Hawaiʻi & USAPI Invasive Insects & Diseases
The invasive species problem on the Hawaiian and western Pacific Islands is both serious and daunting. A new pest reaches Hawaiʻi once every 18 days on average. In 1993, the federal Office of Technology Assessment declared Hawaii's alien pest species problem the worst in the nation. The evolutionary isolation from the continents, and their role as trade/tourist/military hubs of the Pacific, make these islands particularly vulnerable to invasion and destruction by invasive pests.
Assessment
- Large buildup of military on Guam will increase pathways for transport and movement of invasive pests.
- The potential for movement of invasive pests between islands is high.
- Survey methods for some insects have not been developed or are not effective.
- The window of opportunity to eradicate newly detected pests is typically very short; consequently, high levels of tree mortality may occur prior to effective management strategies being developed and implemented.
Priority Species
Myoporum thrips, Klambothips myopori, a new species found in southern California in 2005, caused extensive leaf curling and gall-like symptoms on infested plants and resulted in high levels of mortality to ornamental Myoporum species used for landscaping residential areas and freeway margins. An infestation of naio, Myoporum sandwicense, in Hawaiʻi by myoporum thrips was reported in March 2009. Surveys are ongoing to determine the extent of its distribution on the Big Island. Given the frequency of inter-island transport of goods and people, and the precedence of pest range expansions, the species will likely spread to other Hawaiian Islands. Recently the Hawaiʻi Invasive Species council funded a project to develop rapid response plans for myoporum thrips in the counties of Kauaʻi and Maui.
Coconut rhinoceros beetle (CRB) was detected on Guam in 2007. Adult beetles tunnel through young leaves and into the stem which reduces nut set or kills the host plant; coconut, betelnut and Pandanus are at risk. Attempts to eradicate this beetle on Guam have been unsuccessful and the program is now moving to control and management. Uninfested islands with suitable hosts should be routinely conducting surveys for this beetle.
Erythrina gall wasp (EGW), discovered on Oʻahu in 2005, spread throughout the Hawaiian island chain in less than six months. Most non-native erythrina trees, planted primarily for landscaping, were killed by EGW. EGW’s impact on native trees has been variable, but tree mortality has been high in many areas. The decline and loss of these culturally, ecologically, and aesthetically important species has been devastating. While the release of a biological control agent appears to be reducing the impact of EGW, the long-term effects are still unclear. The continued existence of the endemic wiliwili tree, a species cherished for its ecological and cultural importance, remains in question.
Cycad aulacaspis scale was first detected on Guam in late 2003 on ornamental cycads and quickly spread to native cycads throughout the island causing high levels of plant decline and mortality. The scale was detected on Rota in 2007; and on Palau in 2008; biological control agents were released, and survey and monitoring is ongoing. Cycads are a critical ecosystem component in tropical forested lands.
Black twig borer and its associated pathogens are serious pests on more than 200 species of native and alien shrubs and trees in Hawaiʻi, including several federally listed threatened and endangered plants. In addition the survival of ecologically and economically important Acacia koa trees is significantly impacted by the black twig borer. Forest Health Protection and Southern Research Station entomologists are working with the Hawaiʻi Agriculture Research Center (HARC) to evaluate the efficacy of systemic insecticides to determine the most effective in reducing black twig borer predation of disease resistant Acacia koa seedlings.
'Ōhi'a rust was first detected on Oahu in 2005 and quickly spread throughout the other Hawaiian islands within six months. The rust has killed or severely weakened a high percentage of the exotic and widespread rose apple trees and killed most of the Eugenia koolauensis trees on the islands, a native species that only had a limited distribution. This race of the rust does not seem to be able to attack any of the planted eucalyptus species on the islands, nor strawberry guava; and it has only a very limited effect on ohia trees.
Prevention
Multiple reports are available regarding invasive species for the Pacific Islands which include preventive tools. Some islands have invasive species strategies in place; others are in the developmental phase.
- The first line of defense against the entry of harmful plant pests is through inspection of commodities, conveyances, and passenger baggage at sea ports and airports conducted by APHIS.
- Public awareness campaigns by various agencies are ongoing in an effort to inform people about inadvertently moving invasive insects.
- FHP is partnering with university scientists in Brazil to determine if other races of ohia rust exist that might be more pathogenic on Oahu. If more pathogenic races exist, a program to prevent entrance of Myrtaceous species from the Americas into Hawaii may be needed.
Early Detection and Rapid Response
- Multiple agencies cooperate when new pests are found on the islands. Technical and advisory committees are formed to initiate action to eradicate the pest and/or determine the appropriate integrated pest management strategies.
- The Invasive Species Committees of Hawaii are island-based partnerships of government agencies, non-government organizations, and private businesses working together to protect islands from the most threatening invasive pests.
- Hawaii Department of Agriculture implements the Cooperative Agricultural Pest Survey (CAPS) program in Hawaii.
- Forest health professionals conduct field surveys to assess pest-caused tree injury and/or mortality to determine the specific causal agent.
Control and Management
Depending on the pest, various integrated pest management strategies are implemented. New pest management technologies are researched and developed as needed.
Rehabilitation and Restoration
- FHP provides funding on Federal, State, and Private lands to rehabilitate degraded areas to prevent invasive species infestations or to prevent reoccurrence after invasive species removal.