Detection method for irradiated oriental fruit fly (Dacus Dorsalis) for quarantine purposes

Radiation is one of the techniques used to effectively rid fresh produce of insect pests and efficacy of radiation dose on food is measured by a probit 9 (99.9968% mortality) quarantine security. Present of suitable biochemical markers for irreversible radiation injury in insect pests could be used as convincing proofs of the efficacy of radiation dose. A biochemical marker (designated Gs-protein) for radiation injury in Oriental fruit fly, Dacus dorsalis, was detected in the SDS-PAGE profile of two-day old pupae and adult insect stage. Gs-protein is not observed in larvae and eggs. An apparent molecular weight of 109 kDa was calculated. A tyrosinase enzyme activity was observed in the soluble fraction of pupal total homogenate and SDS-PAGE-isolated Gs-protein; however, no tyrosinase activity was measured in irradiated sample. The optical absorbance of the soluble fraction from unirradiated pupal total homogenate measured at 360 nm was found to increase with time. From the results of the studies, the apparent loss of Gs-protein in irradiated larvae is likely the result of loss of melanization capability in irradiated larvae which is linked to the absence of tyrosinase enzyme. The data presented seems to establish the role of Gs-protein as a biomarker for gamma-irradiation induced deactivation of pupal development and as a convenient indicator of the effectiveness of gamma radiation as a quarantine treatment. (author). 3 refs.; 3 figs