The Case for a Generic Phytosanitary Irradiation Dose of 400 Gy for Lepidoptera That Infest Shipped Commodities as Pupae

Abstract

The pros and cons of a generic phytosanitary irradiation dose against all Lepidoptera pupae on all commodities are discussed. The measure of efficacy is to prevent the F1 generation from hatching (F1 egg hatch) when late pupae are irradiated. More data exist for this measure than for others studied, and it is also commercially tenable (i.e., prevention of adult emergence would require a high dose not tolerated by fresh commodities). The dose required to prevent F1 egg hatch provides a liberal margin of security for various reasons. A point at issue is that correctly irradiated adults could be capable of flight and thus be found in survey traps in importing countries resulting in costly and unnecessary regulatory action. However, this possibility would be rare and should not be a barrier to the adoption of this generic treatment. The literature was thoroughly examined and only studies that could reasonably satisfy criteria of acceptable irradiation and evaluation methodology, proper age of pupae, and adequate presentation of raw data were accepted. Based on studies with 34 species in nine families, we suggest an efficacious dose of 400 Gy. However, large-scale confirmatory testing (> or = 30,000 individuals) has only been reported for one species. A dose as low as 350 Gy might suffice if results of more large-scale studies were available or the measure of efficacy were extended beyond prevention of F1 egg hatch, but data to defend measures of efficacy beyond F1 egg hatch are scarce and more would need to be generated.

Development, Reproduction and Sexual Competitiveness ofConopomorpha sinensis(Lepidoptera: Gracillariidae) Gamma-Irradiated as Pupae and Adults

“…This study also contributed to phytosanitary irradiation (PI) treatments against Lepidoptera that may pupate in shipped commodities. The argument for a generic PI dose of 400 Gy against Lepidoptera by Hallman et al (2013) contains no data from the family Gracillariidae. In this regard, the present study shows that ≥ 200 Gy applied to both sexes of mature pupae of C. sinensis resulted in no hatching of F 1 generation eggs (Fig.…”

Phytosanitary Irradiation

“…A review of literature concluded that 400 Gy would suffice for pupae of Lepidoptera with a measure of efficacy being prevention of hatch of eggs laid by moths emerging from irradiated pupae [19]. This treatment dose was proposed to the International Plant Protection Convention (IPPC) for inclusion in the phytosanitary treatment manual [20], but was rejected for lack of sufficient large-scale tests with tens of thousands of insects.…”

The Potential of Irradiation as a Postharvest Disinfestation Treatment Against <I>Phlyctinus callosus</I> (Coleoptera: Curculionidae)

“…A laboratory colony will also allow further research on the radiation biology of P. callosus and determine the most effective measure of prevention of reproduction. Determining a measure of prevention of reproduction is important in reviewing literature toward the proposal of a generic dose for a group (Hallman et al 2013). Survival of neonate P. callosus larvae that do hatch after treatment with substerilizing dosages should be determined to monitor the development of the F 1 generation.…”