The horticultural industry as a vector of alien snails and slugs: widespread invasions in Hawaii

The horticultural industry is an important vector of alien snails and slugs. Surveys of nurseries in the Hawaiian Islands recorded 31 terrestrial snail/slug species, all but two of them alien and five previously unrecorded. Individual facilities had 1-17 species. In total, 38 non-native terrestrial snail/slug species have become established, originating globally. Numbers on each island do not reflect numbers of survey locations but rather the total numbers established on each island. Species richness and community composition in nurseries differed significantly among islands and among different-sized nurseries. Certain species were more common on Oahu (main port of entry to Hawaii) so most of these alien species may have been first introduced to Oahu and then spread to other islands. Some of them cause damage in nurseries. Some may cause shipments of nursery products to be rejected when they are inadvertently exported with them. When they are transported to and become established in new areas they may cause agricultural, horticultural and environmental problems. Greater awareness of these species is necessary in the nursery industry and among quarantine officials.