Performance of Psyttalia humilis (Hymenoptera: Braconidae) reared from irradiated host on olive fruit fly (Diptera: Tephritidae) in California

The parasitoid Psyttalia humilis (Silvestri) was reared on Mediterranean fruit fly, Ceratitis capitata (Wiedemann), third instars irradiated at 0-70 Gy at the USDA, APHIS, PPQ, Moscamed biological control laboratory in San Miguel Petapa, Guatemala, and shipped to the USDA, ARS, Parlier, CA. Irradiation dose did not affect the parasitoid's offspring sex ratio (53-62% females), percentage of unemerged adults (12-34%), number of progeny produced per female (1.4-1.8), and parasitism (19-24%). Host irradiation dose had no significant effect on the forewing length of female P. humilis and its parasitism on olive fruit fly, Bactrocera oleae (Rossi) and offspring sex ratio, but dissection of 1-wk-old female parasitoids reared from hosts irradiated with 70 Gy had a significantly lower number of mature eggs than females from nonirradiated hosts. Longevity of P. humilis adults decreased with increased temperature from 15 to 35°C, regardless of food provisions, gender, and host irradiation dose. Females survived 37-49 d at 15°C with water and food, and only 1-2 d at 35°C without food, whereas males lived shorter than females at all temperatures and food combinations tested. Adult P. humilis reared from fertile C. capitata and aspirated for dispensing in cups lived significantly longer after shipment than those specimens chilled and dispensed by weight. At 21 and 32°C, 50% of parasitoids departed release cages after 180 and 30 min, respectively, but none departed at 12°C. Thirteen shipments of P. humilis (2,980-21,922 parasitoids per shipment) were received between September and December 2009, and seven shipments (7,502-22,560 parasitoids per shipment) were received between October and December 2010 from San Miguel Petapa, Guatemala. Daily number of olive fruit fly adult and percentage female trap captures ranged <1-19 and 8-58% in 2009, and <1-11 and 0-42% in 2010, respectively. The number of parasitoids released ranged 848-12,257 in 2009 and 3,675-11,154 in 2010. Percentage parasitism of olive fruit fly third instars at all locations ranged 0-9% in 2009 and 0-36% in 2010.