Ionizing radiation quarantine treatments against tephritid fruit flies

Fruit flies of the family Tephritidae are considered the most important insect pest risk carried by exported fruits worldwide. Fruits suspected of harboring fruit fly eggs and larvae must be treated to control virtually 100% of any tephritids present. Irradiation is unique among quarantine treatments in that it is the only treatment used which does not cause acute mortality; instead, insects are prevented from maturing or are sterilized. Tephritids have been the most studied group of quarantined pests as far as irradiation; minimum absorbed doses confirmed with large-scale testing to provide control to the probit 9 level (99.9968%) have ranged from 50 to 250 Gy. Considerable work has been done with the Mediterranean fruit fly, Ceratatis capitata (Wiedemann), one of the most important quarantined pests worldwide, and doses suggested to provide quarantine security have varied widely. The fact that insects are still alive for some time after irradiation has been one of the major obstacles to its use. Irradiation may be the most widely applicable quarantine treatment from the standpoint of fruit quality. However, some important fruits shipped across quarantine barriers (mangoes, Mangifera indica L., and citrus) may suffer from doses as low as 150 Gy when applied on a commercial scale where much of the fruit load may receive > 300 Gy. Fortunately, some of the important tephritids attacking these fruits? such as Anastrepha spp., can be controlled with lower doses. Mainland USA has begun to use irradiation as a quarantine treatment for some fruits imported from Hawaii since April 1995 and remains the only country using irradiation as a quarantine treatment, although on a very limited basis. Irradiation offers some additional risk abatement advantages over other quarantine treatments. (C) 1999 Published by Elsevier Science B.V. All rights reserved.