INFLUENCE OF GUAVA RIPENING ON PARASITISM OF THE ORIENTAL FRUIT-FLY, BACTROCERA-DORSALIS (HENDEL) (DIPTERA, TEPHRITIDAE), BY DIACHASMIMORPHA-LONGICAUDATA (ASHMEAD) (HYMENOPTERA, BRACONIDAE) AND OTHER PARASITOIDS

The effects of guava ripening on abundance and parasitism rates of parasitoids of oriental fruit fly, Bactrocera dorsalis (Hendel), were determined in three guava (Psidium guajava L.) orchards. Diachasmimorpha longicaudata (Ashmead) was released in Kilauea, Kauai, and Waiakea, Hawaii. Natural densities of this parasitoid were measured in a third orchard in Panaewa, Hawaii. Fruits ripening on the tree and the ground after abscission of fruit were classified into four categories, ranging from to mature-green to rotten fruit. The egg parasitoid, Biosteres arisanus (Sonan) was the dominant parasitoid emerging from tree-harvested guavas at all sites and composed 90-98% of all parasitoids recovered but decreased in abundance as guava fruit aged on the ground. In all three orchards, D. longicaudata increased in abundance and parasitism rates were highest in guavas that remained on the ground for 6-10 days. Consequently, the impact of this parasitoid is usually underestimated by sampling commercially ripe guava fruit from the tree or freshly fallen fruit on the ground. The eulophid parasitoid, Tetrastichus giffardianus (Silvestri), was more abundant in 4- to 9-day-old ground fruit. We discuss modified sampling methods for population estimation and augmentative release studies of parasitoids of oriental fruit fly. (C) 1994 Academic Press, Inc.