An analysis of fruit carried into a quarantine area and an evaluation of infestation rate by Queensland fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)

The risk of new establishments of Queensland fruit fly (Qfly), Bactrocera tryoni, in pest-free areas is linked to the fruit carried by road travellers. However, there is little information on what proportion of carried fruit is infested. Previous studies examined the numbers of fruits carried by travellers but not if the fruits were infested. Here, we report on the results of 989 fruit consignments seized on three main entry roads into the Fruit Fly Exclusion Zone and assessed for infestation. We found 1.01% of consignments were infested with tephritids. However, only 0.2% were infested with sufficient Qfly to potentially result in a new establishment. Within the main fruit groups carried, we detected stone fruit, tomatoes, pome fruit, citrus, bananas and tropical fruit in that order. Based on our data and previously published figures, we estimated that there were 1148 consignments infested with tephritids that entered the zone annually. Additionally, we estimated that 227 vehicles carried Qfly-infested fruit consignments into the quarantine zone annually and each of these had the potential to start a new establishment. Our results will help inform managers of quarantine zones.