Invasion of French Polynesia by the glassy-winged sharpshooter, Homalodisca coagulata (Hemiptera : Cicadellidae): A new threat to the South Pacific
The glassy-winged sharpshooter, Homalodisca coagulata (Say), is a major pest of agricultural, ornamental, and native plants. It is native to the southeastern United States and northeastern Mexico. Homalodisca coagulata was first recorded in Tahiti (French Polynesia) in 1999. It reproduced and spread rapidly in French Polynesia and is currently found in almost all islands in the Society Islands group (Tahiti, Moorea, Ralatea, Huahine, Bora Bora, Tahaa, Maupiti), in Nuku Hiva in the Marquesas, and in Tubuai and Rurutu in the Australs. Tahiti and Moorea are the most heavily infested islands, where H. coagulata populations have reached densities far exceeding those observed in California (this pest invaded California in the late 1980s) or in its native range. Major factors responsible for high population densities of H. coagulata in French Polynesia are permissive environmental conditions (mild climate and abundant year-round feeding and oviposition substrates), absence of host-specific natural enemies, intoxication of generalist predators that attack nymphal and adult stages, and limited competition for resources. Homalodisca coagulata causes several problems in French Polynesia: dripping excreta from high densities of feeding adults and nymphs affect outdoor recreation under trees and create a social nuisance, attraction of large numbers of flying adults to lights at night and collisions with people are severe annoyances, and large numbers of H. coagulata feeding on plants can cause impaired growth. The major concern for French Polynesia is the possibility of this pest acquiring and vectoring the lethal plant bacterium Xylella fastidiosa, which could have a disastrous impact on ornamental, agricultural, and native plants. Surveys are currently under way to detect X. fastidiosa in French Polynesia. Presence of large populations of H. coagulata in French Polynesia presents a major threat to agriculture and the biodiversity of South Pacific countries because this insect has clearly demonstrated a high invasion potential.