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The importation of alien insects and pathogens to control invasive alien weeds raises justifiable concern among land managers and conservationists. For the Hawaiian archipelago the dangers are particularly acute. Hawai'i has many endemic species, a substantial percentage of which are at risk of extinction. Over 900 nonindigenous plant species have become naturalized in Hawai'i, more than 90 of which constitute substantial problems for conservation because they compete with native species or so alter ecosystem processes that whole communities are changed). There are good reasons for caution in the use of alien insects and pathogens as control agents for invasive weeds. Nevertheless biological control offers one of the most cost-effective and enduring mechanisms for the control of persistent weeds that have become widely invasive in natural habitats. Chemical and mechanical approaches to the control of weed populations require perpetual maintenance, may inflict unwanted side effects on nontarget species and communities and are of limited use in large diverse ecosystems. Extensive infestations in poorly accessible terrain require considerable long-term investment in personnel and resources, expenditures that may be difficult to justify when short-term economic returns are not apparent. Biological control offers the possibility for control (rarely eradication) of invasive weeds over extensive acreage and inaccessible terrain in perpetuity Clearly the challenge to the community of scientists and managers seeking to use biological control agents in Hawaii is to make the most efficient use of limited space, personnel, and financial resources in bringing the safest yet most effective insect and pathogen agents on line. The most productive research strategies for meeting that goal was the topic of the 2000 Conservation Forum of the Hawai'i Secretariat for Conservation Biology: Biological Control of Invasive Plants in Native Hawaiian Ecosystems.