Detection of Caribbean fruit fly [Anastrepha suspensa Loew (Diptera: Tephritidae)]-infested grapefruit using portable gas chromatography

New technologies are being sought by plant protection officials to more quickly and efficiently identify concealed pests in imported commodities. The zNose portable gas chromatography unit was investigated as a tool for identifying organic volatile signatures indicative of Caribbean fruit fly infestation in grapefruits. For each of the three larval instar stages, the volatile headspace was sampled from infested fruits, as well as for fruit mechanically damaged at the time of sampling, fruit mechanically damaged at the time of infestation and untreated grapefruit. The means of twenty volatiles were found to show differences between treatments. No volatile clearly identified fruit fly infested fruit all the time. However, several volatiles had higher concentrations for infested fruit compared to the other treatments and their potential for predicting infestation is discussed. Fruits from 8 different sources were also analyzed to determine the stability of the key peaks, and to evaluate the effects of ageing on the grapefruit volatile signature.