A controversial evolutionary oddball: Life table analysis of the wekiu bug (Nysius wekiuicola), a unique high alpine desert scavenger lygaeid from Mauna Kea, Hawaii

Monday, November 17, 2008: 9:41 AM
Room A1, First Floor (Reno-Sparks Convention Center)
Jesse A. Eiben , Plant and Environmental Protection Sciences, University of Hawaii-Manoa, Honolulu, HI
Dan Rubinoff , Plant and Environmental Protection Sciences, University of Hawaii - Manoa, Honolulu, HI
The alpine habitat on Mauna Kea represents one of the most extreme environments in the Hawaiian Islands. Daily temperature fluctuations between 25F and 108F, winter snow pack, and virtually no plant life suggest lifelessness. However, there is a specialized endemic fauna. The wekiu bug is an insect predator/scavenger that tolerates very cold temperatures and feeds exclusively on wind deposited low-elevation insects blown to the summit and immobilized by cold. This micropterous seed bug is restricted to the cinder cones of Mauna Kea above 11,700 ft, and exhibits the most extreme morphological and behavioral adaptations in the globally distributed genus Nysius. The wekiu bug is a candidate Endangered Species, due to its decreasing numbers, limited range, specialized habitat requirements, isolated populations, and habitat destruction. We have established the first lab protocols to successfully rear wekiu bugs. This colony was used to describe the wekiu bug life cycle, create a life table, and create a temperature dependent growth curve. Under lab conditions (5-34C, 14:10 L:D, D. melanogaster food source) the wekiu bug has low reproductive capacity compared to other Nysius. Developmental rate increases with temperature between 14C and 34C, adult longevity shows the opposite trend, and egg lay requires a range between 24-30C. Although not surprising for insects, these findings contradict the assumption that the wekiu bug requires the exceedingly low temperatures most prevalent in its habitat. These results suggest that the wekiu bug engages in very active thermoregulation to persist in the alpine environment.