Invasive species in Hawaii and health-related problems. The introduction of mosquitoes to Hawaii has resulted in the spread of avian malaria, and increases the risk of dengue and west Nile virus (not known to be in Hawaii yet). Other native species can be affected by invasive species diseases as well, such as the once-dominant koa tree being killed by koa wilt, which is believed to have been brought into Hawaii on an ornamental acacia plant, and the 'ohi'a tree, now being affected by Rapid Ohia Death. Invasive predators can severely reduce the population sizes of native species, or even drive them extinct, because native
Koa wilt mortality rate over several years due to Koa wilt. It is also a legume, giving it the ability to form symbiosis with nitrogen fixing bacteria, which has led to efforts to use koa in agroecological systems with crops such as coffee and cacao. Ecologically, koa is an important species because it is one of the few native trees that remains dominant in alien mixed forests on the Hawaiian Islands. Invasive species make up the majority of the State's current plant population. Koa trees also are important because provide a habitat for many native bird species. Historically, there were once two