Predatory wasp faces a determined battle
Native trees show extensive damage by the spreading pest
State botanists and entomologists are fighting to save native wiliwili and coral trees used in landscaping and agriculture from an introduced pest, the Erythrina gall wasp.
The wasp, Quadrastichus erythrinae, has spread statewide and is causing extensive damage to Erythrina tree species.
"The sign of the infestation can be seen on all islands: skeletonlike trees with shriveled and stung leaves in place of green," said Peter Young, director of the state Department of Land and Natural Resources.
"We are in danger of losing one of our most celebrated native trees to extinction in a relatively short time, and are taking all measures possible to prevent that outcome," Young said this week.
One measure is establishment of a seed bank at the University of Hawaii Center for Conservation Research and Training facility at Lyon Arboretum. The seed bank is intended for the genetic preservation of the species and restoration of populations in the wild when a remedy for the gall wasp can be found.
About 25,000 seeds from throughout Hawaii have arrived for storage.
Chemical treatments on native wiliwili populations are being tested by the DLNR and the University of Hawaii, using emergency USDA Forest Service funds.
The experimental treatment is to inject the systemic insecticide Imidacloprid into trees, which has been effective in preliminary trials. The chemical stays within the tree and has low environmental impact, according to the DLNR.
Experimental treatments are being carried out at Puu Waa Waa Forest Reserve on the Big Island, at Kekaha on Kauai and in the northern Waianae forest reserve on Oahu. However, even if the treatment is effective, it is practical to treat only a small number of trees.