated populations, and habitat destruction. The first successful lab colony of N. wekiuicola was created with 61 field collected individuals from Mauna Kea in March of 2007. The colony was maintained under controlled conditions based on field microhabitat measurements with unlimited Drosophila melanogaster as food. Observations of mortality, mating, egg lay, egg hatch, and molting were recorded daily. Five nymphal instars were confirmed with head widths from 0.32-0.75mm. Generation time was 105 days with egg hatch after 25 days, and average stadia duration of 15-20 days. Natality under these conditions was a low 15 hatched eggs per female per month, with a hatch rate of 50-70%. The apparently low reproductive output and slow generation time compounds the problems of wekiu bug conservation on Mauna Kea. Ongoing studies are aimed at creating a growth curve to bridge the gap between lab data and actual field microhabitat use and availability.

Species 1: Hemiptera Lygaeidae Nysius wekiuicola (wekiu bug)