Studies on irradiation against Anastrepha ludens and A. obliqua
Irradiation can be used as a quarantine treatment against fruit flies, in particular against Anastrepha ludens and A. obliqua (both EPPO A1 quarantine pests) on citrus. The currently accepted criterion to assess the efficacy of irradiation as a quarantine treatment of fruit flies is prevention of adult emergence, as insects are not killed in a reasonable amount of time at the doses allowed on fresh commodities (£ 1kG). Irradiation would generally be applied after fruit packing. Packed fruits such as citrus are likely to stay at ambient conditions for a few days before being irradiated, allowing third instars to emerge and pupate within the packaging. As pupae are more tolerant to irradiation than eggs and larvae, studies were done in USA to determine the tolerance of these immature stages (feeding third instar, pupariation to pharate adult) of A. ludens and A. obliqua in grapefruit. According to their results, the authors recommended that grapefruit should not remain at ambient temperature (»25°C) for more than 2 or 3 days before being irradiated.
Sources
Hallman, G.J.; Worley, J.W. (1999) Gamma radiation doses to prevent adult emergence from immatures of Mexican and West Indian fruit flies (Diptera: Tephritidae).
Journal of Economic Entomology, 92(4), 967-973.