Submitted to: Biocontrol Science and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/1/2007
Publication Date: 7/1/2009
Citation: Cancino, J., Ruiz, L., Lopez, P., Sivinski, J.M. 2009. The suitability of Anastrepha spp. and Ceratitis capitata larvae as hosts of Diachasmimorpha longicaudata and Diachasmimorpha tryoni: Effects of host age and radiation dose and implications for quality control in mass rearing. Biocontrol Science and Technology. 19:81-94. Interpretive Summary: Fruit flies create quarantine problems wherever they occur, but augmentative biological control is a promising means of their area-wide management. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, in collaboration with Mexican colleagues, develop means to maximize the efficiency and minimize the costs of mass-rearing parasitoids. One such technology is the irradiation of host larvae, which allows the parasitoid to develop, but prevents the emergence of flies from unparasitised hosts. Research has shown that this technique is “robust”; i.e., that different fruit fly hosts and a wide range of radiation doses do not significantly affect yield. This will result in greater flexibility in the production of mass-reared parasitoids.
Technical Abstract: The emergence of parasitoids from irradiated tephritid host larvae of different species and ages was evaluated. Parasitoid and fly longevity and fecundity resulting from each treatment were also assessed. Doses of 5, 10, 20, 30, 40, 50, 80, 100 and 150 Gy were applied to samples (100 larvae) of 6-, 7-, 8- and 9-day-old Anastrepha spp. larvae (A. ludens Loew, A. obliqua Mcquart and A. serpentina Wiedeman) and 6- and 7-day-old Ceratitis capitata (Wiedeman) larvae. Anastrepha larvae were exposed to Diachasmimorpha longicaudata (Ashmead), and C. capitata larvae to D. tryoni (Cameron). Following exposures of 20 Gy, fly emergence was totally suppressed in all ages of A. ludens and A. serpentina, while in A. obliqua and C. capitata, total suppression was achieved at 30 Gy. In all species, fly emergence decreased with increasing radiation dosages from 5 to 20 Gy. Emerged fly fertility and longevity also decreased as the radiation increased. On the other hand, parasitoids did not suffer decreases in longevity or fecundity as host radiation dose increased. Larval age at the time of irradiation did not influence emergence, longevity and fecundity of either flies or parasitoids. When the irradiated cohort size was raised to one liter of larvae (about 32000 Anastrepha or 50000 C. capitata larvae) doses of 40 Gy in A. ludens, A. serpentina and A. obliqua totally suppressed fly emergence but permitted D. longicaudata emergence. In C. capitata larvae, it was necessary to increase the doses to 60 Gy. Quality control tests under mass rearing conditions were applied to D. longicaudata reared using irradiated A. ludens larvae. There was no statistical difference between those derived from irradiated or non-irradiated host for most parameters. Only percent pupation after 72 h differed, along with the consequent differences between the percent emergence and pupal weight. The conclusions drawn from this study lead to a greater flexibility in the use of irradiated hosts in the mass rearing of the fruit fly parasitoids D. longicaudata and D. tryoni.