The case for a generic phytosanitary irradiation dose of 250 Gy for Lepidoptera eggs and larvae

Abstract

The literature on ionizing irradiation of Lepidoptera is critically examined for a dose that could serve as a generic phytosanitary treatment for all eggs and larvae of that order, which contains many quarantine pests that inhibit trade in fresh agricultural commodities. The measure of efficacy used in deriving this dose is the prevention of emergence of normal-looking adults that are assumed not able to fly. A dose of 250Gy is supported by many studies comprising 34 species in 11 lepidopteran families, including those of significant quarantine importance. Two studies with two different species found that doses >250Gy were necessary, but both of these are contradicted by other studies showing that <250Gy is adequate. There is a lack of large-scale (>10,000 individuals) testing for families other than Tortricidae (the most important quarantine family in the Lepidoptera). Because several large-scale studies have been done with tortricids a dose of 250Gy could be justifiable for Tortricidae if it is not acceptable for the entire Lepidoptera at this time.