Generic Radiation Quarantine Treatments: The Next Steps

Abstract

In 2006, U.S. Department of Agriculture-Animal and Plant Health Inspection Service published a landmark rule providing generic radiation quarantine treatments. The rule approved radiation doses of 150 Gy for any tephritid fruit fly and 400 Gy for all other insects except the pupa and adult stages of Lepidoptera. The generic radiation treatments apply to all fresh horticultural commodities. Therefore, if a pest risk assessment demonstrates that no pupae or adult Lepidoptera are associated with a commodity, export approval can be forthcoming with no further research. Generic treatments are the culmination of decades of research but not an end point. Future research on quarantine and phytosanitary uses of radiation should focus on 1) development of specific doses for quarantine Lepidoptera not covered by the generic treatments, 2) reduction of dose levels for specific pests and commodities to shorten treatment time and minimize any deleterious effects of radiation treatment on commodity quality, 3) development of generic doses below 400 Gy for important groups of quarantine arthropods other than fruit flies, and 4) development of information on commodity tolerance and development of value-added irradiated fresh products that use generic radiation treatments. Generic treatments will facilitate safe trade between countries that have approved phytosanitary uses of radiation for fresh agricultural commodities.

Tolerance of Hylurgus ligniperda (F.) (Coleoptera: Scolytinae) and Arhopalus ferus (Mulsant) (Coleoptera: Cerambycidae) to ionising radiation: a comparison with existing generic radiation phytosanitary treatments

“…Given the outliers present at doses of 40 to 100 Gy in the third replicate, it is necessary to conduct further replicates in the future to provide greater confidence in the LD estimates presented here. On the basis of the current study, the radiation dose required to sterilise A. ferus adults and eggs is approximately one order of magnitude lower than the generic radiation dose of 400 Gy currently approved by the USDA for all pests (except for lepidopteran pupae and adults) on horticultural commodities (Follett 2009). No results were obtained on the larval stage as experiments were compromised during posttreatment care.…”

“…The development and approval of generic treatment doses for groups of insect pests by the International Atomic Energy Agency and the US Department of Agriculture over the past 10 years have helped to increase both awareness and acceptance of phytosanitary irradiation treatments (Follett 2009;Hallman 2012).…”

“…Lower doses that prevent successful reproduction are adequate to mitigate phytosanitary risks except for pests known to vector plant pathogens (IPPC 2003). The use of a sublethal dose that leaves pests alive but sterile can challenge the traditional method of verifying treatment efficacy, where complete mortality is currently expected (Follett 2009). For example, the generic radiation dose currently approved by the USDA for all pests (except for lepidopteran pupae and adults) on horticultural commodities is 400 Gy (Follett 2009).…”

Use of Radiation and Isotopes in Insects

“…Tephritid fruit flies are one of the most invasive quarantine pests, attacking 21 of the 24 fresh commodities exported to the United States and to sterilize or disrupt normal development of early stages, doses ranging from 70 to 100 Gy are sufficient for Anastrepha species, whilst Bactrocera spp. and other species may require doses in the range of 100 to 150 Gy (Follett, 2009). After fruit flies, tortricid moths are the most important pests of quarantine concern for fruit and vegetables.…”

Lenticel discolouration, under-skin browning and resin canal disorder in Australian mango fruit cultivars

“…M any countries impose strict regulatory and physical barriers to the importation of fruit that are susceptible to infestation by economically important quarantined insect pests (Follett, 2009). …”