Christmasberry, introduced to Hawaii as an ornamental before 1900, is one of the most aggressive alien weed species threatening Hawaii's native ecosystems. It is currently established on the islands of Oahu, Hawaii, Kauai, Molokai and Maui. It has displaced over 124,000 acres of native dry and mesic forest ecosystems throughout the islands by shading out native understory vegetation and preventing native regeneration. Christmasberry is considered a high priority target weed in Hawaii because it is already widespread and has great potential to expand into other native ecosystems.
Biological control is the most feasible and cost-effective method to control christmasberry.
However, little is known about their current distribution, abundance, life history and impacts on christmasberry. Biological control efforts offer little assistance to Hawaii's natural area managers without post-release monitoring programs. The proposed study will evaluate the establishment, rate of spread, abundance and distribution of these previously released biological control agents christmasberry, as well as estimate damage to christmasberry to assess the effectiveness of these agents. Information will also be collected on the natural enemies associated with christmasberry and damages to the plant. Changes in christmasberry distribution, coverage, and density at Manuka State Natural Area Reserve and Volcanoes National Park will be documented using earlier estimates taken in the 1980's.