Irradiation is a viable quarantine disinfestation treatment which has been studied for 40 years although it has received very little commercial use. Two principal obstacles to commercial application, 1) the fact that insects are not killed immediately, and 2) consumer opposition to irradiation, have been allayed to some extent, but the remaining impediment to large-scale commercial use is development of approved protocols by government regulatory agencies in importing countries. The United States Department of Agriculture has taken the first step by allowing for the movement of a number of quarantined fruits from Hawaii to the rest of the country following irradiation treatment. The measures of efficacy of irradiation disinfestation treatments should be prevention of adult emergence, when only eggs and larvae are present or sterility when pupae or adults are present. This can be accomplished with relatively low doses that are tolerated by many fruits for such pest groups as tephritid fruit flies, curculionid weevils, and some Homoptera. Lepidoptera will require moderately higher doses. The most radiation-tolerant stage is usually the most advanced one present. Female insects are more susceptible to radiation-induced sterility than males; some spider mite (Tetranychidae) females are more tolerant than males. Future research should concentrate on confirming quarantine treatment doses for more insects (this has only been done for several tephritids), arriving at doses for some important groups of organisms for which scant research has been done (Mollusca, Coccoidea, Thysanoptera, Eriophyidae), and identifying and quantifying radiation-modifying factors.
Insecta; Arachnida; gamma radiation; irradiation; postharvest disinfestation
