Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2010
Publication Date: 4/7/2011
Citation: Yokoyama, V.Y., Rendon, P.A., Wang, X., Opp, S.B., Johnson, M.W., Daane, K.M. 2011. Response of Psyttalia humilis (Hymenoptera: Braconidae) to olive fruit fly (Diptera: Tephritidae) and conditions in California olive orchards. Environmental Entomology. 40:315-323.
Interpretive Summary: Over the past decade, olive fruit fly has become a devastating pest of olives in California. Although the pest is limited by high temperatures in the interior valleys where olives are produced for canning, the cool, coastal areas of the state provide a constant source of re-infestation. Biological control with an imported parasitoid from Guatemala has shown promise as an economical and sustainable method of pest control throughout the state. Studies in 2006-2007 demonstrated that the parasitoid developed successfully when released in several regions, and reproduced under adverse conditions during the winter showing that it can survive from year to year. The parasitoid was found to feed on scale honeydew and citrus juice, foods that may be readily available near olive groves. When food was available, high summer temperatures did not limit the peak period of female parasitoid reproduction. Exposure to bait sprays used to control olive fruit fly did not cause parasitoid mortality indicating that biological control was compatible with olive IPM programs. The work supports a $90 million olive industry in California, and the only source of domestic canned olives.
Technical Abstract: The larval parasitoid, Psyttalia cf. concolor (Szépligeti), 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. Parasitoids (3,613-7,823) were released in Orland, San Juan Bautista, Cayucos, Sylmar, Santa Barbara, and San Diego during October through December 2006. The lowest (19%) and highest (61%) mean percentage of females was captured in traps on 8 to 15 December in Sylmar and 2 to 9 November in San Diego, respectively. The lowest (0.5) and highest (29.7) mean number of olive fruit fly adults per day per trap was captured in Orland and Sylmar, respectively. Mean daily temperatures at the locations ranged from 10.7ºC in Orland to 20.9ºC in San Juan Bautista. The lowest (0.01) and highest (2.21) number of third instars per fruit was collected on 9 November in Orland and on 5 October in San Diego, respectively. Lowest (0.3%) and highest (100%) mean percentage parasitism of olive fruit fly third instars occurred on 25 January in Sylmar and on 26 October in Cayucos, respectively. Parasitoids reared on olive fruit fly survived 36 d on honey, 31 d on orange juice and 28 d on honeydew, which was significantly longer than on cut olive fruit (8 d) or without food (11 d). Parasitoids reared on Mediterranean fruit fly survived 31 d on orange juice and 34 d on honey or honeydew. Under the high diurnal temperature regime, the parasitoid longevity was significantly different among water and food conditions, but not between females and males or between food and sexes. The parasitoids survived < 5 days when no food or when only water was provided. Honey and honeydew for food significantly increased the longevity of females and males. Parasitoid life-time fecundity was significantly different among water and food conditions. Water, honey and honeydew significantly increased parasitoid fecundity, when compared to no food. Percent mortality of parasitoid adults was not significantly different among four types of choice tests with artificial honeydew and GF-120.