Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 7, 2008
Publication Date: June 28, 2008
Citation: Yokoyama, V.Y., Rendon, P., Sivinski, J.M. 2008. Psyttalia cf. concolor (Hymenoptera: Braconidae) for Biological Control of Olive Fruit fly (Diptera: Tephritidae) in California. Journal of Economic Entomology. 37: 764-773 Interpretive Summary: Olive fruit fly is an invasive species that has recently become established on olives in California. This pest has potential to destroy the annual olive crop in the state that is the sole producer of canned olives for the U.S. Biological control can be used to control olive fruit fly if natural enemies of the pest adapt to the climatic conditions where olive fruit fly is abundant, and can locate and utilize the pest to produce subsequent populations. A parasitoid, Psyttalia cf. concolor, was imported from Guatemala and tested in laboratory and field tests to determine its ability to control olive fruit fly. The parasitoid was found to be highly adaptable, successfully parasitized olive fruit fly larvae, and survived under the same weather conditions as its host in laboratory, greenhouse, and field tests. Rates of parasitism were especially high along the California coast where high populations of the pest are known to occur. The parasitoid also attacked another pest, walnut husk fly, but did not attack a beneficial fruit fly, the seedhead fly, in yellow star thistle. The imported parasitoid shows great promise as a biological control agent for olive fruit fly and successful establishment of the parasitoid in olives will help protect the production of canned olives and olive oil in California that is valued at $68 million annually.
Technical Abstract: The larval parasitoid, Psyttalia cf. concolor, reared on Mediterranean fruit fly, Ceratitis capitata Weidemann, by the USDA-APHIS, PPQ, Guatemala City, Guatemala, was imported into California for biological control of olive fruit fly, Bactrocera oleae (Gmelin), in olives, Olea europaea L. The maximum life span of parasitoids in the laboratory was 69 d after shipment. Mean percentage parasitism of olive fruit fly 3rd instars infesting fruit in field cages ranged from 7.0 in Grapevine to 59.7 in Santa Barbara, and in free releases ranged from 0 in Grapevine to 10.6 in Santa Barbara. In the laboratory, more parasitoids developed to adults in olive fruit fly larvae that were 11-13 d-old than in larvae 8-10 d-old. Adult parasitoids lived significantly longer when provided with water than adults without water in environmental chambers at 5°C, 85% RH; 15°C, 65% RH; 25°C, 25% RH; and, 35°C, 25% RH. Adult parasitoids lived the longest at 15°C and 65% RH when provided with food and water (48 d), or food and a sucrose solution (32 d). In greenhouse tests, survival of parasitoids without food and water was about 4 d in a simulated coastal climate, and 1 d in a simulated inland valley climate, and was significantly increased by providing food and water. The parasitoid did not develop in the beneficial seedhead fly, Chaetorellia succinea (Costa), in yellow star thistle. Parasitism of walnut husk fly, Rhagoletis completa Cresson, larvae in green walnut husks was 28.4% in laboratory no-choice tests, and 11.5% compared to 24.2% for olive fruit fly larvae in olives in choice tests.