Update on catches of Bactrocera spp. (Tephritidae, Diptera) in Austria

Abstract: Fruit flies of the genus Bactrocera (Diptera: Tephritidae) are among the most serious pests of fresh fruit and vegetables worldwide. In 2011, in the framework of a survey for a nonnative pest species, a specimen of the peach fruit fly (Bactrocera zonata) was unexpectedly caught in a trap in Vienna, Austria. This finding, as well as the frequent reports of introductions of various tropical fruit flies to Europe, gradually increased survey efforts for Bactrocera species (employing Tephri traps with male specific lures) in Austria since 2012. Initially, activities focused on sites in the urban area of Vienna with traps located in allotments/small gardens near fruit markets. From 2016 onwards, sites in other provinces were also sampled with the focus on fruit orchards. Caught tephritids of the genus Bactrocera were identified by morphological and molecular methods (COI barcoding). In addition, sequences of caught individuals were analysed to reveal details about the potential origin of those flies. In total, almost 50 individuals of Bactrocera spp. were exclusively caught in traps in the urban area of Vienna between 2011 and 2023. Next to specimens of the peach fruit fly (B. zonata) also several specimens from the B. dorsalis complex were trapped during this survey. All specimens from this complex were identified as B. dorsalis s.l., except for one specimen that was identified as Bactrocera kandiensis. The result of the irregular trap catches, as well as the harsh winter conditions in Austria, support the theory that the captured fruit flies derived from recurrent introductions – most likely by transport of infested fruits from various non-European origins.