Submitted to: Journal of Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/14/2010
Publication Date: 4/22/2010
Citation: Yokoyama, V.Y., Caceres, C.E., Kuenen, L.P., Wang, X., Rendon, P.A., Johnson, M.W., Daane, K.M. 2010. Field Performance and Fitness of an Olive Fruit Fly Parasitoid, Psyttalia humilis (Hymenoptera: Braconidae) mass reared on irradiated Medfly. Journal of Biological Control. 54:90-99. Interpretive Summary: Olive fruit fly is a major pest of olives grown for canning and oil in California. Biological control of olive fruit fly using natural enemies shows promise as an economical and sustainable method to control the pest. In a large-scale biological control project, a parasitic wasp was mass produced and imported from Guatemala for release into olive orchards infested with olive fruit fly in five regions and nine counties in the state. In most locations, the parasitic wasp successfully reproduced in the immature stages of olive fruit fly and in certain instances slightly reduced the pest numbers. In laboratory tests, the female wasp was found to fly continuously for almost two hours showing that it was capable of dispersing throughout olive growing regions. The wasp reproduced in olive fruit fly in severe winter weather conditions when overnight temperatures were as low as 28 degrees F. These observations support the possibility that the parasitic wasp can survive from year to year on olive fruit fly in olives. Persistence of the wasp in California olive groves would be an environmental friendly means to control the pest without the use of insecticides. The work supports the $90 million olive industry in California, and the only source of U.S. grown and canned olives.
Technical Abstract: Adult Psytallia cf. concolor (Szépligeti) (230,908) were produced from sterile Mediterranean fruit fly, Ceratitis capitata (Wiedemann), larvae at the USDA-APHIS-PPQ, San Miguel Petapa, Guatemala and shipped from September 2008 to January 2009 to the USDA-ARS, SJVASC, Parlier for biological control of olive fruit fly, Bactrocera oleae (Rossi), in California. Total mean parasitoid mortality in 14 shipments was 14% from shipment to release. Parasitoids reared from sterile larvae had a significantly lower number of mature eggs than those reared from fertile larvae. The highest mean number of olive fruit fly adults trapped was 29 per day in San Jose in mid-October, and the lowest mean was <1 per day in the San Joaquin and Sacramento Valleys. The greatest difference between the mean daily high and low temperatures was 21ºC in Strathmore when no olive fruit fly larvae were collected from fruit. Parasitoids, 3,114-18,667 were released in 11 locations, nine counties, and five regions with 0-17% parasitism of olive fruit fly third instars. Parasitism was 17% in Napa when fruit was infested with very low numbers of host, exposed for 20 hrs, and overnight temperature was -2.2ºC. The mean total number of olive fruit fly larvae per fruit in Lodi on 14 December was 0.80 and 1.72 in trees in which parasitoids were released versus control trees, respectively. Continuous flight in different air temperatures and air speeds for female and male parasitoids ranged from 4-20 min and 3-14 min, and the three longest flight times ranged from 53-110 and 20-52 min, respectfully.