Parasitism rate and sex ratio of Psyttalia (=Opius) concolor (Hymenoptera: Braconidae) reared on irradiated Ceratitis capitata larvae (Diptera: Tephritidae)

Abstract Tests were conducted to evaluate use of irradiated Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), larvae as factitious hosts for mass-rearing the parasitoid Psyttalia concolor (Szepligeti) (Hymenoptera: Braconidae). In order to prevent the release of the alternative host adults, eclosion from unparasitized larvae must be prevented. Exposure of medfly larvae to 40, 50 or 60 Gy of 60Co gamma radiation showed that 60 Gy was the most effective dose in inhibiting adult medfly eclosion. The most suitable host:parasitoid ratio was found to be three larvae per parasitoid regardless of exposure time. When three larvae per parasitoid were exposed for 3 h, there was no significant difference in parasitism rates using irradiated vs. unirradiated host larvae (16.4 vs. 18%, respectively). Irradiation of host larvae also had no significant effect on the sex ratio of resulting parasitoids. Implementation of this practice will improve the efficiency of mass production and...