Population dynamics of three Bactrocera spp. fruit flies (Diptera: Tephritidae) and two introduced natural enemies, Fopius arisanus (Sonan) and Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae), after an invasion by Bactrocera dorsalis (Hendel) in Tahiti.
Oriental fruit fly, Bactrocera dorsalis (Hendel), invaded French Polynesia in 1996. In 2002 a natural enemy, Fopius arisanus (Sonan), was released and established. By 2009 mean (±SD) F. arisanus parasitism for fruit flies infesting Psidium guajava (common guava), Inocarpus fagifer (Polynesian chestnut) and Terminalia catappa (tropical almond) fruits on Tahiti Island was 64.8±2.0%. A second parasitoid, Diachasmimorpha longicaudata (Ashmead), was released and established in 2008. Although widespread, parasitism rates have not been higher than 10%. From 2003 (parasitoid establishment) to 2009 (present survey) numbers of B. dorsalis, Bactrocera tryoni (Froggatt), Queensland fruit fly, and Bactrocera kirki (Froggatt) emerging (per kg of fruit) declined. For example, for P. guajava there was a decline of 92.3%, 96.8%, and 99.6%, respectively. Analysis of co-infestation patterns (1998-2009) of B. dorsalis, B. tryoni, and B. kirki, suggest B. dorsalis is now the most abundant species in many common host fruits. Establishment of F. arisanus is the most successful example of classical biological control of fruit flies in the Pacific outside of Hawaii and can be introduced if B. dorsalis spreads to other French Polynesian islands, as was the recent case when B. dorsalis spread to the Marquesas Islands. These studies support F. arisanus as a prime biological control candidate for introduction into South America and Africa where Bactrocera carambolae Drew and Hancock and Bactrocera invadens Drew, Tsuruta, and White, respectively, have become established.